bluuebunny/crossref_metadata_2025 huggingface dataset:
Restriction Fragment Length Polymorphisms (RFLPS) and Crop Improvement
Authors: Young Nevin Dale
Published: October 2008

Restriction fragment length polymorphisms (RFLPs) are genetic markers based on cloned molecules of DNA. Using RFLPs, scientists can construct high density genetic linkage maps and locate economically important genes. Once a gene for a valuable trait has been mapped with RFLPs, desirable genotypes can be selected using RFLPs rather than scoring for the trait itself. This is important when a trait is recessive, difficult to score, or obscured by other characters. RFLPs are particularly valuable in mapping genes controlling complex polygenic characters, including those fundamental to crop improvement. The first RFLP maps were developed in crop species primarily important in temperate countries. Now RFLP maps for major tropical and sub-tropical crop species are also being developed.
Response ofBradyrhizobium-Inoculated Soyabean and Lablab Bean to Inoculation With Vesicular-Arbuscular Mycorrhizae
Authors: Mahdi A. A. , Atabani I. M. A.
Published: October 2008

Pot and field investigations were conducted to study the effects of vesicular-arbuscular mycorrhizal (VAM) inoculation and triple superphosphate fertilization on nodulation, dry matter yield and tissue nitrogen and phosphorus contents ofBradyrhizobium-inoculated soya-bean and lablab bean in the Sudan.

Inoculation of both crops with the VAM fungusGlomus mosseaein clay and sandy soils in pots increased nodulation, dry matter yield and tissue nitrogen and phosphorus contents more than triple superphosphate fertilizer, but even greater responses were obtained fromG. mosseaecombined with fertilizer. Crop responses in the two soils were similar, despite the large differences in soil physico-chemical properties.

In the field, inoculation of both crops with any of four VAM fungi enhanced nodulation, dry matter yield and plant nitrogen and phosphorus contents more than did triple superphosphate.Gigaspora margaritaandGlomus mosseaewere superior toGigaspora calosporaandAcaulosporaspecies and resulted in more extensive root infection, especially in soyabean.
Competitive Effects of a Short Duration, Bush Type Cowpea When Intercropped With Cotton in Zimbabwe
Authors: Natarajan M. , Naik D. M.
Published: October 2008

Cowpea is an important supplement to the staple diet of maize in Zimbabwe, but its productivity is poor beacuse of pest infestations. This paper reports the results of experiments conducted over two crop seasons on the feasibility of producing a grain crop of cowpea intercropped with cotton to take advantage of cotton's slow initial growth and of drift from insecticides applied to it. Intercropping reduced the yield of cotton by between 11.5 and 73% depending on the type of season and the treatments applied, but the reduction was compensated by the yield of cowpea. The yield reduction was greater in the drier first season and with simultaneous planting of the two crops. Cowpea consistently performed better as an intercrop than as a sole crop, mainly because of the protection it received from the insecticides applied to the cotton.
Correction of Acid Infertility in Rwandan Oxisols with Lime from an Indigenous Source for Sustainable Cropping
Authors: Yamoah Charles F. , Burleigh J. R. , Eylands V. J.
Published: October 2008

Sustainable crop production on Rwandan oxisols is limited by widespread soil acidity caused by high levels of exchangeable aluminium. This study was designed to test the effectiveness of an indigenous lime material in counteracting the acidity and enhancing crop yields. Lime application significantly raised pH, exchangeable calcium and effective cation exchange capacity, and reduced exchangeable aluminium and total acidity. Calcium was directly proportional to effective cation exchange capacity (r = 0.962**) and was inversely related to aluminium (r = −0.955**). Consequently, yields of wheat, beans and potatoes, which served as test crops, were significantly increased by liming. Lime at high rates (4–8 t ha−1) had a longer residual effect than at low rates (less than 2 t ha−1), suggesting frequent applications are needed when low lime rates are used. Simple regression analysis showed an increase in pH of 0.154 units and a decrease in exchangeable aluminium of 0.385 meq 100 g−1 for a tonne of lime applied.
Forage Production for Smallholder Farmers in a Rainfed Millet Cropping System in Central Mali
Authors: Bartholomew P. W. , Ly R. , Kone D. , Traore S. F. , Sissoko K.
Published: October 2008

A shortage of available labour early in the growing season, when effort is directed to the weeding ofcereal crops, appeared to be a primary constraint to increased forage cropping by smallholder farmers in the semi-arid zone of central Mali. In experiments with millet, the labour requirement for weeding was reduced by an average of 45% when the crop was weeded at two rather than four weeks after emergence. A combination of weeding by hand and by ox-drawn plough or harrow only slightly increased labour productivity compared with hand weeding alone. Both lablab and cowpea produced good yields of forage when sown in mid July, but average yield declined by 71 kg ha−l for each day's delay in sowing between mid July and mid-August. Green gram was also productive over a two month growing period and appeared to have potential as a late-sown forage crop.
Vesicular-Arbuscular Mycorrhiza and Phosphorus Uptake of Chickpea Grown in Northern Syria
Authors: Weber Edwin , George Eckhard , Beck Douglas P. , Saxena Mohan C. , Marschner Horst
Published: October 2008

