bluuebunny/crossref_metadata_2025 huggingface dataset:
Sesame Agronomy in South-east Tanzania. III. The Effect of Nitrogen and Phosphorus on Seed Yield and Oil Content
Authors: Taylor B. R. , Lamboll David , Kafiriti E.
Published: October 2008

The response of sesame to fertilizer was studied in 11 trials at four different sites, in which phosphorus was applied at rates from 0 to 26 kg ha−1 to the seed bed and nitrogen at rates from 0 to 60 kg ha−1 after thinning. Yield responses, found only to the main effects of nitrogen and phosphorus, are discussed in relation to soil type and previous cropping history of the sites and used to calculate gross cash returns from fertilizer use. Seed oil content was affected by environment, but responses to nitrogen and phosphorus were inconsistent.
The Choice of Groundnut (Arachis hypogaea) Varieties by Smallholders in South-east Tanzania. I. Observations on Different Varieties
Authors: Preston S. R. , Simons J. H. , Taylor B. R.
Published: October 2008

Smallholders in south-east Tanzania grow the groundnut Red Mwitunde (Arachis hypogaea ssp. hypogaea), a long-season variety with seed dormancy, although earlier maturing varieties with no seed dormancy (ssp. hypogaea and fastigiata) usually yielded better in trials, particularly when late sown. Small-seeded, short-season varieties established better in the field than Red Mwitunde and other large-seeded varieties, especially under moisture stress. Trials with selective fungicides to estimate yield losses from leafspots (mainly Cercosporidium personatum) and rust (Puccinia arachidis), jointly and separately, showed no consistent varietal differences.
The Choice of Groundnut (Arachis hypogaea) Varieties by Smallholders in South-east Tanzania. II. Variety × Spacing and Variety × Sowing Date Interactions
Authors: Preston S. R. , Taylor B. R. , Simons J. H.
Published: October 2008

Variety × spacing and variety × sowing date trials in south-east Tanzania showed that the long-season spreading bunch groundnut variety Red Mwitunde (A. hypogaea ssp. hypogaea var. hypogaea) was less tolerant of delayed sowing and more tolerant of wide spacing than Natal Common, a short-season upright bunch variety (ssp. fastigiata var. vulgaris). The same variety × spacing and variety × sowing date interactions were detected in groundnuts intercropped with cassava (Manihot esculenta). These observations help to explain the farmers' preference for Red Mwitunde despite the higher trial yields of Natal Common.
Development and Growth of Pearl Millet (Pennisetum typhoides) in Response to Water Supply and Demand
Authors: Squire G. R. , Marshall B. , Ong C. K.
Published: October 2008

Stands of pearl millet were grown in three controlled environment glasshouses in which were imposed different combinations of atmospheric saturation deficit (1.5 to 2.3 kPa) and soil water content (fully irrigated and not irrigated). Consistent differences in saturation deficit (SD) were maintained throughout the experiment (100 days) but a high water table restricted differences in water supply to the first 40 days. Responses to SD and soil water were observed in some variables but not in others. Developmental processes such as the rate of leaf appearance were unaffected, whereas the efficiency for conversion of intercepted solar energy decreased by 24% and the rate at which the canopy expanded by 50%, in the driest compared to the wettest conditions.
Application of a Systems Approach in a Commodity Research Programme: Evaluating Burundi Highland Maize
Authors: Zeigler R. S.
Published: October 2008

A late-maturing, high-yielding maize released for the Burundi highlands was rejected by subsistence farmers. Analysis of this variety in terms of the local cropping system shows that it offers no advantage over earlier maturing varieties when whole-system biological and economic yield and Land Equivalent Ratios are examined, while farmer risk is apparently substantially increased. The value of incorporating a ‘farming systems’ approach into national commodity research programmes in developing countries is demonstrated.
Effect of Legume Intercropping on Enrichment of Soil Nitrogen, Bacterial Activity and Productivity of Associated Maize Crops
Authors: Singh N. B. , Singh P. P. , Nair K. P. P.
Published: October 2008

Experiments comparing the effects of different legume intercrops on available soil nitrogen, bacterial activity and the yield of maize over two years showed that soyabean and blackgram were more suitable for this purpose than groundnut, substantially increasing NO3and NH4concentrations and populations of active bacteria in the maize rhizosphere. This increased maize yield by 15–20% and grain protein content by 20%.
Summer Grazing Management of a White Clover-Bahiagrass Pasture: Legume Survival
Authors: Dzowela B. H. , Mott G. O. , Ocumpaugh W. R.
Published: October 2008

A grazing management study involving the new white clover cultivar Osceola grown in association with Bahiagrass cv. Pensacola was conducted on wet and dry sites with and without pesticide/herbicide treatment. A combination of heavy grazing pressure and a short deferment period before grazing during the summer and autumn resulted in the largest soil seed reserves and seedling recruitment by the white clover component. However, maximum survival of plants was recorded from a combination of a short deferment period and moderate grazing pressure.

