bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Importance of Lay-out in Determining Error Variance in Field Experiments
Authors: Roberts E. A. 
Published: October 2008

SUMMARYExamples are taken from three biometrical texts, two unpublished experiments and Yates (1937) to illustrate quantitatively how the lay-out of the plots can affect the estimate of error variance in field experiments and how confounding of treatment and positional effects can arise. In two examples in which the plots did not run the whole length or width of the block, the estimates of error were reduced by one half and one quarter respectively by allowing for sub-blocks within blocks or for rows and columns. In split-plot experiments where the main plots were split breadthwise, the sub-plot error was about the same size as the main-plot error or larger whereas it is expected to be at most one third that of the main plots when these are split lengthwise. Serious bias can arise in the estimate of treatment effects due to confounding with positional effects; this is illustrated.
A Design and Methods of Analysis to Monitor Crop Growth Conditions Illustrated with Sorghum Screening Trails for Resistance toStriga
Authors: Gilliver B. , Vasudeva Rao M. J. , Venkateswarlu P. 
Published: October 2008

SUMMARYChecker-board field layouts are used to screen sorghum genotypes for resistance toStriga. A systematic check entry is used to monitor crop growth conditions and methods to analyse the results are assessed.
The Balance between Leaf Area and Photosynthetic Activity in Determining Productivity of Fox-tail Millet (Setaria italica) under Rain-fed Conditions
Authors: Sashidhar V. R. , Prasad T. G. , Patil S. J. , Kumar M. Udaya , Sastry K. S. Krishna 
Published: October 2008

SUMMARYThe relationship of leaf weight ratio (LWR), leaf area ratio (LAR), stomatal frequency and dry matter (DM) production with yield and with photosynthetic efficiency, as reflected by 14CO2 fixation rate, was studied in fox-tail millet (Setaria italica) for three consecutive years. Several genotypes were identified which combined small leaf area and/or low stomatal numbers per plant with productivity under rain-fed conditions equal to that of genotypes with large stomatal numbers. 14CO2 studies in these genotypes showed that the rate of carbon fixation by the leaves was greater, at any canopy position, than in the corresponding large LA/large DM types. Genotypes with consistently small stomatal numbers per plant, associated with good dry matter accumulation and productivity, may also show small transpirational water loss under rain-fed or drought conditions. It is concluded that such genotypes are desirable for better productivity under these conditions.
Density Related Yield Functions for Coconut (Cocos nucifera): an Empirical Estimation Procedure
Authors: De Silva N. T. M. H. , Tisdell C. A. 
Published: October 2008

SUMMARYObtaining yield–density relationships for perennials is difficult. Apart from the long time span involved, problems are also posed by the different types of uncertainty associated with field experimentation. Consequently researchers have explored alternative means. This study uses survey data as an alternative. The data show sufficient variability around the density which is regarded as optimal for Typica variety of coconut (158 palms ha−1) to be of value for estimating its yield–density function. A quadratic function gives a good fit to the data. Results suggest that the yield maximizing density of variety Typica form typica is relatively insensitive to the influence of fertilizer practices adopted by farmers and to variations by agroclimatic sub-regions.
Evaluations of Alternate Cropping Systems for Alfisols of the Indian Semi-arid Tropics
Authors: Reddy M. S. , Willey R. W. 
Published: October 2008

SUMMARYA three-year experiment examined the possibility of increasing the cropping intensity of a medium-deep Alfisol (red soil) by using sequential, relay, ratoon or intercropping systems. It was found that a short-season mungbean (Vigna radiata) crop could be taken before the commonly-grown castor crop but that castor yields were reduced by the delayed sowing. If the castor was sown after the harvest of mungbean in a sequential system the profits were less than from a sole castor system. Relay-sowing the castor 20 days before the harvest of mungbean gave 9 $US ha−1 greater profit than sole castor, but this is probably not enough to justify the more intensive double crop system. On the other hand a reasonable yield of horsegram (Macrotyloma uniflorum) could be produced after an early pearl millet crop, giving a worthwhile extra profit of 21 $US ha−1 compared with sole pearl millet. Ratooning the sorghum gave ratoon yields that averaged only 14% of the first crop, so this system was not considered suitable for these lighter Alfisols.Intercropping systems of pearl millet/groundnut, sorghum/pigeonpea and groundnut/pigeonpea gave average yield increases of 24, 47 and 46%, respectively, compared with both component crops grown separately. Compared with growing only the higher value sole crop, increases in profits were 16, 82 and 120 $US ha−1 for the same three systems, respectively. It is concluded that intercropping systems provide the best opportunity for increasing cropping intensity on medium-deep Alfisols.
Effects of Melon (Colocynthis vulgaris) Population Density on Intercropped Maize (Zea mays) and Melon
Authors: Wahua T. A. T. 
Published: October 2008