Inoculation with vesicular-arbuscular mycorrhizal fungi (VAMF) improved growth of chick-pea (Cicer arielinumL.) and doubled phosphorus (P) uptake at low and intermediate levels of P fertilization in a pot experiment on sterilized low-P calcareous soil. In field experiments at Tel Hadya, northern Syria, growth, shoot P concentration and seed yield of spring-sown chickpea remained unaffected by inoculation with VAMF or by P fertilization. The mycorrhizal infection of chickpea was high (approximately 75% of root length mycorrhizal at the flowering stage) irrespective of inoculation with VAMF or P fertilization and may ensure efficient P uptake under field conditions.
Small Farmer Mechanization in the Santa Cruz Colonization Zone: a Failure of Farming Systems Diagnosis?
Authors: Thiele Graham
Published: October 2008

This paper uses survey results to show how one group of small scale farmers in Santa Cruz, Bolivia, were able to mechanize annual cropping despite a farming systems diagnosis which indicated that this was not a viable development path. It attempts to identify the underlying causes of farmer success and diagnosis failure.
Prospects for Improving Mediterranean Grasslands in Lebanon through Seeding, Fertilization and Protection from Grazing
Authors: Osman Ahmed E. , Cocks Phil S.
Published: October 2008

Grassland productivity was studied for four years near Terbol, Lebanon. In the first year pasture availability and plant numbers were monitored along transects, and in the following three years the effects of sowing four Mediterranean annual legumes (three cultivars of subterranean clover and a local ecotype of Medicago rigidula) and top-dressing with super-phosphate were studied. The results indicated that natural grasslands were dominated by annual grasses (Aegilops, Hordeum, Bromur, Lolium and Poa). Legume density was low, which resulted in poor legume productivity, especially in winter. Exotic legumes only resulted in a slight improvement in pasture productivity even when phosphate fertilizer was added. However, partial protection from grazing (for one or two months in late winter and spring) more than doubled the number of legume seeds in the seed bank compared with full protection and open grazing. The build up of seeds in the soil is an essential step towards the improvement of productivity in these degraded pastures, which form a large part of the land surface in Lebanon and on which small ruminant production largely depends.
The Importance of Liming Acid Soils of the Sahel Regions of Africa to Sustain High Crop Productivity—a Case Study from the Republic of Cameroon
Authors: Prabhakaran Nair K. P. , Ngachie V. , Nzetchoung F.
Published: October 2008

Groundnut (Arachis hypogaea) has very great economic importance in Cameroon. In pot experiments, groundnut yields on highly acidified but limed soil were 50% greater than those on unlimed soil. These results demonstrate that severely acidified soils of the western highlands of Cameroon should be limed at moderate rates to sustain crop productivity.
Data Analysis in Agricultural Experimentation. III. Multiple Comparisons
Authors: Pearce S. C.
Published: October 2008

Multiple comparison methods are described. It is noted that they have always been controversial, partly because they emphasize testing at the expense of estimation, partly because they pay no regard to the purpose of the investigation, partly because there are so many competing forms and, not least, because they can lead to illogical conclusions. There are many identified instances where they have been found misleading.

An alternative approach is to designate ‘contrasts of interest’ from the start and to concentrate estimation and testing upon them. In many experiments the approach is powerful and definite in use, but sometimes there is no reason to designate one contrast rather than another, for example, in the assessment of new strains or new chemicals. In such circumstances some have found multiple comparisons useful, especially when the problem is to ‘pick the winner’. Bayesian methods and cluster analysis are considered briefly as other alternatives.

The current over-use of multiple comparisons is deplored. It is thought to arise in part from bad teaching and in part from the general reluctance of non-statisticians to venture into the unknown territory of specifying contrasts. A bad situation is made worse by the availability of software that carries out multiple comparisons as a matter of course.
Clonal Responses of Tea Shoot Extension to Temperature in Malawi
Authors: Smith R. I. , Harvey F. J. , Cannell M. G. R.
Published: October 2008

Although the relationship between the length of a growing tea shoot and time is not truly exponential, the exponential relative shoot extension rate (ERSER) can be used for comparisons when both the initial shoot lengths and the periods of measurement are identical. An empirical method to adjust ERSER for variations in initial shoot length was developed for weekly field measurements of seven tea clones in Malawi. ERSERs, measured throughout the two growing seasons after the bushes had been pruned, were standardized to an initial shoot length of 2.5 cm and were then related to mean weekly air temperatures and to vapour pressure deficits. There were large clonal differences in the response of ERSER to temperature within the range 18–23°C. Shoots of the vigorous Malawi clone SFS 150 elongated rapidly at all temperatures, but notably at the lower temperatures (18–20°C). Two Kenyan clones, BB/35 and K6/8, did not grow well at about 18°C, which is normal for growth in Kenya but which coincides with the period of short daylengths (less than 12 h) in Malawi. A significant decrease in ERSER was found with increased vapour pressure deficit over the whole range of field measurements and ERSERs were uniformly lower in the second year after pruning. The results suggest that the usual calculations to derive an inherent base temperature for elongation are not valid unless elongation is truly exponential and therefore, in general, base temperatures should not be used for comparisons between experiments.
A Case of Farmer Adaptation and Adoption of Contour Hedgerows for Soil Conservation
Authors: Fujisaka Sam
Published: October 2008