A slight increase in plant survival and seedling recruitment was shown on the wet site. Survival potential was least in pasture treated with pesticide and herbicide. Heavy grazing pressure and short deferment periods appear essential for the survival of the clover component. Annual seedling recruitment from soil seed reserves was the primary mechanism of white clover survival from spring to spring in pasture associations based on tropical bahiagrass.
Intercropped Corn-Soyabean Density Studies. II. Yield Composition and Protein
Authors: Putnam D. H. , Herbert S. J. , Vargas A.
Published: October 2008

If corn-soyabean intercrops are to replace corn grown alone, maintenance of yield and improvements in forage quality are important. Total yields and inter-crop competition in corn-soyabean intercropping experiments have been discussed previously (Putnam et al., 1985). In Part II yield composition, components and protein content are presented for intercrops of varying planting patterns and corn densities. Most intercrop patterns produced more forage than sole crops compared at the same yield ratio of corn-soyabean as in the intercrop harvested mixture. At high plant density ear yields in the intercrop were increased while in sole crops they were reduced or unaffected. The increase was a result of an increased number of ears, weight per ear and kernel, and number of kernels per row in the intercrops. Increases in crude protein content over sole crop corn of 11–51% were shown for the various intercrop treatments. Crude protein yields in the intercrops were greater than either sole crop in 1981 and greater than corn and similar to soyabean in 1982, and greater than the crude protein yields expected from an equal planted area of sole crop corn and soyabean in both years. Intercrop forage quality was improved over sole corn both by the addition of protein from soyabean pods and an increased ear: stover ratio of the intercropped corn.
A Pear and Vegetable Interculture System: Land Equivalent Ratio, Light Use Efficiency and Productivity
Authors: Newman S. M.
Published: October 2008

The productivity, land equivalent ratios (LERs) and light use efficiency of a pear and radish interculture system were assessed. Pear yield was unaffected by intercropping. Relative yields for the radish component varied between 0.5–1.01 depending upon the yield index and spatial arrangement employed. This gave LER values for the system of 1.5–2.01. The overall trans-missivity of the pear canopy was 73%. A 47% reduction in photosynthetically active radiation (PAR) gave a yield reduction of 65% in terms of number of saleable radish, but did not affect total dry matter productivity. Reductions in radish yield directly beneath pear trees was thought to be due to other factors besides PAR. The total dry matter productivity of a system containing five successive radish crops was estimated at 26.25 tonnes ha−1 yr−1.
A Spot Test for Estimating Ureides in Soyabean Petioles
Authors: Glenister Richard A. , LaRue Thomas A.
Published: October 2008

The ureides allantoic acid and allantoin form a bright pink compound with acidic p-dimethylamino cinnamaldehyde. It is possible to estimate the ureide content of a soyabean petiole segment by crushing it on filter paper and developing the colour with this reagent. There is a strong correlation between the spot test and estimates from colorimetric determination of ureides. In field grown soyabeans, there was a positive correlation between the petiole ureide content during pod fill and the integrated seasonal acetylene reduction activity. The spot test can be used to identify plants with low nitrogen fixation activity.
Technology Development and the Spread of Direct-Seeded Flooded Rice in Southeast Asia
Authors: De Datta S. K.
Published: October 2008

Increased labour costs and area under irrigation, the development of modern early-maturing varieties and improved fertilizer and weed management techniques have encouraged many farmers in the Philippines, Malaysia and Thailand to switch from transplanted to direct-seeded flooded rice culture. This paper summarizes the development and spread of the technology for direct-seeded flooded rice in southeast Asia and the contribution made by research at IRRI and by national programmes. It covers research on crop establishment, varietal requirements, fertilizer management, weed control and economics and examines the advantages and disadvantages of direct-seeding compared with transplanting.
The Association of Planting Density and Plant Type in French Bean (Phaseolus vulgaris)
Authors: Tripathi S. S. , Singh P. P.
Published: October 2008

Five varieties of French bean of contrasting growth habit were grown at a range of plant densities. Most varieties yielded best at 30 plants m−2, but the bush type variety Contender yielded best at 50 plants m−5. The best yield was obtained from the semi-spreading variety Rufus.
A Method for Farmer-participatory Research and Technology Transfer: Upland Soil Conservation in the Philippines
Authors: Fujisaka Sam
Published: October 2008

Although viewed as important for on-farm adaptive research, farmer-participation has often been superficial and has not led to meaningful incorporation of farmer perspectives. This paper describes the use of a method involving the understanding of farmers' perceptions in determining priorities for research which integrates the different concerns and contributions of farmers and scientists with the transfer of technology from farmer to farmer.
Growth, Nodulation and Nitrogen Fixation in Stylosanthes: Effect of Different Root Temperatures at two Shoot Temperatures
Authors: Date R. A. , Ratcliff D.
Published: October 2008

