bluuebunny/crossref_metadata_2025 huggingface dataset:
Was This in Your Statistics Textbook? IV. Frequency Data
Authors: Finney D. J.
Published: October 2008

Observations that are frequencies rather than measurements often call for special types of statistical analysis. This paper comments on circumstances in which methods for one type of data can sensibly be used for the other. A section on two-way contingency tables emphasizes the proper role of χ2 a test statistic but not a measure of association; it mentions the distinction between one-tail and two-tail significance tests and reminds the reader of dangers. Multiway tables bring new complications, and the problems of interactions when additional classificatory factors are explicit or hidden are discussed at some length. A brief outline attempts to show how probit, logit, and similar techniques are related to the analysis of contingency tables. Finally, three unusual examples are described as illustrations of the care that is needed to avoid jumping to conclusions on how frequency data should be analysed.
Pre-planting Treatment of Seed Potato Tuber Pieces to Break Dormancy, Control Tuber Piece Decay and Improve Yield
Authors: Shashirekha Mysore N. , Narasimham Pattisapu
Published: October 2008

Laboratory experiments and field tests were used to study the effects of seven anti-microbial agents and a trace element salt mixture (TEM) on the decay of cut pieces of seed potatoes. The effect of a mixture of gibberellic acid and ethrel (GA + E), TEM, and TEM with GA + E on the sprouting behaviour and yield of tubers was also studied. All the anti-microbial agents inhibited decay, although TEM and oxine were superior to other treatments. There was an increase in crop yield when seed tubers were treated with TEM. In laboratory tests, the GA + E mixture and TEM were effective in breaking dormancy.
The Use of Transparent Flexible Tubes for Studying the Root Extension and Elongation of Beans (Vicia faba)
Authors: El-Shazly M. S. , Warboys I. B.
Published: October 2008

Two bean genotypes differed in rate of root extension and elongation when grown under different soil water stresses in transparent tubes placed at an angle of 25°. Root intensity (the root length visible cm−2 of the viewing surface) gave a quick indication of the distribution of the total root length when screening cultivars for drought resistance.
Studies of the Phosphate Dynamics in a Vertisol in Relation to the Yield and Nutrient Uptake of Rainfed Cotton
Authors: Pundarikakshudu R.
Published: October 2008

Field studies of the dynamics of transformation and availability of applied phosphorus in a Vertisol cropped with rainfed cotton showed that phosphorus application increased available phosphorous in the soil. However, 70–80% of the phosphorus was fixed when more than 40 kg P2O5 ha−1 was applied. Maximum uptake of phosphorus by cotton occurred during the active growth period 40 to 80 days after germination, as reflected in a steep decline in the labile pool of available phosphorus in the soil. Over 50% of the total inorganic phosphorus occurred as Ca-P, which was the major contributor to the labile pool available to the cotton crop. The maximum response of cotton in terms of both dry matter and seed cotton and the maximum uptake of nitrogen, phosphorus and potash occurred when phosphorus was applied at 40 kg P2O5 ha−1. Phosphorus application increased the length, spread, volume and weight of roots.
Population, Growth and Water Use of Groundnut Maintained on Stored Water. I. Root and Shoot Growth
Authors: Rao R. C. Nageswara , Simmonds L. P. , Azam-Ali S. N. , Williams J. H.
Published: October 2008

The growth of roots and shoots was measured in stands of groundnut grown at a number of populations on stored water in central India. Total weight and length of roots per unit land area increased with population density, but the proportional increases were much less than for shoot weight. Consequently the root:total weight ratio increased from 0.3 in the densest stand to almost 0.5 in the widely spaced crop. The denser stands produced a greater proportion of their roots at depth. In wide rows there was little change in rooting density across the inter-row space.

Total dry matter per unit land area increased with population, although the weight per plant was less in denser stands. Although the crops were harvested prematurely, pod yield per unit land area, unlike total dry matter, was no greater in dense stands than in more widely spaced crops. The greatest number of pods per unit land area was recorded at an intermediate population density.
Population, Growth and Water Use of Groundnut Maintained on Stored Water. III. Dry Matter, Water Use and Light Interception
Authors: Azam-Ali S. N. , Simmonds L. P. , Rao R. C. Nageswara , Williams J. H.
Published: October 2008

At a field site in central India, four populations of groundnut (Arachis hypogaea L.) were grown on stored water to investigate how the production of shoot and root dry matter is related to transpired water and intercepted radiation. Throughout the season, total dry matter was closely related to transpiration (slope = 3.0 mg dry matter g−1 water) and the amount of radiation intercepted by foliage (slope = 0.74 g dry matter MJ−1 radiation intercepted). Accumulated transpiration increased linearly with intercepted radiation at 0.37 kg water MJ−1 in the sparser stands. In the densest spacing, the initial slope of the relation at 0.28 kg MJ−1 decreased later in the season because water deficits curtailed growth without a concomitant reduction in the interception of radiation.
Evaluation of Alternative Legumes for Green Manure and Grain under African Highland Conditions
Authors: Potts M. J. , Biranguza E. , Bweyo C.
Published: October 2008

