Three strains of Rhizobium able to fix nitrogen in symbiosis with lentils in saline soil were screened. Nodulation pattern, N2-fixation and grain yield were all influenced by Rhizobium strain and lentil genotype. Genotypes DL-443 and Pant L-406 were found to be more salt tolerant than others, and gave the highest grain yield.

Nitrosoguanidine-induced mutation frequencies for resistance to streptomycin, spectinomycin, erythromycin and novomycin were studied in Azospirillum brasilense. Lentil inoculated with A. brasilense and its mutants and Rhizobium strains produced increased nodule dry weight, nitrogenase activity of nodules and roots and grain yield compared with an uninoculated control.

To increase the productivity of fields growing direct-seeded upland rice, which usually gives low yields because of weed competition, unsatisfactory establishment and exposure to intermittent drought, an experiment on intercropping of rice with blackgram was conducted in two seasons under rainfed conditions on a sandy loam soil. Blackgram, when intersown simultaneously in one row in every 30 cm wide space left between the stand of 10 cm apart paired rows of rice, reduced the yield of rice by 1·64 t/ha. When one row of blaokgram was intersown, 21 days after sowing of rice (after completing weeding) between the paired rows of rice, rice yield was reduced by only 0·24 t/ha compared with solecropping of rice with weeding. This system provided mean yields of 2·48 t/ha of riceand 0·95 t/ha of blackgram. The price of blackgram being high, it showed a mean monetary advantage of Rs. 2373/ha over sole cropping of rice. The blackgram reduced the weed population appreciably.

In many instances soils are routinely air-dried and sieved prior to chemical analysis to permit ease of handling and decrease variability. Such drying, however, can increase the extractability of some elements, for example, the amount of P extracted by 0'5 m-NaHCO3 (Brookes, Powlson & Jenkinson, 1982). Much of the increased P is derived from soil micro-organisms killed by the soil drying (Brookes et al.1982). Similarly, much of the flush of C and N mineralization that occurs after rewetting of dried soils can be derived from killed soil micro-organisms (Jenkinson & Powlson 1976; Marumoto et al.1977; Marumoto, Anderson & Domsch, 1982).

Kura or Caucasian clover (Trifolium ambiguum Bieb.) is a perennial, rhizomatous legume indigenous to Caucasian Russia and adjacent regions (Kannenberg & Elliott,1962; Bryant, 1974). Those agronomic characteristics that lend it potential significance, namely an extensive root-rhizome system, winter-hardiness, resistance to numerous and serious clover pests, and the production of nectar-rich flowers, were enumerated by Parker & Allen (1952). These authors also pointed out that usage of kura clover was hampered by ineffective nodulation. However, in recent years commercial and effective inoculant preparations have become available. Consequently, it has been suggested that kura clover could have potential as a pasture legume and for soil conservation purposes (Bryant, 1974; Spencer et al.1975). Pertinent literature on kura clover is scanty. The present study evaluated the nutritional characteristics of kura clover relative to otherforage legumes.

It has been found from controlled environment studies that high temperatures lead todepressions in milk production (Johnson, 1965; Hafez, 1968; McDowell, 1972). Under outdoor situations where all climatic variables may act simultaneously on the animal, responses may vary from the classical chamber studies.

Research conducted on sowing dates for wheat shows a trend towards increased yield as sowing is advanced (U.K.: Walker, 1980; Bingham et al. 1983; the Netherlands: Darwinkel, Hag & Kuizenga, 1977; Canada: Nass et al.1975; Briggs & Aytenfisu, 1979). In a review of the influence of drilling time on winter wheat in the U.K. McLean (1981) suggested October planting as the optimum. However, sowing before this time often results in increased yield (Bingham et al.1983).

Soils derived from Gault Clay in the eastern region of England are notorious for giving very variable yields of wheat. Whereas in recent years yields on other soil types have increased remarkably, largely owing to the use of high-yielding varieties and increased use of nitrogen (e.g. Holbrook, Osborne & Ridgman, 1982), yields from Gault Clay soils have remained at much the same level as the best crops of 30 years ago.

In earlier papers, it has been demonstrated that many features of the production system in the lowland tropics affect the growth and development of pigeon pea differentially depending on the prevailing conditions (Tayo 1982 a, b, c, 1983 a, b). It has also been noted that when plant size is reduced as a consequence of reduced soil moisture, slight variations in production input tend to have a more significant effect on crop performance (Tayo, 1983b).

India is the second largest litchi producing country in the world after China (Syamal & Mishra, 1984), yet the number of litchi cultivars grown in the country is quite small compared with mango (Mangifera indica). In mango most of the choicest Indian cultivars have been obtained from chance seedlings (Singh, 1960) grown in the past without any definite aim in mind. Litchi, as a result of crosspollination (Chaturvedi, 1965), is a highly heterozygous fruit, and as such, its seedlings, like those of mango, exhibit a wide range of variation which helps in the selection of new desired types. It has, thus, been emphasized that litchi should be grown in bulk from seeds to introduce genetic variability (Kumar & Thakur, 1981). Kadman & Slor (1974), encouraged by excellent success in grafting, have also stressed the need for raising plants through seeds for rootstocks.

Rice is the major food crop grown on black soils of southern India and these soils have problems of high zinc fixation due to high clay content, high pH and dominance of smectite minerals causing zinc deficiency problems. The addition of zinc fertilizers to these soils has often been ineffective as the element is transformed to unavailable forms particularly under flooded rice conditions. Studies on the distribution of fertilizer zinc among different pools of soil zinc (Viets, 1962) could be useful in formulating methods of zinc application for higher efficiency of utilization. An attempt was therefore made to study the transformations of added zinc in soils in field experiments conducted in a rice-rice sequence involving the use of 65Zn as a tracer.

The potential for twice-yearly lambings by tropical sheep is well recognized (Brown, Cameron & Ngere, 1972; Goode, Linnerud & Tugman, 1980; Osinowo, 1982). In order for ewes to lamb every 6 months the rebreeding interval must be 33 days or less. Factors affecting rebreeding in post-partum ewes have been reviewed (Hunter, 1968a, b Van Niekerk, 1979).