The effects of the time of sowing on growth and chemical composition of carrots grown from May to November were studied during 3 years.

Delaying sowing for 1 or 2 months after the beginning of May resulted in a reduction in the growth of both roots and foliage and gave roots with lower dry-matter content and glucose/fructose ratio but higher amounts of hexoses, total nitrogen and amino nitrogen in root dry matter. Sowing date had no influence on the concentration of sucrose, phosphorus, potassium, calcium and magnesium in root dry matter up to 137 days from sowing. Carotene decreased only after the last sowing. Sucrose concentration of the roots increased throughout the periods studied irrespective of the time of sowing. The longer the growing period the higher was the sucrose concentration. The concentration of hexoses decreased from the first harvest at 70 days to reach a constant level at about 130 days from sowing.

The results did not indicate the presence of a well-defined stage of biochemical maturity in the autumn when carrot roots are expected as most suitable for harvest and subsequent long-term storage.

Two trials designed to measure progress in the yield of durum wheat cultivars released in Mexico by the Institute Nacional de Investigaciones Agrícolas over the period 1960–84 were grown in the Yaqui Valley, Sonora, Mexico, during the 1983–4 and 1984–5 cropping seasons. The trials compared grain yield, above-ground biomass, harvest index (ratio of dry grain yield to dry above-ground biomass), yield components, grain-growth rates and phenological characters for eight key cultivars and the modern advanced line, Carcomun ‘S’, when grown at a high level of agronomic inputs and management.

The grain yield of durum wheat was estimated to have risen for 25 years of breeding from 3·70 to 8·40 t/ha. The estimated average annual rates of increase in grain yield for the periods 1960–71 and 1971–85 were 251 and 121 kg/ha respectively. Grain yield improvements were based on a linear increase in the number of grains/m2 over the 25-year period, the result of more grains per spikelet. An improved above-ground biomass at maturity was a feature of the two modern genotypes, Altar 84 and Carcomun ‘S’. Harvest index increased with each new cultivar up to the release of Mexicali 75 in 1975, but thereafter the higher grain yields achieved with the modern genotypes were not associated with a higher harvest index. Thousand-grain weight remained steady for the released cultivars but fell slightly for the advanced line Carcomun ‘S’. Improvements in yield were not associated with a longer cropping cycle.

It is concluded that a breeding strategy combining selection for morphological characters thought to confer high yield potential, such as a more erect leaf posture and high number of grains per spikelet, with selection for grain yield per se has been successful in improving the grain yield of durum wheats adapted to north-west Mexico. Improvements have come not only in the size of the grain sink and the efficiency of assimilate partition to grain but also in the biomass produced above ground.

Japanese mint (Mentha arvensis L.), one of the important essential-oil-bearing crops of India, is a potential source of natural menthol which is widely used in various pharmaceutical and cosmetic preparations. Generally under intensive cultivation, the application (broadcast with incorporation) of phosphorus leads to enhanced herb and oil yields of different mint species (Rao, Rao & Singh, 1983; Singh et al. 1983; Vadivel & Sampath, 1981), but the knowledge that P-adsorption to soil surface reduces plant availability suggests that a P application method limiting soil-P contact may improve P availability and use efficiency (Phillips & Webb, 1971). Therefore, the placement depth and method may be an important factor in the proper use of applied phosphorus. Since uptake of P is reduced in dry soils (Reichman & Grunes, 1966; Simpson, 1960), P placed deeper in the soil would remain more available because of increased soil moisture. Another factor involved is the positional availability of the P source (Cooke, 1954). If placed too close to the surface, the roots may not come in contact with the fertilizer or too few would contact the band to maximize uptake.

Competitive and regulatory effects of defined inflorescences on the development of other inflorescences and subsequent yield performance of field beans (Vicia faba L.) were investigated. Genotypes differing greatly in yield performance (two inbred lines and the F1 hybrid produced from the two inbred lines) were used in both field and pot experiments. Yield was manipulated by the removal of defined inflorescences at various times and positions.

In comparison with untreated control plants the removal of up to four inflorescences from basal, central or apical nodes caused a loss of yield potential of up to 65%. Nevertheless the final seed yield per plant was not reduced. This was because additional pods and seeds developed at remaining inflorescences. After the removal of inflorescences from either basal or apical regions of the plant significant overcompensation effects occurred. The effects were influenced by the growing conditions. The capacity for compensation existed at differing yielding levels regardless of different genotypes or growing conditions.

The results are discussed with respect to the utilization of the initiated yield potential and to yield reliability.