Three species of lupin, three vetches and a soyabean were evaluated as green manures under tropical highland conditions. With moderate soil fertility and 150 days of rain, all lupin types and a locally obtained vetch gave yields of about 80 t ha−1 fresh material. Under less favourable conditions, low soil pH and high aluminium saturation, only Lupinus luteus achieved these yields. During the short season, with about 60 days of rain, the yield of L. luteus was reduced to 30 t ha−1 and establishment of the vetches was slow and they yielded poorly. Growth of soyabean was poor under cool conditions. Under fertile conditions, lupin grain yields of up to 5.2 t ha−1 were obtained in the long season but in the short season, yields were less than 1 t ha−1. Rhizoctonia solani was the major disease encountered.
Was This in Your Statistics Textbook? V. Transformation of Data
Authors: Finney D. J.
Published: October 2008

Additivity, variance homogeneity, and normality are often regarded as prerequisites for analysis of variance. Although they are desirable, their truth is never certain; they are important to probability levels in significance tests, but not to the general informativeness of the analysis. Transformation of data may improve conformity to these desiderata at the cost of producing results on a scale ill-suited to the objectives of the experiment. In this paper the generalized power transformation and the inverse sine transformation are described, and the practical problems of choosing an optimal transformation discussed. An ideal choice can seldom be based on the evidence of one experiment, and adopting the same transformation for a series of similar experiments is usually more helpful than a search for the ‘best’. Warnings are given about inappropriate guides to the choice of transformation. In some experiments, separate analyses for two or more obviously distinct sets of treatments may be more rewarding than any attempt to find a transformation that will enable all to be handled at once. When one or two treatments (or treatment combinations in a factorial experiment) show data wildly out of line with all others, consideration of reasons should precede and possibly replace any approach through transformation. A sound general principle is that data are usually most clearly interpreted on the original scale of measurement. Therefore, transformations should be avoided unless clearly necessary; by this advice, I do not imply prohibition. Finally, attention must be given to the presentation of results; the most effective presentation does not necessarily employ a transformation or other special device adopted earlier in a statistical analysis.
Seed Yam Multiplication by the Mini-sett Technique in Three Yam Species in a Tropical Guinea Savanna Location
Authors: Kalu B. A. , Norman J. C. , Pal U. R. , Adedzwa D. K.
Published: October 2008

Seed yam production potential of three yam species (Dioscorea rotundata, Dioscorea alata and Dioscorea cayenensis) was assessed for two systems – the traditional method using 100 to 200 g setts, and the mini-sett technique using 25, 20, 15 and 10 g setts cut from mother tubers. The mini-sett technique required only 6–33% of the number of tubers needed for the traditional planting system, and resulted in plants superior to those produced by the traditional method in all their production attributes especially in the case of D. alata and D. rotundata.
Effect of Irrigation Regimes on the Water Status, Vegetative Growth and Rubber Production of Guayule Plants
Authors: Benzioni Aliza , Mills David , Forti Meir
Published: October 2008

Three irrigation regimes (250, 450, 650 mm year−1) were applied to guayule (Parthenium argentatum), a rubber-producing plant, in such a way as to provide periods of good soil water status alternating with periods of water stress. The relative water content and transpiration rate of the plants decreased only when the available soil water was depleted to about 40%. Very low values (< 30%) were measured for the relative water content. Water-stressed plants recovered as soon as irrigation was resumed. Growth and biomass accumulation, as well as the yields of rubber and resins, were directly related to the irrigation rates. The water regimes applied and the use of the drip irrigation method resulted in a relatively high water use efficiency.
Effects of Alternating Sodic and Non-sodic Irrigations on the Build-up of Sodium in the Soil and on Crop Yields in Northern India
Authors: Bajwa M. S. , Josan A. S.
Published: October 2008

In a field experiment, the effects of irrigating crops alternately with sodic water (high in sodium adsorption ratio and) and good quality canal water were investigated for six years on a well drained sandy loam (Typic Ustochrept). The irrigation treatments included: irrigation with non-sodic canal water (CW), irrigation with sodic water (SW), CW irrigation alternating with one or two SW irrigations, and two CW irrigations alternating with one SW irrigation. The results showed that the use of sodic water increased the sodium saturation of the soil and decreased rice and wheat yields. The build-up of sodium depended on the number of SW irrigations during the season. The increase in sodium saturation and decline in crop yields were progressive over the years. The improvements in yield due to alternating sodic and non-sodic irrigations compared with the use of sodic water alone increased over the years. Alternating sodic and non-sodic irrigations could therefore be considered a practical way to alleviate the problems caused by sodic water. The number of sodic irrigations during a season should, however, be kept to a minimum and the build-up of sodium in the soil over time should be monitored.
On-farm Experiments with Millet in Niger: Crop Establishment, Yield Loss Factors and Economic Analysis
Authors: Mcintire J. , Fussell L. K.
Published: October 2008

