bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of Crop Production Relations and Their Use in Farm Planning
Authors: Barlow C.
Published: October 2008

Although all methods of planning for the maximization of farm profits require knowledge of the basic ‘input-input’ and ‘input-output’ relationships, particularly detailed information is required when using linear programming. Specially designed crop experiments are one major source of such information, but it is important that each experiment should include all major interacting variables, since the response curves estimated from the data, and the relationships extracted from these curves, will otherwise be of little use for determining economic optimum input combinations. Where the matter of interest is the most likely production response, under the planning conditions envisaged, the best available estimate will usually be the average response estimated from a sample of experiments distributed randomly within the conditions. In each experiment of such a sample, the variables being examined should be at the same series of input levels, whilst other variables which are not of interest, but can be controlled, should be held constant at the same general level. With respect to the design of experiments established to generate production relationships, complete factorial and composite or rotatable arrangements are considered to be most suitable, although each of the types has certain disadvantages. Regarding the derivation of ‘input-input’ and ‘input-output’ relationships from the response curve fitted to the data obtained from such experiments, it is felt that this curve should first be ‘scaled down’, to allow both for the more favourable experimental conditions and for losses between the field and the point of use. After this, a number of individual production relationships should be selected, on that portion of the curve expected to be of economic interest. The relationships can then be employed in a linear programming procedure designed to generate a farm plan incorporating that combination of enterprises likely to earn the maximum profit.
Effects of Nitrogen, Phosphate and time of cutting on Green Material and Oil Yields from Geranium (Pelargonium Hybrid) in West Kenya
Authors: Weiss E. A.
Published: October 2008

Since the profitability of the geranium crop depends to a great extent on the total yield of oil per acre, methods of increasing this yield are of prime importance. Two trials were laid down to determine the responses to nitrogen, phosphate and cutting at various times during the year. Phosphate increased total weight of green material, nitrogen had little effect, and neither significantly affected the yield of oil per ton cut. Time of cutting influenced both oil and green material yields. Climatic factors producing higher yields of green material had the opposite effect on yields of oil per ton of material cut, and vice versa. Fertilizers had no discernable effect on oil quality, but there was an appreciable difference between oil produced after wet and dry periods.
Effects of Age on Establishment and Yield of Cocoyam Setts (Xanthosoma Sagittifolium Schott.)
Authors: Enyi B. A. C.
Published: October 2008

The chemical composition of setts of cocoyam (Xanthosoma sagittifolium) varied in different sections. The highest concentration of N, P and fat occurred in the youngest part but crude fibre and Ca were highest in the oldest portions. Dry matter was lowest in the youngest section. Positive linear relations were found between N and K percentage, Ca/P ratio and age of the various sections of the corm, with the highest N/P ratio towards the middle portion of the corm. The high sprouting percentage of the youngest sections of the corm was attributed to both greater bud number per given area and to the short period of their dormancy. Better establishment in the field was achieved by using setts from the oldest section of the corm, probably because they were less vulnerable to decomposition by soil micro-organisms. Positive linear relations were established between P concentration and sprouting percentage. Setts from the two oldest sections of the corm produced plants with the greatest leaf blade area, total dry weight and dry weight of various organs and it is recommended that planting setts should be obtained from the less succulent section of the corm. There were also positive linear relations between Ca concentration of setts and dry matter production in the field, and between leaf blade area at time of harvest and corm yield.
Evaluation of Fungicides for Use against Marasmius Palmivorus On Oil Palms
Authors: Turner P. D.
Published: October 2008

On some estates in Malaya the incidence of Marasmius bunch rot reaches serious proportions through causes other than poor sanitation or pollination. In such areas fungicidal sprays may be of value in both therapy and prophylaxis. In laboratory tests, using the paper disc diffusion and liquid culture methods, 32 fungicides were tested for activity against Marasmius palmivorus to provide an indication of promising formulations for field trials. A number of compounds showed strong inhibition of fungal growth in both series of tests, and amongst these the organo-mercury preparations were outstanding, especially Antimucin WBR. Other promising fungicides included Fylomac 90, Seprisan, Hyamine, Izal, Thiram and PCNB. In field trials in which Antimucin WBR and Verdasan were used for treatment of partially-infected immature bunches, these fungicides checked disease development, with a significant reduction in losses through disease. The value of fungicidal sprays formerly recommended in estate practice, and their potential value in prophylaxis, are discussed.
Effect of Temperature and Photoperiod on Bulbing of the Common Onion (Allium Cepa L.) Under Arid Tropical Conditions of the Sudan
Authors: Abdalla Abdalla A.
Published: October 2008

Under the arid tropical conditions of the Sudan, where seasonal variations in photoperiod are small but where temperatures are high, there is evidence from the performance of both local and introduced onion varieties that temperature has considerable influence on bulbing. The onset of bulbing does not prohibit the emergence of bladed leaves under such high temperature conditions. The size of the onion plant may be an important factor in the bulbing response under conditions of high temperature and small variations in photoperiod.
Summer Cropping Groundnuts in North Bihar
Authors: Thakur C. , Chowdhury S. K.
Published: October 2008