After farmer-to-farmer training, farmers at an upland research site in the Philippines adapted and adopted contour hedgerows over a period of four years. They developed hedgerow establishment methods that required less labour, eliminated grasses that were too competitive with crops, stopped planting trees that were initially intended to produce green manures, and planted species that might provide direct cash returns. The different systems they used controlled soil erosion equally and effectively, although grazing of hedgerows by neighbours’ cattle was a problem. The farmers who learned about the technology but who did not establish contour hedgerows on their farms were those who had a higher proportion of flat land and/or off -farm or non-farm income opportunities.
Altitude, Temperature and Shoot Production of Tea in the Kenyan Highlands
Authors: Squire G. R. , Obaga S. M. O. , Othieno C. O.
Published: October 2008

Shoot production was examined for two clones at four sites in western Kenya, differing by up to 300 m in altitude and from 16.4 to 18.1°C in mean air temperature. The duration of the shoot growth cycle increased with altitude, and the rate of shoot extension decreased, mainly because of the temperature differences. Outside a dry season, linear regressions of both extension rate and 1/duration on temperature were significant for Clone S.15/10, and gave apparent base temperatures around 7.5°C, but were not significant for Clone TN.14/3 which responded only slightly to temperature. The dry weight per shoot was stable and the growing point frequency did not change systematically with altitude. Analysis that excluded the effects of drought indicated that the yield of Clone S.15/10 decreased from 740 g m-2 at the lowest site by about 10% per degree fall in temperature, whereas the yield of TN.14/3 did not change systematically with altitude.
Plant Nematodes and Sustainability in Tropical Agriculture
Authors: Page Sam L. J. , Bridge John
Published: October 2008

Although plant nematodes are ubiquitous and pathogenic to a wide range of crops, research into these pests in the tropics has been concentrated on commodity crops. While modern intensive tropical agriculture has become unsustainable and often relies on the use of toxic nematicides to control damaging populations of plant nematodes, many traditional subsistence farmers have been able to suppress nematodes by promoting crop diversity and selecting for tolerance and resistance. This paper gives examples of sustainable systems which suppress nematodes. Other examples of once sustainable systems in which nematode problems now occur are discussed and reasons for this instability suggested. The need for farmers to retain responsibility for the development of sustainable systems is stressed. Nematologists and other plant protectionists are encouraged to take a wider view of the complex issues that affect the sustainability of agriculture in the tropics.

Los nemátodos de las plantas y la agricultura continua
Agricultural Research Strategies for Favoured and Marginal Areas: the Experience of Farming Systems Research in Pakistan
Authors: Byerlee Derek , Husain Tariq
Published: October 2008

This paper draws on the results of farming systems research (FSR) conducted over five years at eight sites distributed throughout Pakistan. The main research findings with respect to the irrigated plains, or favoured areas (four sites), and the marginal mountainous and rainfed areas (four sites) are summarized, with emphasis on the role of system interactions in technology development. In favoured areas, most system interactions occur between crops grown in multiple cropping patterns, whereas in marginal areas, crop-livestock interactions dominate. Appropriate research strategies for each kind of environment are discussed. It is concluded that although there is a need for quite different research strategies for favoured and marginal areas, the methods and perspective of FSR are equally appropriate and even critical for achieving future gains in agricultural productivity in each type of environment.

Estrategias de investigación agricola en zonas favorecidas y marginales: Experiencias recogidas durante la investigación de sistemas agrícolas en Pakistán
Yield and Water Use Efficiency of Faba Bean Sown at Two Row Spacings and Seed Densities
Authors: Silim S. N. , Saxena M. C.
Published: October 2008

The performance of promising genotypes of faba bean developed for areas with limited rainfall was compared with the local landrace, ILB 1814, at Tel Hadya in Syria during 1989–1988 using different row spacings and sowing densities. In the last two years of the trials the performance of the improved genotypes and ILB 1814 was compared with and without supplemental irrigation. Yields of ILB 1814 were better than the highest yielding genotypes in some years and similar to them in others. In seasons with limited rainfall the best yields were obtained by using a narrow row spacing and dense sowing, and yields were significantly improved by irrigation. Grain yield was correlated with biomass and the number of pods per unit area. The percentage of radiation intercepted was highest in ILB 1814, particularly when sown with a narrow row spacing and at a high plant density. Soil water extraction, evapotranspiration and water use efficiency were improved by sowing at a narrowrow spacing and high plant density.

Los nemátodos de las plantas y la agricultura continua
Observations of Some Tree Root Systems in Agroforestry Intercrop Situations, and their Graphical Representation
Authors: Rao M. R. , Muraya P. , Huxley P. A.
Published: October 2008

