Showing papers in "Experimental Agriculture in 1973"
TL;DR: While intercropping maize with either beans or cowpeas decreased total yield of grain (cereal and legume) per hectare, intercropped sorghum with pigeon peas increased total grain yield per hectar.
Abstract: Intercropping maize or sorghum with pigeon peas, cowpeas or beans led to a reduction in leaf area indices, fresh weight yield at time of anthesis, straw yield at harvest and grain yield of the cereal crops. In sorghum, pigeon peas and cowpeas had a greater adverse effect on grain yield than beans, but with maize, beans and cowpeas had a more adverse effect on grain yield than pigeon peas. While intercropping maize with either beans or cowpeas decreased total yield of grain (cereal and legume) per hectare, intercropping sorghum with pigeon peas increased total grain yield per hectare.
89 citations
TL;DR: In this article, the authors showed that the optimal LAI for oil yield is considerably below the critical LAI (LAI for maximum crop growth rate) for maximum oil yield, but the amount of dry matter per palm incorporated in vegetative tissues is unaffected by density.
Abstract: Crop growth rate of oil palm increases with leaf area index (LAI) to about 40 tons/ha./yr at the highest LAIs obtained. Net assimilation rate and dry matter production per palm decrease with increasing LAI, but the amount of dry matter per palm incorporated in vegetative tissues is unaffected by density. As a result the optimal LAI for oil yield is considerably below the critical LAI for maximum crop growth rate.
49 citations
TL;DR: The variety Nigerian Synthetic-5 was sown on eight occasions, five in the first season and three in the second season, at approximately 15-day intervals from 15 April to 15 June, and on 20 August, 4 September and 23 September.
Abstract: The variety Nigerian Synthetic-5 was sown on eight occasions, five in the first season and three in the second, at approximately 15-day intervals from 15 April to 15 June, and on 20 August, 4 September and 23 September The method of seed bed preparation and time of planting both affected yields, effects that could be related to soil temperature and soil moisture reserve during crop development Maize planted in August produced the highest yield; heaps and ridges gave the lowest yield at all planting dates, while planting on the flat or in furrows produced the highest yield
36 citations
TL;DR: In this article, the authors discuss the risks of introducing bias, the reliability of the data, and the resources required for these methods of grazing are discussed, and criteria are described for choosing between the methods.
Abstract: Pasture experiments may be grazed using either variable (put-and-take) or fixed stocking rates. Considerations such as the risks of introducing bias, the reliability of the data, and the resources required for these methods of grazing are discussed, and criteria are described for choosing between the methods.
34 citations
TL;DR: Drought resistance in terms of yield and its components was studied in the field in twenty-one agronomically-adapted high-performance grain sorghum (Sorghum bicolor Moench) hybrids, finding resistant hybrids performed better than susceptible ones under stress by producing a relatively higher number of panicles per unit area, and more grains per panicle branch.
Abstract: Drought resistance in terms of yield and its components was studied in the field in twenty-one agronomically-adapted high-performance grain sorghum (Sorghum bicolor Moench) hybrids. Resistance was considered to be indicated by a minimal decrease in yield under stress as compared with non-stress conditions. Water stress, imposed by a decreasing amount of stored soil moisture during the growing season, decreased grain yield and number of panicles per unit area, increased the number of grains per panicle, the number of branches per whorl and the number of grains per branch, and decreased the number of whorls per panicle. Thus a compensatory effect was observed in some components for reduction in tillering under stress. Resistant hybrids performed better than susceptible ones under stress by producing a relatively higher number of panicles per unit area, and more grains per panicle branch. Susceptible hybrids performed better than resistant ones under non-stress (irrigated) conditions due to the relatively higher number of panicles per unit area and larger 1000-grain weight. Some of the implications regarding selection for yield performance under drought are discussed.
32 citations
TL;DR: In this paper, the authors show that leaching is unlikely to be a serious problem in the nitrogen nutrition of early-planted maize under three levels of nitrogen, 56, 112 and 224 kg. N ha.−1, involving altogether nine different timing and splitting treatments.