Nodulated plants of Stylosanthes hamata, S. guianensis, S. humilis, S. scabra and S. fruticosa were grown in controlled environments with varied root and shoot temperatures. Measurement of dry matter and nitrogen content suggested that shoot temperature may be more important than root temperature in controlling growth and nitrogen fixation. There were strong interactions with variety. A fall in relative growth rate with increase in shoot temperature was least for S. guianensis and greatest for S. hamata and S. scabra. The optimum root temperature for growth and nitrogen fixation was approximately 30°C. Ninety percent maximum yield was achieved between root temperatures of 15–36°C for growth and 23–34°C for nitrogen fixation but varied with variety. Nitrogen fixation was more sensitive than dry weight to root temperature. The pattern of response of percentage nitrogen and nitrogen fixation efficiency reflected those for dry weight and nitrogen yields. Shoot to root ratios decreased toward the optimum root temperature then increased at the highest temperature. The reaction of varieties to root and shoot temperatures may be an important factor in determining their suitability for new regions.
On the Standard Errors and Other Moments for Ratios of Biological Measurements
Authors: Oyejola B. A. , Mead R.
Published: October 2008

A method of obtaining the standard error and some other moments for the ratios of biological measurements is given, with the conditions to be satisfied by the variables used to form such ratios. Some applications of the distributional properties of the ratios in the analysis of results from experiments are discussed.
Effects of Green-stage Grazing on Rainfed Barley in Northern Syria. I. Tiller Production and Other Agronomic Characters
Authors: Yau S. K. , Mekni M. S. , Naji I.
Published: October 2008

Effects of simulated and actual grazing at the tillering stage on tiller production and other agronomic characters were studied over a number of seasons at two sites in northern Syria with two local barley landraces. In general, grazing encouraged tiller production but reduced head number per unit area because of a higher tiller mortality or infertility. Seed number per head and seed weight were not affected by grazing except in one season. Grazing delayed heading and maturity and reduced plant height. Simulated and actual grazing produced similar effects on the different characters investigated.
Agronomic and Physiological Constraints to the Productivity of Tropical Grain Legumes and Prospects for Improvement
Authors: Lawn R. J.
Published: October 2008

Growth and development of the tropical grain legumes are generally highly sensitive to photo-thermal regime, so that seasonal and regional effects on phenology and yield potential can be large. Yet failure adequately to recognize and fully exploit the consequences of genotype × latitude/sowing date × density interactions has frequently constrained both agronomic and genetic advance with these species. Thus there is opportunity for short term productivity improvements through agronomic strategies which accept the implications of phenological plasticity, and seek to optimize management practices such as sowing date and sowing density, to exploit more effectively the yield potential and broaden the adaptation of existing cultivars. The greatest physiological potential for genetic improvement in the productivity of the tropical grain legumes lies not with increasing total biomass, but with increasing the proportion of bio-mass partitioned into seed, i.e. with improved harvest index (HI). There are difficulties in selecting for higher HI, including its association with phenology, although the latter provides the most powerful tool for manipulating HI in the short term. As with the cereals, more productive genotypes are likely to be characterized by reduced sensitivity to photothermal conditions, shorter growth duration, a more synchronous reproductive ontogeny, and greater HI, than is typical of traditional cultivars. Accordingly, optimal sowing densities will be higher, and crops will need more inputs, better management and more effective protection, than afforded to them in subsistence systems of production. Moreover, the increases in productivity will be achieved, at least partially, at the expense of the potential for yield homeostasis in adverse environments, and of non-seed components such as forage, fuel or tubers - attributes that are often highly valued in subsistence agriculture where many of the tropical food legumes are presently grown. Improvement programmes will therefore need to adopt strategies in particular situations which reflect local perceptions of the importance of productivity improvement relative to that of minimizing inputs and risk.
Studies on the Productivity of Egyptian Clover and Oats under Intercropping
Authors: Singh Virendra , Joshi Y. P. , Verma S. S.
Published: October 2008

A trial was carried out at Pantnagar in India during 1984–85 and 1985–86 to study the productivity of Egyptian clover and oats under intercropping. Cross sowing of both the crops either at full or half seed rates and line sowing of oats in broadcast Egyptian clover was better than other intercropping systems or sole cropping in respect of herbage production, digestible dry matter yield and land equivalent ratio but crude protein yield from the mixed crops was similar to that from sole cropped Egyptian clover.
Alley Farming with Leucaena: Effect of Short Grazed Fallows on Soil Fertility and Crop Yields
Authors: Atta-Krah A. N.
Published: October 2008

A long-term trial with Leucaena leucocephala was initiated in 1982 to test the sustainability of Leucaena-based alley farming compared to a conventional cropping system without trees and with continuous cultivation of maize. It assessed the integration of short grazed fallows in rotation within Leucaena alleys and their effect on soil fertility and crop yields.