Results of farm-level experiments with pearl millet are reported from four villages in semi-arid Niger in 1982 and 1983. Crop establishment, yield loss factors (insects, diseases, striga) and economics of new practices were studied in a randomized design which included density, fertility, cultivar, and intercropping with cowpea as treatments. Improved cultivars did not establish significantly better than local ones, but fertilizer occasionally improved establishment. Incidence of yield loss factors was low, and only small effects of cultivar and fertilizer were seen. Fertilizer increased grain yields of the local cultivar by as much as 153%. The use of fertilizer and improved cultivars increased grain yields by as much as 171% over an unfertilized local millet. Even without government subsidies, fertilizer use was profitable for 56% of farmers on all cultivars. In general, fertilizers and improved cultivars had a small positive impact on profitability, with little adverse impact on grain yield variability, so that they could be recommended to farmers with some prospect of success. The intercropping treatment failed in both years, and would have to be modified before extension.
Comparative Patterns of Dry Matter Production in Bushy and Spreading Sweet Potato Cultivars
Authors: Pardales J. R. , Belmonte D. V.
Published: October 2008

Dry matter production in a bushy and spreading cultivar of sweet potato was studied in two trials comparing dry matter partitioning between plant components. The bushy cultivar, VSP-2, accumulated more tuber dry matter than the spreading cultivar, BNAS-51. The number and yield of tubers of VSP-2, was also greater but its foliage dry weight was less than that of BNAS-51. The vine and root dry weight of BNAS-51 increased with time but that of VSP-2 reached a peak about 10–12 weeks after planting. The tuber dry weight of BNAS-51 at harvest was similar to its foliage dry weight but that of VSP-2 was three times greater. The proportion of total dry matter partitioned to the tubers of VSP-2 was greater than that in BNAS-51 at all stages of growth.
Root Growth of Four Common Bean Cultivars in Relation to Drought Tolerance in Environments with Contrasting Soil Types
Authors: Sponchiado B. N. , White J. W. , Castillo J. A. , Jones P. G.
Published: October 2008

Root growth of two drought tolerant and two drought sensitive bean (Phaseolus vulgarisL.) lines was compared at two locations in Colombia differing primarily in soil conditions. At Palmira, roots of drought tolerant lines reached a depth of 1.3 m, while drought sensitive lines only reached 0.8 m. These differences were associated with differences in seed yield, crop growth, canopy temperature and soil moisture extraction. Under acid soil conditions at Quili-chao, seed yields of supposedly drought tolerant genotypes were similar to those of the drought sensitive lines, and root growth of all four lines was restricted to less than 0.8 m. Drought avoidance through greater root growth and extraction of soil moisture appears to be an important drought tolerance mechanism in common beans, but its usefulness is limited where soil conditions restrict root growth.
Comparison of Variety Means Using Cluster Analysis and Dendrograms
Authors: Jolliffe I. T. , Allen O. B. , Christie B. R.
Published: October 2008

In many experiments which compare a large number of different treatments or varieties, it is necessary to decide which sub-sets of treatments or varieties do not differ significantly from each other. Multiple comparison procedures provide a commonly used, but much criticized, way of tackling this problem. As an alternative, techniques known collectively as cluster analysis can be used. An advantage of using certain types of cluster analysis is that their results can be displayed as a dendrogram or tree diagram which gives a very useful picture of the overall relationship between treatments or varieties. These procedures can also be extended readily to multivariate observations from each plot.
Improving Water use Efficiency of Annual Crops in the Rainfed Farming Systems of West Asia and North Africa
Authors: Cooper P. J. M. , Gregory P. J. , Tully D. , Harris H. C.
Published: October 2008

Farming systems in west Asia and north Africa have evolved to cope with the problems of highly variable and, frequently, chronically deficient rainfall. Cereals (mainly wheat and barley) are the dominant arable crops with food legumes (chickpea, lentil and faba bean) occupying only 5 to 10% of the area planted to cereals. Livestock is closely integrated into the farming system and crop production practices often reflect the importance of animals as a major source of income, particularly on the smaller farms. Soils of the region are predominantly calcareous, frequently phosphate deficient, and their depth and texture are important in determining the maximum amount of water that can be stored which, in turn, may determine the effective length of the growing season.

Rain falls mainly during the winter months so that crops must often rely on stored soil moisture when they are growing most rapidly. Analysis of equations relating crop growth and water use shows that there are three ways in which the ‘water use efficiency’ of dry matter production can be increased. First, the amount of dry matter produced per unit of water transpired might be increased; second, if the water supply is limited, the amount of water transpired might be increased relative to evaporation from the soil surface; and third, the total amount of water used might be increased to produce extra growth provided that this results in increased transpiration rather than simply increasing evaporation from the soil surface.

These three possible routes to increased crop growth are reviewed in relation to possible improvements in water management and crop genotypes in the Mediterranean environment. Scope for improving transpiration efficiency is limited although genotypic differences exist and may be useful in the future. More immediately, changes in crop management, such as applications of fertilizer, improved tillage and better weed control, will all increase the amount of water transpired. Application of mulches will also reduce evaporation from the soil surface but crop residues are usually eaten by livestock and are, therefore, often unavailable.

The barley/livestock farming system of west Asia is used as a case study to illustrate how the Fanning Systems Programme of ICARDA has developed on-farm research programmes of direct relevance to current farming systems. Research on experimental sites directed at improving water use efficiency has been developed into on-farm trials and into collaborative trials with the Syrian Soils Directorate.
Efficiency of Isobutylidene Diurea, Sulphur-Coated Urea and Urea Plus Nitrapyrin, compared with Divided Dressings of Urea, for Dry Matter Production and Nitrogen Uptake of Ryegrass
Authors: Halevy J.
Published: October 2008

Two slow-release nitrogen fertilizers, isobutylidene diurea (IBDU) and sulphur-coated urea (SCU), and urea plus nitrapyrin were compared with urea alone for their effect on the growth and nitrogen uptake of ryegrass in a greenhouse experiment.