Abstract: Maize was grown for three years at three levels of nitrogen, 56, 112 and 224 kg. N ha.−1, involving altogether nine different timing and splitting treatments. Measurements were made of grain yield, plant nitrogen status and total-N-uptake, and, in one year, movement of nitrate-N in control plot soils. Where only 56 kg. N ha.−1 was applied, its time of application made very little difference to yield; at higher rates of nitrogen an unsplit application as late as seven weeks was very inefficient, but only at the highest rate did a split application give any appreciable yield increase over an unsplit application to the seed bed. Consideration of the soil nitrate-N data and the long-term pattern of rainfall distribution leads to the conclusion that leaching is unlikely to be a serious problem in the nitrogen nutrition of early-planted maize.
30 citations
30 citations
TL;DR: Maize plants (Sweetcorn cv. Earliking) were grown in plots where four types of soil surface coverings were used to induce soil temperature differences during the vegetative stage of growth, and relative rates of leaf area increase were found to be closely correlated with mean daily soil temperatures at 5 cm.
Abstract: Maize plants (Sweetcorn cv. Earliking) were grown in plots where four types of soil surface coverings were used to induce soil temperature differences During the vegetative stage of growth measurements were made of total leaf area per plant on a daily basis, and relative rates of leaf area increase were found to be closely correlated with mean daily soil temperatures at 5 cm. depth. The results were consistent with evidence that the temperature of the apical meristem strongly influences rates of leaf expansion in maize seedlings.
28 citations
TL;DR: Crop yield on continuously cultivated tropical forest soil was maintained at a fairly high level by the application of mineral fertilizer, and there was a significant effect on pH of the soil resulting in a reduction of the divalent cations on the exchange complex.
Abstract: Crop yield on continuously cultivated tropical forest soil was maintained at a fairly high level by the application of mineral fertilizer. Although the low rate of nitrogen applied as ammonium sulphate did not increase yield, there was a significant effect on pH of the soil resulting in a reduction of the divalent cations on the exchange complex. The effect of mulch was mainly chemical through the release of nutrients.
22 citations
TL;DR: Preliminary observations on tubers of yam showed that there were increases in nematode populations during storage at ambient temperatures, whereas nematodes counts were very low after storage at lower temperatures, although the effect of ethylene dibromide was not lasting.
Abstract: Preliminary observations on tubers of yam (Dioscorea spp.) showed that there were increases in nematode populations during storage at ambient temperatures, whereas nematode counts were very low after storage at lower temperatures (12–13°C). Hot water treatments (50°C) for different lengths of time reduced the number of nematodes but damaged the tubers. Fumigation with methyl bromide, ethylene dibromide and hydrogen phosphide was not successful, as concentrations which reduced nematode numbers caused injury to the tubers. The effect of ethylene dibromide was not lasting.
21 citations
TL;DR: Satisfactory yields of cowpea could be obtained by maintaining only about one-half to two-thirds of the potential leaf-area of the plants, suggesting that a reduction in the number and area of leaves, coupled with a better display of the fewer remaining leaves, could make cowpeas more productive than hitherto.
Abstract: The yield of cowpeas could be increased by judicious defoliation of the older leaves or by topping the growing apices at the onset of flowering. Limited defoliation at the pre-flowering stage did not reduce the yield of beans significantly but severe defoliation at any stage prior to maturity drastically reduced yield. Satisfactory yields of cowpea could be obtained by maintaining only about one-half to two-thirds of the potential leaf-area of the plants, suggesting that a reduction in the number and area of leaves, coupled with a better display of the fewer remaining leaves, could make cowpeas more productive than hitherto.
TL;DR: The results suggest that the competitive effects of perennial weeds are due both to nutrient depletion and to biologically active substances.