Root systems of unprunedCassia siameaandLeucaena leucocephalatrees and regularly pruned hedges ofC. siamea, L. leucocephalaandGliricidia sepiumwere examined in a semi-arid area in Kenya. Trenches were dug across rows of trees or hedges, soil profiles washed, and different sized roots counted in small 5 × 5 cm grids fully covering both faces of the trench. The roots were displayed using two computer software programmes written for this purpose: a spline technique that displays smoothed root densities in different shades; and a random dot method which displays roots as dots, using any specified scale. The fine roots of four-and-a-half-year-oldC. siameapenetrated the soil to meet with rocks at depths between 0.60 and 2.0 m, and spread laterally to 9 m, traversing adjacent crop plots. Roots of eight-year-oldL. leucocephalacovered an extensive soil volume and included a greater density of fine roots thanC. siameaat comparable distances. Above-ground pruning restricted the roots of hedges to a depth of 1.5 m, although roots of different hedges spaced 5 m apart intermingled freely in the alley space.L. leucocephalaroots filled the alley very densely while those ofG. sepiumwere sparse, particularly in the middle of the alley. Rooting density ofC. siameawas intermediate. The dot method is more precise when rooting densities are low but when densities are high the splining method appears to be more visually helpful. These graphical methods greatly facilitate overall comparisons of sections of tree root systems, but quantification of root densities at different distances away from trees is still needed to understand more precisely the competitive effects of trees and associated crops.

Systemas de raices de los árboles
Wheat Growth as Influenced by the Interaction of Drainage Water and Nitrogen Fertilization
Authors: Al-Abdulsalam M. A. , Al-Tahir O. A. , Al-Jasim A. A. , Burhan H. O.
Published: October 2008

Bread wheat is grown under irrigation in Saudi Arabia. Since water resources are limited, any additional agricultural development must make use of sources of water that are less than ideal, for example, saline drainage water. A two year field study was conducted to compare the effects of irrigating bread wheat with normal water, with a 1: 1 mixture of normal water and drainage water, and with drainage water alone, at three levels of nitrogen fertilizer use. The mean electrical conductivity of the irrigation water was 2.6, 8.6 and 14.6 ds m−1, respectively, in the two seasons of the study. Irrigation with drainage water decreased yield and yield components but increased the protein content of the grain of the two wheat cultivars studied. Drainage water depressed straw yields more than it depressed the yield of grain. Nitrogen application increased yield and yield components in all the irrigation treatments, partially overcoming the adverse effects of the use of saline drainage water.

Efectos del agua salada y el nitrógeno en el trigo
Statistical Analysis of Field Experiments in Coconut Using Fewer Recordings
Authors: Peiris T. S. G.
Published: October 2008

Coconut is harvested at bimonthly intervals (six picks per year) in all field experiments carried out by the Coconut Research Institute in Sri Lanka. Because recording of individual picks is costly and time consuming, it is of interest to know whether or not recording can be restricted to fewer picks without prejudicing the results of experiments. Yield data from five long-term field experiments conducted at five different locations showed that the sum of the first, third and fifth picks could provide a good estimate of the sum of six picks. Yield recording can therefore be confined to these three picks and the cost and time of recording in an experiment reduced by 50%. These three picks can conveniently be used to assess treatment effects on total annual yield.

Análisis estadístico del rendimiento de coco
Effects of High Soil Surface Temperature on Seedling Survival in Pearl Millet
Authors: Peacock J. M. , Soman P. , Jayachandran R. , Rani A. U. , Howarth C. J. , Thomas A.
Published: October 2008

A field technique to screen pearl millet genotypes for their emergence and survival at high soil surface temperatures is described. Genetic variation in seedling emergence and survival is shown and it is argued that this variation is largely due to tolerance of high temperatures rather than tolerance of soil moisture deficit, although some interaction occurred. An index for ‘thermotolerance’ is defined and genotypes are ranked accordingly for this trait, which is shown to be highly heritable. The technique is repeatable and allows a large number of genotypes to be screened at the same time.
Field Evaluation of the Possible Impact of Some Pesticides on the Soil and Water Environment in Nigeria
Authors: Sangodoyin A. Y.
Published: October 2008

A study conducted at Ibadan, Nigeria, showed that some community water supplies were slightly polluted by the pesticides applied on adjacent farms. There was also evidence of soil degradation as a result of agrochemical use, with differences in the physico-chemical properties of soils in fields where agrochemicals had been applied and in adjacent fields that had not been cultivated. Measures that can be taken to minimize some of the environmental dangers inherent in the application of agrochemicals are discussed.
Effects of Light, Temperature, Irrigation and Fertilizer on Photosynthetic Rate in Tea (Camellia Sinensis)
Authors: Gail Smith B. , Stephens William , Burgess Paul J. , Carr M. K. V.
Published: October 2008

Photosynthetic rates were monitored during the warm dry season in tea Clone 6/8 in a line-source irrigation × fertilizer experiment in the Southern Highlands of Tanzania. Irrigation and fertilizer increased photosynthetic rate both by enhancing photosynthetic rate per unit leaf area (A) in healthy leaves and by increasing the proportion of sunlight intercepted by photosynthetically efficient leaves. Irrigation-induced increases in A could be accounted for by increases in stomatal conductance (g) and associated reductions in leaf temperature. Fertilizer at an annual application rate of 225 kg N ha-1 caused increases in A associated with increases in g and improved responses to ambient CO2 concentration and illuminance (photon flux density, PFD). However, a further increase in fertilizer application rate to 375 kg N ha-1 a-1 decreased A in spite of increasing g. Light-saturation of photosynthesis occurred only at the higher fertilizer application rate. In unfertilized tea or tea fertilized at the lower rate, A decreased at a PFD of between 1400 and 2000 μmol m-2 s-l. These results are discussed in terms of the relation between photosynthesis and yield in tea.