The IBDU and the SCU were applied in one dressing before sowing and the urea in five dressings (one after each cut). Dry matter yield and nitrogen uptake of the six cuts at the optimum levels of 3 and 6 g N pot−1 (equivalent to 1120 and 2240 kg N ha−1 on a weight basis) were similar for the slow-release fertilizers and urea, showing that SCU and IBDU can be effective sources of nitrogen for ryegrass at rates far above those regarded as safe for conventional nitrogen fertilizers when applied in a single dose.

Nitrapyrin at 20 ppm effectively inhibited nitrification for 12 weeks, then its effect rapidly declined, disappearing after 18 weeks. Ryegrass growth was retarded by nitrapyrin treatment, probably as a result of an accumulation of NH4-N in the soil.
Effect of Transplanting Date and Seedling Age on Stand Establishment and Grain Yield of Rice in Rainfed Lowland (Intermediate Deep-Water) Conditions
Authors: Reddy B. B. , Ghosh B. C. , Reddy M. D.
Published: October 2008

Water depth at or shortly after planting is critical for the establishment and subsequent tolerance of excess water in rice. A crop transplanted early in the season produced twice as much grain as a later planted crop. A semi-dwarf variety (CR 1018) and a taller variety (CR 1030) performed similarly after early transplanting, but the tall variety performed better when planted late under excess water. Seedling age did not greatly alter the yields when crops were transplanted early, but after late planting 45-day-old seedlings were best.
Permanence of Free Water on Coffee Leaves
Authors: Guzman O. , Gomez L.
Published: October 2008

The presence of free water on both surfaces of the leaves of shaded and unshaded coffee trees was evaluated at Cenicafé, Colombia. Rainfall was the main source of humidity and dew was not registered during the experiment. Five mm of rain caused canopy saturation and water began to reach the underside of the leaves. The period of wetness lasted 9.7 hours on average and no significant moisture differences were found between leaves on east or west facing branches, at different levels within the tree, or externally or internally positioned on the branches, either for exposed or shaded trees. Between 1700 and 0500 h (local time), a close relation was found between the time of rain initiation and the duration of the period of wetness. Leaves dried out at approximately 1000 h.
Relationship of Cassava Mosaic Severity in Planting Material to Mosaic Development, Growth and Yield of Cassava in Zaire
Authors: Muimba-Kankolongo A. , Phuti K.
Published: October 2008

The performance of a cassava clone susceptible to cassava mosaic disease (CMD) was tested over two successive years for CMD development, plant vigour and yield of fresh tuberous roots. Cuttings from plants with different CMD infection levels were used. There was a significant increase in mosaic incidence, severity and proportion of leaves showing symptoms of the disease in the subsequent crop as the levels of CMD primary infection in planting material increased. Plant height and stem diameter were also adversely affected and the yield of plants from severely affected cuttings was reduced by 60–70%.
Effect of Gypsum and Drought on Pod Initiation and Crop Yield in Early Maturing Groundnut (Arachis hypogaea) Genotypes
Authors: Rajendrudu G. , Williams J. H.
Published: October 2008

Gypsum application and irrigation increased yield in early maturing groundnut genotypes in experiments using line source and conventional irrigation. Response to gypsum varied with genotype; with some gypsum increased yields at all water application rates, in some genotypes there was no response, while with others gypsum increased yield in drought conditions.

In a separate study of the effect of gypsum and drought on pod initiation and development in three groundnut genotypes, gypsum did not greatly influence pod initiation when adequate irrigation was applied, but was beneficial when water was withheld during pod set and again during pod filling. Crops where the combination of gypsum and genotype were most advantageous in the first drought period subsequently grew more slowly so that there were no final differences in response to gypsum. Cultivar EC 76446(292) had a higher requirement for gypsum and was more susceptible to drought than the other two genotypes.
Effect of Sowing Depth on Nodulation, Nitrogen Fixation, Root and Hypocotyl Growth, and Yield in Groundnut (Arachis hypogaea)
Authors: Nambiar P. T. C. , Rao B. Srinivasa
Published: October 2008

Hypocotyl length in groundnut is a function of sowing depth. In field experiments deep sowing increased the mass of hypocotyl but decreased that of roots, pods and haulm. Few nodules were formed on the hypocotyls of plants from shallow sown seeds (4–5 cm deep). More hypocotyl nodules occurred on Virginia types when deep sown but the number and activity of nodules on the roots decreased. Nodules on the hypocotyl appeared later and fixed less nitrogen than root nodules. Although hypocotyl nodules fixed nitrogen during the later stages of plant growth, this activity could not compensate for the loss in nitrogenase activity due to deeper sowing. Deeper sowing also resulted in decreased pod yields.
Clove Tree Yields in the Islands of Zanzibar and Pemba
Authors: Martin Peter J. , Riley Janet , Dabek Andrew J.
Published: October 2008