The various treatments had no effect on soil pH during the four-year period of the trial. The organic carbon and total nitrogen contents of the soils under conventional cropping were lower by the end of the fourth year than those under alley cropping and alley grazing treatments, whereas soil phosphorus levels were lower in the alley cropping and grazing plots. Foliage dry matter production of Leucaena under alley cropping management ranged from 6.0 to 6.7 t ha−1 a−1 under continuous cropping and reached 8 t ha−1 when alley cropping was preceded by a grazed fallow. Crop yields were consistently higher with alley cropping than with conventional cropping. Alley cropping plots in rotation with two year grazed fallows gave significantly higher crop yields during cropping years than those under continuous cultivation.
An Agronomic Evaluation of Jackbean (Canavalia Ensiformis) in Yucatan, Mexico. I. Plant Density
Authors: Kessler C. D. J.
Published: October 2008

Effects of plant density were studied in field experiments carried out over four successive years as part of an evaluation of the potential of jackbean and in order to determine appropriate cultural practices for the crop. Flowering, biomass accumulation, and seed yield and its components were examined. Increased plant density led to earlier canopy development and biomass accumulation, and to increased seed yield in long growing seasons. Maximum seed yield ranged from about 1.0 to 3.8 t ha−1 between years of short and of prolonged rainy seasons, respectively. Plant size and branching were reduced at high density. Variation in seed yield was associated with differences in pod number; single seed weight and number of seeds per pod remained more constant
An Agronomic Evaluation of Jackbean (Canavalia Ensiformis) in Yucatan, Mexico. II. Defoliation and Time of Sowing
Authors: Kessler C. D. J.
Published: October 2008

Effects of defoliating jackbean for forage production and time of sowing were studied in field experiments as part of an evaluation of the potential of jackbean and in order to determine appropriate cultural practices for the crop. In a long growing season, seed yield after cutting for forage was similar to that of an uncut crop but was reduced by two thirds in a short growing season. Flowering appeared to be stimulated in short days. Delayed sowing after the beginning of the rainy season progressively reduced seed yields
An Agronomic Evaluation of Jackbean (Canavalia Ensiformis) in Yucatan, Mexico. III. Germplasm
Authors: Kessler C. D. J.
Published: October 2008

A field experiment was carried out to compare the performance of 18 accessions of jackbean from different origins. Plant development and phenology, final plant biomass, and seed yield and its components were evaluated. Flowering time ranged from 56 to 109 days after sowing. Bush and climbing types were identified and differences in seed yield were recorded, the largest yield occurring in a mid-season flowering accession. It was concluded that more material should be screened since germplasm introduction appears to be a promising route to larger jackbean yields in Yucatan
Intercropping Morphologically Different Cowpeas With Pearl Millet in a Short Season Environment in the Sahel
Authors: Ntare Bonny R.
Published: October 2008

The effects on yield of varying the planting date and planting pattern of morphologically different cowpea cultivars intercropped with pearl millet were studied in two field trials. The interaction between cowpea cultivars and planting date was highly significant. There was a sharp reduction in cowpea yields with late planting. Millet yields were reduced less when sown simultaneously with early cowpea cultivars than when sown with a late maturing local cultivar. Early maturing cowpea cultivars planted in closely spaced hills had less effect on millet yields than a late maturing cultivar sown in widely spaced hills. An appropriate cowpea cultivar for intercropping with peal millet would be one that was weakly competitive and that yielded both grain and fodder.
Nutritive Value and Yields of Some Forage Legumes and Barley Harvested as Immature Herbage, Hay and Straw in North-West Syria
Authors: Thomson E. F. , Rihawi S. , Nersoyan N.
Published: October 2008

The nutritive value and yield of forage legumes and barley harvested as immature herbage, hay and straw were measured in two experiments. The voluntary feed intake of peas at all stages of maturity and immature herbage from woollypod vetch was substantially lower than that of common vetch and chickling. At each stage of maturity barley was less digestible than all the forages except immature peas. Despite exceptionally cold weather in February/March 1985, yields of common vetch were higher in 1984/85 than in 1985/86 when there was less rain. Peas yielded the most hay, and chickling yielded less seed and straw than common vetch, peas and barley. Yields of digestible dry matter from straw and seed exceeded those from hay but protein yield at the two stages was similar. Mechanical baling substantially reduced the yields of baled hay but these losses would be reduced to less than 10% if the residues were grazed.
Seasonal and Clonal Differences in Shoot Extension Rates and Numbers in Tea (Camellia sinensis)
Authors: Stephens William , Carr M. K. V.
Published: October 2008

Shoot extension rates and numbers recorded over an 18 month period in Tanzania from three contrasting clones were analysed to determine variation between and within seasons. Clonal differences in base temperatures for shoot extension ranged from 10.3 to 14.5°C, whilst variability in the response of shoot growth rates to temperature could be ascribed to the shoot selection technique employed. Considerable clonal variation in shoot population densities occurred, with maxima ranging from 200 to 1200 shoots m−2. Total active shoot extension, the product of shoot growth rates and population densities, varied between 4 and 35 m m−2 week−1, shoot numbers being the dominant component. The implications of these results are discussed in terms of shoot measurement techniques, clonal selection criteria, yield modelling and harvesting policies.
The Determination of Bunch Yield Components in the Development of Inflorescences in Oil Palm (Elaeis Guineensis)
Authors: Breure C. J. , Menendez T.
Published: October 2008