Fotosíntesis en el té
Effect of Taking a Fodder Crop on Maize Grain Yield and Soil Chemical Properties in Leucaena and Gliricidia Alley Farming Systems in Western Nigeria
Authors: Larbi A. , Jabbar M. A. , Atta-Krah A. N. , Cobbina J.
Published: October 2008

The effect of managing hedgerow foliage for mulch and fodder in Leucaena leucocephala and Gliricidia sepium alley farming systems on maize grain yield and soil chemical characteristics was studied in on-station and on-farm experiments in southwestern Nigeria. Yields increased as the proportion of mulch applied increased but the extra increases obtained when more than half the foliage was applied as mulch were relatively small, suggesting that half the foliage may be removed as feed without detrimental effect. Soil organic carbon, nitrogen and available phosphorus tended to increase with increasing proportion of prunings applied as mulch.

Follaje para ‘mulch’ y forraje en la agricultura de sendero
Responses of Tea (Camellia Sinensis) to Irrigation and Fertilizer. III. Shoot Extension and Development
Authors: Stephens William , Carr M. K. V.
Published: October 2008

Rates of shoot extension and development (the unfolding of leaves) were recorded in an irrigation × fertilizer experiment on Clone 6/8 at Ngwazi Tea Research Unit in southern Tanzania. The wide range of mean temperatures (from 15–20°C) meant that the duration of the shoot replacement cycle (the time taken for an axillary bud released from apical dominance to develop three leaves and a terminal bud), in fully irrigated tea receiving 450 kg N ha-l, varied from 65 d in the warm wet season to 95 d in the cool dry season, compared with 75 to 180 d for unirrigated and unfertilized tea. Regression analysis indicated that the base temperature for extension, for Clone 6/8 in high-input plots, was about 10°C, some 2–3°C more than that for development. As a result of these differences in base temperature, the length of shoots with three leaves and a bud varied considerably between treatments and seasons, ranging from 15 mm in the unirrigated plots (at the end of the dry season) to 130 mm in the high-input plots at the start of the rains. Shoots from well fertilized tea were always longer (at a given stage of development) than those from unfertilized tea. The results are discussed in terms of the possible mechanisms responsible for the observed responses (changes in partitioning between roots and shoots), commercial harvesting practices and yield modelling.

Extensión y desarrollo de broies en el té
Effects of Temperature, Soil Water Status and Depth of Planting on Germination and Emergence of Maize (Zea Mays) Adapted to Semi-Arid Eastern Kenya
Authors: Itabari J. K. , Gregory P. J. , Jones R. K.
Published: October 2008

The effects of temperature and soil water potential on maize germination were investigated in controlled environment conditions and the effects of depth of planting and a mulch on maize emergence were studied in a field experiment in eastern Kenya. The rate of germination increased to an optimum temperature of 33.6°C above a base temperature of 6.1°C and decreased above the optimum to zero germination at 42.9°C. The thermal time for median germination increased from 51.5°Cd to 56.4°Cd as soil matric potential decreased from -5 to -40 kPa. Soil water content, depth of planting, and their interaction had significant (P < 0.001) effects on final germination and emergence but mulch, or any interactions involving mulch, had no such effects. Increasing depth of planting by 1 cm increased the thermal time required for emergence by 2.8°Cd, and decreasing water content by 1% increased the thermal time required for emergence by 3.2°Cd.

Germinación y emergencia del maíz
Spatial Variability in Soil Chemical Properties under Dactyladenia barteri, Alchornea cordifolia, Senna siamea and Gmelina arborea Hedgerows on an Acid Ultisol
Authors: Ruhigwa B. A. , Gichuru M. P. , Tariah N. M. , Isirimah N. O. , Douglas D. C.
Published: October 2008

Spatial nutrient distribution was studied under a three-and-a-half-year-old fallow of Dactyladenia barteri, Alchornea cordifolia, Senna siamea and Gmelina arborea hedgerows grown on an acid Ultisol in southeastern Nigeria. The objectives were to evaluate the nutrient cycling capacity and suitability of the hedgerow species for alley cropping. No consistent patterns were observed in the lateral distribution of soil pH, total nitrogen, organic carbon, available phosphorus, exchangeable cations (potassium, calcium, magnesium and sodium), total acidity and effective cation exchange capacity in the 4 m wide alleys formed between the hedgerow species. Senna siamea and Gmelina arborea tended to increase soil organic carbon, calcium, magnesium and effective cation exchange capacity, particularly in the top 50 cm, compared with Alchornea cordifolia and Dactyladenia barteri, and can therefore be recommended for soil fertility regeneration on acid Ultisols during periods of fallow. However, they appear to be less suitable for alley cropping than Dactyladenia barteri because they are shallow rooting.

