bluuebunny/crossref_metadata_2025 huggingface dataset:
Evapotranspiration, Water Use Efficiency, Moisture Extraction Pattern and Plant Water Relations of Rape (Brassica campestris) Genotypes in Relation to Root Development under Varying Irrigation Schedules
Authors: Raja V. , Bishnoi K. C.
Published: October 2008

A field experiment was conducted on sandy loam soil at Hisar, India during the autumn seasons 1984–85 and 1985–86 to study root characters, evapotranspiration, water use efficiency, moisture extraction pattern and plant water relations of rape genotypes under varying irrigation schedules. Root volume and dry weight increased, while tap root and lateral root lengths decreased with irrigation. Increased irrigation frequency increased evapotranspiration but decreased water use efficiency. The relative water content and osmotic potential of the leaves increased with more frequent irrigation, but plant water retention capacity decreased. There were genotypic differences between the characters examined.
Grain and Forage Yield and Stover Quality of Sorghum and Millet in Low Rainfall Environments
Authors: Youngquist J. B. , Carter D. C. , Clegg M. D.
Published: October 2008

The potential for using sorghum and millet crop residues as fodder was studied in southeastern Botswana. This region is characterized by low, unevenly distributed rainfall and shallow sandy soils. There were significant differences among cultivars for grain and stover yield, digestibility, crude protein, and mineral content, but no species advantage. Stover from all entries was adequate for cattle maintenance inin vitrodry matter digestibility (IVDMD) and most of the minerals tested, but crude protein and phosphorus levels did not always meet the minimum requirement. The deficient phosphorus levels were compounded by high calcium levels. This mineral imbalance could lead to bone abnormalities and reduced fertility in livestock.
Root Response to Water Stress in Rainfed Lowland Rice
Authors: Thangaraj M. , O'Toole J. C. , De Datta S. K.
Published: October 2008

The relation between soil mechanical impedance as a result of soil drying, and root system growth (mass and length density) of rice was investigated in greenhouse and field studies. In a greenhouse experiment, soil drying for 16 days increased mechanical impedance in the 0–20 cm soil layer from near 0 to 2.5 MPa, and decreased root growth by 47% compared to the continuously flooded control. Root length density decreased with decreasing soil moisture and increasing soil mechanical impedance. In a lowland field experiment using a sprinkler irrigation gradient treatment for 19 days during the vegetative growth stage, soil mechanical impedance as low as 0.01 MPa inhibited root growth while values greater than 0.3–0.5 MPa decreased root growth and extension by 75%. The relative loss of potential root growth was continued after reflooding. Root length density, measured at flowering, was linearly related to yield.
Time and Method of Weed Control in Pearl Millet
Authors: Singh Rajinder , Yadav S. K
Published: October 2008

Field experiments during the rainy seasons (July–October) of 1984 and 1985 at Hisar, India showed that removing weeds in pearl millet from 10 to 60 days after sowing led to fewer weeds at harvest, and significantly higher grain yields were obtained when weeds were removed 20 days after the crop was sown. All the weed control methods tried (hand hoeing, hand wheel hoeing, or application of terbutryne or atrazine) were successful and significantly increased crop growth and grain yield. The maximum grain yield was obtained with atrazine at 0.5 kg ha−1 and the minimum in the unweeded control.
Photosynthesis of Cassava (Manihot esculenta)
Authors: El-Sharkawy Mabrouk A. , Cock James H.
Published: October 2008

In recent studies of cassava at CIAT, net CO2uptake rates of 20 to 35 μmol CO2m−2s−1were commonly observed. Cassava photosynthesis has a high optimum temperature (35°C) and a wide plateau (25 to 35°C) corresponding to the temperature range under which cassava is cultivated. Leaf photosynthesis requires high saturation irradiance (1500 μmol m−2s−1) and the rates are greatly reduced by leaf-air vapour pressure differences above 1.5 kPa; this reduction is associated with stomatal closure. Cassava leaves have low photorespiration, low CO2compensation point, high percentage of carbon fixation in C4acids and a high PEP-carboxylase activity (15–35% of that in maize), but cassava does not have the typical ‘C4-Kranz’ anatomy. Field measurements of single leaf photosynthesis among a wide range of cultivars grown under rain-fed conditions showed that when light interception was not limiting, there were significant correlations between leaf photosynthesis, total biomass and root yield. This suggests that the use of parental materials with high photosynthetic capacity, in combination with other yield determinants, could be a successful strategy for developing high yielding cultivars. This might be done by exploiting any genetical variations in leaf anatomy and biochemistry that could enhance photosynthesis efficiency and hence productivity.
The Digestibility of Fodder Maize and Maize Silage
Authors: Harris C. E.
Published: October 2008

The dry-matter and organic-matter digestibilities of eight samples of fodder maize and five samples of maize silage were measured, using sheep. The maizes were harvested and ensiled in such a way that comparisons could be made between the digestibilities of either the same maturity types, harvested on different dates, or of different maturity types harvested on the same date, or of maize and silage made from similar material. The total range of organic matter digestibility for all types of maize on all dates was within the range 70·6 to 75·2 per cent. The digestibilities of maize silages were found to be slightly lower than those of the original materials.
Effects of Ground Covers and Fertilizers on Establishment and Yield of Cocoa on Clear-Felled Land in Ghana
Authors: Acquaye D. K. , Smith R. W.
Published: October 2008

