Six genotypes of lentil (Lens culinaris) were grown in pots in a glasshouse under natural photo-periods of 10–12 h, extended to an inductive photoperiod of 16 h by supplementary illumination from incandescent lamps. The illuminance of the supplementary light was varied by placing replicate pots at different distances from the lamps; it decreased geometrically with distance (i.e. down an illuminance gradient) from about 2000 lux directly beneath the lamps to about 40 lux at a distance of 6 m from them. All genotypes came into flower progressively later as illuminance decreased; those selected in northern temperate regions were especially sensitive, taking about twice as long to flower at an illuminance of 40 compared with 2000 lux. We suggest, however, that these quantitative responses do not reflect differences in sensitivity to illuminance per se, but are the consequences of genotypic differences in sensitivity to photoperiod. The implications of these data are discussed in terms of adaptation to the aerial environment and strategies for screening germplasm and plant breeding in lentils and other grain legumes.

The Land Equivalent Ratio (LER) concept is presented and interpreted. Several different intercropping systems are considered and the need for methods to evaluate them is discussed. A general form of the LER is proposed for the evaluation, in particular, of a system that combines two intercrops having different yield proportions. Appropriate LER curves, obtained by varying the yield proportions, are used to compare different intercropping systems, and the importance of this approach is discussed.

Objectives of different intercrop experiments need to be kept in view while analysing the data from them. There is no single straightforward way of analysing the data and certain situations require innovative approaches. Types of situations that are encountered in dryland agricultural research are exemplified and methods of meaningful analysis and interpretation of data from them are indicated here. Agronomically-sound meanings are imputed for different ways of calculating LER. Use of the concept ‘Staple Land Equivalent Ratio’ for assessing intercrop systems in particular situations is illustrated.

Eight triticale lines were evaluated in Cyprus during the period 1977–82 and compared with the best other cereal varieties grown locally. One triticale line was selected which outyielded Athenais barley by 8.3% and Pitic 62 aestivum wheat by 11.4% in drylands, and durum and aestivum wheat by 20% in irrigated areas. Regression analysis showed that Athenais was the best yielding crop in the least productive environments while under medium or favourable conditions triticale gave maximum yields. Number of grains per spike, harvest index and the N content of grain were larger but ear number, 1000-grain weight and N content of straw were smaller in triticale than in barley. The yield component most sensitive to drought was 1000-grain weight.

Field studies designed to investigate the effects of sett size and spacing on tuber yield of white Guinea yam were conducted in three locations over a two year period in the rainforest and savanna zones of Nigeria. Sett weights larger than 400 g could be used for maximum tuber yields in both forest and savanna zones. Spacing had no significant effects on tuber yield in the savanna zone, but optimum spacing has yet to be identified in the forest zone.

In two experiments, carried out on non-irrigated fields in the Northern Negev region of Israel, inoculation of Sorghum bicolor with bacteria of the genus Azospirillum resulted in significant increases over controls of 17% in grain yield of cv. 610 and of 19% in the forage yield of cv. 6078. In addition, significant increases over controls in plant dry weight, mineral content (N, P and K) and panicle number were obtained by inoculation of cv. 610.

Cassava (Manihot esculenta Crantz) has generally been reported to possess hypostomatal leaves. Several cultivars have now been found to possess clusters of functional stomata around the veins on the upper leaf surface and two cultivars (M Col 88 and M Col 90) have significant numbers of stomata (83–140 mm−2) dispersed over the entire upper leaf surface. Stomatal density on the lower leaf surface ranged from 322–553 mm−2 among cultivars, with a relative stomatal area of 3.4–6.1%. The CO2 uptake by the upper leaf surface (27% of total) and the transpiration loss (32% of total) corresponded closely to the ratio of relative stomatal areas on the upper and lower leaf surface of cv. M Col 88.

Plants of two genotypes of chickpea (Cicer arietinum), classified as early or late-maturing in the field, and relying either on dinitrogen fixation by nodules or on nitrate-N, were grown in various simulated tropical environments in growth cabinets. Plants were transferred between cabinets at various times so that they experienced either warm (30°C) or hot (35°C) days (both in combination with a typical night temperature of 10°C) for different durations of reproductive growth, after growing in average (30°C day - 10°C night) or warmer than average (30° - 18°C) temperatures for the first 28 days from sowing and then average temperatures until transferred into the hot regime. Diurnal vapour pressure deficits were adjusted so that plants experienced a constant atmospheric relative himidity (70%) in all thermal regimes. The greater the proportion of the reproductive period spent in hot days the smaller the seed yields produced; plants transferred at 50% flowering were almost barren. The implications of these data for breeding chickpeas well adapted to hot environments are discussed.