A field experiment was conducted to see if a successful crop of groundnuts can be raised in North Bihar (India) during summer in rotation with paddy. The experiment was designed to find a suitable variety, and the best time of sowing and digging. Three promising varieties of groundnut, one early-bunch and two late-spreading types, were included in the test. Emergence and flowering were rapid in the early-bunch variety as compared to the two late-spreading varieties. Though flowering was less in the bunch variety, the percentage of mature kernels was higher. The earlier the sowing and the later the digging, the greater was the pod yield in all cases. On the basis of these results and other practical considerations, the best combination seems to be to sow the early variety AK 12-24A about 15 January and to dig about 22 June.
Effects of Shade on the Structure and Chlorophyll Content of Arabica Coffee Leaves
Authors: Hollies M. A.
Published: October 2008

Leaves of Coffea arabica L. were sampled from an artificial shade trial to examine the effects of two levels of shade, compared with full exposure, on size, structure and chlorophyll content. A grid was designed for the rapid measurement of leaf areas in the field, and individual leaf areas were found to increase progressively with shading. Since dry weight per leaf was not affected, an increase in specific leaf area was entailed. Leaf size varied greatly with season of formation, a wider range occurring in selection N39 than KP162, but the reasons for the variation were not clear. Neither lamina thickness nor proportion of palisade tissue varied with shade treatment. Chlorophyll per unit weight increased with shade in KP162 but with N39 was only greater under dense shade. Chlorophyll per unit area did not alter with shade, but N39 had significantly more chlorophyll than KP162 on both a weight and an area basis.
Premature Death of Groundnut Plants in Northern Nigeria
Authors: Perry D. A.
Published: October 2008

Premature wilting and death of groundnut plants in Northern Nigeria was caused mainly by termites excavating the xylem tissue of the root. Lepidopterous larvae which damaged the crown of the plant were a less common cause. Occasional wilted plants had discoloured vascular systems from which Pythium myriotylum was consistently isolated. Wilting was also caused by mechanical damage inflicted during weeding operations. Complete severance or blockage of the water-conducting tissue of the primary root did not result in immediate death of plants, because the pods and pegs were able to absorb sufficient moisture to maintain the leaves above permanent wilting point until the onset of the dry season.
Effects of Lindane and Carbaryl on Insects, Soil and Plant Nitrogen, and Grain Yield of Rice
Authors: de Datta S. K. , Ayyangar R. S. , Magbanua J. T.
Published: October 2008

Experiments were conducted during three crop seasons to determine the effects of lindane and carbary1, applied to the irrigation water or incorporated in the soil, on the control of insects, on the nitrogen status of the soil and plant, and on grain yield of lowland rice. In two crop seasons the highest grain yield was obtained from three applications of lindane to the irrigation water and carbaryl sprays at 7- to 10-day intervals, and in the third season from 20 kg/ha. carbaryl incorporated in the soil without any lindane treatment or carbaryl spray. In two seasons, soil-incorporated carbaryl at 20 kg/ha. active ingredient gave a significantly higher yield than the no-insecticide control, and in one season the increase in grain yield was just below the significant level. Most of the grain yield increase with 20 kg/ha. carbaryl incorporated into the soil was caused by better control of stem borer and leafhopper and a significant reduction in virus infection.
The Races of Sorghum in Nigeria: their Distribution and Relative Importance
Authors: Curtis D. L.
Published: October 2008

Sorghum is the principal foodcrop grown in Northern Nigeria. A survey of local varieties grown during the rains was carried out in 1958 and the 821 samples collected were assigned to seven morphologically distinct races, of which four are important. Varieties belonging to the Guinea race, with loose, open panicles, are mainly cultivated in high rainfall areas south of latitude 11°30′N. Further north, three races, Kaura, Farafara and Chad are grown in the dry Sudan Savanna zone. Varieties of these races have compact panicles and bulging grains. Estimates of the contribution made by each of the four major races indicate that the Guinea race accounts for nearly 50 per cent of the total sorghum production in Northern Nigeria.
Tolerance of Three Olive Varieties to Soil Salinity in Israel
Authors: Bidner-Barhava Nehama , Ramati B.
Published: October 2008

An investigation was undertaken on the relative tolerance to salinity of the olive varieties Manzanillo, Souri and Sigoise in the arid zone of Israel (Negev), in an experimental grove of the Jewish National Fund, using 11-year-old trees that were grown on saline and non-saline soils under irrigation with sewage water. Manzanillo was the most sensitive to salinity, yields and development of trunk, crown and root system all being adversely affected. Sigoise was the most tolerant to salinity and vegetative development was not impaired at all. Souri was intermediate in sensitivity to salinity. In spite of the susceptibility of Manzanillo it is preferred because of its high yield, which was greater even on a saline soil than yields of the other two varieties on non-saline soil.
Nitrogen Fixing Capacity of some Nigerian Legumes
Authors: Oke O. L.
Published: October 2008

The fixation of nitrogen in root nodules of pigeon pea, Centrosema pubescens and Styloxanthes gracilis were studied, and the transfer of nitrogen to other parts of the plant. Fixation reached a maximum of 14·5, 10·3 and 4·6 mg. per day per plant respectively, and the rate of transfer of nitrogen from the nodules was at a high constant rate throughout the experimental period. With pigeon pea and Centrosema younger plants seem to be more efficient fixers of nitrogen than older on, but the reverse was true with Styloxanthes.
Comparisons Between Strains of Eragrostis Curvula in South Africa
Authors: Leigh J. H.
Published: October 2008