Attention is drawn to the large annual fluctuations of clove yields in Zanzibar and Pemba which appear to result from a synchronization of clove production by trees. Linear regression analyses are presented which show that in years of peak production tree yield is often correlated with tree canopy area and that when trees yield in two consecutive years, yield in the second year is usually negatively correlated with yield in the first year; equations including both variables often leave considerable variation in yield unaccounted for. It is suggested that some of the year to year variation in tree yield may result from an environmental stimulus affecting clove bud differentiation.
Root Growth and Yield Response of Rainfed Lowland Rice to Planting Method
Authors: Sharma P. K. , De Datta S. K. , Redulla C. A.
Published: October 2008

Field experiments were conducted on two soils (clay loam and sandy loam) with varying texture and water table depth to study the effects of two planting methods (dry seeding and transplanting) on the root growth and grain yield of rainfed lowland rice. About 75% of the roots were found in the top 10 cm soil. Root length density at the flowering stage and grain yield in the sandy loam soil, with a water table deeper than 1.5 m, were less in dry-seeded than in transplanted rice, probably because of the greater moisture stress in dry-seeded rice between late tillering and harvest. In the clay loam soil, with the water table mostly at the soil surface, there was no difference in grain yield between dry-seeded and transplanted rice.
A Pedal-assisted Unit for Making Leaf Juice
Authors: Pirie N. W.
Published: October 2008

Extracted leaf protein is now used regularly as human food in several places. For preliminary, or domestic, trials the equipment used is inconveniently large. A miniature extraction unit, which does not depend on electricity, is described.
Influence of Chlormequat on the Growth and Yield of Irrigated and Rainfed Indian Mustard (Brassica juncea) in the Field
Authors: Saini J. S. , Jolly R. S. , Singh O. S.
Published: October 2008

The effect of the field application of chlormequat on the growth, yield and seed oil content of Brassica juncea grown under irrigated and rainfed conditions was evaluated for three consecutive crop seasons. Foliar application at the flower initiation stage increased the number of primary branches, number and length of siliquae, weight of seeds and seed oil content. Chlormequat (50 AS) applied at 80 ml ha−1 increased seed yield by more than 50%. The increase was greater in unirrigated crops.
Plant Population, Rainfall and Sorghum Production in Botswana. II. Development of Farmer Recommendations
Authors: Jones M. J.
Published: October 2008

Regional population recommendations for sorghum production in Botswana were calculated by applying long-term meteorological records to an experimentally developed model linking sorghum yield to plant population and rainfall. The basic recommendation at any place was taken to be that population maximizing local long-term yield means while keeping the risk of crop failure to one year in ten or less. Values ranged from 25 000 to nearly 70 000 plants ha−1, according to rainfall amount and reliability. The modifications of these basic recommendations necessary to allow for differences in standards of husbandry and for sorghum variety are discussed.
Farming Systems Research: Procedures for Technology Development
Authors: Collinson M. P.
Published: October 2008

Procedures for better decision making in agricultural research are considered. Fanning Systems Adaptive Research (FSAR) has evolved to complement the more traditional research approach, allowing better decisions to be made on recommendations to fanners and on priorities for technical research. This is done through the identification of research results most relevant to the development of specific farming systems; the testing of these results by experiments in farmers' fields; and the identification of factors limiting productivity in local farming systems.

FSAR involves interdisciplinary cooperation between production agronomists, farm economists and, where appropriate, animal production scientists, in close cooperation with other production specialists and with farmers.
Effect of De-Branching on the Yield and Yield Components of Mustard (Brassica juncea)
Authors: Chauhan Y. S. , Bhargava S. C. , Tomar D. P. S.
Published: October 2008

Branches are an important yield attribute of the mustard (Brassica junceo)crop. However, not all the branches are equally productive and some of those arising from the basal portion of the plant may form parasitic sinks for assimilates. The effect of de-branching at the 50% flowering stage in the apical (AHD) and the basal halves (BHD) of two mustard genotypes, Pusa Bold and Varuna, was examined. The BHD treatment increased the seed yield per plant of Pusa Bold by 36% and of Varuna by 75% over the control. The increase in yield due to the BHD treatment was mainly due to an improvement in the total number of pods per plant in both genotypes. In Pusa Bold, an improvement in both 1000-seed weight and number of seeds per pod, mainly on late formed branches, was also observed. The AHD treatment reduced seed yield but not significantly so. The results suggest that improvement in the yield of mustard cultivars by suppressing branching on the basal portion of plants should be possible.
Effects of Planting Time and Harvest Age on Cassava (Manihot esculenta) in Northern Australia. I. Crop Growth and Yield in Moist Environments
Authors: Hammer G. L. , Hobman F. R. , Shepherd R. K.
Published: October 2008

A range of planting times, with sequential harvests to age 24 months, was used to determine crop growth and yield of cassava at two locations, one having a humid tropical climate and the other humid sub-tropical. Yield was doubled during the second year at the sub-tropical site. At the tropical site yield was very high after one year, but root rots occurred in the second year. The dry matter percentage of storage roots fluctuated seasonally and was highest during the cooler months when canopy vigour was lowest. Known or inferred environmental controls of the yield-determining factors of growth rate, growth duration, and partitioning to harvestable organs were used to interpret the results and thus derive guidelines for timing of planting and harvesting in moist environments.
Intercropping Sorghum with Cowpea in Dryland Farming Systems in Botswana. II. Comparative Stability of Alternative Cropping Systems
Authors: Lightfoot C. W. F. , Dear K. B. G. , Mead R.
Published: October 2008