SUMMARYIn a study of the optimum population for melon when intercropped with maize, melon at 5000, 10 000, 15 000 and 20 000 plants ha−1 was intercropped with maize at 40 000 plants ha−1. Melon biomass and seed yield increased linearly with population density in mixed and pure stands while maize yield components were virtually unaffected. Intercropping reduced melon seed yields, mainly because of a reduction in number of fruits per plant, but did not affect seed size. For good weed and erosion control and increased total yields, maize can be intercropped with up to 20 000 plants ha−1 of melon.
Hydraulic Press Measurements of Leaf Water Potential in Groundnuts
Authors: Rajendrudu G. , Singh M. , Williams J. H. 
Published: October 2008

SUMMARYThe hydraulic press was compared with the dew point psychrometer and the pressure chamber methods for measuring leaf water potential (Ψ) in groundnuts (Arachis hypogaea L.). For measurements on the same leaf, regression analysis revealed that the slopes did not differ significantly from unity. An analysis of functional relations between measurements made by the press and the dew point psychrometer or the press and the pressure chamber showed that the error variance of the press was similar to those of the two other methods. Therefore, we conclude that for groundnuts the performance of the press, the dew point psychrometer and the pressure chamber are similar.
Fifty Years ofExperimental AgricultureII. The Maintenance of Soil Fertility in Tropical Africa: A Review
Authors: Padwick G. Watts 
Published: October 2008

SUMMARYShifting agriculture is an ancient basis for maintaining soil fertility but pressures of population have caused it to give place in most countries to rotations and bare fallows which, in turn, have had to be reduced or modified. Research on various measures to shorten the duration of fallows and increase their effectiveness is reviewed. These measures include the use of organic manures and inorganic fertilizers, green manuring, mulches and the growing of legumes and grasses, which are discussed in relation to their effects on the soil and on crop yields. The increasing use of the factorially-designed experiment is recognized as a major contributor to this research.
Crop-Weed Competition Studies in Mung Beans (Vigna radiata)
Authors: Yadav S. K. , Bhan V. M. , Singh S. P. 
Published: October 2008

SUMMARYField experiments were done during the rainy seasons of 1980 and 1981 at Hissar, India; they studied the effects of time of weed removal on the yield of mung beans. Removing weeds at 10, 20 or 30 days after sowing led to significantly larger yields than that of the weedy check. Maximum seed yields in booth years were obtained when weeds were removed 20 days after sowing
Maize/Weed Competition Experiments: Implications for Tropical Small-Farm Weed Control Research
Authors: Vernon R. , Parker J. M. H. 
Published: October 2008

SUMMARYTwo sets of experiments examined the effects of weeds on maize yields using weeding methods typical of small farms in Zambia where oxen are used for cultivation. Maize yield losses of 30% due to weeds were evident with common weeding practices. A critical period of competition, during which the crop should be kept clean, was demonstrated from 10 to 30 days after emergence. This is a period of peak labour demand and the prospect of using chemical weed control to ease the situation is considered. The value of weed competition data, given its variability between sites, is discussed.
Utilization of Natural Hybrids in the Improvement of Groundnuts (Arachis hypogaea)
Authors: Nigam S. N. , Rao V. Ramanatha , Gibbons R. W. 
Published: October 2008

SUMMARYGroundnuts (Arachis hypogaea L.) are generally considered to be self-pollinated, but natural hybrids due to outcrossing have been observed in cv. Robut 33-1. Selections in segregating generations of these natural hybrids identified stable lines with large yield potentials in more than one environment. The role of natural hybrids in generating useful additonal variability is discussed.
Preparing Papers for Scientific Journals
Authors: Hudson J. P. 
Published: October 2008

