bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Light, Temperature, Irrigation and Fertilizer on Photosynthetic Rate in Tea (Camellia Sinensis)
Authors: Gail Smith B. , Stephens William , Burgess Paul J. , Carr M. K. V. 
Published: October 2008

SUMMARYPhotosynthetic rates were monitored during the warm dry season in tea Clone 6/8 in a line-source irrigation × fertilizer experiment in the Southern Highlands of Tanzania. Irrigation and fertilizer increased photosynthetic rate both by enhancing photosynthetic rate per unit leaf area (A) in healthy leaves and by increasing the proportion of sunlight intercepted by photosynthetically efficient leaves. Irrigation-induced increases in A could be accounted for by increases in stomatal conductance (g) and associated reductions in leaf temperature. Fertilizer at an annual application rate of 225 kg N ha-1 caused increases in A associated with increases in g and improved responses to ambient CO2 concentration and illuminance (photon flux density, PFD). However, a further increase in fertilizer application rate to 375 kg N ha-1 a-1 decreased A in spite of increasing g. Light-saturation of photosynthesis occurred only at the higher fertilizer application rate. In unfertilized tea or tea fertilized at the lower rate, A decreased at a PFD of between 1400 and 2000 μmol m-2 s-l. These results are discussed in terms of the relation between photosynthesis and yield in tea.Fotosíntesis en el té
Effect of Taking a Fodder Crop on Maize Grain Yield and Soil Chemical Properties in Leucaena and Gliricidia Alley Farming Systems in Western Nigeria
Authors: Larbi A. , Jabbar M. A. , Atta-Krah A. N. , Cobbina J. 
Published: October 2008

SUMMARYThe effect of managing hedgerow foliage for mulch and fodder in Leucaena leucocephala and Gliricidia sepium alley farming systems on maize grain yield and soil chemical characteristics was studied in on-station and on-farm experiments in southwestern Nigeria. Yields increased as the proportion of mulch applied increased but the extra increases obtained when more than half the foliage was applied as mulch were relatively small, suggesting that half the foliage may be removed as feed without detrimental effect. Soil organic carbon, nitrogen and available phosphorus tended to increase with increasing proportion of prunings applied as mulch.Follaje para ‘mulch’ y forraje en la agricultura de sendero
Responses of Tea (Camellia Sinensis) to Irrigation and Fertilizer. III. Shoot Extension and Development
Authors: Stephens William , Carr M. K. V. 
Published: October 2008

SUMMARYRates of shoot extension and development (the unfolding of leaves) were recorded in an irrigation × fertilizer experiment on Clone 6/8 at Ngwazi Tea Research Unit in southern Tanzania. The wide range of mean temperatures (from 15–20°C) meant that the duration of the shoot replacement cycle (the time taken for an axillary bud released from apical dominance to develop three leaves and a terminal bud), in fully irrigated tea receiving 450 kg N ha-l, varied from 65 d in the warm wet season to 95 d in the cool dry season, compared with 75 to 180 d for unirrigated and unfertilized tea. Regression analysis indicated that the base temperature for extension, for Clone 6/8 in high-input plots, was about 10°C, some 2–3°C more than that for development. As a result of these differences in base temperature, the length of shoots with three leaves and a bud varied considerably between treatments and seasons, ranging from 15 mm in the unirrigated plots (at the end of the dry season) to 130 mm in the high-input plots at the start of the rains. Shoots from well fertilized tea were always longer (at a given stage of development) than those from unfertilized tea. The results are discussed in terms of the possible mechanisms responsible for the observed responses (changes in partitioning between roots and shoots), commercial harvesting practices and yield modelling.Extensión y desarrollo de broies en el té
Effects of Temperature, Soil Water Status and Depth of Planting on Germination and Emergence of Maize (Zea Mays) Adapted to Semi-Arid Eastern Kenya
Authors: Itabari J. K. , Gregory P. J. , Jones R. K. 
Published: October 2008