The comparative stability of sorghum–cowpea intercropping and monocropping was assessed by determination of variances, regression against an environmental index, and probability of failure to achieve minimum levels of gross income. Significant differences between the cropping systems were not detected in any of the assessments though intercropping did have a lower probability of failure at the income levels for which risk was more than minimal. The failure of intercropping to show clearly greater stability in this study in which the environmental conditions were harsh provides a conflict with the conventional view.
Environmental Modulation of Flowering in Mung Bean (Vigna radiata): a Reappraisal
Authors: Summerfield R. J. , Lawn R. J.
Published: October 2008

The phenology of mung beans is extremely plastic; responsiveness tobothphotoperiodandtemperature is known to modulate flowering. A previous conclusion, perpetuated uncritically now for almost forty years, has been that both (quantitative) short- and long-day flowering responses exist in the mung bean germplasm. However, our re-analysis of the original data leads us to an alternative conclusion: that genotypes of mung bean are quantitative short-day plants with different optimum mean diurnal temperatures for flowering. This alternative interpretation (which is plausible biologically and in evolutionary terms) is discussed.
A General form of the ‘Land Equivalent Ratio’
Authors: Riley Janet
Published: October 2008

The Land Equivalent Ratio (LER) concept is presented and interpreted. Several different intercropping systems are considered and the need for methods to evaluate them is discussed. A general form of the LER is proposed for the evaluation, in particular, of a system that combines two intercrops having different yield proportions. Appropriate LER curves, obtained by varying the yield proportions, are used to compare different intercropping systems, and the importance of this approach is discussed.
Effects of Sett Size and Spacing on Tuber Yield of White Guinea Yam (Dioscorea rotundata) in the Rainforest and Savanna Zones of Nigeria
Authors: Kayode G. O.
Published: October 2008

Field studies designed to investigate the effects of sett size and spacing on tuber yield of white Guinea yam were conducted in three locations over a two year period in the rainforest and savanna zones of Nigeria. Sett weights larger than 400 g could be used for maximum tuber yields in both forest and savanna zones. Spacing had no significant effects on tuber yield in the savanna zone, but optimum spacing has yet to be identified in the forest zone.
Response of Non-irrigatedSorghum bicolortoAzospirillumInoculation
Authors: Sarig S. , Kapulnik Y. , Nur I. , Okon Y.
Published: October 2008

In two experiments, carried out on non-irrigated fields in the Northern Negev region of Israel, inoculation ofSorghum bicolorwith bacteria of the genusAzospirillumresulted in significant increases over controls of 17% in grain yield of cv. 610 and of 19% in the forage yield of cv. 6078. In addition, significant increases over controls in plant dry weight, mineral content (N, P and K) and panicle number were obtained by inoculation of cv. 610.
Stomatal Characteristics among Cassava Cultivars and their Relation to Gas Exchange
Authors: El-Sharkawy Mabrouk A. , Cock James H. , de Cadena Giovanna
Published: October 2008

Cassava (Manihot esculenta Crantz) has generally been reported to possess hypostomatal leaves. Several cultivars have now been found to possess clusters of functional stomata around the veins on the upper leaf surface and two cultivars (M Col 88 and M Col 90) have significant numbers of stomata (83–140 mm−2) dispersed over the entire upper leaf surface. Stomatal density on the lower leaf surface ranged from 322–553 mm−2 among cultivars, with a relative stomatal area of 3.4–6.1%. The CO2 uptake by the upper leaf surface (27% of total) and the transpiration loss (32% of total) corresponded closely to the ratio of relative stomatal areas on the upper and lower leaf surface of cv. M Col 88.
Sensitivity of Chickpeas (Cicer arietinum) to Hot Temperatures during the Reporductive Period
Authors: Summerfield R. J. , Hadley P. , Roberts E. H. , Minchin F. R. , Rawsthorne S.
Published: October 2008

Plants of two genotypes of chickpea (Cicer arietinum), classified as early or late-maturing in the field, and relying either on dinitrogen fixation by nodules or on nitrate-N, were grown in various simulated tropical environments in growth cabinets. Plants were transferred between cabinets at various times so that they experienced either warm (30°C) or hot (35°C) days (both in combination with a typical night temperature of 10°C) for different durations of reproductive growth, after growing in average (30°C day - 10°C night) or warmer than average (30° - 18°C) temperatures for the first 28 days from sowing and then average temperatures until transferred into the hot regime. Diurnal vapour pressure deficits were adjusted so that plants experienced a constant atmospheric relative himidity (70%) in all thermal regimes. The greater the proportion of the reproductive period spent in hot days the smaller the seed yields produced; plants transferred at 50% flowering were almost barren. The implications of these data for breeding chickpeas well adapted to hot environments are discussed.
Confounded Experiments are Simple, Effficient and Misunderstood
Authors: Mead R.
Published: October 2008

