An experiment was carried out to determine the partitioning and accumulation of nitrogen in plant components, nitrogenase activity and their relationships with seed yield of a local cultivar of winged bean (Psophocarpus tetragonolobus (L.) DC.) grown on three support systems of 0, 1, and 2 m height under field conditions. Total nitrogen accumulation and nitrogen partitioning were determined throughout the growing season by measuring nitrogen content and concentration in above-ground plant tissues (leaves, stems, petioles and pods). Support heights of 1 and 2 m significantly increased total nitrogen accumulation in component parts of the plant, nitrogenase activity, nodulation, total dry matter accumulation and seed yield compared with the control. Plants grown on supports accumulated significantly higher leaf nitrogen at the vegetative stages and the contribution of seed nitrogen was also significantly higher compared with unsupported plants. Nitrogenase activity increased with onset of flowering but declined during the pod formation stage in plants grown on a support system. Unsupported plants showed higher nitrogenase activity prior to flowering possibly due to lack of photosynthate and, consequently, early senescence of leaves.

Analyses of total N and P in coffee leaves from different geographic areas have been compared. The levels of these nutrients are correlated with each other and the quadratic regression equation for leaf N on leaf P has been derived. The value of N/P ratio in the coffee leaf for diagnosing nutritional status is assessed. No correlations were observed between Mg and either N or P. Irrigation of coffee in Kenya on latosolic soils raises leaf P but not N levels, in the absence of organic mulch and fertilizers. Effects of organic mulch, N and P fertilizers on leaf levels of N or P are discussed.

Field experiments were conducted for 4 years to study the yield of ‘kharif’ and ‘rabi’ crops grown in sequence on two soils differing in water-holding capacity. The results indicated that drought caused greater reduction in yield of rainy-season crops on loamy sand than on sandy loam soil. In low retentivity soil it was more profitable to raise a single crop of wheat on soil-stored water. In sandy loam soil of higher retentivity, two crops a year gave much higher yields than a single crop. Of the sequences tried, maize followed by wheat gave the highest and most stable yields. For ‘rabi’ crops, stored water showed a better yield response than an equivalent amount of rain during the growing season.

Dry matter production in a bushy and spreading cultivar of sweet potato was studied in two trials comparing dry matter partitioning between plant components. The bushy cultivar, VSP-2, accumulated more tuber dry matter than the spreading cultivar, BNAS-51. The number and yield of tubers of VSP-2, was also greater but its foliage dry weight was less than that of BNAS-51. The vine and root dry weight of BNAS-51 increased with time but that of VSP-2 reached a peak about 10–12 weeks after planting. The tuber dry weight of BNAS-51 at harvest was similar to its foliage dry weight but that of VSP-2 was three times greater. The proportion of total dry matter partitioned to the tubers of VSP-2 was greater than that in BNAS-51 at all stages of growth.

Estimates of variety × environment interactions for grain yield were obtained from a study involving 16 sorghum varieties grown at the same three locations over a 3-year period. Whereas the variety × year interaction was small and not significant, the variety × location and the variety × location × year interactions were highly significant. Evidence was presented suggesting that the years of testing could be reduced by increasing the number of test locations. T.F.M.7 and Karkatib 4/1/1 were identified as desirable varieties, combining high yield and stability of performance, thereby deserving a place both in commercial production and future breeding programmes.

Results of a two-year field study show that even under hot northern Indian conditions, sugar-beet planting dates can be advanced to 20 September to permit an early harvest from mid-March onwards. Seeding the crop on the northern side of east-west ridges gave root yields of 45–50 t ha−1 with a sucrose content of 12–14%. Transplanting gave the highest tonnage but led to a high incidence of branched tap roots. For timely planting during October, direct seeding in north–south rows was also satisfactory. Such staggered seeding and harvest schedules could help extend the milling period to 90–100 days as against the present 45–50 days.

Using coffee trees sprayed with cuprous oxide and captafol it has been shown that both fungicides are redistributed within the tree canopy by rain. Under conditions of light rain fungicides are removed from upper parts of trees and redeposited at lower levels within the canopy in amounts capable of providing effective protection against coffee berry disease (CBD). With heavy rainfall, however, redeposition of fungicide at effective levels is less likely to occur. The results are discussed in relation to the success of overhead boom sprayers in controlling CBD and the observations that shoots in the upper parts of coffee trees are an important source of spores of the CBD strain of Colletotrichum coffeanum.

