The pressure-chamber technique has been used for the first time to measure leaf-water potentials in chickpea under field conditions. Available soil-water contents at different depths for irrigated and non-irrigated crops are presented along with the diurnal variation in leaf-water status, to show that pressure-chamber measurements correspond closely with available soil water. Leaf-water potential has also shown differences in leaf-water status among different cultivars. The rapidity and ease with which measurements can be made in the field make the technique suitable for quick measurements of leaf-water status for chickpea.

With the exception of leafy and daylength-sensitive cultivars, cowpea (Vigna unguiculata (L.) Walp), produced larger yields in the first season (April-July) than in the second season (September-November) at Ibadan, Western Nigeria, whether or not the crop was protected by insecticide. The populations of major cowpea pests were low at the start of the rainy season and reached their peaks in September or October. The implications of these results in insect control strategy are discussed.

Experiments were carried out in which injuries caused by Diopsis macrophthalma larvae were simulated. The results show that these larvae can have negative or positive effects on rice (number of stems, height, maturation time, number of ears and yield), depending on time and level of attack, growing conditions and variety. The results suggest that under normal conditions the effect on number of stems, height, number of ears and yield is positive, and only becomes negative if poor growing conditions are combined with a late, heavy attack. An experiment with Diopsids was carried out to evaluate the simulation experiments.

This study examined the economic, technical, and social feasibility of an improved groundnut production technology at the farmer's level vis-à-vis traditional practices. Improved practices are shown to be superior, but several economic and technical issues are raised.

Three cultivars of mustard (B. juncea) were grown on field plots with five levels of fertilizers and with or without irrigation. Irrigation gave 59% more seed yield than no irrigation, accompanied by improved performance of ancillary characters. Significant increases in seed yield and most of the other characters were noted with increased levels of fertilizers, with a significant cultivar × fertilizer interaction due to the negative response of one cultivar to increased levels of fertilizers. The importance of irrigation and fertilizer in mustard seed production was thus demonstrated.

Measurements indicate that the tea crop—which consists of young shoots—is sink-limited and that the plucking of immature shoots, essential for quality tea, is a major factor limiting yields of the crop. The importance of this aspect in selecting for high-yielding plant material is discussed.

Twenty-five cultivars of soyabean (Glycine max (L.) Merr.), differing in their origin, crop duration and seed size, were planted four times at bi-weekly intervals during the major rainy season at Ibadan, Nigeria and harvested at optimum maturity or two weeks later. Delayed harvest and intense rainfall during pod maturation were essential for selecting for resistance to field weathering, but 2 weeks' delay enabled susceptible and resistant cultivars to be identified. Percentage of infected seed had the highest correlation with potential germination at harvest (r=−0·869**) but may not be a suitable criterion for use in a screening programme. An alternative would be to screen cultivars for resistance to weathering on the basis of seed size and the proportion of smooth and clean seed, since these characters were highly correlated to potential germination (r=−0·562** and 0·632** respectively).

Pigeonpeas (Cajanus cajan) are normally sown in June or July in India, at the beginning of the monsoon, but trials were carried out at Hyderabad by sowing in October or November as a winter crop. The duration of the crop, especially of the ‘medium’ and ‘late’ cultivars, was much reduced. In 1975–76, October-sown pigeonpeas gave yields comparable to those of the normal season but much lower yields were produced by planting in November 1975. ‘Medium’ and ‘late’ cultivars significantly outyielded early ones. Optimum plant populations for winter crops were 3–5 times higher than are normally used in the monsoon. Pigeonpeas at relatively high population densities could have considerable potential as a winter crop in peninsular India.

An aqueous solution of a morphactin (chlorflurenol) was applied at 100–1000 ppm to plants of corn (Zea mays L.) variety White Ganga-2 to examine its influence on growth, sex expression, yield and carbohydrates in the grain. At concentrations up to 600 ppm morphactin decreased height, weakened apical dominance, increased the number of tillers and thickness of stem, and caused an appreciable increase in female sex expression, yield and carbohydrates in the grain but reduced them at 800 and 1000 ppm.

Trials on ferrallitic soils in Uganda showed that crops responded to lime after the first year of cropping on soils which had a pH up to 6·0, and to potassium on soils which had an extractable K level up to 18 mg 100 g−1. Soil and leaf analyses indicated that responses to lime on soils of pH above 5·2 were due to an increase in phosphate availability. Low yields at several sites in the first year were apparently due to immobilization of nutrients during rapid mineralization of soil organic matter. In later years soil organic matter did not decline appreciably, and yields dropped only at sites where potassium or minor element deficiencies apparently developed.

Methods are described for releasing HCN from cassava leaves and tubers by organic solvents and its spectrophotometric estimation as the red complex formed with alkaline picrate. Chloroform was the most efficient solvent, with toluene an acceptable alternative, using enough solvent to wet samples thoroughly to maximize cyanide yield. Cyanide content was concentrated in the veins and towards the base of leaves and declined linearly with leaf age. Release of HCN with solvent compared favourably with traditional homogenization/steam distillation with leaves and parenchymal tissue, but was unsatisfactory for tuber peel. The effective removal of HCN from cooked cassava leaves depends chiefly on release of enzymes by efficiently chopping them before boiling, which only slowly destroyed potential cyanide content of unchopped leaves.

Four hybrids of pearl millet (Pennisetutn typhoides) were screened for photoperiod sensitivity in a heated temperate glasshouse and the effects of 12 h short day induction on the reproductive development and plant morphology were examined. All the hybrids (BK 560, MBH 104, MBH 110 and ICH 105) responded to 14 short days by a considerable reduction in the time to anthesis, plant height and the final number of leaves produced, without any adverse effect on head development. In another experiment BK 560 required at least four short days for floral initiation and another four for subsequent development. Short day induction had no apparent effect on the rate of leaf appearance. The results were compared to those reported for millets in general and to millets grown in the tropics.

The effects of nitrogen fertilization and cutting intervals on extractable protein have been studied in three arid zone grasses, viz. Cenchrus setigerus, C. ciliaris and Lasiurus sindicus. Depending on the number of cuts and soil fertility status, maximum protein could be harvested from C. ciliaris followed by C. setigerus and L. sindicus. It is concluded that the maximum yield of leaf protein per unit area of land can be achieved with short intervals of cutting coupled with the application of nitrogenous fertilizer.

The change in seed oil percentage and 100-seed weight of Brassica juncea Varuna was studied as the crop matured during rabi 1977–78. Statistically, the oil percentage reached its highest value at 55 days from flowering, whereas the 100-seed weight was highest about 20 days later, when the pods were fully yellow. Oil yield (the product of oil percentage and seed weight) also reached its highest value when the pods were fully yellow. This information should enable the crop to be harvested at the proper physiological stage (yellow-podded) for maximum oil yield.

Three field experiments were conducted at Guneid, Sudan, in which N was applied to sugarcane (A) in one dose, (B) in split doses at 2 and 4 months, and (C) as a single dose 4 months from planting. Nitrogen application generally increased the yields of both cane and sugar but did not significantly affect sucrose recovery. Correlation coefficients for yields of cane and sugar suggested that the application of 88–176 kg N/ha 2 months after planting was economic.