SUMMARYThe effects of temperature and soil water potential on maize germination were investigated in controlled environment conditions and the effects of depth of planting and a mulch on maize emergence were studied in a field experiment in eastern Kenya. The rate of germination increased to an optimum temperature of 33.6°C above a base temperature of 6.1°C and decreased above the optimum to zero germination at 42.9°C. The thermal time for median germination increased from 51.5°Cd to 56.4°Cd as soil matric potential decreased from -5 to -40 kPa. Soil water content, depth of planting, and their interaction had significant (P < 0.001) effects on final germination and emergence but mulch, or any interactions involving mulch, had no such effects. Increasing depth of planting by 1 cm increased the thermal time required for emergence by 2.8°Cd, and decreasing water content by 1% increased the thermal time required for emergence by 3.2°Cd.Germinación y emergencia del maíz
Spatial Variability in Soil Chemical Properties under Dactyladenia barteri, Alchornea cordifolia, Senna siamea and Gmelina arborea Hedgerows on an Acid Ultisol
Authors: Ruhigwa B. A. , Gichuru M. P. , Tariah N. M. , Isirimah N. O. , Douglas D. C. 
Published: October 2008

SUMMARYSpatial nutrient distribution was studied under a three-and-a-half-year-old fallow of Dactyladenia barteri, Alchornea cordifolia, Senna siamea and Gmelina arborea hedgerows grown on an acid Ultisol in southeastern Nigeria. The objectives were to evaluate the nutrient cycling capacity and suitability of the hedgerow species for alley cropping. No consistent patterns were observed in the lateral distribution of soil pH, total nitrogen, organic carbon, available phosphorus, exchangeable cations (potassium, calcium, magnesium and sodium), total acidity and effective cation exchange capacity in the 4 m wide alleys formed between the hedgerow species. Senna siamea and Gmelina arborea tended to increase soil organic carbon, calcium, magnesium and effective cation exchange capacity, particularly in the top 50 cm, compared with Alchornea cordifolia and Dactyladenia barteri, and can therefore be recommended for soil fertility regeneration on acid Ultisols during periods of fallow. However, they appear to be less suitable for alley cropping than Dactyladenia barteri because they are shallow rooting.Propiedades químicas delo suelo bajo cuatro especies de seto vivo
An Analysis of the Adoption and Diffusion of Carioca Beans in Zambia Resulting from an Experimental Distribution of Seed
Authors: Grisley W. , Shamambo Moffat 
Published: October 2008

SUMMARYSeed of the new heavy yielding bean cultivar Carioca was distributed directly to 400 farmers in Zambia during 1986 in order to speed its adoption and diffusion. Three years after distribution, 55% of the farmers who participated in a follow-up survey were still sowing Carioca. Diffusion of the new cultivar had occurred, with 3.7 times as many farmers estimated to be growing Carioca in 1988/89 as in 1986, an annual rate of diffusion of approximately 49%. Use of a logistic modelling framework suggested that the variables directly associated with the decision to adopt the cultivar were the farmer's total area in cultivated crops and the area in local maize. Variables indirectly associated with adoption were the level of education of the household head, the average number of years that the fields had been in continuous cultivation and the number of cattle owned. These results will help guide the development of effective strategies for the release and distribution of new bean cultivars from national bean research programmes in sub-Saharan Africa.Adopción y difusión del poroto Carioca en Zambia
Weed Control in Wet-Seeded Rice
Authors: Moody Keith 
Published: October 2008

SummaryIncreasing transplanting costs in southeast Asia have encouraged farmers to adopt labour-saving crop establishment techniques for rice, such as wet seeding. This practice has been accompanied by an increase in weed problems and a shift in the dominant species to grassy weeds. Other problems are encountered with wet seeding but weeds are the most severe and most widespread constraint. It is impossible to produce rice economically without a well-planned weed control programme. The problems caused by weeds in wet-seeded rice and ways of controlling them by preventive, ecological, managerial, physical and chemical means are discussed in this paper. Herbicides are the most cost-effective weed control method in wet-seeded rice but there is a need to reduce the almost total reliance on them for weed control; cultural practices need to be integrated with judicious herbicide use. Worldwide concerns over environmental issues also need to be addressed.Control de malezas en el arroz de siembra húmeda
Growth and Yield of Millet and Cowpea in Relay and Intercrop Systems in the Sahelian Zone in Years when the Onset of the Rainy Season is Early
Authors: Sivakumar M. V. K. 
Published: October 2008