Stages in oil palm inflorescence development which determine the number and weight of the fruit bunch components were identified by thinning to intervene in development and dissection of a sample of the felled palms. This showed that the ratio of female to total inflorescences and the number of flowers per spikelet were determined eight leaves prior to spikelet initiation. The number of spikelets per inflorescence was linked with the meristematic development of the primary axis. Inflorescences were prone to abortion at the onset of rapid expansion of the primary axis. The weight of the frame responded to thinning at these three developmental stages. The weight of single fruits responded shortly after the fruit set was fixed at anthesis; the response levelled off in axils of the six older leaves. At the start of an abortion phase nearly all aborted inflorescences were female, but subsequently female and male inflorescences aborted in equal proportions. Our study suggests that the number and weight of fruit bunch components are determined at a specific developmental stage but that the time to anthesis may vary considerably as a result of fluctuations in the speed of inflorescence development.
The Effect of Planting Density on the Yield Components of Oil Palm (Elaeis Guineensis)
Authors: Breure C. J. , Menendez T. , Powell M. S.
Published: October 2008

Yield components in oil palm were recorded in a spacing experiment comparing 56, 110, 148 and 186 palms ha−1. The higher densities reduced the number of female inflorescences (due to a decrease in the proportion of female to total inflorescences and an increase in the proportion of leaves with aborted inflorescences), the weight of the frame and the number of flowers per inflorescence. The results suggest that the production of seed per bunch can be increased by at least 15% by thinning around selected palms in seed gardens. The sex ratio and the components of flower number per inflorescence were more sensitive to competition for light than the weight of the frame and floral abortion. Components determining the oil and kernel extraction showed no response to density when assisted pollination was used, but with the successful introduction of insect pollinators, oil and kernel extraction increased with planting density as a result of an increase in fruit per bunch.
Prospects for Brassica Carinata as an Oilseed crop in India
Authors: Malik R. S.
Published: October 2008

Twenty one strains of Brassica carinata were tested under irrigated, rainfed and saline soil conditions and five strains under late sowing conditions along with five varieties each of B. juncea, B. napus and B. campestris var. yellow sarson, brown sarson and toria. Brassica juncea had the largest seed and oil yield under irrigated conditions but B. carinata performed much better than other species under late sowing, rainfed and saline soil conditions.
A Review of Methods for Measuring Crop Production from Smallholder Producers
Authors: Poate Derek
Published: October 2008

Four methods of measuring crop production are reviewed in the context of different survey objectives. A popular technique, crop cutting, tends to overestimate yields and does not produce good estimates of individual plots. For high accuracy, harvest of the whole plot is the best method. If statistics of regional production are required output can be sampled after harvest, or, if the farmer harvests in consistent units, his own estimate can be taken. Limited evidence shows that farmers' estimates may be no more biased than crop cutting, but require fewer resources and supervision. There is no best method. The method used must be chosen for the purpose of the study. Whichever method is chosen a distinction should be made between biological and economic yield and correction must be made for threshing and moisture content.
Sorghums in the Post-Rainy Season. I. Effect of Irrigation and Date of Sowing on the Grain and Stover Yields of Diverse Cultivars
Authors: Reddy Belum V. S. , Seetharama N. , House L. R.
Published: October 2008

In India, sorghum is grown during the post-rainy season on Vertisols with stored soil moisture. As water stress towards the end of the growing season is believed to be a major cause of poor yields in these crops, an experiment was carried out involving five sorghum genotypes and four sowing dates with and without irrigation.

Supplementary irrigation with 40 mm of water in the earliest sown crop increased grain yields by 24 and 26% in 1979 and 1982, respectively, while irrigation with a total of 120mm water in the latest sown crop increased yields by 87 and 60% compared with the corresponding dryland crops. Early sowings always resulted in better stover and grain yields irrespective of irrigation treatment. Grain yields of hybrids were similar to those of the cultivars but their stover yields were less. The post-rainy season cultivar SPY 86 gave the best grain yield across sowing dates. The widely grown post-rainy season cultivar M 35–1 yielded less but produced more stover and its yields were more stable. The importance of the stability of grain and stover yields and of evaluating the materials for more than one date of sowing in selecting sorghums for the post-rainy season is discussed.
The Effect of Different Planting Densities on Yield Trends in Oil Palm
Authors: Breure C. J.
Published: October 2008

Sixteen years' yield and growth data from an oil palm planting experiment, comparing 56, 110, 148 and 186 palms ha−1, and additional records from a progeny experiment, were used to study the effect of palm age and planting density on carbohydrates incorporated in total above-ground dry matter production per palm (TDMc) and its components: fruit bunch yield (Yc) and vegetative growth (VDMc). The canopy efficiency (e), the amount of carbohydrate incorporated in dry matter production per unit of absorbed radiation per hectare, decreased from the fifth to eighth year then levelled off, but increased once crown expansion was completed. The decrease in e paralleled the expansion of the intercepting leaf surface, and might therefore be linked to an increase in maintenance respiration losses. These losses were apparently not compensated for by an increase in photosynthetic production. The subsequent increase in e in older palms appears to have been due to improved light distribution as a result of an increase in light penetration. The effects of changing levels of light interception and distribution on e were more pronounced at higher density, and resulted in marked differences in changes of TDMc with age between densities. Corresponding differences occurred with Yc, so that the optimum density for current yield decreased until 12 to 13 years from planting, then markedly increased. These findings are discussed in relation to the measures which might be used to increase yield per unit area.
The Effect of Palm Age and Planting Density on the Partitioning of Assimilates in Oil Palm (Elaeis guineensis)
Authors: Breure C. J.
Published: October 2008