Twenty strains of Eragrostis curvula, together with E. plana, Chloris gayana and Digitaria smutsii, have been compared on the basis of (a) herbage yields and (b) nitrogen, phosphate and potash composition and yield, from broadcast stands in a randomized block experiment over two seasons. The strains of E. curvula were grouped into types for which the names Curvula, Robusta Blue, Robusta Green, Robusta Intermediate, and Chloromelas were used. Significant differences were demonstrated in herbage yield between certain of these types, but there were no clear differences in nitrogen content. Chloris, Digitaria and the three Robusta types had the highest phosphate and potash content, whereas the Chloromelas type and E. plana were intermediate and the Curvula type was lowest in these constituents. Robusta Green, Robusta Intermediate and Curvula types had the highest nitrogen yield, Robusta Green and Robusta Intermediate types the highest phosphate yield, and Robusta Intermediate and Robusta types the highest yield of potash. The superiority of types other than Curvula (Ermelo and Tanganyika strains), and the need for research on the types, has been demonstrated.
A Computer Programme for the Calculation of Confidence Limits of Expected Rainfall
Authors: Walker J. T. , Rijks D. A.
Published: October 2008

Essential features are described of a computer programme, written in F.A.S., for the evaluation of 1 : 1 and 4 : 1 confidence limits of expected ‘twenty-day’ totals of rainfall. The paper deals briefly with the availability and utility of the programme to agricultural research workers in Africa.
Problems in Plant Pathology and Entomology Field Trials
Authors: Freeman G. H.
Published: October 2008

The problems arising in field trials in plant pathology and entomology are considered under five headings: (1) experimental design, (2) conduct of experiments, (3) records, (4) analysis and (5) interpretation. Solutions to the problems are not always given, but it is useful to recognize their existence. Examples are given from a wide range of crops
Chemical Weed Control in Tropical Root and Vegetable Crops
Authors: Kasasian L.
Published: October 2008

Chemical weed control in six root crops and fourteen vegetable crops, commonly grown in the tropics, is reviewed.
Calculating the Weight of Young Coffee Trees from Non-Destructive Observations
Authors: Wormer T. M. , Ngugi D.
Published: October 2008

The weights of the branches, stems and roots of two or three year oldarabicacoffee trees were compared with the diameters of the stumps or stems and with the heights of the trees. No formula could be derived, relating the weight of the plants to one or more non-destructive observations, which was valid for all three treatments to which the trees had been subjected, i.e. stripped of crop when two years old, cropping when two years old, and bearing a crop when three years old. Bearing a crop when two years old resulted in thin, light stems and a poor root system.
Flowering, Pollination and Pod Formation in Bambara Groundnut (Voandzeia Subterranea) in Ghana
Authors: Doku E. V.
Published: October 2008

Although bambara groundnut (Voandzeia subterranea) is an important pulse crop in Africa and particularly in Ghana, information on the crop is not only very limited but conflicting, especially as regards flowering and mode of pollination. Both self- and cross-pollination can take place in varying degrees, depending on variety or strain, and this is brought about by two species of ants, Pheidole megacephala and Monomorium pharaonis, without which pollination might be severely limited or prevented altogether. The extent of cross pollination may be greater in varieties or strains with a more open habit, i.e.. varieties resembling the wild uncultivated ancestors, whereas the bunch cultivated types are more likely to be self-pollinated. It is suggested that varieties or strains may show differences in their ability to cross with one another.
Effects of Nitrogen and Spacing on Castor Bean in Sandy Soils in Egypt
Authors: El-Hamidi A. , Moursi M. A. , Ahmed S. S.
Published: October 2008

Castor beans grew well in sandy soils in U.A.R. where field crops had previously failed to produce good yields. Calcium nitrate up to 300 kg. per feddan resulted in increased yields of seeds and oil in a two-year experiment. Better yields were obtained by increasing the number of plants up to 3 per hill at distances of 45 cm. apart. The oil percentage and other properties were not influenced by nitrogen fertilizers or plant density.
Long Term Experiments with Fertilizers and Manures on Sugarcane in India
Authors: Singh Ambika , Roysharma R. P.
Published: October 2008

The yield and soil data are presented of four long-term experiments on sugarcane at Muzaffarnagar (Uttar Pradesh), Anakapalle (Andhra Pradesh), Padegaon (Maharashtra) and Shahjahanpur (Uttar Pradesh). On soils where phosphorus and potash were not limiting, application of ammonium sulphate over 14 years at Muzaffarnagar and Anakapalle gave higher yields than those obtained by application of farmyard manure, and the fertility status of ammonium sulphate plots was in no way inferior to plots treated with farmyard manure. When phosphorus was also limiting, the application of a basal dose of compost on black cotton soil maintained yield levels. There was a steady decline in yields of cane in plots which received a dressing of ammonium sulphate without any basal dose of compost, but when N.P.K. equivalent to the compost were added the yields were equal to those from plots receiving compost. Thus the effect of compost is explanable on its nutrient content rather than on its effect on physical properties of the soil. In Shahjahanpur there was a decrease in cane yield as the experiment progressed, but the decline in yield in ammonium sulphate treated plots was of the same magnitude as from the plots receiving no dressing of ammonium sulphate. By changing the cane variety and the rotation simultaneously, the yield from all plots went up but subsequently showed a declining tendency.
Responses of Grasses and Legumes to Fertilizer Treatments in Nigeria
Authors: Tewari G. P.
Published: October 2008

