Sorghum hybrids and varieties show similar responses to changing environment, with constant relative yield increases from the hybrids over a wide range of conditions due almost entirely to more florets and grains per plant and per hectare. Carbohydrate production of the leaves of good varieties is probably not much in excess of requirements for filling the grain. The extra spikelet number of the hybrid, increases in photosynthetic area and probably increased photosynthetic efficiency together enable the extra grains be filled. There is also an advantage in size and activity of the root system. The yield increase is strongly buffered against environmental fluctuations. The fact that hybrids can increase over a wide range of farming conditions should result in big increases in production simply by changing from varieties to hybrids, as is already happening in several countries.

Sisal showing symptoms of parallel streak developed more slowly than symptomless plants, both leaf length and number of leaves unfurled being reduced. In streaked areas of the leaf, ground tissues surrounding the peripheral and internal fibre bundles collapsed; decortication of streaked leaves was difficult and fibre quality was adversely affected by reduction in length and discoloration. Parallel streak was seen only in vegetatively propagated Agave sisalana, in leaves lacking marginal spines. The condition was observed only where the mean minimum temperature fell below 16°C; symptoms appeared five months after the onset of a period of low temperature. Apparently every A. sisalana plant in Kenya is affected, but the condition is masked in coastal regions due to high mean minimum temperature. The disease seems not to be due to bacterial or fungal pathogens, or to nutritional factors, but may be caused by a virus, or a genetic ‘disease’ similar to June Yellows of strawberries.

Results from five years trials showed that irrigation was frequently needed to ensure early and adequate germination of cotton, that the use of a water balance to determine time and amount of irrigation was practical and economic, that there was no appreciable effect of fertilizer on yield of seed cotton on these soils, and that there was no significant change in the fertility of the soil after four crops of cotton.

A method is described for estimating leaf area of the oil palm. Significant correlations were found between leaf area and yield in a number of progenies of palms growing in West Malaysia.

To evaluate the potential efficacy of fungicides for the control of birds' eye spot in rubber nurseries, 49 formulations were tested in the laboratory by the paper disc diffusion and liquid culture methods. After discarding phytotoxic fungicides, only certain of the carbamate compounds, especially thiram, and those containing manganese and difolatan showed mazked activity in both series of tests. The results were compazed with field experience, and for the most part good correlations were found between laboratory and field results, a marked exception being the poor in vitro inhibition shown by zineb. A bimodal growth response was shown by the fungus to some of the carbamate formulations.

Nursery trials have shown that carbamate fungicides containing zinc or manganese are effective against Helminthosporium heveae. The addition of a wetting or sticking agent did not improve control, and in one test significantly reduced it.

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.

At Ukiriguru, in Western Tanzania, cattle often lose weight appreciably in the first few weeks of the wet season. Three levels of supplementary hay feeding, compared over this period, showed initial effects, but the final weight differences between treatments were not significant due to the effects of later compensatory growth. Differences between treatments during the weight loss and compensatory growth phases can be mainly attributed to differences in dry matter intake, rather than differences in actual body weight.

Pollen of the oil palm (Elaeis guineensis) was vacuum dried for various lengths of time and stored under vacuum in ampoules at 28°, 5° and −10°C. Little loss in viability over a period of 12 months was observed in any of the storage treatments when vacuum drying did not exceed one hour. Progenies resulting from crosses with pollen stored three months under vacuum have shown no anamolous seedling development.

Multivariate statistical methods are used increasingly in biological research to investigate the responses of organisms considered as a whole, whereas established statistical methods are usually concerned with measured characteristics considered one at a time. Multivariate techniques are mostly explained in terms of matrix algebra, which is a way of dealing with groups of numbers rather than individual ones. A brief description is given of some elementary results of matrix algebra and a method is presented whereby hypotheses can be generated about interrelations within an organism. Two techniques, principal component analysis and canonical analysis, are described in greater detail. It is emphasized that hypotheses need to be tested even though they have been generated by objective statistical means.