Yield and growth records from an oil palm planting density experiment, comparing 56, 110, 148 and 186 palms ha−1, and a progeny experiment, planted at 115 and 143 palms ha−1, were used to estimate the partitioning of assimilates into those used for structural dry matter (DM) production, and those used for growth and maintenance respiration.

Gross photosynthetic assimilation (A) for closed canopies was estimated from absorbed photosynthetically active radiation (PAR), derived from actual sunshine hours, and the assimilation-light response curve, to be 128 t CH2O ha−1year−1. A for non-closed canopies was calculated by correcting for the degree of light transmission, which in turn was estimated from recorded leaf area index values (L), i.e. the total leaf area per unit ground area.

Forty-eight percent of gross assimilation was used for DM production, about half of this being lost in growth respiration. The remaining 52% was lost in maintenance respiration. These losses appeared to level off before crown expansion was completed, and since trunk biomass continued to increase, maintenance respiration per unit biomass (R) decreased with age.

An increase in planting density reduced the assimilates available for bunch DM, had little effect on those for vegetative growth, but strongly reduced maintenance respiration and, since biomass was little affected, reduced R. Assimilates for bunch DM ha−1reached a maximum at L = 5.6.

The observed trends in R as a function of palm age and planting density merit further study.
Strengthening Linkages in Agricultural Research through a Farming Systems Perspective: The Role of Social Scientists
Authors: Byerlee Derek , Tripp Robert
Published: October 2008

The principal contribution that the farming systems perspective brings to agricultural research is a farmer and problem-solving orientation. Development of this orientation helps strengthen linkages in national research systems between commodity programmes and between disciplines for both applied and adaptive research. It can also strengthen linkages between research and extension and between research and policy analysis. Issues in strengthening each of these linkages are briefly reviewed with particular emphasis on the socio-economic dimensions and the potential role of social scientists. It is argued that the farming systems perspective in agricultural research should be seen as performing an integrative role in research systems. This can often be developed without significant institutional reorganization.
Was this in your Statistics Textbook? I. Agricultural Scientist and Statistician
Authors: Finney D.J.
Published: October 2008

This is the first of several papers that will present ideas on statistical method in agricultural research, especially in relation to the planning and analysis of experiments, based upon experience but not found explicitly discussed in standard textbooks. Indeed, some of the contents of these papers may appear to conflict with what can be found in books: closer examination is likely to disclose lack of real disagreement with the better texts. The first paper outlines a plan for the series. Thereafter, it concentrates on relations between agricultural scientists and statisticians and on some of the issues that are too easily overlooked when one of the former, often for good reason, chooses to be his own statistician.
Performance of Varietal Mixtures in Sugarcane
Authors: Kapur Raman , Bhat S. R. , Tripathi B. K.
Published: October 2008

Six sugarcane varieties grown alone and in mixtures containing equal proportions of two or three varieties were evaluated for the economically important traits of the first crop and subsequent ratoon crops over a three year period. An increase in the yield of cane and sugar of up to 25% more than the average for the pure components was observed in some mixtures. The number of millable canes, sucrose content and cane yield in the mixtures was more stable than in the pure varieties. The advantages of growing varietal mixtures of sugarcane are discussed.
Analysis of Experiments Involving Line Source Sprinkler Irrigation
Authors: Morgan D. D. V. , Carr M. K. V.
Published: October 2008

The line-source sprinkler irrigation system provides a continuously variable water application rate, which depends on distance from the line-source. The system is simple to set up and minimizes the amount of land required for experimental work. As the irrigation treatments are allocated systematically, the assumptions of analysis of variance are not satisfied. It is proposed that the effects of irrigation treatments be assessed using analysis of covariance, with distance from the sprinkler line as covariate, thus adjusting for a linear fertility trend. This method of analysis provides an approximate residual mean square for the fitting of response curves, but could be vulnerable to a quadratic fertility trend.
The Mineral Status of Soil, Forage and Cattle Tissues in the Middleveld of Swaziland
Authors: Ogwang B. H.
Published: October 2008

The mineral status of soil, native forage and cattle tissues in the Swaziland middleveld was investigated during the dry and wet seasons of 1985/86. In relation to beef cattle requirements, forage Mg, P, Na, Cu, Zn and crude protein were deficient during both seasons and K was low during the dry season. Cattle serum and liver samples were generally low or deficient in P, Zn, Cu and Mn, while their Fe content was in excess of normal requirements. The forage, liver and serum analyses indicate that cattle in the middleveld are likely to require supplementary Na, K, Cu, Zn, Mn and crude protein, but Ca, Mg and Fe levels appear to be adequate.
Responses of Some Turkish Wheat Cultivars to Vernalization and Photoperiod
Authors: Terzioğlu Serpil
Published: October 2008