A two-year field investigation was conducted to evaluate the response of two varieties of Guinea grass and two leguminous species, grown alone and in mixtures, to fertilizer treatments. Styloxanthes gracilis and a Guinea grass variety ‘Liconi’ were observed to be superior to others in their yielding ability. Styloxanthes and the Liconi Guinea grass appeared to be mutually compatible at particular seeding rates. Sabi Guinea grass and Centrosema pubescens were the poorest performers under all conditions. Findings also suggested that the adapted and mutually-compatible legumes and grasses could be grown in mixture under tropical conditions, and high yields obtained without the use of expensive nitrogenous fertilizers.
Growth Analysis of Perennial Grasses in Tropical India I. Herbage Growth in Pure Grass Swards
Authors: Singh R. D. , Chatterjee B. N.
Published: October 2008

Herbage production from twelve perennial grasses was analysed under two frequencies of defoliation. There were differences in the speed of establishment from seed, Heteropogon contortus, Pennisetum pedicellatum and P. polystachyon being most rapid. Once the grasses were established, the highest yields were obtained from Andropogon gayanus and Brachiaria brizantha and the lowest from Paspalum notatum. Yields were higher at the lower frequency of cutting. There were large differences in production throughout each year, with yields during winter and the dry season (November to April) only about one-tenth of those obtained in the rainy season. A. gayanus, B. brizantha, Chloris gayana and Dichanthium caricosum gave higher yields than other species during winter. Variations in yield between species could generally be ascribed to variations in the extension of leaf area, although some species maintained high net assimilation rates during unfavourable growth periods.
Growth Analysis of Perennial Grasses in Tropical India II. Herbage Growth in Mixed Grass/Legume Swards
Authors: Singh R. D. , Chatterjee B. N.
Published: October 2008

The perennial grass Pennisetum polystachyon was grown alone or in mixture with the indigenous legumes Atylosia scarabaeoidesand Clitoria ternata and the exotic species Calopogonium mucunoides, Centrosema pubescens and Stylosanthes gracilis. Only the last two persisted for more than one or two years. Mean annual yield from the mixture containing Centrosema was 61 to 65 q./ha., of which 20 per cent was legume herbage. The protein content of grass was about 3 to 6 per cent and of legumes 10 to 14 per cent. Mixed swards produced as much protein as in a previous experiment where pure swards of Pennisetum polystachyon received 44. kg./ha. of nitrogen in fertilizer form. Soil nitrogen increased under the Centrosema mixture and yields from the mixture increased during the experiment. Yields of grass herbage from the mixtures were generally lower than those of the grass swards. The reduction in yield of grass grown in mixed swards was mostly due to decreases in the area of foliage rather than to reductions in net assimilation rate.
Agronomic Aspects of Broad Beans (Vicia Faba L.) Grown in the Sudan
Authors: El Saeed E. A. K.
Published: October 2008

Field experiments in three successive growing seasons (1963–66) studied effects of variety and plant density on yield components of broad beans. In 1963/64 total seed yield of a local variety (Beladi), increased with increasing seed rates from 70 to 280 lb per feddan, but yield increment diminished beyond 140 lb. The same results were obtained with Beladi and Rebaya 34 in 1964/65 and 1965/66, but Rebaya 34, yielded less than Beladi at all seed rates. Growth analysis revealed that Rebaya 34 had greater growth rate at the beginning of the season, due to its relatively large seed size, but eventually Beladi overtook it. Maximum pod growth in both varieties occurred when leaf dry weight was declining. The proportion of dry matter was greater in pods of Beladi than Rebaya 34 because of more sinks in the former variety. The present seed rate of 70 lb per feddan seems to be suboptimal and factors affecting establishment and/or effective leaf area at the time of pod growth are detrimental to the final yield.
Studies on the Nutrient Status of Some Coconut Soils in Ceylon 10. Minor Soil Series and Conditions in the Chilaw District
Authors: Santhirasegaram K.
Published: October 2008

The results are reported of pot experiments, using indicator plants, on the nutrient status of three soils varying in fertilizer history. All soils were deficient in nitrogen, and in the absence of added nitrogen yield of grass was below 10 per cent of the potential. All forms of nitrogenous fertilizers were equally effective. All soils showed an acute deficiency of phosphorus at the early stages of the experiments, but with time, and depending on the amount of fertilizer applied in the past, the response to phosphorus decreased. There was little or no response to potassium at the early stages of the experiments, but relative yields later fell linearly with time. Calcium was necessary in small quantities as Ca(OH)2, CaCO3 to correct soil acidity, particularly for legume growth. Magnesium increased yields at the latter stages of the experiments. Sulphur was deficient in all soils. The soils had adequate amounts of the minor nutrients. A cheap and quick technique was used with simple and factorial designs to obtain preliminary information, as a guide to planning detailed field experiments on the nutrient requirements of perennial crops like coconuts and other intercrops.
Potential Productivity of Tropical Perennial Crops
Authors: Corley R. H. V.
Published: October 2008

