Onion bulbs were stored at 30°C at relative humidities of 50, 80 and 95 per cent in 1971–72 and at the same temperature at 35, 50, 60 and 70 per cent RH in 1972–73. Losses from rotting, sprouting and desiccation were recorded. The latter were lowest at 95 per cent RH and not correlated with humidity in the range 35–80 per cent RH. Rotting losses similarly were not correlated with humidity but were highest at the highest humidity.

Tomato leaf curl virus disease (TLC) was checked by frequent and early applications of Anthio, Folimat, Malathion and Phosdrin against the aleyrodid vector, Bemisia tabaci. Conversely, up to two-fold increases of fruit yield resulted from such applications of the insecticides. Though seed-bed or field applications, separately, gave satisfactory results on occasions, treatments of the plants in the seed-bed and the field were often both essential. Field observations during the experimental period, over four consecutive seasons, showed peak infection rates within the first 8–12 weeks of tomato planting. There were marked inter-seasonal fluctuations of disease incidence, ranging from < 50 to 100 per cent. There was no clear correlation between spread of the disease and the wind direction. Epidemiological behaviour of the disease is discussed in relation to its chemical control.

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.

Ethephon substantially increased pod numbers of a rust-susceptible cultivar, by inducing leaf fall and a second flowering, but had no such effect on a rust-resistant cultivar. The treatment reduced seed number per pod in both cultivars. B-9 increased pod number in the rust-resistant cv. but reduced mean pod weight and seed number per pod.

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.

The effects of rainfall on yield of rainfed grain sorghum in a rotation experiment have been investigated over six years. There was a positive association between yield and rainfall during May and from the beginning of July to the first half of September, but a negative association at other times of the year. Total rainfall in August and September, and the annual total, were positively related to yield, while the totals of June and July were inversely related. Variation in monthly rainfall accounted for up to 86 per cent of the variation in yield, while the total rainfall in August and September accounted for up to 96 per cent.

Precipitation in Western Nigeria is principally from thunderstorms with sharp, high-intensity rainfall peaks. The time of occurrence of the peak intensity period in a rainstorm has an influence on whether or not runoff occurs in smaller storms. Runoff and soil loss on bare, cultivated Iwo soil are closely related to an EI30 erosivity index, modified by the time-position of the peak intensity. The soil erodibility factor in the universal soil-loss equation could be reasonably estimated from easily measured soil parameters.

Upland rice and Stylosanthes guyanensis were sown simultaneously in pure and mixed culture at varying densities at Na Pheng, central Laos. Vegetative growth of the rice was negatively related to stylo density over the range o to 81 stylo plants/m.2 Rice grain yield varied from 98·4 gm./m.2 in monoculture to 63·4 gm./m.2 when grown with 81 stylo plants/m.2 Rice was more competitive than stylo, but stylo growth was relatively independent of rice density over the range 20 to 120 rice plants/m.2

Simultaneous undersowing of upland rice with Stylosanthes guyanensis at Khon Kaen, north-east Thailand did not affect vegetative growth of rice but reduced grain yield by 19 per cent. Grain yield was not significantly affected if stylo undersowing was delayed by 10 days. Stylo growth was reduced by one half by delayed sowing and was negatively related to dry matter yield of rice variety.

The results are reported of an experiment on the Lilongwe Plain to investigate the effects of under-sowing maize with a mixture of Rhodes grass and silverleaf desmodium. Undersowing caused no significant reduction in any component of maize yield, and mixed swards with a good legume content were established. Nitrogen application had no significant effect on yields of grain or pasture, but in the following year undersown swards outyielded those directly seeded. Some practical advantages of undersowing are discussed.

The application of lime to natural pastures in Rio Grande do Sul, Brazil, did not increase herbage yields, but nitrogen fertilizer, alone and in combination with phosphorus fertilizer, enhanced dry matter productivity significantly. Dry matter yields of the natural pasture were more than doubled at the highest fertilizer rate, though the botanical composition of the sward was only modified slightly by various lime and fertilizer treatments.

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.

Groundnuts given a mixture of S35-labelled ground rock phosphate and sulphur at planting were radioactive 14 days later, when go per cent of the seedlings had emerged. Forty days after planting one-third of the total plant-S was from the fertilizer, and the mean recovery of fertilizer-S was 18 per cent by harvest. In field experiments the mixture outyielded ground rock phosphate and was as good as single superphosphate, though drought diminished yields generally. At three sites which were harvested the percentages of applied-S recovered were 12, 20 and 27 per cent. Significantly more P was taken up by the crop receiving the mixture than was recovered from the ground rock phosphate alone.

The growth and nitrogen yield of Stylosanthes guyanensis undersown with upland rice were negatively related to level of urea application at Khon Kaen, north-east Thailand. In the absence of applied urea the nitrogen yield of rice monoculture was 3·3 gm./m.2 whilst the addition of stylo increased nitrogen yield of the association to 9·6 gm./m.2 Stylo was initially dominated by rice but exploited environmental growth factors more effectively in the latter part of the growing season, accentuating competition for water and phosphorus. Simultaneous stylo and rice sowing reduced rice grain yield by 12 per cent, the greatest reduction occurring at a low level of urea application, mainly due to abortion of spikelets after panicle exsertion.

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.

Mild manual defoliation of pigeon pea plants had little effect on pod numbers, pod weights, or number of seeds per pod in two experiments. The effects of severe defoliation depended on timing and differed between pigeon pea cultivars. Late severe defoliation reduced pod numbers in both experiments, but early and intermediate severe defoliation also differed in their effects. Some physiological implications of these results are suggested.

Introductions were made to Oxford, England, of a number of strains of the pearl lupin (Lupinus mutabilis Sweet) from South America. In the first season of growth, two of these strains showed considerable promise for development as a field crop in England. Analysis of the seeds confirmed that they are comparable to the soya bean in their content of protein and oil. The chief disadvantage of the species is that the seeds contain toxic alkaloids. Alkaloid-free strains of this species have twice been bred in the past; the seed of these strains has been lost, but such work could be done again. (It is regretted that there is no surplus seed available for distribution from Oxford at present.)

The growth of plants is controlled by the availability of photosynthesized carbohydrates. Since both rainfall and sunshine are needed for photosynthesis an empirical expression is proposed which relates vegetative growth to the product of rainfall and bright sunshine hours over a specified period. Tea is a crop in which the yield is entirely vegetative and harvested throughout the year. Laycock's data for tea yields from constant treatment plots in Malawi show that yield was strongly correlated with the product of rainfall per month (R) and average daily hours of sunshine per month (S) for the previous month (r=0·972). The graph of yield vs RS for the previous month gives a straight line passing through the origin. This empirical weather parameter RS appears suitable for the study of vegetative harvests.

Different methods of undersowing maize with a mixture of Rhodes grass and silverleaf desmodium were compared, together with the effects of applied nitrogen, in an experiment on the Lilongwe Plain. Drilling the legume on the ridge or in the furrow was superior to broadcasting, and caused no substantial reductions in maize yield. Nitrogen application increased all aspects of maize production but slightly reduced legume yield. The data generally confirm previous findings that undersowing causes no appreciable and consistent reduction in maize yield, and results in the establishment of mixed swards with a high legume content.

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.