Propiedades químicas delo suelo bajo cuatro especies de seto vivo
An Analysis of the Adoption and Diffusion of Carioca Beans in Zambia Resulting from an Experimental Distribution of Seed
Authors: Grisley W. , Shamambo Moffat
Published: October 2008

Seed of the new heavy yielding bean cultivar Carioca was distributed directly to 400 farmers in Zambia during 1986 in order to speed its adoption and diffusion. Three years after distribution, 55% of the farmers who participated in a follow-up survey were still sowing Carioca. Diffusion of the new cultivar had occurred, with 3.7 times as many farmers estimated to be growing Carioca in 1988/89 as in 1986, an annual rate of diffusion of approximately 49%. Use of a logistic modelling framework suggested that the variables directly associated with the decision to adopt the cultivar were the farmer's total area in cultivated crops and the area in local maize. Variables indirectly associated with adoption were the level of education of the household head, the average number of years that the fields had been in continuous cultivation and the number of cattle owned. These results will help guide the development of effective strategies for the release and distribution of new bean cultivars from national bean research programmes in sub-Saharan Africa.

Adopción y difusión del poroto Carioca en Zambia
Weed Control in Wet-Seeded Rice
Authors: Moody Keith
Published: October 2008

Increasing transplanting costs in southeast Asia have encouraged farmers to adopt labour-saving crop establishment techniques for rice, such as wet seeding. This practice has been accompanied by an increase in weed problems and a shift in the dominant species to grassy weeds. Other problems are encountered with wet seeding but weeds are the most severe and most widespread constraint. It is impossible to produce rice economically without a well-planned weed control programme. The problems caused by weeds in wet-seeded rice and ways of controlling them by preventive, ecological, managerial, physical and chemical means are discussed in this paper. Herbicides are the most cost-effective weed control method in wet-seeded rice but there is a need to reduce the almost total reliance on them for weed control; cultural practices need to be integrated with judicious herbicide use. Worldwide concerns over environmental issues also need to be addressed.

Control de malezas en el arroz de siembra húmeda
Growth and Yield of Millet and Cowpea in Relay and Intercrop Systems in the Sahelian Zone in Years when the Onset of the Rainy Season is Early
Authors: Sivakumar M. V. K.
Published: October 2008

Field trials conducted previously in Niger have shown that in years when the onset of the rains is 15–20 days earlier than average, the long growing season can be exploited by growing a relay crop of millet (Pennisetum glaucum) and cowpea (Vigna unguiculata). In the trials reported here, the advantages of relay cropping were compared with intercropping with improved management and intercropping under traditional management during the 1989, 1990 and 1991 rainy seasons at the ICRISAT Sahelian Center, Sadore, Niger. The length of the growing season varied from 139 to 150 days over the three seasons. The relay crop produced more dry matter and leaf area and yielded more than the intercrops in all three years, confirming that in years when the onset of the rains is early, relay cropping with millet and cowpea is a better option than growing the same two species as an intercrop. Relay cropping avoids the competitive effects inherent in intercropping systems, while offering the additional advantages of rotating cereals with legumes.

Mijo y caupí en sistemas de relevo y de cultivo simultáneo
Guidelines for Improved Agronomic Management and Economic Evaluation of Crop Rotation Trials in Mediterranean Environments
Authors: Keatinge J. D. H. , Somel K.
Published: October 2008

This paper offers guidelines for successful crop rotation trials derived from experience at ICARDA in the period 1980–1990. Emphasis is placed on the need to determine realistically the likelihood of the long-term, successful completion of the trial and the importance of considering carefully experimental design criteria prior to trial establishment. This involves assessment of what primary and secondary information to collect for the trial, and over what duration, in order to ensure an appropriate return for the large investment generally undertaken in any crop rotation trial.

Principios para ensayos con rotación de cultivos
Seed and Seedling Dynamics Over Four Consecutive Years from a Single Seed Set of Six Annual Medics (Medicago SPP) in North Syria
Authors: Cocks P. S.
Published: October 2008

The fate of seed of six annual medics produced in spring 1987 and used in the pasture phase of cereal-pasture rotations was followed over four years. The medics were sown at low and high density, and seed set beyond 1987 was prevented by cultivation in 1988, and by herbicides in 1989 and 1990. The breakdown of hard seed was measured in the summer and autumn of each year, and the number of seedlings was counted after the first seasonal rains in the final three years. The survival of seeds buried at three depths was monitored. Seed of Medicago noeana lived longer than that of M. rotata and M. polymorpha. Survival of M. rigidula and M. truncatula seed was intermediate and there was no effect of planting density on survival. Breakdown of hard seed was least in the first year and increased in the second and third years. Within any year breakdown began in late summer or early autumn, beginning earlier as the seed aged. Seed burial enhanced germination in the year following seed set, depressed it in the second and third years, and had little effect in the fourth year. The net effect of seed burial on survival was therefore slight. The results suggest that the use of medics that have harder seeds than currently available cultivars, and medics in which germination is delayed until late in the autumn, will increase the sustainability and productivity of cereal-pasture rotations in semi-arid areas.

