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.

Potassium, calcium and magnesium in coffee leaves are presented as total K + Ca + Mg in dry matter and as percentages (proportions) of this sum. Brazilian coffee and leaf samples collected in different parts of Kenya generally fell within the normal ranges of values reported from the Kivu area in the Congo Republic. Data for Kenya coffee leaves are examined for the influence of season, cultural treatments such as organic mulch and fertilizers, and cropping level, on the concentration and balance of the nutrients.

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.

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.

Results of an investigation to select intercrops showed that cotton can be grown with more profit with groundnut or gora paddy than when grown alone. Growing food or cash crops along with cotton enables an early crop to be produced and the practice may help to extend cotton cultivation in Chotanagpur and Santhal Parganas, a potential cotton belt of the future.

Fifteen Australian and exotic wheat varieties revealed genotypic differences in their patterns of root development and drought tolerance. Earliness in plant maturity, which accounted for 40 to go per cent of the observed variation in drought tolerance, appeared to be by far the most important characteristic of tolerant genotypes, but there nevertheless appeared to be a measurable relationship between some parameters of root development, water use efficiency and drought tolerance. The impact of study of this kind on the problem of breeding for drought tolerance is briefly discussed.

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.

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.

Pot experiments with Malaysian rice variety Reyong-20 showed that sea water supplied at a concentration of 3 per cent increased yields of both grain and straw; a 6 per cent solution increased straw but not grain yields; yields were depressed at 9 and 12 per cent but tolerance of higher concentrations of sea water increased with age of the plants.

On a site in the Sudan Savanna, chemical properties of soils (except for phosphate) and the composition of cotton leaves were determined after fifteen annual treatments including dung, ammonium sulphate, single superphosphate and potassium chloride, in all combinations of three levels. In the soils dung increased C, N, cation exchange capacity, exchangeable Ca and Mg and pH, and decreased soluble Al and Mn; ammonium sulphate decreased pH, increased soluble Al and Mn, and decreased exchangeable Ca and Mg; potassium chloride had no obvious effects. In the plants dung increased P and reduced Mn; ammonium sulphate reduced Ca and Mg, and increased Mn; superphosphate increased P, Ca and Mg, and reduced K; potassium chloride increased K slightly. The most important results were the ability of ammonium sulphate to acidify the soil, as shown by soil properties and reflected in tissue composition, and the ability of dung to ameliorate these effects. Reduction of crop yield in the presence of adequate nutrient supply seems to have been due to excessive soil acidity.

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.

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.

Field trials were carried out using an aerial spray of Magniosan 55 (55 per cent magnesium nitrate) for the correction of severe magnesium deficiency in a Valencia orange orchard. Two treatments were applied, in autumn and spring respectively, each containing 50 l. Magniosan 55 solution in 200 l. water per hectare. The spray did not cause damage to fruit or leaves, penetrated satisfactorily into the lower and interior part of the canopy, and increased the Mg content of the leaves of treated trees from 0·095 to 0·190 per cent.

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.

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.

Pods of bhindi (Abelmoschus esculentus) developed most rapidly for the first 11 days after the opening of bhindi flowers, after which development slowed down. Seeds matured in about 21 days after flower opening and attained up to 97 per cent germinability. Water potentials lower than −500 joules/kg. in the germination medium adversely affected germination of bhindi seeds. Seeds up to two years old but of > 1 density (i.e. those which sink in water) germinated better than lighter seeds which float.