Effects of daylength and night temperature on the onset of flowering of selected cowpea cultivars have been investigated, using automatically controlled glasshouses at Reading. The results show close agreement with those from field trials in Nigeria, wherein low intensity incandescent lighting was used to extend the natural daylength. As the field technique has proved an effective screen for daylength insensitivity, future screening work in glasshouses can be for effects of night temperature on time to first flower and for day temperature on the rate of leaf senescence and components of seed yield. This integrated approach can accelerate the screening of cowpea cultivars for sensitivity to environmental factors over ranges characteristic of the low altitude, humid tropics.

Late planting of a 136-day variety of maize led to reduced yields only when planting was later than about four weeks after the start of the main rains. The reductions were caused by drought at the end of the season and by high rainfall in the first 35 days after planting. Drought beginning 80–100 days after planting (DAP) reduced weight per seed but drought beginning earlier than 80 DAP reduced seed number per cob and increased the number of barren plants. Late showers alleviated the reduction in weight per seed but not the other symptoms of drought. High rainfall after planting was associated with reduced plant size at flowering and reduced seed number per cob at harvest.

An experiment is described on the establishment of the grass Andropogon gayanus in the presence of different companion crops. Maize and soyabean proved the most suitable companion crops; mucuna and the annual grass Pennisetum pedicellatum were too competitive. The companion crops significantly reduced weed invasion. The establishment of A. gayanus was improved by early harvesting of companion crops. Dry matter yields were highest where grass had been sown in rows. Inclusion of a companion crop is a promising method of increasing herbage production without harming the establishment of the under-sown seeds.

After 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.

Soil alkalinity imposes important limitations to lupin productivity; however, little attention has been paid to investigate the effects of soil alkalinity on plant growth and development. Many lupins are sensitive to alkaline soils, but Lupinus albus material from Egypt was found to have tolerance to limed soils. The aim of this study was to compare the growth response of two cultivars of L.albus L. – an Egyptian cultivar, P27734, and an Australian cultivar, Kiev Mutant, to different soil pH levels and to understand the physiological mechanisms underlying agronomic alkalinity tolerance of P27734. Plants were grown under three pH levels (5.1, 6.7, and 7.8) in a temperature-controlled glasshouse. For both cultivars, the greatest dry mass production and carboxylate exudation from roots were observed at alkaline pH. The better performance of the Egyptian cultivar at high pH was entirely accounted for by its greater seed weight. From a physiological perspective, the Australian cultivar was as alkaline-tolerant as the Egyptian cultivar. These findings highlight the agronomic importance of seed weight for sowing, and both cultivars can be used in alkaline soils.

A three-year study on the development of oil, protein and dry matter in sesame seeds showed that oil percentage increased rapidly 11–17 days after fertilization, reaching a maximum in 20–23 days. There was no change in the iodine value of the oil after 18 days from fertilization. Accumulation of protein was more gradual, but there was no appreciable increase after the ‘seeds’ were 27 days old. Dry matter increased more slowly than either oil or protein and there was little increase after the ‘seeds’ were 34 days old. The implications of these findings on problems of harvesting the crop are discussed.

Agricultural extension requires close communication with farmers, and researchers must consider farmers’ perspectives on crop management. Farmers tend to take into account the canopy appearance when they decide on fertilizer application, and this is often neglected in crop management recommendations by researchers. Our objectives were to dissect the growth characteristics that farmers implicitly account for in nutrient management of tropical rice. Farmer participatory trials were conducted in irrigated and rainfed lowlands in the Philippines during the wet seasons of 2014, 2015, and 2016. Each year, 30 participating farmers made decisions on fertilizer management for plots with different seedling ages and planting densities. These treatments greatly changed the canopy appearance, and affected farmer decisions on nitrogen (N) management, particularly in the first year. We found that plant height and leaf greenness were the major determinants of their decisions in irrigated lowlands. Under rainfed conditions, the risk of drought made farmers focus on tillering rather than plant elongation and leaf color during early growth stages, and on canopy cover and plant elongation during later stages. Across years and water regimes, farmers applied 78% more N than researchers without generally increasing grain yield. Since crop diagnosis is a key for successful management by farmers, guidelines for efficient nutrient management should include numerical targets for the traits emphasized by farmers. That will help farmers better understand their crops, and the guidelines will be more user-friendly than providing only a fertilizer application prescription.