Abstract: In a short-term competition experiment in large containers, growth of cotton planted 3 weeks after bermudagrass (Cynodon dactylon), johnsongrass (Sorghum halepense) or purple nutsedge (Cyperus rotundus), was severely reduced; after 10 weeks of competition, weedy cotton weighed only 15 per cent of the weed-free control. Cotton sown before weeds, or weeds planted before cotton, were only slightly affected by competition. Highly significant negative correlations were found between growth parameters of cotton and weeds. Inhibiting effects, and in some cases transitory stimulation, were produced on mustard seedlings by leachate from weed-infested soil and by extracts from subterranean weed parts, suggesting that the competitive effects of perennial weeds are due to nutrient depletion and to biologically active substances.
TL;DR: Effects of environmental temperature on boll maturation period of cotton and the genotype response, investigated in a 3-year field experiment, showed a negative correlation between period and mean temperature and revealed genotypic differences regarding degree of temperature influence and sensibility to temperature changes.
Abstract: Effects of environmental temperature on boll maturation period of cotton and the genotype response, investigated in a 3-year field experiment, showed a negative correlation between period and mean temperature and revealed genotypic differences regarding degree of temperature influence and sensibility to temperature changes. The observed genotype × temperature interactions may help cotton breeders in establishing breeding centres and in creating desirable gene combinations for wider adaptability to temperature.
TL;DR: In this paper, the authors show that irrigation, mulch and N-fertilizers increased the yield of fresh fruit/tree by 66 per cent due to increases of 42 per cent in the number of fruiting nodes/tree, 14 per cent increase in number of fruits/node and 15 per cent of fresh weight/fruit.
Abstract: Irrigation, mulch and N-fertilizers increased the yield of fresh fruit/tree by 66 per cent due to increases of 42 per cent in the number of fruiting nodes/tree, 14 per cent in number of fruits/node and 15 per cent in fresh weight/fruit; these three yield components accounted for 42, 13 and 6 per cent of the variation in yield among all treatment combinations. Bean/fruit weight ratios and times of flowering were not affected. Correlations between yield components were positive, suggesting that still more nodes could be produced per tree and per unit area before physiological limits to yield were reached.
TL;DR: In this paper, a field experiment was conducted to study the effect of irrigation with brackish water on the growth and composition of millet and corn, fertilized with various combinations of N and P.
Abstract: A field experiment was conducted to study the effect of irrigation with brackish water on the growth and composition of millet and corn, fertilized with various combinations of N and P. Millet irrigated with water of EC 3.30 mmho/cm. produced yields 79 to 93 per cent of the control (tap water of 0.61 mmho/cm.), depending on the N and P treatment applied. With water of EC 5.05 mmho/cm. yields equivalent to 52–72 per cent were obtained. Corn yields were 78–90 per cent of the control with irrigation water of 4.60 mmho/cm., and 55–64 per cent when irrigated with water of 7.06 mmho/cm. The N and P contents were mostly higher in plants grown on plots irrigated with brackish water.
TL;DR: A detached-leaf technique is described for assessing susceptibility of Hevea clones to Oidium heveae, based on intensity of sporulation, which offers a rapid, systematic method of screening clones in vitro against the disease.
Abstract: A detached-leaf technique is described for assessing susceptibility of Hevea clones to Oidium heveae , based on intensity of sporulation. This offers a rapid, systematic method of screening clones in vitro against the disease, in place of the current nursery and field methods.
TL;DR: The leaching of boron, studied after high rates of application under different management practices, indicated that leaching was rapid and that the presence of cover crops was likely to reduce the immediate availability of the main crops as discussed by the authors.
Abstract: The leaching of boron, studied after high rates of application under different management practices, indicated that leaching was rapid and that the presence of cover crops was likely to reduce the immediate availability of boron to the main crops.
TL;DR: In this paper, four-year-old seedlings of twenty-eight hybrid progenies were infected with the Ghanaian swollen-shoot virus strain A, but all were too severely affected to be of practical value in combating the disease.