A study was made under rainfed (unirrigated) conditions in a subtropical and semi-arid region of northern India during the winter (October–March) seasons of 1980–1 and 1981–2 to evaluate the growth, resource use and seed yield performance of four intercropping systems, namely mustard alone, ⅔ mustard +⅓ chickpea, ⅓ mustard + ⅔ chickpea and chickpea alone grown at 7·5, 15·0, 22·5 and 30·0 plants/m2.

The total economic productivity of intercrop systems was greater than that of either component grown alone. The components of seed yield (number of primary and secondary branches, number of pods, seed weight per plant and weight of seed) increased in mustard where intercropped but the opposite occurred in chickpea. These growth attributes were decreased with an increase in plant population density. The two crop species needed an individual density less than their sole crop optima to form an optimum density when intercropped. A mixture of ⅓ mustard + ⅔ chickpea appeared to be the best system for the rainfed conditions in which these experiments were made and produced greatest yield advantage.

Chickpea grown in ⅓ mustard + ⅔ chickpea combination had greater nodulation with higher dry weight per nodule. A greater leaf area index (LAI) for both the crop species was noted in ⅓ mustard + ⅔ chickpea mixture than were found in other systems. The maximum LAI of mustard and chickpea was attained at 60 and 120 days after sowing respectively and this may be why a lower proportion of mustard plants in the intercrop was more advantageous.

A combination of ⅓ mustard + ⅔ chickpea removed more nitrogen from the soil, had better water use efficiency and comparatively less soil moisture depletion than the sole crop. Soil nitrogen utilization and soil moisture depletion were less at higher densities.

A new protein supplement in the form of water-washed neem (Azadirachta indica) seed kernel cake for tropical countries such as India, Pakistan, Ceylon, Burma and also for tropical regions of Australia, Africa, the Middle East and South-East Asia which could be successfully fed to cattle has been reported by Nath, Rajgopal & Garg (1983). The adverse effect of the bitter or toxic principles contained in the neem seed kernel cake could be removed by water washing. It has a potential of providing Rs.350 million worth of additional feed in India alone and if all the neem seeds produced in India could be harvested and utilized for the preparation of oil, the production of the cake could reach 7–8 times its present value.

There is currently considerable interest in the use of anabolic compounds to improve the efficiency of animal growth and to produce leaner carcasses. While the majority of work has centred on beef production, the growth performance of sheep is also improved (Galbraith & Topps, 1981). However, little is known of the effects of anabolic steroid hormone administration on wool growth. The few experiments which have been conducted indicate that exogenous oestrogens depress wool output (Slen & Connell, 1958) while exogenous testosterone has consistently enhanced both greasy and clean wool yields (Slen & Connell, 1958; Osborne, 1968; Southcott & Royal, 1971). Little is known, however, of the effects of the synthetic steroids on wool growth. Coehlo, Galbraith & Topps (1981) reported a reduction in wool per unit body weight in sheep implanted with trenbolone acetate and oestradiol-17β, suggesting lowered efficiency of wool growth. Similarly Yasin & Galbraith (1981) noted that trenbolone acetate, in combination with either oestradiol-17β or zeranol, reduced wool output per unit body weight. Neither of these trials attempted to isolate the effects of trenbolone acetate alone from those of the androgenplus-oestrogen combination.

Para-rubber (Hevea brasiliensis Muell-Arg.) is a major plantation crop in South-East Asia. In addition to its economically important latex, the para-rubber tree produces seeds that serve as a source of industrial oil. Rubber seed meal (RSM), a by-product of the oil extraction, contains moderately high amounts of crude protein and is available at lower prices than most traditional vegetable protein supplements in the region. The estimated availability of RSM in South-East Asian countries is about 1·2 million tonnes.

Recently, radiotelemetry has been widely used in the measurements of various physiological attributes, e.g. body and skin temperatures, heart rate and heat flux across the surface in unrestrained animals (Zervanos & Hadley, 1973; Moen, 1978; Mautz & Fair, 1980). The present note provides some basic information on heat flux across the skin in untethered black Marwari goats of the Rajasthan desert, measured by radiotelemetry during winter.

There is little information on rates of protein synthesis in individual muscles in ruminant animals. Skeletal muscle is the largest single tissue and, as such, has a considerable effect on nitrogen transactions in the body. Arnal (1977) found a substantial decline in synthetic rate between 1 and 16 weeks of age in lambs and also observed differences between red and white muscles. Bryant & Smith (1982a) measured synthesis in several muscles of mature sheep and they observed lower rates than Arnal (1977) with little difference between most muscles. Vastus intermedius muscle in the hind leg, however, had higher rates of synthesis than other muscles. Here we report rates of protein synthesis in individual muscles in rapidly growing lambs approximately 12 weeks of age. The major back muscle, the longissimus dorsi, and two hind leg muscles, the vastus lateralis and the vastus intermedius, were chosen for study.