SUMMARYMany of the papers submitted to this Journal fall far short of the standard of presentation that editors are entitled to expect. This tends to sour the all-important relation between editor and author, making unnecessary work for the former and perhaps even prejudicing acceptance of the latter's paper. The author, typist, editor and copy-editor have specific roles to play in preparing copy for the compositor and this article explains those roles, in the hope that the explanation may help authors to present their papers in the correct form.
Time of Planting, Rainfall and Soil Moisture Effects on Cowpea in Sierra Leone
Authors: Kamara C. S. , Godfrey-Sam-Aggrey W. 
Published: October 2008

SUMMARYAn experiment was conducted during the minor season in Sierra Leone to determine the optimum planting date for a photo-insensitive cowpea cultivar and study the relations between total rainfall and soil moisture available at different growth stages. Cowpeas planted in early September produced the tallest plants and higher grain yields than from other planting dates, since they benefited from 90% of the season's rainfall and made use of stored soil moisture. Average weekly rainfall or soil moisture in the top 15 cm of soil, recorded from planting to 50% flowering, can be used to predict cowpea grain yield.
Effects of Ethephon on Anthesis and ‘Fruit Collapse’ Disease in Pineapple
Authors: Lim W. H. , Lowings P. H. 
Published: October 2008

SUMMARYEthephon (ethrel) sprayed once on to pineapple inflorescences at the onset of flowering, at rates of 400, 800 and 1200 ppm, suppressed anthesis, with the highest suppression from the latter concentration. Suppression was associated with failure of flowers to open; where flowers did open they were usually short, shrivelled and devoid of nectar. One application was sufficient to affect anthesis for the following 16 days. Ethephon-treated plots had a significantly lower incidence of ‘fruit collapse’ (a disease caused by Erwinia chrysanthemi entering via the open flowers). Highest control (2·3% incidence) was achieved with ethephon at 1200 ppm compared with 7·0% in the control (P < 0·01). A highly significant correlation was established between disease incidence and the mean number of open flowers.
Zinc in Flooded Rice on Clay Soils in Lake Chad Basin, Nigeria
Authors: Beavington F. , Varley J. A. 
Published: October 2008

SUMMARYLow levels of zinc are reported in flooded rice grown on alkaline clay soils in the Lake Chad basin, north-east Nigeria. Zinc was added at 0, 5, 10 and 20 kg/ha to sample plots. For the untreated plots, the mean levels of zinc in young rice leaf and ‘available’ zinc in the supporting soil, using the alkaline extractant method of Trierweiler and Lindsay (1969), were 18·2 and 0·33 ppm respectively; corresponding mean levels for plots with 20 kg/ha added zinc were 36·5 and 1·54 ppm. There is a correlation between the two variables of r=+0·61 (P<0·01). Levels of nitrogen, phosphorus, potassium, magnesium and calcium in the rice leaf are also reported.
Effects of Variety and Spacing on Growth, Development and Dry Matter Distribution in Groundnut (Arachis hypogaea L.) at Two Locations in Nigeria
Authors: Yayock J. Y. 
Published: October 2008

SUMMARYAn investigation for 2 years at Kano and 1 year at Samaru evaluated the effects of plant density on vegetative growth, development and dry matter production and distribution of five varieties of groundnut. Growth and branching of individual plants were reduced at high populations but more dry matter was produced per unit area. Dense plants, particularly Spanish 205, developed a larger leaf area earlier in the season and were presumably able to make better use of light. Varieties F439.4 and 439.2 suffered the least reduction in the number of vegetative branches but the extra branches contributed few useful reproductive nodes.
Partitioning of Dry Matter and Nutrients in Oil Palm Seedlings Grown in Polybags
Authors: Lucas E. O. , Ataga D. O. , Thomas G. O. 
Published: October 2008

SUMMARYMonthly partitioning of dry matter (DM) and nutrient contents of polybag oil palm nursery seedlings, planted at three spacings, showed that leaves and petioles accounted for about half of the DM up to 11 months. There was no spacing effect on the nutrient contents of seedlings, K being always higher than other nutrients followed by N, Ca, Mg and P in that order. Most of the nutrients were in the leaves and petioles, with a dramatic increase in the amount of nutrient taken up by the seedlings in November. Fertilizer rates and frequencies were deduced for an oil palm nursery based on the nutrient contents of seedlings.
Response of Rice Varieties to Seasons in Taiwan
Authors: Chang W. L. , Yang S. C. 
Published: October 2008