An experiment is described on the establishment of cocoa on clear-felled land, using various ground covers on which 22 NP:KMg factorial treatments were later superimposed. Growth of cocoa was improved in mulched and clean-weeded plots and the unshaded trees began bearing two years after planting, which is exceptionally early for young cocoa in Ghana. In the third year responses to NP fertilizer were obtained and in the following year yields were very high, up to 2170 pounds dry cocoa per acre. This was partly responsible for K deficiency, particularly in plots without mulch and KMg, which led to declining yields especially on the NP plots. Significant increases were thence obtained from the KMg fertilized plots. Mulching at the rates used in this experiment is too expensive and uneconomic, but K fertilizer applied at rates higher than the present rate of 75 lb K2O/acre/annum may be needed on Ghanaian forest soils if they are clear-felled for growing unshaded cocoa.
The Production of Raphia Wine in Nigeria
Authors: Tuley P.
Published: October 2008

The pattern of yield and productivity of a typical Raphia swamp is described and suggestions are made for improving the crop by selection
Effects of Grass Mulch on Groundnuts in the Gambia
Authors: Ashrif M. I. , Thornton I.
Published: October 2008

The effect of grass mulch on groundnut yield and shelling percentage has been studied at three locations in the Gambia. Yield increases have been mainly attributed to physical factors but residual increases were found for only one year after application. Mulching gave rise to significant increases in exchangeable soil potassium, in percentage potassium in the plant at harvest and in total potassium uptake by the plant. In the absence of response to potassium fertilizer, increased uptake was ascribed to luxury consumption. It was suggested that reduced shelling percentage from mulched plots was due to potassium-calcium antagonism.
Integrating Agronomic and Economic Perspectives into the Diagnostic Stage of On-farm Research
Authors: Byerlee Derek , Triomphe Bernard , Sebillotte Michel
Published: October 2008

Crop production surveys, which integrate the collection of data on both agronomic and economic variables, are increasingly common in on-farm research. A conceptual framework for designing and analysing such surveys is provided. Methodological issues in conducting crop production surveys are reviewed with respect to type of information collected, level of field observation, degree of quantification, frequency of observation, sampling, measurement of yields and yield components, and analysis of yield limiting factors. It is concluded that, while better integration of agronomic and economic perspectives in diagnosis may increase costs, the information and analysis obtained have considerable potential to improve the efficiency of experimentation.
Farming Systems Adaptive Research: Achievements and Prospects in Southern Africa
Authors: Low Allan , Waddington S. R.
Published: October 2008

Farming Systems Adaptive Research (FSAR) has contributed much to the understanding of maize production constraints on smallholder farms in southern Africa in the last six to eight years. But its production impact has been constrained by the often inappropriate technology available to FSAR from component research and the ineffective use of its results by extension staff. However, FSAR has demonstrated the utility of a problem (client) orientated approach to technology development, which is now being taken up by some maize commodity research and extension programmes, though effective linkages have not usually been developed. Nevertheless, experience in southern Africa suggests that the FSAR approach can provide a framework for developing more effective integration between key groups involved in technology generation, dissemination and support.
Control of Grain Yield by Sink Capacity and Assimilate Supply in Various Rice (Oryza sativa) cultivars
Authors: Fukai S. , Li L. , Vizmonte P. T. , Fischer K. S.
Published: October 2008

The objective of this study was to identify whether grain yield in four contrasting rice cultivars is limited by supply of assimilate to fill the grains or by sink capacity to accept the assimilate. Grain yield was limited mostly by sink capacity, with little variation in single grain weight among cultivars, but an old cultivar showed some ability to adjust single grain weight. Sink capacity was very sensitive to variation in assimilate supply immediately after anthesis. Reduction in assimilate supply in the anthesis to early grain filling period reduced filled grain percentage and grain yield, particularly in high yielding cultivars with a large number of grains per panicle.
Effect of Intensity and Timing of Defoliation on Growth, Yield Components and Grain Yield in Maize
Authors: Yao N'Guettia R. , Yeboua Kabrah , Kafrouma Angbonou
Published: October 2008

Early season defoliation of maize significantly reduced plant height and leaf area index but leaf number and leaf emergence rate were not affected. Ear development was significantly affected by both early and late season defoliation although tassel development was barely influenced. Silk growth was the phase of ear development most sensitive to defoliation. Early season defoliation significantly reduced all yield components, leading to yield losses ranging from 54 to 100%. The position of the leaves which were removed had an important effect on the final grain yield. Harvest index was affected by both the intensity and timing of defoliation.
Effect of Sowing Date on the Growth and Yield of Lentil in a Rainfed Mediterranean Environment
Authors: Silim S. N. , Saxena M. C. , Erskine W.
Published: October 2008