SummaryField trials conducted previously in Niger have shown that in years when the onset of the rains is 15–20 days earlier than average, the long growing season can be exploited by growing a relay crop of millet (Pennisetum glaucum) and cowpea (Vigna unguiculata). In the trials reported here, the advantages of relay cropping were compared with intercropping with improved management and intercropping under traditional management during the 1989, 1990 and 1991 rainy seasons at the ICRISAT Sahelian Center, Sadore, Niger. The length of the growing season varied from 139 to 150 days over the three seasons. The relay crop produced more dry matter and leaf area and yielded more than the intercrops in all three years, confirming that in years when the onset of the rains is early, relay cropping with millet and cowpea is a better option than growing the same two species as an intercrop. Relay cropping avoids the competitive effects inherent in intercropping systems, while offering the additional advantages of rotating cereals with legumes.Mijo y caupí en sistemas de relevo y de cultivo simultáneo
Guidelines for Improved Agronomic Management and Economic Evaluation of Crop Rotation Trials in Mediterranean Environments
Authors: Keatinge J. D. H. , Somel K. 
Published: October 2008

SummaryThis paper offers guidelines for successful crop rotation trials derived from experience at ICARDA in the period 1980–1990. Emphasis is placed on the need to determine realistically the likelihood of the long-term, successful completion of the trial and the importance of considering carefully experimental design criteria prior to trial establishment. This involves assessment of what primary and secondary information to collect for the trial, and over what duration, in order to ensure an appropriate return for the large investment generally undertaken in any crop rotation trial.Principios para ensayos con rotación de cultivos
Seed and Seedling Dynamics Over Four Consecutive Years from a Single Seed Set of Six Annual Medics (Medicago SPP) in North Syria
Authors: Cocks P. S. 
Published: October 2008

SummaryThe fate of seed of six annual medics produced in spring 1987 and used in the pasture phase of cereal-pasture rotations was followed over four years. The medics were sown at low and high density, and seed set beyond 1987 was prevented by cultivation in 1988, and by herbicides in 1989 and 1990. The breakdown of hard seed was measured in the summer and autumn of each year, and the number of seedlings was counted after the first seasonal rains in the final three years. The survival of seeds buried at three depths was monitored. Seed of Medicago noeana lived longer than that of M. rotata and M. polymorpha. Survival of M. rigidula and M. truncatula seed was intermediate and there was no effect of planting density on survival. Breakdown of hard seed was least in the first year and increased in the second and third years. Within any year breakdown began in late summer or early autumn, beginning earlier as the seed aged. Seed burial enhanced germination in the year following seed set, depressed it in the second and third years, and had little effect in the fourth year. The net effect of seed burial on survival was therefore slight. The results suggest that the use of medics that have harder seeds than currently available cultivars, and medics in which germination is delayed until late in the autumn, will increase the sustainability and productivity of cereal-pasture rotations in semi-arid areas.Dinámica de semilla de los Medicago spp anuales en Siria
Environmental and Agronomic Effects on the Growth of Four Peanut Cultivars in a Sub-tropical Environment. I. Dry Matter Accumulation and Radiation Use Efficiency
Authors: Bell M. J. , Wright G. C. , Harch G. R. 
Published: October 2008

SummaryFour peanut cultivars of Spanish or Virginia botanical type and varying time to maturity were grown at a range of plant densities (44 000 to 352 000 plants ha-1) and spatial arrangements under irrigated conditions in sub-tropical southern Queensland, Australia. Total and pod dry matter production of the very early maturing Spanish cultivar Chico showed strong positive responses to increased plant density up to the highest density tested. Responses were less pronounced for the later maturing Spanish cultivar McCubbin and were minimal for the Virginia cultivars Early Bunch and Mani Pintar. All cultivars were insensitive to spatial arrangements. Accumulation of total dry matter, adjusted for the higher synthesis costs of oil and protein during seed filling, was well correlated to intercepted photosynthetically active radiation (PAR). Much of the variation in dry matter production among cultivars and plant populations could be accounted for by the effects of differing leaf area duration on cumulative intercepted PAR. Radiation use efficiency was negatively associated with the canopy extinction coefficient (k) within most sowing dates, and also negatively associated with minimum temperature across sowing dates for all cultivars except Mani Pintar.Crecimiento y eficacia del use de radiación en el maní
Environmental and Agronomic Effects on the Growth of Four Peanut Cultivars in a Sub-tropical Environment. II. Dry Matter Partitioning
Authors: Bell M. J. , Wright G. C. , Harch G. 
Published: October 2008