Large yields and dry matter production rates have been recorded for tropical perennial crops, despite the fact that little research has been done on most of them. Considerable increases in productivity should still be possible, since the potential energy fixation rate for such crops is estimated to be about 1.2 TJ ha−1a−1. The dry matter equivalent of this energy varies between species; the oil crops and rubber, in particular, have large energy contents in their respective economic products. Hot leaf temperatures appear to limit productivity in some crops, while unfavourable partitioning of assimilates limits yield at the large leaf area indices necessary to maximize dry matter production. Respiratory losses are large in these crops and selection for smaller respiration rates could lead to considerable improvements in their net productivity.
Effect of Rhizobium Numbers on Nodulation and Dinitrogen Fixation in Groundnut
Authors: Nambiar P. T. C. , Ravishankar H. N. , Dart P. J.
Published: October 2008

Glasshouse studies have shown that nodulation and dinitrogen fixation in groundnuts grown in a sand/vermiculite mixture increased with an increase in Rhizobium numbers inoculated onto each seed. Cultivars Robut 33-1 and TMV 2 required 106 rhizobia seed−1 for maximum nodulation and dinitrogen fixation, while cv. Kadiri 71-1 required larger numbers.
Nutrient Uptake by Intercropped Maize and Cowpeas and a Concept of Nutrient Supplementation Index (NSI)
Authors: Wahua T. A. T.
Published: October 2008

Accumulation curves for N, P, K and Ca were determined for intercropped maize and cowpeas given different fertilizer combinations. Both species competed for these four elements, with cowpeas suffering relatively more than maize. A concept of a Nutrient Supplementation Index (NSI) was developed to aid studies on fertilization of crop mixtures. Using this index, it was estimated that an additional 9.7, 24.0, 9.7 and 30.6% of N, P, K and Ca, respectively (based on the requirement of sole-crop maize), might be needed to satisfy the combined needs of a 1:1 row maize–cowpea intercrop.
Effect of Soil Crusting on Seedling Growth in Contrasting Sorghum Lines
Authors: Soman P. , Jayachandran R. , Peacock J. M.
Published: October 2008

Seedling growth from sowing to emergence of two crust tolerant and two susceptible sorghum genotypes is described. Tolerant genotypes had longer mesocotyls with faster growth rates than the susceptible genotypes. The mechanism involved in crust tolerance appears to be that of avoidance by fast growth.
Site-factor Influence on Barley Response to Fertilizer in On-farm Trials in Northern Syria: Descriptive and Predictive Models
Authors: Jones M. J. , Wahbi A.
Published: October 2008

The effects of site and rate of application of fertilizer on the grain and straw production of barley were investigated in 75 trials on representative farmers' fields. Grain and straw production were strongly but curvilinearly correlated with growth-period rainfall over the range 136–568 mm, almost irrespective of soil type, previous crop or fertilizer rate, and responded positively to applied nitrogen and/or phosphorus in 74 of the trials. Responses to nitrogen increased and those to phosphorus decreased with increasing rainfall. Yields tended to be lower but responses to nitrogen were higher where barley followed barley and were influenced by the availability of phosphate and mineral nitrogen in the soil at planting time.

These results are summarized in regression equations, which express yield quadratically in terms of fertilizer rates, seasonal rainfall and their interactions over the full 75-trial data set and within representative sub-sets. The wide differences in crop response to fertilizer highlight the problem of recommending fertilizer rates for a low and variable rainfall environment. Simple second-order multiple regressions for different geographical areas, rainfall zones, crop rotations etc., based on mean rainfall values, account for around 40% of the variance in yield response to nitrogen and phosphorus fertilizer; only a small proportion of the remaining variance appears attributable to rainfall variability. Alternatively, yield may be expressed as a function of fertilizer rate and rainfall using rainfall probability values derived from long-term records. This can be used to estimate the probabilities of predetermined yield responses for specified sites and fertilizer rates and to produce maps of those probabilities.
Plant Genetic Resources and Plant Improvement as Tools to Develop Sustainable Agriculture
Authors: Ceccarelli S. , Valkoun J. , Erskine W. , Weigand S. , Miller R. , Van Leur J. A. G.
Published: October 2008

This paper addresses the current and future contributions of plant genetic resources and plant improvement to sustainable agriculture with reference to the activities of the International Center for Agricultural Research in the Dry Areas (ICARDA) in association with national programmes in West Asia and North Africa. These regions constitute the primary centres of diversity of crops such as wheat, barley, chickpea and lentil. Genetic erosion is being curtailed by germplasm collection and preservation. Selection for low-input cultivars of barley is conducted under low input conditions, and new cultivars of lentil and barley are often intentionally heterogeneous to stabilize their performance in dry rainfed areas. The importance of genetic differences in the cultivars on subsequent crops in the rotation and on straw quality for livestock is under study. Insect pests and diseases contribute to yield instability. Because of the potential adverse impact of pesticides on the fragile ecosystems of the region, integrated control strategies based on agronomic management, host plant resistance, biological control agents and strategic use of selective insecticides are being developed.
Fruiting Activity, Growth and Yield of Oil Palm. I. Effects of Fruit Removal
Authors: Corley R. H. V. , Breure C. J.
Published: October 2008