The effect of advancing the sowing date from early February to November on the growth and seed and straw yields of three large seeded and three small seeded lines of lentil (Lens culinaris) was studied under rainfed conditions in northern Syria between 1982 and 1985. The average seed and straw yields from early winter sowing were 838 and 2476 kg ha−1 compared with 679 and 1470 kg ha−1, respectively, from a late sown crop. There were seasonal differences in the advantage in seed yield from early sowing, largely because infestation by Orbanche species limited the use of early sowing. There were no overall differences between the growth and yields of large and small seeded lines, but genetic variation within groups was apparent for all characters. A high rate of dry matter accumulation, manifested as early vigour, was always related to a high final economic biomass.
Responses of Tea (Camellia sinensis) to Irrigation and Fertilizer. I. Yield
Authors: Stephens William , Carr M. K. V.
Published: October 2008

The yield responses of clonal tea (Clone 6/8) to irrigation and fertilizer were studied in a field experiment (based on the line-source technique) at a high altitude site (1840 m) in the Southern Highlands of Tanzania over a three-year period. In this area (latitude 8°33′S) the annual dry season can last up to six months with potential soil water deficits reaching 600 to 700 mm. In the third year of the experiments yields for the fully irrigated, well fertilized (375 kg N ha−1) treatments had reached 4.9 t ha−1 of made tea. These were reduced by about 2.9 kg ha−1 for each mm increase in the potential soil water deficit. For tea with little or no fertilizer applied the loss of yield was about 1.4 kg ha−1 mm−1. These figures provide a basis for assessing the potential benefits from irrigation where other factors, such as large saturation deficits of the air, do not restrict shoot extension and yield. Yield responses to nitrogen (applied as N:P:K 20:10:10) were essentially linear up to a maximum of about 375 kg N ha−1 in the fully irrigated plots, and 300 kg N ha−1 for the unirrigated plots. Irrigation increased the proportion of crop harvested during the dry season, up to 45% in the fully irrigated treatments. The commercial implications of these results for ‘high’ and ‘low’ input producers are discussed.
Effects of Sweet Potato Virus Disease (SPVD) on the Yield of Sweet Potato Genotypes in Cameroon
Authors: Ngeve J. M. , Bouwkamp J. C.
Published: October 2008

Sweet potato virus disease (SPVD) causes strap-shaped leaves, vein-clearing, puckering, chlorosis and stunting in susceptible sweet potato varieties and yields are much reduced. To investigate the tolerance of genotypes and obtain a better appraisal of yield loss caused by SPVD, eight sweet potato varieties showing symptoms of SPVD were studied for two years in an area where SPVD is severe. Two varieties, although showing symptoms, were tolerant of the disease; their yields were not significantly depressed by SPVD. Among the remaining six varieties, storage root fresh yields were reduced by 56–90% in plants showing SPVD symptoms. Marketable yields, as well as total and marketable numbers of storage roots were similarly depressed by SPVD in the less tolerant varieties. Significant correlations were found between disease severity rating and yield reduction among cultivars.
Improving Productivity of an Upland Rice and Maize System: Farmer Cropping Choices or Researcher Cropping Pattern Trapezoids?
Authors: Fujisaka Sam
Published: October 2008

Cropping systems research to improve the productivity of an acid upland rice and maize-based farming system is described and evaluations by co-operating farmers are presented. Farmers rejected introduced patterns. The cropping choices of non-cooperating farmers are described in terms of cost–benefits and the reasons underlying their decisions. An approach that combines an understanding of farmers' systems in order to conduct focused research on the weak points of such systems, together with an evaluation of farmer technology and adaptation, may be more effective than researcher-designed, farmer-implemented cropping pattern trials.
A Comparison of Natural Rock Phosphate with Imported Cotton Fertilizer in Cotton/Cereal Rotations in Mali
Authors: Kagbo Robert B.
Published: October 2008

On-farm trials were carried out in the Operation Haute Vallée project, Mali, to assess the possibility of replacing, partially or entirely, imported cotton fertilizer with natural rock phosphate from a local source, and to assess the residual effect on maize and sorghum grown after cotton. The maize/cotton sequence, although not normally used by Malian farmers, was more profitable than either pure cotton grown alone or a cotton/maize sequence when local rock phosphate was used instead of imported fertilizer.
The Effect of Tied Ridge Cultivation on the Yield of Maize and a Maize/Cowpea Relay in the Gambia
Authors: Wright J. P. , Posner J. L. , Doll J. D.
Published: October 2008

The growing season in the semi-arid region of West Africa is drought prone and of irregular duration. Two experiments were conducted in 1986 and 1987 to test the effects of flat cultivation and tied ridge cultivation (TRC) on the yields of maize and the component crops of a maize and cowpea relay cropping system. The two research sites, with slopes of 0.05% and 3%, were near Sapu, The Gambia, on an Aridic Kandiustalf in the 700 mm rainfall zone.

