The growth and grain production of four rice varieties were compared under controlled environment conditions at two minimum night temperatures (15 and 23°C) and at two daylengths (11½ and 13 hours) where the period of daylight for active photosynthesis was kept constant at 8 hours. The lower night temperature prevented flowering but at the higher one grain yields were associated with panicle weights rather than panicle numbers, and production of so-called photoperiod-insensitive varieties was affected by photoperiod. Although the periods of natural light were constant, and photoperiods were extended by low intensity incandescent light, in-creased total plant weights, not due to effects on tillering, were observed under longer days.

Uptake of the major nutrients by maize was determined throughout the growing season. Little phosphorus was accumulated, as reflected in its distribution within the plants, but uptake of labelled phosphorus showed two distinct peaks associated with root development. One fifth of the applied phosphorus was recovered by the plants.

During the wet summer season of northern tropical Australia higher yields were attained by introduced weakly photoperiod-sensitive short-duration rice varieties than by locally-bred strongly photoperiod-sensitive varieties resembling traditional tropical indicas. There was no clear relationship between growth durations and yields. Dry season yields were lower, associated with shortened durations (especially of the reproductive phase) and lower cumulative radiation totals in the late phases of growth. Dawn, a variety of U.S. origin imported from the Philippines, outyielded all other varieties. In both wet and dry seasons yields depended largely on panicle weights, which in turn depended on high seed numbers per panicle. Individual seed weights were of less importance. The results tended to confirm a prior interpretation of climatic data, i.e. that there is no environmental factor limiting wet season yields in the region to levels below those obtained elsewhere in the tropics, provided the crop receives a high standard of care and attention.

Application of S, alone or in combination with P, significantly increased the number, yield and nitrogen content of root nodules on pigeon pea and guar. Sulphur, applied at different levels with NPK, increased the methionine content and yield of plants significantly but had no significant effect on the N content. Sulphur at 20 p.p.m., alone or in combination with P, increased the methionine content of pigeon pea significantly but the effect decreased at higher levels of S. In general, higher values of methionine were obtained in the presence of S than when it was absent.

To study control of Hemileia vastatrix leaf disease in Coffea arabica L., an experiment was run for a year in Coorg District of Mysore State. Three and four early-season sprays coupled with two mid-season ones gave a reasonable control, as evaluated by leaf spot counts, but a high proportion of rust-affected leaves were retained on the bushes. Infection commenced in the hot weather, immediately after showers, and the number of infected leaves appears to have been more important than the average leaf spot counts. Control of leaf disease up to December, and a late incidence of the rust during January, may not affect crop prospects appreciably. It is suggested that reduced early sprays coupled with pre-monsoon and timely mid-season schedules should reasonably control the incidence of rust.

Limited moisture supply caused reduction in leaf area, number of effective tillers, ratio of sound to unsound grains and the nitrogen, phosphorus, iron and manganese content of rice. Crop yield was adversely affected in the absence of standing water. Two levels of nitrogen (40 and 60 kg.N/ha.) caused no significant difference in yield in 1965, but in 1966, when 30 and 60 kg. N/ha. were used, the latter gave better yields.

The results from a 33 and two 25 factorial fertilizer experiments are presented. N-deficiency limited female flower production, rate of bunch production, and yield; K-deficiency reduced the setting of flowers and yield; nuts were larger where P was applied. The results are interpreted in the light of foliar analyses, and the concept of independant critical levels of the major nutrients is challenged. It is suggested that yield is related to the ratios between foliar N and K, but that the K level should in turn be interpreted in the light of a balance between the monovalent and divalent cations. Female flower production and setting can be used as a ready field guide to nutrient requirements.

Experiments in two successive seasons showed that planting date and spacing of bulbs affected the seed yield of Sudanese onions, but not the number of branches and seed heads produced by bulbs. Yield per plant increased with increase in spacing, but closer spacing gave the highest yield per unit area. Later sowing depressed seed size, weight and yield.

Principal component analysis is a mathematical technique for summarizing a set of related measurements as a set of derived variates, frequently fewer in number, which are definable as independent linear functions of the original measurements. Consideration of their mathematical nature shows that they do not, themselves, necessarily correspond to sensible biological concepts, though they are more amenable to statistical study than the original measurements. Further, by assessing the extent to which they are in accordance with biological hypotheses, or with the results of other, similar, analyses, they can be transformed into other linear functions which are meaningful in the biological sense, or consistent with other results. Thus the specific technique of principal component analysis is developed into a more general component analysis approach. With proper regard for the purpose the analysis is intended to serve and for the mathematical restrictions involved, this approach can lead to a useful condensation of a mass of data, a better under-standing of the observed individuals as entities rather than collections of isolated measurements, and to the formulation of new hypotheses for subsequent examination.