Abstract: Four-year-old seedlings of twenty-eight hybrid progenies were infected with the Ghanaian swollen-shoot virus strain A, but all were too severely affected to be of practical value in combating the disease. Sensitivity was assessed by comparison with uninoculated controls; reduction in crop and in growth and deterioration of canopy were correlated. The Amelonado × Amazon crosses were no more sensitive than the better inter-Amazon progenies. The rapid decline of the infected trees may have been partly due to infection coinciding with the slowing down of vegetative growth as cropping commenced.
TL;DR: In this paper, the effect of applying calcitic lime and gypsum on haulm weight, pod-filling and kernel yield of groundnuts grown in soils of Northern Malawi was assessed.
Abstract: Glasshouse and field trials have been used to assess the effect of applying calcitic lime and gypsum on haulm weight, pod-filling and kernel yield of groundnuts grown in soils of Northern Malawi. Incorporation of lime prior to planting and topdressing gypsum at flowering both rectified poor pod-filling and improved kernel yield. Gypsum decreased haulm weight and usually produced lower overall kernel yield than lime. The relative merits of lime and gypsum application are discussed, together with the need for supplementation by phosphorus and sulphur.
TL;DR: Effects of fertilizers on harvest time and yield of cowpeas were studied on upland soils in Sierra Leone and in a randomized complete block experiment, there was a significant difference in total yield of dry pods between the control and most treatments.
Abstract: Effects of fertilizers on harvest time and yield of cowpeas were studied on upland soils in Sierra Leone. In a 2 5 confounded factorial trial, on soil which had been cropped successively with 2 years of Smooth Cayenne pineapples and 14 months of cassava, the treatments did not affect harvest time significantly, but N, P and NP Mg produced very favourable effects on grain yields. In a randomized complete block experiment on soil previously cropped with two successive cassava crops, there was a significant difference in total yield of dry pods between the control and most treatments.
TL;DR: In fifteen field trials with Phaseolus vulgaris cv.−1, a response in yield was obtained from 11 kg. N ha as mentioned in this paper, but there was no effect of source of nitrogen or response to phosphate, potash or inoculation.
Abstract: In fifteen field trials with Phaseolus vulgaris cv. Canadian Wonder time of planting was the most important factor affecting yield of dry beans in the Shire Highlands of Southern Malawi. Under-cropping maize with beans had no deleterious effect on the yield of maize and gave a worthwhile yield of beans. Little response was found to different plant populations when conditions for growth were good, but when conditions were poor yields were greatest from the highest population of 47,000 plants per hectare. A response in yield was obtained from 11 kg. N ha.−1 but there was no effect of source of nitrogen or response to phosphate, potash or inoculation.
TL;DR: The seed of American Cotton, Var. 134, was stressed at 50, 60, 70, 80 and 90°C for 24 or 48 hours before seeding as mentioned in this paper, which had a stimulatory effect on seedling emergence and subsequent performance.
Abstract: The seed of American Cotton, Var. 134, was stressed at 50, 60, 70, 80 and 90°C for 24 or 48 hours before seeding. Stresses at 50 to 70°C had a stimulatory effect on seedling emergence and subsequent performance of the cotton plants, but higher temperatures caused thermal injury or killed the seed.
TL;DR: In this article, a method for estimating boron requirements of the oil palm, and factors influencing the leaf Boron concentration of the palm are discussed, and a method is described for estimating BORON requirements of oil palm.
Abstract: A method is described for estimating boron requirements of the oil palm, and factors influencing leaf boron concentration of the palm are discussed.
TL;DR: C cultivation of NCo 310 fields with high smut incidence was concluded to be a major hazard to the industry.
Abstract: Sugarcane yields and smut incidence levels were observed in three successive crops. The effect of pathogen upon host was primarily one of stress, as smut infection was shown to increase sucrose content of cane whilst depressing yields in tonnes of cane per ha. Where infection levels were high, roguing was shown to increase disease incidence. However, smut whip removal was confirmed as the best roguing treatment for commercial fields. Disease control and yield responses related to roguing effort were much better in NCo 376 than NCo 310; and, therefore, continued cultivation of NCo 310 fields with high smut incidence was concluded to be a major hazard to the industry.