Both growing seasons had above average rainfall. In both years, maize on level sites showed no response to tillage practices. On the sloped site in 1987, soil moisture 10 and 15 days after the last rain was greater with TRC than with flat cultivation and yields of sole cowpea and maize were 25% and 18% greater, respectively. On the level site, TRC had no effect on residual soil moisture or grain yield. When rainfall was well distributed, tied ridging did not appear to be a viable tillage alternative for maize-based systems on flat land in central Gambia but with modest slopes, tied ridges markedly increased soil water reserves in the 0.15 to 0.60 m depth after maize harvest.
Mixed Planting of Potato Cultivars: Growth, Yield and Leafminer Damage in the Cool Tropics
Authors: Midmore D. J. , Alcazar J.
Published: October 2008

The influence of planting mixtures of two potato cultivars on the incidence of leafminer fly (Liriomyza huidobrensis (Blanchard)) and on damage to potato foliage, and the effect on growth and yield, was studied in two field experiments in coastal Peru. Climatic differences between the two years of the experiments (1983 and 1984) had a greater effect than did cultivar mixtures on adult fly populations and on the numbers of feeding punctures and pupae per leaflet. Mixtures reduced the number of pupae in the tolerant cultivar, but increased it in the susceptible cultivar; in contrast, mixed planting tended to decrease the adult populations and feeding punctures in the susceptible cultivar of each mixture. In neither year did mixture yields or intercepted radiation exceed those of the highest-yielding sole crop, although land equivalent ratios (LER) reached 1.19. Considering the cultivars' different maturity rates and their tuber growth curves, it is probable that the later maturing cultivar of each mixture was able to exploit available light after, and perhaps even before, senescence of the earlier cultivar. Mixed planting of potato could be beneficial but only to farmers who plant both early and late cultivars, under conditions where the early harvest commands a premium price.
An Evaluation ofRhizobiumSurvival in two Carriers new to Sudan
Authors: Elshafie A. E. , Elhussein A. A.
Published: October 2008

The suitability of charcoal and filter mud as carriers for the survival ofRhizobiumisolates at low and high temperatures was investigated. Both carriers were found to be suitable and maintained high rhizobia populations (1.0 × 108rhizobia g−1). In Sudan, inoculants can safely be stored for 6–10 weeks in the ambient temperature (up to 37°C).
Dry Matter and Nitrogen Accumulation and Partitioning in Field Grown Winged Bean
Authors: Weil R. R. , Belmont G. S.
Published: October 2008

Growth and the partitioning of dry matter and nitrogen were studied in winged bean ‘SLS-40’ grown with single stake supports at two sites in Sri Lanka. Plant parts (leaves, petioles, stems, roots, nodules, flowers, green pods, mature seeds, and mature pod-walls) were collected periodically, if present, for up to 32 weeks after emergence. Slow growth up to the seventh week was followed by rapid growth (2.8 g plant−1 day−1) for the next 15–17 weeks. Little leaf senescence was observed and the nitrogen content of the leaf tissue remained close to 45 mg N g−1 throughout growth. The rate of nitrogen accumulation was 2.3–2.7 kg N ha−1 day−1 between weeks 13 and 32. The final accumulation of nitrogen in the above ground material was 280 to 312 kg N ha−1, only 34% of that being in the mature seed. The harvest index for dry matter was 17.5–20% and the dry seed yield almost 2 t ha−1.
Institutionalizing the Farming Systems Perspective in Multi-commodity Research Institutes: The Role of Systems-based Research Groups
Authors: Spencer Dunstan S. C.
Published: October 2008

Research institutes in Africa have had limited success in producing new technologies appropriate to the needs of small farmers because of an inadequate understanding of small farmers' goals and resource limitations and over-reliance on the transfer of technologies from other regions. Farming systems research (FSR) is an effective way of improving the focus of scientists on the problems farmers face. Vertically segmented thematic research programmes make institutionalization of FSR difficult within multi-commodity research centres, particularly the International Agricultural Research Centres. The Farming Systems Research Group has proved effective at overcoming such difficulties at the International Institute of Tropical Agriculture. Its organization, operation and effects on the performance of the research programmes are described.
Towards the Reliable Prediction of Time to Flowering in Six Annual Crops. I. The Development of Simple Models for Fluctuating Field Environments
Authors: Summerfield R. J. , Roberts E. H. , Ellis R. H. , Lawn R. J.
Published: October 2008

Despite numerous altempts, the development of generalixed models capable of accurate predictions of the times from sowing to flowering (f) of crop plants in field environments has remained elusive. Models which seek to correlate;ʃwith various states of environmental factors such as photoperiod,P, and temperature,T, using formal statistical procedures arc often complex. Here, we describe a family of photothermal responses (involving unambiguous parameters and limits) which quantify the linear, non-interacting effects ofPandT notonʃbut on 1/ʃ, i.e. on therateof progress towards flowering. Based on these relations we suggest that the modelling of crop phenology will be simplified, more reliable and more biologically plausible.
The Search for a Viable Alternative to Slash and Burn Agriculture in the Lowland Plains of Bolivia
Authors: Wilkins J. V.
Published: October 2008

A multidisciplinary team has attempted to find a sustainable alternative to slash and burn agriculture in deciduous forest in the Bolivian lowlands for those who do not have access to tractor power. Farm size ranges from 30 to 50 hectares and labour and capital are major constraints to development. Fertilizers are not used because of their high price. The alternative proposed is that the farm should contain an area of not more than one hectare in alley cropping producing the family's requirements in farinaceous foods and vegetables, and an area, limited by labour constraints, of perennial crops for cash income. The balance of the farm would be in a silvipastoral system producing various tree products, beef and cheese for sale and sheep for home consumption.
Use of Growth Measurements and Foliar Nutrient Content as Criteria for Clonal Selection in Tea (Camellia sinensis)
Authors: Nyirenda H. E.
Published: October 2008