SUMMARYThe adaptability of rice varieties to crop seasons in Taiwan was evaluated for 106 varieties. Average grain yield was higher in the first than second crop seasons. Indica varieties yielded better than Japonicas, particularly in the second crop season, when temperatures are higher. In both the Indica and Japonica groups, varieties developed in Taiwan outyielded those from overseas. Japonica varieties from Japan were lowest yielders in both seasons. Some IRRI varieties were outstanding in the first, while several Ponlais and Taiwan Indicas appeared promising in the second crop seasons.
A Laboratory Technique to Screen Seedling Emergence of Sorghum and Pearl Millet at High Soil Temperature
Authors: Soman P. , Peacock J. M. 
Published: October 2008

SUMMARYApparatus was built to screen sorghum and pearl millet for seedling emergence through a hot soil surface. Seeds were sown in soil in long clay pots arranged in a steel water tank so that the top 7 cm of the pots was above the water level. The soil in the pots was heated with infra-red lamps fitted to a frame above the tank. By adjusting the height of the frame the temperature of the soil could be changed. The system allows emerging plumules to be subjected to high soil temperatures (up to 50°C) but without water stress. Both crops exhibited genotypic differences in emergence.
Development of a Laboratory Screening Technique, Based on Embryo Protein Synthesis, For the Assessment of High-Temperature Susceptibility During Germination ofSorghum bicolor
Authors: Ougham H. J. , Stoddart J. L. 
Published: October 2008

SUMMARYThe capacity of sorghum lines to germinate at high soil temperatures (above 40°C) is clearly related to the temperature sensitivity of embryo protein synthesis. The development and optimization of a simple laboratory technique based on this correlation for the rapid large-scale screening of sorghum lines is described. Embryo-containing half seeds are incubated in the presence of14C-labelled amino acids at different temperatures and the resulting radio-labelled proteins extracted and bound to nitrocellulose discs for counting. The extent to which incorporation of14C-label into proteins is inhibited by elevated temperatures can be used to predict the likely temperature sensitivity of a given line during germination.
Examination of the Staple and Effective Land Equivalent Ratios
Authors: Riley Janet 
Published: October 2008

SUMMARYTwo extensions to the Land Equivalent Ratio (LER) concept, the Effective LER and the Staple LER, are evaluated for an intercrop of two species. The use of different standardizing sole-crop yields in the Effective LER equation is emphasized for the formation of different comparisons between intercrop and sole-crop yields. The Staple LER for different standardizing sole-crop yields is introduced. The equivalence of the Staple and Effective LERs under certain conditions is shown and illustrated.
Water Relations of Winter Wheat: the Root System, Petiolar Resistance and Development of a Root Abstraction Equation
Authors: McGowan M. , Tzimas E. 
Published: October 2008

SUMMARYThe vertical distribution of water potentials within the leaf canopy, along the stem and within the soil profile of a winter wheat crop was analysed and it is concluded the failure by previous workers to recognize the significance of petiolar resistance has probably resulted in over-estimates of the resistance of the soil to water uptake by root systems of field crops.From an analysis of the water relations of several winter wheat crops an equation is developed to describe the extraction of soil water reserves by crop root systems, based upon values of soil water potential, root xylem potential and ‘effective’ resistance to water uptake which can be obtained from field experiments. The equation provides an empirical basis to specify the minimum desirable root system for efficient capture of soil water reserves, to analyse the effects of differing root distributions and thus to help identify situations where it would be profitable to modify rooting either by tillage or by plant breeding.
Influence of Intercropping on the Yield and Food Value of Rainfed Sunflower and Companion Legumes
Authors: Narwal S. S. , Malik D. S. 
Published: October 2008

SUMMARYUnder rainfed conditions in north west India, intercropping with soyabean, peanut, greengram and clusterbean reduced sunflower yields by 25–50%. The number of pods per plant and grain yield of the leguminous intercrops were also reduced. The maximum LER (1.05) was obtained from the sunflower–greengram mixture. Intercropping increased the protein percentage of the sunflower but decreased that of the companion legumes. It had no effect on percentage oil content of sunflower.
Growth and Water Relations of Groundnuts (Arachis hypogaea) in Two Contrasting Years in the Irrigated Gezira
Authors: Ishag H. M. , Fadl Osman A. , Adam H. S. , Osman A. K. 
Published: October 2008