Factorial treatment structure and, in particular, confounded designs are important methods of using experimental resources efficiently. Confounded experiments are not used, and possibly not understood, by experimenters. However, the construction and analysis of confounded designs is logically extremely simple, and can be expressed in terms of simple principles. Modern computing facilities can make confounded designs even more useful.
Effects of Planting Density on Water Use and Productivity of Pearl Millet (Pennisetum Typhoides) Grown on Stored Water. I. Growth of Roots and Shoots
Authors: Azam-Ali S. N. , Gregory P. J. , Monteith J. L.
Published: October 2008

Pearl millet (Pennisetum typhoides) was grown on stored water at Niamey, Niger, using three row spacings (38, 75 and 150 cm), to determine the physiological basis of exploitation and conservation of water by crops during drought Between 18 and 32 days after sowing, roots grew rapidly beneath all crops reaching 140 cm in the narrow spacing, but there were differences between crops in the pattern of growth. Soil cores and trench profiles indicated that plants in wider rows had fewer, deeper roots. Substantial differences in both the amount and pattern of shoot growth were recorded in the different populations. Initially growth was fastest at the narrow spacing but stopped by day 45 and eventually the wide spacing produced most dry matter due mainly to greater survival of tillers. The partitioning of above ground dry matter into vegetative and reproductive fractions was similar at all three spacings and was consistent with figures for comparable crops elsewhere. The important role of tillers is discussed in relation to the development and maintenance of a canopy.
Effects of Planting Density on Water Use and Productivity of Pearl Millet (Pennisetum Typhoides) Grown on Stored Water. II. Water Use, Light Interception and Dry Matter Production
Authors: Azam-Ali S. N. , Gregory P. J. , Monteith J. L.
Published: October 2008

Pearl millet was grown on stored water at Niamey, Niger, using three row spacings. Water extraction based on neutron probe readings was compared with crop transpiration using a porometer and allied measurements. Between 23 and 52 days after sowing, plants at the narrow and medium spacings used about 77 and 100 mm of water, respectively, and those at the wide spacing used between 59 and 75 mm. Estimates of seasonal crop evaporation from leaf resistances and from the green leaf area index (GLAI) of the crops were 103, 130 and 123 mm for the narrow, medium and wide spacings, respectively. The water use per unit of dry weight produced was similar for both narrow and medium spacings but water was used more efficiently in the wide spacing. Dry weight increased in proportion to intercepted radiation with the same efficiency (1·3 g MJ−1) irrespective of spacing.
Effect of the Germinating Seed Environment on Crop Yields. II. Effect of the Water and Air Regime During Germination on Cereal Yields
Authors: Haller E.
Published: October 2008

Differences in the water and air regime of the germination environment may cause variations of 30% and over in the yield of barley, wheat and oats.
Coated and Uncoated Urea in Ramie Leaf Production
Authors: Sarkar Apurba , Sarkar Gitasree , Sarkar Anupam
Published: October 2008

Ramie (Boehmeria nivea Gaud.), which can provide fodder in addition to bast fibre, was supplied with nitrogen in three different forms: as neem cake coated urea (NCU), lac coated urea (LCU) and standard urea, at rates of 60, 120, 180, 240 and 300 kg N ha−1 annually in four equal applications. The ramie was cut four times a year for two years. NCU increased fresh weight, leaf dry matter yield and leaf protein at almost every cutting compared with the other forms of nitrogen, and there was an indication of increased residual nitrogen in the soil. Leaf dry matter and protein content increased with increasing levels of nitrogen up to 180 kg ha−1. It is suggested that coating urea with neem cake makes it a better source of nitrogen for ramie leaf production.
Sorghum-Legume Intercropping and the Effects of Nitrogen Fertilization. I. Yield and Nitrogen Uptake by Crops
Authors: Waghmaref A. B. , Singh S. P.
Published: October 2008

Six intercropping systems and four levels of nitrogen were compared at the Indian Agricultural Research Institute, New Delhi, in the summer rainy seasons (July-October) of 1978 and 1979. The maximum increase in sorghum yield was obtained when it was associated with fodder cowpea, followed by association with grain cowpea and greengram. The application of 40, 80 and 120 kg N ha−1 increased sorghum yield by 8.6, 16.1 and 18.2% in 1978 and by 2.9, 8.1 and 14.1% in 1979, respectively, compared with unfertilized sorghum. The nitrogen uptake by sorghum, and by the total system, was greater in sorghum-legume intercropping systems than in sole sorghum. Nitrogen application also increased the nitrogen uptake by sorghum and by the whole system.
Sorghum-Legume Intercropping and the Effects of Nitrogen Fertilization. II. Residual Effect on Wheat
Authors: Waghmaref A. B. , Singh S. P.
Published: October 2008

Wheat yield was increased significantly when grown after sorghum intercropped with cowpeas (both for fodder and grain) or with groundnut compared with sole sorghum in the previous season. The nitrogen requirement for the target wheat yield of 4.0 t ha−1 was 108 kg ha−1 after sole sorghum and this was reduced by 87, 61, 83 and 38 kg ha−1 after intercrops of sorghum with fodder and grain cowpeas, groundnut and greengram, respectively. The different levels of nitrogen applied to the sorghum-legume intercropping systems also allowed savings of between 18 and 55 kg ha−1 of fertilizer nitrogen on wheat in the following season.
Efficiency of Nitrogenase Activity and Nodule Mass in Predicting the Relative Performance of Genotypes Assessed by a Number of Characters in Groundnut (Arachis hypogaea)
Authors: Arunachalam V. , Pungle G. D. , Dutta M. , Nambiar P. T. C. , Dart P. J.
Published: October 2008