A selection programme conducted on young clonal tea plants grown in large sleeved bags and in a field trial established criteria for selecting high yielding field clones on the basis of their growth in early years. Bush area, number of branches and shoots per bush, and foliar phosphorus content at the second crop peak were correlated with yield but the correlation between stem circumference at ground level and yield was inconsistent. It is therefore concluded that all these bush and growth characters, apart from stem circumference, may be reliably used to predict and select high yielding tea clones.
Rain-fed Crop Production Systems of Upland Balochistan: Wheat (Triticum aestivum), Barley (Hordeum vulgare) and Forage Legumes (Vicia species)
Authors: Rees D. J. , Islam M. , Samiullah A. , Rehman Fahema , Raza S. H. , Qureshi Z. , Mehmood S.
Published: October 2008

The effects of variety and fertilizer on wheat and barley production, and of inoculation with rhizobium on Vicia crop production under rain-fed conditions were observed in farmers' fields in Balochistan from 1985 to 1988. Weeding and application of phosphate fertilizer had little effect on wheat yields, but in the ‘good‘ rainfall year, 1986/87, application of nitrogen fertilizer resulted in increased economic yields. Barley varieties from Syria generally produced better grain yields and, with the exception of Arabi abiad, poorer straw yields than a local variety. Genotype–environment analyses indicated that Arabi abiad could be expected to produce more grain, similar amounts of straw and larger gross benefits than the local variety in all except the most severe environments, when crop failure was inevitable. V. villosa ssp. dasycarpa showed negligible amounts of cold damage, and produced greater herbage and straw yields than the other legume crops. Inoculation with Rhizobium leguminosarum produced large yield increases in 1986/87.

The economic returns from crop production were poor and variable, but the results suggest that the productivity of the crop–livestock system could be increased by greater emphasis on barley, and by the introduction of Arabi abiad barley and V. villosa ssp. dasycarpa.

D. J. Rees et al.: Cultivos regadospor la lluvia de las tierras altas de Balochistan.
Institutional Considerations in Strengthening On-farm Client-Oriented Research in National Agricultural Research Systems: Lessons from a Nine-Country Study
Authors: Merrill-Sands D. M. , Biggs S. D. , Bingen R. J. , Ewell P. T. , McAllister J. L. , Poats S. V.
Published: October 2008

Many national research systems have launched major on-farm research efforts aimed at generating relevant technologies for resource-poor farmers, but institutional and policy factors have often hindered the effectiveness of these efforts. Experience has shown that on-farm research, linking farmers, researchers, and technology transfer agents, poses special organizational and managerial challenges. Institutional innovations and strong policy commitment are needed if on-farm research is to succeed in meeting the needs of resource-poor farmers. Sound research methods alone are not sufficient.

This paper reviews key policy, organizational and managerial considerations for integrating on-farm client-oriented research as an effective and stable component of national agricultural research systems. It summarizes the findings of a major study sponsored by the International Service for National Agricultural Research on institutional factors affecting the performance and sustainability of such research systems. The conclusions are based on the systematic analysis of over 25 discrete on-farm research efforts in nine developing countries. The objective is to provide research managers, on-farm researchers and on-farm research advisors with concrete and practical insights for strengthening on-farm research and its contribution to the generation and transfer of relevant technologies.

Integración de la investigación de granja con los sistemas nacionales
productivity of wheat and alfalfa under intercropping
Authors: Abdel Magid H. M. , Ghoneim M. F. , Rabie R. K. , Sabrah R. E.
Published: October 2008

Field experiments were carried out under irrigation in Central Saudi Arabia during the winters of 1987–88 and 1988–89 to examine the productivity and quality (grain protein content) of wheat intercropped with inoculated and uninoculated alfalfa with or without additional nitrogen. Nitrogen increased wheat grain yield and protein percentage but inoculation of the alfalfa had no additional effect. Herbage yield of intercropped alfa4fa was unaffected by nitrogen application. Added nitrogen reduced the protein percentage in alfalfa but increased its protein yield. Intercropping had benefits for alfalfa, increasing its protein content and yield.

Siembra simultánea de trigoy alfalfa
Growth and Yield of Maize Genotypes during Dry Seasons in Northern Nigeria
Authors: Yunusa I. A. M. , Gworgwor N. A.
Published: October 2008

Two tropical and one temperate genotypes of maize were grown during the cool dry winter seasons in northern Nigeria. The tall tropical genotypes produced a greater leaf area index and more above-ground dry matter, and so had a higher crop growth rate, than the dwarf temperate genotype. However, the early flowering temperate genotype yielded more grain than the late flowering tropical genotypes. Although the initial low winter temperatures prolonged the preflowering growth period in the tropical genotypes, the terminal high temperatures hastened maturity and were associated with poor grain filling.