The relation between current yield and future yield components in the oil palm (Elaeis guineensis Jacq.) was investigated by removing a proportion of inflorescences before anthesis. This disbudding caused mean fruit bunch weight to increase by over 60%, with corresponding increases in the components of bunch weight. The total number of inflorescences produced increased by 10%, the sex ratio increased from 72 to 91% females, and inflorescence abortion and bunch failure rates were halved. As a result, the number of bunches harvested was reduced by less than the level of disbudding, and removal of 75% of inflorescences only reduced yield by 42%. Disbudded palms also grew more vigorously. The time intervals between a change in the level of fruiting activity and the resulting changes in yield components were determined by recording the yield components during the period after disbudding was stopped.
Fruiting Activity, Growth and Yield of Oil Palm. II. Observations in Untreated Populations
Authors: Breure C. J. , Corley R. H. V.
Published: October 2008

The extent to which the number and weight components of oil palm fruit yield are affected by the total weight of fruit bunches on the palm (fruiting activity) was investigated by multiple regression analysis, with plant available water and sunshine hours as additional covariates. Fruiting activity significantly increased the percentage of aborted inflorescences six months after leaf opening, and reduced the ratio of female to total inflorescences (sex ratio) seven to eight months prior to leaf opening. Mean weight of bunches was negatively affected by fruiting activity ten to eleven months before harvest, the number of flowers per spikelet and the mean single fruit weight being the only components to show a clear response. Fruiting activity significantly reduced the petiole cross sectional area of leaves six months before opening.

Simulation models for oil palm yield forecasting must take account of the endogenous yield cycles resulting from these effects of fruiting activity.
Changing Concepts in Crop Plant Evolution
Authors: Hutchinson Sir Joseph
Published: October 2008

Evolutionary studies in the cottons began with the demonstration by Harland that true cottons could be divided into four genetically distinct species, each carrying an internally balanced genotype that was disrupted in crosses with any other. Harland's genetic classification has stood the test of time, and contributes substantially to our understanding of speciation in other genera, as for example,Phaseolus. In addition, it provides a genetic basis for the observations described by Anderson as ‘introgression’.

Studies of cottons found growing wild, and of their relationship to cultivars in the same areas, led to the hypothesis that all true cottons are cultivars, and those now found wild are escapes. This hypothesis, though it led to purposeful exploration of the distribution and relationships of the cottons, was found to be inadequate. A new approach to the relationships of the cottons became possible following Thoday's demonstration of ‘disruptive selection’ inDrosophila. The disruptive situation has been shown to obtain as between cultivars and their wild relatives inSorghumand in a number of other crop plants.

Consideration of the time scale of agricultural evolution makes it clear that the recent origin theory is untenable, and a review of the status of the ‘wild’ cottons shows that they are adequately accounted for as weedy relatives of the cultivars, descended from common wild ancestors under disruptive selection.

It is concluded that crop plant evolution has gone on very largely within the balanced gene pools which Harland regarded as genetic species.
Effects of Soil Moisture Stress on Two Varieties of Upland Cotton in Israel. III. The Bet-She'an Valley
Authors: Marani A. , Amirav A.
Published: October 2008

The effects of moisture stress during various stages of the development of two varieties of upland cotton (Acala 4–42 and Deltapine Smoothleaf) were studied in two irrigation experiments in the Bet-She'an valley, where summer temperatures were high and evapotranspiration in the fully irrigated treatments was up to 8–10 mm./day in July and August. Optimum time for first irrigation in the Bet-She'an valley was two or three weeks before flowering and six or seven irrigations, if timed to prevent moisture stress, were sufficient to give high yields and good lint quality. Lint yield ranged from 270 kg./ha. in non-irrigated to 2000 kg./ha. in the fully irrigated treatments in 1966.
The Incidence of Climatic Conditions Favourable to Coffee Berry Disease in Kenya
Authors: Waller J. M.
Published: October 2008

Climatic conditions affecting the development of CBD are assessed by measuring wetness within the tree canopy and air temperature. Saturation of the tree canopy, necessary for spore dispersal, occurs most frequently at the tops of trees and the duration of wetness permitting spore germination is most prolonged at night. Night air temperatures are closest to berry temperatures and are important in assessing infection periods. Disease development in 1968 and 1969 was related to the number of infection periods during the growing season. Polythene tree covers which kept trees sufficiently dry to stop disease development were used in determining infection at different times of the year.
Effects of Fertilizing and Other Factors on Yams in Barbados
Authors: Gooding E. G. B.
Published: October 2008

In 1968–9 and 1970–1 small-scale experiments were set up on over a hundred farms in Barbados, simple enough for farmers to carry out with a minimum of supervision. Results were obtained from more than 70 in each year. NK fertilizing gave no increase in yield in 1968–9, but a significant increase of 800 lb per acre in 1969–70. In each year NPK gave a highly significant increase of 1000 lb per acre. There was also a general increase in yield with increasing rainfall up to about 40 inches during the growing season and with closer than normal spacing especially under conditions of low rainfall. Planting later than usual led to marked decreases in yield.
Early Results from a Trial of Upper Amazon Cocoa Clones in Ghana
Authors: Lockwood G.
Published: October 2008