The vernalization and photoperiodic response of six locally adapted bread wheat cultivars grown under natural daylength conditions during the summer or winter months was examined in glasshouse experiments. The wheat was vernalized by chilling imbibed grains at 2 ± 1°C for 0, 15 or 45 days. Vernalization for 45 days followed by long summer days led to floral initiation in all cultivars within 28 days but vernalization for 0 or 15 days only led to floral initiation in one cultivar. Vernalization followed by long days reduced the time from transplanting to anthesis, resulting in early ear emergence. Vernalization followed by short days accelerated the development of all the cultivars, but normal development could also occur without vernalization at this time of year. Apical differentiation of the primary shoot and its length and development gave the most reliable information on the period of vernalization required.
Frequency of Weeding Okra (Abelmoschus esculentus) for Optimum Growth and Yield
Authors: Iremiren G. O.
Published: October 2008

Field experiments were carried out during the rainy seasons of 1985 and 1986 to examine the frequency of weeding necessary for the optimum growth and yield of okra in Nigeria. Weed removal within 12 weeks of sowing generally resulted in significantly better crop growth and yield than that in the weedy check. Weeding once as early as four weeks was as beneficial to okra growth and yield as two or three weedings later in the 12 week period. Weed removal four times at 3, 6, 9 and 12 weeks significantly enhanced crop growth and pod yield over all other treatments. For good pod yields, protection from weed competition over most of the duration of crop growth is therefore essential. Such weed removal may enhance crop yield partly by increasing aeration and water movement in the soil.
The Yield Stability of Maize Genotypes across International Environments: Full Season Tropical Maize
Authors: Crossa J. , Westcott B. , Gonzalez C.
Published: October 2008

Evaluation of the yield stability of a group of CIMMYT tropical maize populations across international environments, measured by the performance of varieties derived from them, showed that the populations Mezcla Tropical Blanca, La Posta and Amarillo Dentado produced the most stable varieties across environments. Mezcla Tropical Blanco and Amarillo Dentado produced selections with good stability in both low and high yielding environments while La Posta produced varieties with better performance in favourable environments. ‘Across-site’ varieties were not consistently more effective than ‘site-specific’ varieties in improving yield stability. Varieties selected for some specific population-environment combinations have been very stable in other areas of the world.
Farmer Participatory Research: Editorial Introduction
Authors: Farrington John
Published: October 2008

This paper places the participatory approaches to research presented in the six following papers into the broader debate on priorities in agricultural research and on the role of specific approaches to research. It reviews the principal features of the approaches outlined, the extent to which they have been incorporated into existing institutions such as national agricultural research services, and their implications for support services. Key issues which future participatory research should address are highlighted.
The Impact of Regular Research Field Hearings (RRFH) in On-farm Trials in Northeast Brazil
Authors: Baker Greg , Knipscheer Hendrik C. , De Souza Neto Jose
Published: October 2008

The study of livestock in farming systems research presents several challenges. Factors such as the small number of observations, high statistical variability in measurements, and the difficulty in valuing non-market inputs and outputs make it difficult to evaluate on-farm research. Regular Research Field Hearings (RRFH) can improve communication between scientists and farmers, thereby increasing mutual understanding, willingness to collaborate in evaluation, potential technologies, and also improving test results. Of three groups of sheep and goat farmers involved in on-farm testing in northeast Brazil, the group which participated in RRFH experienced a significantly higher level of success with the technology as measured according to performance criteria such as weight gains and farmers' perceptions of their animals' performance. The results confirm the importance of farmers' participation in agricultural research.
Developing a Partnership between Farmers and Scientists: the Example of Zambia's Adaptive Research Planning Team
Authors: Kean Stuart A.
Published: October 2008

The Adaptive Research Planning Team in Luapula Province (ARPT-LP) is one of nine provincial teams in Zambia conducting farming systems research within the Research Branch of the Ministry of Agriculture and Water Development. ARPT-LP has been relatively successful in developing a partnership with farmers, involving them in both the planning and implementation of the team's research programme. This paper examines the formal and informal occasions on which farmers have been involved in the team's activities, with examples to illustrate how farmers' opinions have influenced decisions made by ARPT-LP. The factors which have influenced the frequency and quality of the scientists' interaction with farmers are discussed.
A Participatory Method for Systems-Problem Research: Rehabilitating Marginal Uplands in the Philippines
Authors: Lightfoot C. , De Guia O. , Ocado F.
Published: October 2008