Maíz de temporada seca en Nigeria
Observations on Insect Infestation and Damage in Cowpea (Vigna Unguiculata) Intercropped With Tomato (Lycopersicon Esculentum) in a Rain Forest Area of Nigeria
Authors: Ofuya T. I.
Published: October 2008

Insect infestation and damage in cowpea (Vigna unguiculala), planted sole or intercropped with tomato (Lycopersicon esculentum) was monitored in 1987 and 1988 in Akure, Nigeria. Infestation of cowpea byEmpoasca dolichiwas significantly reduced by intercropping with tomato in both years, except in the early season of 1988. Infestation of cowpea byOotheca mutabilis, Aphis craccivora, Megalurothrips sjosledti and Maruca testulaliswas not affected by intercropping with tomato in either year. Damage by pod-sucking bugs and Heliothis armigera was significantly higher in sole cowpea than in cowpea intercropped with tomato, in both years. Sole cowpea had a significantly lower seed yield than cowpea intercropped with tomato.

Observaciones en cuanto a la infestación de insectos y daños en el caupí(Vigna unguiculata)sembrado en forma simultánea con tomate(Lycopersicon esculentum)en una zona de bosque tropical en Nigeria
Rock Phosphates in Agriculture
Authors: Le Mare P. H.
Published: October 2008

The principles that control effectiveness of rock phosphates as fertilizer are now fairly well understood so that the potential effect of a material can be predicted with some confidence from laboratory analysis of the raw material. Soil characteristics, especially acidity, and calcium and phosphate status, are important: if these are not conducive to dissolution, crop response to rock phosphate is small. Some crop characteristics, especially the extent of root systems and whether they are infected with mycorrhizae, also affect utilization of rock phosphate. Dissolution of rock phosphates may be too slow for rapidly growing crops but may be adequate for perennial crops.

Such factors limit the use of rock phosphates for direct application, so that much greater knowledge of the characteristics of the phosphates, soils and crops, and their interactions, is necessary for their successful use than for the soluble phosphates. Economic considerations are important also. Because the phosphate content is less than that of concentrated soluble fertilizers, the cost of transporting rock phosphates, per unit of phosphorus, may not be economic. However, for acid and calcium deficient soils the larger amounts of calcium that rock phosphates supply may be an advantage and may lessen or eliminate the need for lime, especially for crops that require relatively large amounts of calcium.

Fosfatos de roca en la agricultura
Using On-farm Trials to Study the Benefits of Feed Legumes in Barley-based Rotations of North-West Syria
Authors: Thomson E. F. , Jaubert R. , Oglah M.
Published: October 2008

On-farm trials were conducted for seven years in north-west Syria to investigate the use of land left fallow after a barley crop to grow feed legumes for small ruminants. Common vetch (Vicia sativa), forage peas (Pisum sativum) and common chickling (Lathyrus sativus), with and without applied phosphate fertilizer, were grown in rotation with barley and a barley-fallow rotation was used as a control.

Vetch was preferable for grazing whereas chickling yielded more grain and straw and had a higher harvest index. Both species showed substantial responses to phosphate fertilizer. Yields of subsequent barley crops were slightly lower after unfertilized feed legumes than after fallow but after fertilized feed legumes, barley yields were higher than after fallow. The milk production of ewes and liveweight gains of lambs grazing vetch, chickling and common land were similar.

The project showed how results from on-farm research can modify on-station research objectives and identify questions for further on-station research.
On-farm Experiments as a Diagnostic Method: Constraints to Nitrogen Fertilizer Use on Sorghum in Semi-arid Tropical India
Authors: Dvořák Karen Ann
Published: October 2008

On-farm diagnostic experiments were used to study constraints to nitrogen fertilizer use, define recommendation domains, and test fertilizer management techniques for two sorghum cropping systems in semi-arid tropical India. In the post-rainy season sorghum cropping system, nitrogen fertilizer use remains negligible because crop response is poor when sorghum is planted after the end of the monsoon, as is traditional. An earlier planting date would introduce high risks. In the dependable rainfall region, nitrogen fertilizer use on hybrid sorghum could be enhanced by tailoring recommendations to broad farmer-designated soil groups, and by educational programmes on the use of complex fertilizers. Additional research on fertilizer efficiencies on shallow Vertisols is needed. Diagnostic experiments proved a useful, relatively rapid and low cost method of research when complemented by farm management and on-station research data.
On-Farm Assessment of Improved Crop Production Practices in Northwest Syria. I. Chickpea
Authors: Pala M. , Mazid A.
Published: October 2008

Thirty on-farm trials were conducted in northwest Syria over a period of four seasons to examine the main effects and interaction of sowing date, sowing method, Rhizobium inoculation, phosphate application and weed control on chickpea (Cicer arietinum). Advancing the sowing date from spring or late winter to early winter resulted in substantial yield increases. The effects of Rhizobium inoculation were small and inconsistent. Chemical weed control significantly increased grain yield compared with the unweeded control treatment in winter-sown crops but was less effective than hand weeding. Phosphate application significantly increased yield in the first three seasons, the overall increase being 10%. Drilling chickpea seed gave an overall 10% increase in yield compared with the broadcast sowing commonly practised by farmers. There is no economic or environmental risk to the farmer in adopting the proposed practices either singly or in combination. However, the greatest gains in yield and net revenue are derived from a combination of early winter sowing, drilling, weeding and, where appropriate, phosphate application.
On-farm Assessment of Improved Crop Production Practices in Northwest Syria. II. Lentil
Authors: Pala M. , Mazid A.
Published: October 2008

