Uptake of P32 from labelled KH2PO4 solutions, injected in the top-soil at points distributed over 4000 cm.2 in the zone of high root activity, was measurable soon after application with accumulation of P32 in leaves increasing thereafter with time. The recently-acquired P32 was distributed uniformly in the tree canopies. Uptake of P32 reached a maximum when the number of injection points was increased from 15 to 30 per tree, with 45 and 60 injection points leading to little further change in P32 content of leaves. In the zone of high root activity, strip application of P32 was as efficient as application in a circle around each tree. The practical implications of these observations in relation to P-fertilization of coffee are discussed.

Crosses were made between tea (Camellia sinensis L.) and Wilson's camellia (C. irrawadiensis Barua), using tea as the female parent, but reciprocal crosses were not successful. The F1 hybrids were intermediate in morphological and anatomical characters between the parents. Regular meiosis and high pollen fertility in the hybrids clearly indicate a close relationship between the parental genomes.

Cytological investigations carried out on a natural triploid tea plant revealed its alloploid origin. The plant is partially fertile and produces viable gametes with various chromosome numbers.

The effect of inoculation and added nitrogen fertilizer on soybean variety TK-5 were studied in pot and field experiments. In the former bean yields with IARI and CB 1809 inoculants were better than with Nitragin-S. In the field experiment, inoculation alone was inadequate to supply the nitrogen need of the crop, 30 kg. N/ha. being needed with inoculation, and 60 kg. N/ha. without inoculation, for maximum yield. Higher nitrogen application, combined with inoculation, increased dry matter, N-uptake, bean yield, pod number, bean weight and nitrogen content of seed. Oil content of the seeds decreased with inoculation and nitrogen application.

Low-temperature stress in eggplant during the cool season causes gradual loss of pollen fertility and leads to the development of seedless fruit, but female fertility is not similarly affected. The temperature-induced male sterility is transient, and full pollen fertility is regained with normal seed development, as temperature conditions improve.

Total yield and yield components (tuber numbers and mean tuber weights) of six local sweet potato cultivars were compared in wet and dry season crops. There were significant negative correlations between tuber number and mean tuber weight in five of the six cultivars, and positive correlations between these yield components and total yield, suggesting that cultivars may be grouped into ‘tuber number-tuber weight’ and ‘tuber weight’ types, as well as a ‘random type’ in which yield is related to neither component. Marketable yield tended to be directly related to both components, and cultivars with lower tuber numbers usually produced a higher percentage of marketable yields. The significance of these findings for sweet potato yield improvement is discussed.

Variabilities in total yield, marketable yield and components of yield (tuber numbers and mean tuber weights) were studied in six sweet potato cultivars over two seasons, in crops harvested at two dates. Yield variability was high, particularly in marketable tubers, and was related to either or both components of yield. High-yielding cultivars had lower variabilities and the commercial cultivar 049 the lowest. The contribution of yield components to variability in total yield was evaluated and sources of yield variation were attributed to planting material, tuber development and season.

The effect of boron nutrition on the susceptibility of young tenera oil palm seedlings to red spider mite attack was studied. Highest concentrations of mites were recorded in seedlings which had received little or no boron in the growing media. Injuries by mites were greatest when the leaves had the highest number of mites per unit area, the lowest boron concentration and the lowest concentration of cyanidin.

Optimum transplanting age and relative growth rate in three groups of rice varieties differed with types and maturity periods. Transplanting 52 day old seedlings reduced the shoot number, and the magnitude of reduction was higher in early than in mid-early and medium varieties. Early transplanting reduced the number of days to flowering in all three groups compared with transplanting later. Senescence was much earlier in early types transplated as 52 day old seedlings. Grain production in early types was more sensitive to late transplanting than the mid-early and medium types. Medium varieties outyielded the early and mid-early ones when transplanted at 38 days after seeding.