SummaryThe partitioning of dry matter between vegetative and reproductive yield components was analysed for four diverse peanut cultivars at a range of sowing dates and plant populations in sub-tropical Queensland, Australia. Rates of accumulation of pods (pod addition) varied significantly with both cultivar and sowing date. Within cultivars, much of this variation could be attributed to variation in crop growth rate during the critical pod addition period. The proportion of current assimilate distributed to pods depended on inherent cultivar characteristics and also correlated well with the current crop growth rate relative to the crop growth rate during pod addition (that is, with relative source activity). Neither plant density nor spatial arrangement had any significant effects on patterns of assimilate distribution. All cultivars appeared capable of remobilizing stored assimilate to maintain constant rates of pod yield increase despite fluctuations in crop growth rate which might be expected to produce short term source limitations to pod yield accumulation. The harvest index (HI) increased linearly during the entire pod fill period in all cultivars except the very early maturing Spanish cultivar Chico. Neither density nor spatial arrangement affected rate of increase in HI except in Chico, where increased density produced increased rates of increase in HI. Variation in the rate of HI increase among sowing dates was small.Distributión de la materia seca en el maní
Dissemination of New Technology in a Farming Systems Research and Extension Programme: Diffusion of Rice Varieties in an Area with Poor Production Potential
Authors: Wijeratne Mahinda , Chandrasiri P. A. N. 
Published: October 2008

SummaryThe diffusion of rice varieties introduced into an area with poor production potential and problems of soil degradation was studied in a farming systems research and extension programme. Two rice varieties, BW. 272–3 and At. 85–1 were identified as appropriate for the area and efforts made to transfer the experimental results to the farmers. BW. 272–3 was widely adopted by farmers in the lower, intermediate and upper areas of the recommendation domain but adoption of At. 85–1 was confined to the intermediate and upper areas. Adoption of rice varieties was mainly governed by the characteristics that allowed a variety to perform well under adverse conditions and by the farm gate price it could command, which depended on grain pericarp colour.Difusión de nuevas variedades de arroz
Plant Water Relations, Irrigation Management and Crop Yield
Authors: Fischer Ralph A. , Hagan Robert M. 
Published: October 2008

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

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

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

SummaryThe analysis of radiation climate is a central problem of agricultural meteorology because rates of photosynthesis depend on the receipt of visible light and rates of transpiration depend on the net exchange of radiation by a crop canopy. Both short-wave (solar) and long-wave (terrestrial) radiation are correlated with cloud amount, and in south-east England the income of net radiation in summer is proportional to the income of solar radiation.In principle, the fraction of total radiation in the visible waveband depends on cloud cover and on the amount of absorption and scattering in the atmosphere, but in practice the fraction is often between 0·40 and 0·45. The calculation of photosynthetic efficiency needs a figure for the number of quanta (or Einsteins) per unit energy, and this figure can be calculated from the mean wavelength of the radiation weighted by energy, about 0·55μ for direct sunlight.The reflection of radiation by vegetation changes with solar elevation, and at angles between 40° and 60° it ranges between 0·15 for a rough crop (e.g. pineapple) to 0·26 for smoother crops (e.g. sugar beet, kale). The transmission of radiation through the canopy can be expressed as a function of the leaf area index and a parameter that depends on the distribution and orientation of leaves.
Effects of Nitrogen, Phosphorus and Potassium on Nodulation in Cowpea
Authors: Tewari G. P. 
Published: October 2008

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

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

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