The production of lentil (Lens culinaris) was examined in 24 on-farm trials conducted over three seasons (1985/86 to 1987/88) in northwest Syria to examine the main effects and interaction of sowing date, weed control, Sitona weevil control, and fertilizer application (phosphorus and nitrogen). Advancing the date of sowing from late winter (mid January) to early winter (mid-November) resulted in an increased yield of grain and straw in all years across locations. Responses to phosphorus application were also significant in all years. Controlling Sitona weevil increased grain yield by 20% in early sown crops and by 14% in those that were sown late. Weed control by the pre-emergence application of cyanazine and pronamide increased grain yield by 59% in early sowings and by 20% in late sowings. Economic analysis of the improved production practices showed that early sowing combined with the control of Sitona and weeds, and phosphorus application, gave the highest probability of an increase in net revenue with virtually no risk of economic loss to the farmer.
Farming Systems Research in Remote Areas in Nepal: The Need for a New Approach to On-farm Research and Extension
Authors: Gibbon David , Schultz Michael
Published: October 2008

On-farm research in remote areas demands methods that keep down costs and reduce the need for subsequent research and extension inputs and yet that still produce useful and sustainable recommendations. An important part of the process is to identify existing resource user groups and use them, rather than individual farmers, as a starting point for on-farm research. This approach is discussed in the context of farming systems research in the eastern hills of Nepal.
Intercropping and Diversity: An Economic Analysis of Cropping Patterns on Smallholder Farms in Malawi
Authors: Shaxson Louise , Tauer Loren W.
Published: October 2008

The diversity of cropping patterns on smallholder farms in southern Malawi was analysed using a framework that explicitly incorporates the extent of intercropping in each field. Diversity is defined as the relative abundance of each crop in the overall cropping pattern. Six indices of diversity were constructed for 208 farms and used in a model of a welfare-maximizing farm household to examine the reasons for diversity in cropping patterns; multiple regression techniques were used to determine the effect of different household characteristics on diversity. The results suggest that an increase in labour availability over the production period is associated with a more diverse cropping pattern. Landholding size also influences diversity, which rises to a maximum and then falls as the area cultivated per capita increases. Farmers who grow a non-food cash crop (tobacco) have more diverse cropping patterns than those who do not. As diversity increases, farmers use intercrop patterns that are more substitutive than additive.
Data Analysis in Agricultural Experimentation. I. Contrasts of Interest
Authors: Pearce S. C.
Published: October 2008

An experiment has its origin in the need to find answers to stated questions. From the start great care is given to its correct conduct (e.g. the application of treatments and the method of recording) as well as to statistical design, always with the original questions in mind. The analysis of its data is the climax of a long process and the questions to be answered must dominate all else. It is not enough to feed data into a computer package in the hope that it will provide an automated path to a true interpretation.

Where the treatments have been chosen with care to answer specific questions, the statistical way of designating purpose is to declare ‘contrasts of interest’, each corresponding to a degree of freedom between treatments. They derive solely from the reasoning behind the selection of treatments. If possible the questions posed should be equal in number to the degrees of freedom and should admit of separate study because no one can give a single answer to several diverse questions.

This paper shows how to define a contrast of interest and how to isolate it in the analysis of variance. Attention is given both to its contribution to the treatment sum of squares and to its variance (i.e. the precision with which it is estimated). Independence of estimation is also considered. Algebraic formulae are given for a restricted though important range of designs, which includes those that are completely randomized, in randomized blocks or in Latin squares, all treatments having the same replication. The methods can, however, be generalized to cover all designs. With these formulae it is possible both to test the existence of an interesting effect and to set confidence limits round its estimated value.
Measuring Light Interception and the Efficiency of Light Utilization by the Coconut Palm (Cocos nucifera)
Authors: Moss J. R. J.
Published: October 2008

A mobile sampling method was used to measure the amount of photosynthetically active radiation (PAR) transmitted through the canopies of coconut palms in two long term field trials. PAR transmissions were measured at approximately monthly intervals for one year. Fractional interception of light was found to vary considerably between months, and to be associated with frond shedding caused by dry season water stress. Palms receiving potassium fertilizer intercepted more light and replaced leaf area lost during the dry season more rapidly than those receiving no potassium. Palms planted at a higher density intercepted more light and carried more fronds per palm, but intercepted less light per frond than those planted at a lower density. The ratio of moles of carbohydrate yield to moles of intercepted PAR quanta was calculated for six plots of hybrid palms, giving a dimensionless light efficiency index (LEI) comparable to harvest index. Mean LEI for all plots was 1.275 × 10−4 and was found to increase with increased light interception, results suggesting that there is a basal level of light interception below which no yield is produced. The potential for using LEI in agronomic experimentation on sole cropping and multicropping and as a criterion for genetic selection of coconut palms is discussed.
Banana and Bean Intercropping: Factors Affecting Bean Yield and Land Use Efficiency
Authors: Wortmann C. S. , Sengooba T. , Kyamanywa S.
Published: October 2008

Beans and bananas were grown in sole crop and intercrop systems for three seasons in 1989 and 1990 to determine the effects of cropping system on diseases, insects and land-use efficiency and the roles of certain bean plant physiological traits on bean yield in the two systems.