Twenty one genotypes belonging to Spanish, Valencia and Virginia groups of groundnut were studied at Patancheru and a further seventeen at Delhi. Their relative performance based on a large number of characters spanning the entire growth phase was assessed. Nitrogenase activity and nodule mass were measured at three stages of crop growth starting from first flowering, and these two characters alone when measured at 30 days after flowering closely matched the measure of relative performance based on the entire set of characters.
The Movement of 14C-Labelled Products from Source Leaves During the Growth and Development of Broad Bean
Authors: Ismail A. M. A.
Published: October 2008

Selected leaves of broad bean on separate plants were supplied with 14CO2, at four stages during development and the distribution of radiocarbon products determined quantitatively 24 h later. These leaves retained substantial amounts of the radiocarbon they fixed initially. In the vegetative phase, basal and middle leaves exported more carbon up than down while the apical leaves exported mainly downwards. During the flowering and pod-setting phase, basal and middle leaves exported carbon equally up and down whereas the apical leaves continued to export mainly downwards. Since assimilates produced by basal, middle and apical leaves at any developmental stage in the life of the broad bean plant were moved both acropetally and basi-petally, it must be concluded that bidirectional transport of assimilates occurred in the stem. During the life of the crop all sources supplied assimilates to all sinks.
Effect of Iron on Maize Yields in Forest and Savanna Zones of Nigeria
Authors: Kayode G. O.
Published: October 2008

The results of a two year field study to determine the effect of iron on the yield of maize in the forest and savanna zones of Nigeria have indicated that new and old fields in the savanna, and old fields in the forest zone, require additional iron. The optimum iron requirement for maize in both zones is 3 kg ha−1.
Tree Crops and Farming Systems Development in the Humid Tropics
Authors: Watson G. A.
Published: October 2008

Examples are presented of tropical tree commodity plantation crops, tea, coffee, rubber and oil palm, as models for farm system development. They are environmentally benign in comparison with annual food crops, have been organized on a large scale with smallholder participation, and make significant contributions to local and national economies. It is suggested that lessons learned in their development might be used in the large-scale development of other potentially major tree crops, including timber, fruit and nut producing species.
Farmer-Researcher Collaboration in Developing Cropping Practices that Involve the Complementary Use of Mechanical Tied Ridge and Fertilizer Technology for Sorghum in Burkina Faso
Authors: Nagy J. G. , Ohm H. W. , Sawadogo S.
Published: October 2008

Specific soil fertility and water retention constraints limit increased crop production in the subsistence-oriented farming systems of Burkina Faso. Previous attempts to introduce apparently promising technologies based on research that had not directly involved the fanner and that had not benefited from farmer-feedback have been largely unsuccessful. Active farmer involvement can help to identify relevant constraints to production and to identify and modify technologies to make them viable. Formal and informal farmer surveys and farmer participation in field experiments have led to the development of potentially useful cropping practices involving the complementary use of mechanical tied ridge and fertilizer-based technology.
Effect of Gypsum Compared with that of Grasses on the Yield of Forage Crops on a Highly Sodic Soil
Authors: Kumar Ashok
Published: October 2008

A field experiment was conducted from 1979 to 1986 to compare the amelioration of a highly sodic soil by the application of gypsum compared with that achieved by growing Karnal or Para grass for between one and three years. After studies of the growth of rice and wheat on the experimental plots, the growth of four forage crops, less tolerant of sodic conditions, was studied between 1984 and 1986. The forage yields suggest that their order of tolerance to soil sodicity is Persian clover > Egyptian clover > teosinte > maize, the rabi (winter season) forage crops being more tolerant than the kharif (rainy season) ones.
Effect of Time of Planting and Age at Harvest on the Yield of the Stem-tuber and Shoots in Ginger (Zingiber officinale) in the Rainforest Zone of South-eastern Nigeria
Authors: Okwuowulu P. A. , Ene L. S. O. , Odurukwe S. O. , Ojinaka T. I.
Published: October 2008

The yield of ginger following different dates of planting and harvesting was investigated at Umudike. The largest yields of stem-tubers were obtained seven months after planting while maximum yield of shoots was attained five months after planting. The interaction of yield with time of planting and age at harvest was highly significant. Maximum yields were obtained from mid-April plantings harvested six or seven months later in two years with contrasting weather patterns.
Differential Response of Wheat and Barley Genotypes to Substrate-induced Salinity under North Indian Conditions
Authors: Nair K. P. Prabhakaran , Khulbe N. C.
Published: October 2008

Ten wheat and six barley genotypes were tested for their response to soil salinity regimes varying from 0 to 16 mmhos cm−1. Barley showed remarkable resistance to salt stress, linked to its capability to resist efflux of potassium ions from the plant system. Both crops showed substantial yield reductions at 12 mmhos cm−1, but barley still outyielded wheat by over 50%. There were significant interactions between salinity levels and genotypes in wheat but not in barley.The wheat variety Sonalika showed poor salt tolerance. The implications of these findings in breeding salt-tolerant varieties are discussed.