Yields in a trial of Upper Amazon clones, derived from high yielding Upper Amazon selections, were low in the early years. One Upper Amazon clone was significantly higher yielding than any other clone, but generally yields from the Upper Amazons were comparable to those of Local Trinitario selections included as controls. The Upper Amazon clones were highly variable in establishment, yield and losses from diseases. The relationship between the performance of some of the clones and their parent seedlings is discussed.
Leguminous Cover Crops for Maintaining Soil Fertility in Sisal in Tanzania II. Effects on Moisture Status of Soil and Sisal
Authors: Hopkinson D.
Published: October 2008

The effect of covers of controlled volunteer vegetation, Pueraria phaseoloides, and clean weeding on the soil moisture content and on the succulence of sisal leaves was studied. The surface soil tended to dry out further when exposed by clean weeding, but moisture in the profile as a whole was not much depleted. The plant covers dried soils to at least 300 cm. in dry periods. Although sisal leaves had a slightly higher dry matter content in dry weather there was no evidence of competition for water between the plant covers and the sisal.
Nitrogen Mineralization in West Indian Soils
Authors: Cornforth I. S.
Published: October 2008

Soil properties influencing N mineralization, and hence the potential N-supplying power of 154 West Indian soils, have been studied. Mineralizable N was correlated with the activity of the soil biomass measured as extractable glucose, with exchangeable bases in base-deficient soils and with total N in soils well supplied with bases, but not with other estimates of the nature of soil organic matter (e.g. extractable chlorophyll or C : N ratio). It is suggested that cation exchange capacity and percentage base saturation may influence the N-supplying power of West Indian soils more than their total N content.
A Method for Studying the Distribution of Absorbing Roots of Fruit Trees
Authors: Weller F.
Published: October 2008

A method is described for studying the distribution of absorbing roots of fruit trees using the number of light root tips per unit of soil space as a criterion for characterizing the spatial distribution of the absorbing parts of the root systems. As examples of the use of this method, some results are shown from investigations with apple trees in South-Western Germany. They demonstrate the influence of soil-type and soil management on the distribution of absorbing roots. Striking temporal variations in the number of root tips were observed in the same tree.
Yield and Plant Development of Reduced Cotton Stands in Malawi
Authors: Matthews G. A. , Rowell J. G. , Beeden P.
Published: October 2008

Yield response to a range of plant densities (0·7–7·2 plants m.−2) achieved by uprooting plants at random was curvilinear, with an optimum plant density of 3·3 plants m.−2 at which fertilizer increased the yield at Makoka by over 1000 kg. ha.−1 to 2227 kg. ha.−1. There was no interaction between fertilizer and plant density. At Ngabu there was no response to fertilizer. Top dressing was effective on unfertilized cotton at Makoka, but filling in was ineffective at both sites. A method of partitioning components of yield is described which illustrates the stages of plant development which benefitted or were adversely affected by the different agronomic practices.
Seed Rate, Time of Thinning and Weeding of Cotton in Malawi
Authors: Matthews G. A. , Beeden P.
Published: October 2008

Experiments on seed rate, time of weeding and thinning confirmed that lower seed rates, weeded and thinned early, give higher yields. A reduction in yield of 400 kg.ha.−1 seed cotton caused by late weeding emphasized that farmers who spray should limit their acreage to that which can be weeded satisfactorily.
Oil, Protein and Dry Matter Development in Sesame Seed
Authors: Khidir M. O. , Khattab A. H.
Published: October 2008

A three-year study on the development of oil, protein and dry matter in sesame seeds showed that oil percentage increased rapidly 11–17 days after fertilization, reaching a maximum in 20–23 days. There was no change in the iodine value of the oil after 18 days from fertilization. Accumulation of protein was more gradual, but there was no appreciable increase after the ‘seeds’ were 27 days old. Dry matter increased more slowly than either oil or protein and there was little increase after the ‘seeds’ were 34 days old. The implications of these findings on problems of harvesting the crop are discussed.
Effects of Artificial Defoliation (Simulating Pest Damage) on Varieties of Upland Rice
Authors: Taylor W. E.
Published: October 2008

Artificial defoliation was used to simulate grazing by cutting-grass or cane-rat (Thryonomys swinderianus), on three rices with durations of 110–115, 130–135 and 140–145 days respectively, defoliated before, during and soon after tillering by removing leaves to half, two-thirds and the total height of the plants. All varieties showed marked compensatory growth, resulting in increased tillering and yield, especially when defoliated during tillering, but yield fell when foliage was removed after tillering, especially with shorter duration rice. Defoliation to half the height of the plant during tillering had the most beneficial effect, whereas removal of all leaves to soil level after the tillering stage had the most adverse effect.
Soil Temperature and Leaf Expansion in Zea mays
Authors: Watts W. R.
Published: October 2008

Maize plants (Sweetcorn cv. Earliking) were grown in plots where four types of soil surface coverings were used to induce soil temperature differences During the vegetative stage of growth measurements were made of total leaf area per plant on a daily basis, and relative rates of leaf area increase were found to be closely correlated with mean daily soil temperatures at 5 cm. depth. The results were consistent with evidence that the temperature of the apical meristem strongly influences rates of leaf expansion in maize seedlings.
Uptake of Sulphur and other Nutrients by Groundnuts (Arachis hypogaea) in Northern Nigeria
Authors: Bromfield A. R.
Published: October 2008