Bean yield in the intercrop system was 52% of bean sole crop yield. Shading reduced yield, but stem starch levels, chlorophyll content and the chlorophyll a:b ratio were not related to seed yield in either system. Leaf area index was linearly related to yield in the intercrop system, suggesting that a higher plant density may result in higher yields. Nutrient concentration levels in the foliar tissues indicated that low potassium and high manganese availability constrained intercrop bean yield. Leaf manganese levels were higher in beans grown under bananas, reaching levels normally considered toxic for beans. Competition for other nutrients did not appear to affect bean yield. Apparently, interspecies competition for soil moisture did not much reduce bean yields as moisture levels did not differ with cropping system. Disease and insect pest levels were similar for the two bean production systems.

Banana yields were associated with potassium levels in the soil. Bananas appeared to be more competitive than beans in the intercrop system. The land equivalent ratio of the banana and bean intercropping system over the three seasons was 1.60.
Canopy Duration and Structure of Pigeonpea Intercropped with Upland Rice
Authors: Ramakrishna A. , Ong C. K. , Reddy S. L. N.
Published: October 2008

Interactions between upland rice and three phenologically distinct pigeonpea cultivars were examined on a medium deep Vertisol. The productivity of each intercrop component and its respective sole crop was determined in terms of a crop performance ratio (CPR). The extra-early pigeonpea cultivar recorded the largest partial CPR of grain followed by early and medium genotypes. Spreading genotypes had a larger partial CPR than semi-compact genotypes. However, the CPR of intercropped rice was less (0.65–0.69) with spreading pigeonpeas but exceeded unity with compact types. The canopy structure of pigeonpea appeared to be more important than differences in phenology. A large range of light transmission coefficients (K) existed in pigeonpea (from 0.45 to 0.78) but it is argued that a further reduction in K may not be necessary since intercropped rice yield was unaffected even with a K of 0.64. The relative height of intercropped pigeonpea and upland rice may also determine competitive ability since rice is very sensitive to low light and shading, particularly during the reproductive phase.
Genetic Vulnerability of Oceania's Traditional Crops
Authors: Lebot Vincent
Published: October 2008

The traditional crops of Oceania are asexually propagated and are losing their positions in cropping systems because of their genetic vulnerability. This paper reviews genetic reasons explaining the deterioration of their agronomic performance, using information mostly derived from surveys of genetic resources conducted in more than 50 Pacific islands, coupled with genetic investigations. More than 2000 cultivars have been analysed for isozyme variation. Cultivars and wild forms showed greater isozymic variation in Melanesia than in Polynesia and Micronesia but the genetic base for many of these crops was much narrower than morphological and chemical variation had suggested. No correlations were found between zymotypes, chemotypes, and morphotypes. Cultivars exhibited variation in qualitative traits as a result of human selection of somatic mutations. Accumulation of viral particles in propagules and build-up of pest and pathogen populations are often responsible for poor agronomic performance. If breeding of these traditional crops is to have any future, it is important to exchange genotypes to broaden the base of existing programmes.
Genotypic and Environmental Variation in Nodal Root Growth of Post-rainy Season (Rabi) Sorghum
Authors: Soman P. , Seetharama N.
Published: October 2008

Rapid initiation and growth of nodal roots (NR) are critical for the establishment of post-rainy season (rabi) sorghums grown in drying soil. The growth of NR was studied in sorghum in the field when sown at different depths in order to vary the crown depth, when different levels of irrigation water were applied to create different moisture contents in the topsoil, and in a number of cultivars to assess genotypic variability. Variation in sowing depth did not result in differences in NR growth, partly because of the capacity of sorghum to vary the mesocotyl length, which brought the crown to approximately the same depth. Different soil moisture levels in the field affected the elongation rate of NR, but not their initiation. Genotypic variation existed in the thermal time required for NR initiation and rate of elongation. The variation in NR growth was independent of the variation in shoot growth. The genotypic variability in NR growth offers an opportunity for combining root-related traits with useful agronomic characters.
Data Analysis in Agricultural Experimentation. II. Some Standard Contrasts
Authors: Pearce S. C.
Published: October 2008

In the preceding paper in this series (Pearce, 1992) it was explained how an experimenter can ask specific questions about the treatment responses and can obtain answers to them by using contrasts of interest. Here, two standard cases are examined, one in which treatments are quantitative in nature, like the amount of fertilizer applied or the dates on which spraying takes place, and the other in which the treatment set is formed from all combinations of two or more other sets. (Such a ‘factorial set’ might be formed from several kinds of herbicide being used with a range of cultivations.) Finally, a non-standard example is examined in which a well considered set of treatments provided information directly relevant to the subject of enquiry. The subject is considered with some emphasis on testing, but in many instances estimation would be better.