A participatory method that promotes farmer involvement in systems-problem research was developed in response to the failure to adopt improved cropping patterns among upland farmers. Techniques to identify systems problems involved group and individual farmer meetings. Problems concerning the cultivation of marginal cogonal (Imperata cylindrica) uplands were identified. An informal random sample survey, guided by topics of inquiry and biological measurements that employed systems analytical tools, was used to obtain a farmers' perception of ‘systems-problems’. Systems diagrams also provided a framework for searching and screening solutions. A sequence of vining legumes was tested in rehabilitating the marginal uplands. For this experiment farmers elaborated hypotheses on control of Imperata, recovery of soil fertility, and reduced labour costs in re-cultivation. Extensive research activity among the farmers indicates the value of this participatory method.
Improved Livelihoods, Genetic Diversity and Farmer Participation: A Strategy for Rice Breeding in Rainfed Areas of India
Authors: Maurya D. M. , Bottrall A. , Farrington J.
Published: October 2008

The present structure of plant breeding and seed multiplication in India is highly centralized. Furthermore, only a small number of new varieties is officially released each year. The system therefore appears inappropriate for the requirements of the large proportion of Indian farmers located in risk-prone and highly diverse environments. An alternative strategy is described whose central feature is close matching of the characteristics of farmers' traditional rice varieties with those of advanced breeders' lines. A selection from these lines is then distributed in small quantities for on-farm trials managed by farmers themselves. If the success of these initial efforts is to be sustained, a more decentralized approach to breeding and multiplication will be necessary.
Farmers, On-farm Research and the Development of New Technology
Authors: Sumberg J. , Okali C.
Published: October 2008

Most commonly, on-farm research has sought to validate and demonstrate technologies developed under controlled experimental conditions. It is argued here that on-farm research has a role in all stages of technology development, and that methodologies and objectives transplanted from the research station are inappropriate, particularly given the restrictions they impose on farmers' capacity to experiment with new technology. Drawing on experience with alley farming in W. Africa, it is shown how the farm and farm family can be incorporated fully throughout the process of technology development. The example is used to clarify the role of researchers in participatory technology development.
A Comparison of Thermocouple Psychrometer and Pressure Chamber Measurements of Leaf Water Potential in Peanuts
Authors: Wright G. C. , Rahmianna A. , Hatfield P. M.
Published: October 2008

The pressure chamber method for measuring leaf water potential in peanuts was compared with the thermocouple psychrometer technique. The pressure chamber over-estimated leaf water potential by an average of 0.4 MPa over the range −0.5 to −5.0 MPa. It is suggested that the pressure chamber technique may be appropriate in comparative studies of peanut water stress. However, where absolute measurements are required, as in the calculation of leaf turgor potential, either a correction factor should be applied or, preferably, the thermocouple psychrometer technique used. If no account is taken of the discrepancy between techniques, erroneously large negative turgor potentials will result.
A Simple Model for a Quantitative Comparison of the Regrowth of Perennial Fodder Crops
Authors: Kamidi R. E. , Wanjala J. B. W.
Published: October 2008

The rate of regrowth in realtion to total dry matter yield is important for smallholders fodder crop production. A simple regression technique is used to compare the rates of regrowth of eight perennial fodder crops cut at the same time. A brief interpretation and discussion of results from data illustrative of the model' use in given.
Soil Physical Properties of Tied Ridges in the Sudan Savannah of Burkina Faso
Authors: Hulugalle N. R. , Rodriguez M. S.
Published: October 2008

The soil physical properties of tied ridges were measured in a trial, established in 1983, comparing three treatments: handhoe cultivation and planting on the flat; planting directly without any cultivation on tied ridges constructed the previous year; and handhoe cultivation and remoulding of tied ridges constructed the previous year. Two maize varieties and two management levels were used. The soil properties monitored were particle size distribution, penetro-meter resistance in the surface 20 mm, bulk density, water infiltration, soil water retention and soil temperature.

Soil physical properties were affected mainly by the type of seedbed. Clay content in the surface 0.05 m was greater with tied ridging, with that in the furrows being higher than that in the ridge slopes. Daily maximum soil temperature was greatest in the flat planted plots and in the ridge slopes of the tied ridged plots. Penetrometer resistance at a soil water content of 0.05 kg kg−1 was greater in the tied ridged plots. Cumulative infiltration after 2 h was greatest with flat planting. The bulk density of ridge slopes in tied ridged plots was less than that in the furrows and in the flat planted plots. Soil water retention was greatest in the furrows of the tied ridged plots. Clay content was the major factor determining all the soil physical properties measured.
Effect of Crop Geometry (Row Proportions) on the Water Balance of the Root Zone of a Pigeonpea and Rice Intercropping System
Authors: Jena D. , Misra C.
Published: October 2008

Rice, pigeonpea and rice + pigeonpea systems (in the row proportions of 1:2 and 2:5) were compared. Soil water depletion and percolation were determined during selected dry spells and yields ascertained after harvest. The mean evapotranspiration rates of rice, pigeonpea, rice + pigeonpea (1:2) and rice + pigeonpea (2:5) were 0.28, 0.79, 0.40 and 0.35 cm d−1, respectively, during a dry spell around 60 days after sowing. In general low rainfall intensity and frequent dry spells in the growing season increased pigeonpea yield but depressed that of rice. Intercropping thus ensured yield stability and hence the profitability of the system as a whole.