The uptake of S followed a similar pattern to dry-matter production by groundnuts given enough fertilizer-S to prevent S-deficiency. The fastest rate at which dry matter was produced was 140 kg./ha./day. Of the 6857 kg./ha. at harvest, 3401 were in haulm, 967 in shells and 2489 in kernels. S was taken up fastest during the eighth week, when the daily average was 0·22 kg./ha.; at harvest, of the 11·6 kg./ha. in the plants, 5·4 was in the haulm, 0·8 in shells and 5·4 in the kernels. Of the 157 kg. N/ha. in the harvested crop 62 per cent was in shells and kernels and of the 13·5 kg. P/ha., 64 per cent was in shells and kernels.
Effects of Clone and Irrigation on the Stomatal Conductance and Photosynthetic Rate of Tea (Camellia sinensis)
Authors: Smith B. Gail , Burgess Paul J. , Carr M. K. V.
Published: October 2008

Stomatal conductances (g) and photosynthetic rates (A) were monitored in six tea clones planted in a clone X irrigation experiment in the Southern Highlands of Tanzania. Measurements were made during the warm dry seasons of 1989 and 1990. There was no genotype X treatment interaction in the response in A or g of the various clones to irrigation. Irrigation increased A more than it increased g. Irrigation also increased the temperature optimum for photosynthesis and decreased photo-inhibition at high illuminance. Clones differed in g and A, and in the relationship between leaf temperature and A. The implications of these findings for clone selection are discussed.
Towards the Reliable Prediction of Time to Flowering in Six Annual Crops. IV. Cultivated and Wild Mung Bean
Authors: Ellis R. H. , Lawn R. J. , Summerfield R. J. , Qi A. , Roberts E. H. , Chay P. M. , Brouwer J. B. , Rose J. L. , Yeates S. J. , Sandover S.
Published: October 2008

Eight genotypes of cultivated mung bean, black gram and rice bean (Vigna mungo, Vigna radiatassp.radiataandVigna umbellata, respectively) were sown at six sites in Australia on various dates in order to provide a range of photothermal environments. In addition, four accessions of the related wild speciesVigna radiatassp.sublobatawere sown on five occasions. Times from sowing to first flowering (f) varied between environments from 34 to 317 d; pre-flowering temperature and photoperiod means ranged from 12.7° to 29.1°C and from 11.8 to 15.5 h d−1. No effect of photoperiod was detected on rate of progress towards first flowering (1/f) in four genotypes, but in each case a significant positive relation was detected between 1/fand mean temperature. These simple thermal time relations did not differ significantly among these four genotypes; the common base temperature was 7.9°C. In two genotypes observations were well described by a thermal response plane when the mean photoperiod was less than 13 h d−1(p < 0.01) but photoperiods greater than 14 h d−1delayed flowering. In each of the remaining genotypes the observations were best described by photothermal planes, that is, 1/fwas modulated by temperature and photoperiod. Predictions from the models based on our data were in good agreement with the times to first flowering observed in three genotypes in an earlier controlled environment study.
Evaluation of Stored Maize Losses in Cameroon
Authors: Mchugh Dermot
Published: October 2008

Farmer surveys have consistently shown maize storage losses to be of primary concern to farmers in the western highlands of Cameroon. Past attempts at evaluating these losses, however, have proved to be unsatisfactory, mainly because of failure to consider qualitative, as well as quantitative, losses or to take account of consumption patterns (that is, timing and end use). A simulation model is presented that overcomes these deficiencies while providing a reliable estimate of the economic value of storage losses to the farmer, albeit at the cost of requiring fairly exacting data. The model is used to estimate the value of storage losses to farmers in the North West Province of Cameroon.
Yield Performance of Yam Bean in Tonga, South Pacific
Authors: Grum M. , Halafihi M. , Stölen O. , Sørensen M.
Published: October 2008

Twenty one accessions of yam bean (PachyrhizusRich. ex DC.) were tested in yield trials under short day conditions in Tonga, South Pacific. Fresh weight tuber yields ranged from 5.3 to 72.0 t ha−1, dry matter content from 8.0 to 20.8% and dry matter yields from 1.20 to 8.57 t ha−1. Crude protein content of peeled tubers varied between 5.1 and 9.8% of dry matter, yielding 71–540 kg ha−1of crude protein. Varietal variation in leaf defoliation by the rose beetle,Adoretus versutusHar., was noted.
Low Input Technology Options for Millet-based Cropping Systems in the Sahel
Authors: Klaij M. C. , Renard C. , Reddy K. C.
Published: October 2008

Pearl millet is a staple cereal cultivated mainly by subsistence farmers on 14 million ha of the West African semi-arid tropics. Increasing pressure on the land has reduced the length of the fallow periods, which are necessary to restore soil fertility, resulting in declining yields. To investigate ways of reversing this decline, three systems combining phosphorus fertilizer application, improved varieties of millet and cowpea, and improved agronomic practices were compared with the traditional millet–cowpea intercrop system in a three year experiment. The most productive system involved the rotation of fertilized millet and cowpea. Pre-sowing tillage increased hay and fodder yields in all the improved systems. The application of fertilizer increased the amount of available phosphorus in the soil. Soil pH declined somewhat in all treatments, although the initially low soil organic matter did not change.