Dinámica de semilla de los Medicago spp anuales en Siria
Environmental and Agronomic Effects on the Growth of Four Peanut Cultivars in a Sub-tropical Environment. I. Dry Matter Accumulation and Radiation Use Efficiency
Authors: Bell M. J. , Wright G. C. , Harch G. R.
Published: October 2008

Four peanut cultivars of Spanish or Virginia botanical type and varying time to maturity were grown at a range of plant densities (44 000 to 352 000 plants ha-1) and spatial arrangements under irrigated conditions in sub-tropical southern Queensland, Australia. Total and pod dry matter production of the very early maturing Spanish cultivar Chico showed strong positive responses to increased plant density up to the highest density tested. Responses were less pronounced for the later maturing Spanish cultivar McCubbin and were minimal for the Virginia cultivars Early Bunch and Mani Pintar. All cultivars were insensitive to spatial arrangements. Accumulation of total dry matter, adjusted for the higher synthesis costs of oil and protein during seed filling, was well correlated to intercepted photosynthetically active radiation (PAR). Much of the variation in dry matter production among cultivars and plant populations could be accounted for by the effects of differing leaf area duration on cumulative intercepted PAR. Radiation use efficiency was negatively associated with the canopy extinction coefficient (k) within most sowing dates, and also negatively associated with minimum temperature across sowing dates for all cultivars except Mani Pintar.

Crecimiento y eficacia del use de radiación en el maní
Environmental and Agronomic Effects on the Growth of Four Peanut Cultivars in a Sub-tropical Environment. II. Dry Matter Partitioning
Authors: Bell M. J. , Wright G. C. , Harch G.
Published: October 2008

The partitioning of dry matter between vegetative and reproductive yield components was analysed for four diverse peanut cultivars at a range of sowing dates and plant populations in sub-tropical Queensland, Australia. Rates of accumulation of pods (pod addition) varied significantly with both cultivar and sowing date. Within cultivars, much of this variation could be attributed to variation in crop growth rate during the critical pod addition period. The proportion of current assimilate distributed to pods depended on inherent cultivar characteristics and also correlated well with the current crop growth rate relative to the crop growth rate during pod addition (that is, with relative source activity). Neither plant density nor spatial arrangement had any significant effects on patterns of assimilate distribution. All cultivars appeared capable of remobilizing stored assimilate to maintain constant rates of pod yield increase despite fluctuations in crop growth rate which might be expected to produce short term source limitations to pod yield accumulation. The harvest index (HI) increased linearly during the entire pod fill period in all cultivars except the very early maturing Spanish cultivar Chico. Neither density nor spatial arrangement affected rate of increase in HI except in Chico, where increased density produced increased rates of increase in HI. Variation in the rate of HI increase among sowing dates was small.

Distributión de la materia seca en el maní
Dissemination of New Technology in a Farming Systems Research and Extension Programme: Diffusion of Rice Varieties in an Area with Poor Production Potential
Authors: Wijeratne Mahinda , Chandrasiri P. A. N.
Published: October 2008

The diffusion of rice varieties introduced into an area with poor production potential and problems of soil degradation was studied in a farming systems research and extension programme. Two rice varieties, BW. 272–3 and At. 85–1 were identified as appropriate for the area and efforts made to transfer the experimental results to the farmers. BW. 272–3 was widely adopted by farmers in the lower, intermediate and upper areas of the recommendation domain but adoption of At. 85–1 was confined to the intermediate and upper areas. Adoption of rice varieties was mainly governed by the characteristics that allowed a variety to perform well under adverse conditions and by the farm gate price it could command, which depended on grain pericarp colour.

Difusión de nuevas variedades de arroz
Plant Water Relations, Irrigation Management and Crop Yield
Authors: Fischer Ralph A. , Hagan Robert M.
Published: October 2008

Responses of crop yield to water stress are classified on the basis of physiological considerations. Crop growth is sensitive to water stress, particularly because of the physiological effects of stress on the production and maintenance of photosynthetic tissue. Crop yield, depending on the nature of the harvested organ and the origin of its constituents, may be more or less sensitive to water stress than crop growth. In applying this information to irrigation management, there is a need for simple quantitative measures of plant water status. The problem of avoiding water stress during critical ontogenetic stages and, conversely, the possibility of using moderate water stress at certain times to improve yield and the efficiency of water usage, are discussed.
The Influence of Fertilization and Cutting on a Tropical Grass-Legume Pasture
Authors: Moore A. W.
Published: October 2008

Experiments involving N, P, and K fertilization, and height and frequency of cutting, were carried out on a mixed pasture of giant stargrass (Cynodon plectostachyus) and centro (Centrosema pubescens) at the University of Ibadan during the growing seasons 1951–61. For the first cut after fertilization yield responses of 17 and 24 per cent resulted from applications of 50 and 100 lb N per acre respectively in various experiments but the effect was transient and recovery of fertilizer nitrogen probably did not exceed 30 per cent. Nitrogen fertilization of sown pastures is unlikely to be an economic practice in Nigeria in the forseeable future. Yield responses of 30 per cent resulted from applications of 2½ and 5 cwt superphosphate per acre with a marked residual effect two years after application. Significantly higher concentrations of extractable inorganic soil P at the higher P fertilization rate after 2 years were largely a reflection of the levels of the iron phosphate fraction, but similar trends were evident in the aluminium and calcium phosphate fractions. No differences were found in total, organic, or residual P. The proportion of centro in one 1959 cut for the 0 and 5 cwt rates of superphosphate were 46 and 38 per cent whereas N had no effect, the reverse of the response normally encountered in a temperate mixed pasture. No response to K was obtained. Increased frequency and height of cutting both resulted in decreased yields of dry matter but cutting at 2–4 inches at 8-weekly intervals appears to be the most satisfactory method of managing this pasture for hay production, with yields of approximately 2¼ tons dry matter per acre.
Storage of Cocoa Seeds
Authors: Swarbrick J. T.
Published: October 2008