SUMMARYA field study was conducted on vertisols to determine the effect of three watering regimes and two plant densities on growth and yield of groundnuts. Total water requirements ranged from 486 to 597 mm depending on treatments. Three quarters of the water depletion was from the upper 20–30 cm. Plants in the sparse population were more sensitive to water stress so that the watering interval could be lengthened in the dense population without seriously reducing yield.
Growth and Developmental Stages of Alaska Peas
Authors: Meicenheimer R. D. , Muehlbauer F. J. 
Published: October 2008

SUMMARYGrowth and developmental stages of Alaska peas, from planting to dry seed maturity, were examined and described. Node counts were determined by designating the cotyledonary node as 0 and counting successive nodes up the plant to the highest visible one with unexpanded stipules. Five additional nodes are already determined in the shoot apex beyond the highest one with unexpanded stipules, indicating that damage to the shoot apex would result in losses of flowers and fruits that would have developed later if damage had not occurred.
Environmental Factors Affecting the Yield of Tea (Camellia sinensis). I. Effects of Air Temperature
Authors: Tanton T. W. 
Published: October 2008

SUMMARYThe response of tea shoots to temperature was studied in the field and in controlled environments. Shoot extension stopped below about 12.5°C. Shoots of mature tea took 491 day degrees above the base temperature of 12.8°C to grow to a harvestable size of 15 cm.
Environmental Factors Affecting the Yield of Tea (Camellia sinensis). II. Effects of Soil Temperature, Day Length, and Dry Air
Authors: Tanton T. W. 
Published: October 2008

SUMMARYTemperature is the major environmental variable affecting the yield of tea, but within the framework of a temperature model shoot extension is severely depressed when daily maximum vapour pressure deficits rise above 2.3 kPa. Day length does not affect shoot extension when the nights are cool (10°C), but growth rate is depressed by short days (11 h) when nights are warm (20°C). Soil temperatures between 18–25°C do not affect shoot extension.
Liming Needs of Sweet Potato in Malaysian Acid Peat
Authors: Chew W. Y. , Joseph K. T. , Ramli K. , Majid A. B. A. 
Published: October 2008

SUMMARYIn two field experiments, sweet potato showed symptoms of lime deficiency, and consequently produced extremely low DM, at the natural pH of local peat (3.5–3.7). Liming to increase pH remarkably increased tuber and vine dry matter to pH 5.5 and harvest index to pH 3.8, but higher pH values decreased dry matter and harvest index. Tuber and vine yields generally decreased with continuous monocropping, probably because of increasing infestation with weevils (Cylas formicarius) and other pests, and depletion of available nutrients.
Nitrogen Fertilization of Guinea and Napier Grass (Panicum maximum and Pennisetum purpureum) in Malaysian Oligotrophic Peat
Authors: Chew W. Y. , Ramli K. , Majid A. B. A. 
Published: October 2008

SUMMARYTwo field experiments studied the nitrogen fertilizer requirements of guinea and napier grass on peat. Plants in the control plots, though optimally limed and fertilized with other nutrients, absorbed only 1.7 and 2.4% of total peat N in a year and N fertilization improved DM yield, with an optimum at 900 kg/ha/yr. Further positive response was not observed, probably because of a reduced ratio of N to other nutrients. Optimum N uptake, and N concentration in the DM, were achieved at 600 kg/ha/yr N but N recovery decreased linearly with increasing fertilizer N at the rate of about 2–4% per 100 kg/ha/yr N.
Stylosanthes guyanensis Standing Hay as a Source of Dry Season Protein for Cattle in Malawi
Authors: Lamboll David 
Published: October 2008

SUMMARYThree cultivars of Stylosanthes guyanensis, under two management regimes, were assessed for yield, quality, palatability and persistence under grazing. During the dry season progressive leaf abscission resulted in unpalatable bare stem, but both leafy stem and fallen leaf remained palatable. Between May and September there was a decline in crude protein (from 16 to 11%), phosphorus (0.22 to 0.18%) and potassium (2.3 to 1.7%), but not in digestibility (average 53%). Partial rather than total accumulation of wet season growth ensured less trampling damage, hence better persistence. Cultivar ranking for persistence and leaf yield was Schofield, Cook, Endeavour, although Cook was initially the most productive.