After a review of previous work, experiments on cocoa seed storage at the West African Cocoa Research Institute are described. Although no definite recommendations are made as to the optimum methods of storing cocoa seed, the effects of temperature, fungicides, pre-storage in the pod after harvest, air-drying, and some minor factors are described and discussed.
Radiation and Crops
Authors: Monteith J. L.
Published: October 2008

The analysis of radiation climate is a central problem of agricultural meteorology because rates of photosynthesis depend on the receipt of visible light and rates of transpiration depend on the net exchange of radiation by a crop canopy. Both short-wave (solar) and long-wave (terrestrial) radiation are correlated with cloud amount, and in south-east England the income of net radiation in summer is proportional to the income of solar radiation.

In principle, the fraction of total radiation in the visible waveband depends on cloud cover and on the amount of absorption and scattering in the atmosphere, but in practice the fraction is often between 0·40 and 0·45. The calculation of photosynthetic efficiency needs a figure for the number of quanta (or Einsteins) per unit energy, and this figure can be calculated from the mean wavelength of the radiation weighted by energy, about 0·55μ for direct sunlight.

The reflection of radiation by vegetation changes with solar elevation, and at angles between 40° and 60° it ranges between 0·15 for a rough crop (e.g. pineapple) to 0·26 for smoother crops (e.g. sugar beet, kale). The transmission of radiation through the canopy can be expressed as a function of the leaf area index and a parameter that depends on the distribution and orientation of leaves.
Effects of Nitrogen, Phosphorus and Potassium on Nodulation in Cowpea
Authors: Tewari G. P.
Published: October 2008

A factorial (3 × 3 × 3) experiment using three levels of nitrogen, phosphate and potassium was conducted to evaluate the effects of these elements on the formation of nodules. Results indicated that increasing levels of nitrogen depressed the formation of both effective and ineffective nodules, but phosphorus and potash did not produce any significant effects. Although the soils of the experimental plots were highly leached and strongly acid in nature, the native strains of rhizobia were able to produce copious amounts of effective nodules on plants growing on plots where no nitrogen was applied. It appeared that the naturally occurring rhizobia strains in these soils are well adapted to their natural environments.
Deferred Grazing and Nitrogen Fertilization in Southern Australia
Authors: Cocks K. D.
Published: October 2008

A perennial rye-subterranean clover pasture in Western Victoria, Australia, was fertilized at three levels of sulphate of ammonia and subjected to eight cutting treatments over four months in autumn–winter. The cutting treatments simulated deferment of grazing for different periods followed by fortnightly defoliation. Both nitrogen and cutting had significant effects on first cut and total yields for the period. There was interaction between nitrogen, cutting and first cut yield but not between nitrogen, cutting and total yield for the period. The results are used to argue that, in the year of the trial, deferred grazing was likely to have been profitable and nitrogen fertilization to have been unprofitable.
Effects of Fertilizers and Management on Three Promising Tropical Grasses in Jamaica
Authors: Richards J. A.
Published: October 2008

Yields are presented for a 54-week cutting experiment (1962–3) in which coastal bermuda (Cynodon dactylon sp.), pangola (Digitaria decumbens) and guinea (Panicum maximum) grasses were subjected to three cutting heights (1, 3 and 6 inches), four cutting intervals (1, 3, 6 and 9-weeks) and four nitrogen fertilizer regimes (0, 8, 16 and 32 cwt sulphate of ammonia per acre per annum). The results indicate that coastal bermuda and pangola grasses will tolerate severe cutting but not guinea grass. The highest dry matter yields were obtained from guinea grass, at 16½ tons/acre. Whereas the highest yields of coastal bermuda and pangola were 12½ and 12 tons/acre respecitvely. In the absence of measures of nutritive value it is impossible to say which is the best management system to adopt, but the facts presented may help to determine management practices.
The Presentation of Numerical Results of Experiments for Publication in a Scientific Agricultural Journal
Authors: Clarke R. T.
Published: October 2008

Suggested rules are given for the presentation of numerical data in a scientific agricultural journal. These are that all tables of numerical results should be sufficiently clear to render unnecessary any reference to the accompanying text; and that treatment means (and other statistics) should always be accompanied by their standard errors, rather than by least significant differences or by asterisks showing the results of significance texts. Examples are given of correct and incorrect presentation of results, and the graphical presentation of results is also discussed.
An Investigation into Remedies of Sarna (Sarcoptic Mange) of Alpacas in Peru
Authors: Alvarado J. , Astrom G. , Heath G. B. S.
Published: October 2008

At doses of 75 mg./kg. given per os, Neguvon was ineffective against Sarcoples scabiei var. Auchenidae. Benzene hexachloride (BHC) per os was ineffective at doses of 20 mg./kg. and killed alpacas when the dose was increased. Spraying the lesions with BHC killed the acari and lesions quickly disappeared. Psoroptes communis, the cause of otitis in alpacas, was equally susceptible to spraying. Lesions and their location are described and attention is drawn to the possible role of acari in nostrils and perinea in the epidemiology of the disease. Dipping is, at present, the only method of cure worth using, but the search for systemic acaricides should be continued.