A comparison has been made of drip and conventional check basin methods of irrigation, using onions and ladies finger as test crops. Significant increases in yield and water use efficiency in drip irrigated over conventionally irrigated plots resulted from increased availability of soil moisture at low tensions and reduced surface evaporation losses. Reduced soil strength in drip irrigated plots was also a factor resulting in increased yield of onions.

Cultural standards and the husbandry techniques used on small farmers' fields are seldom the same as those practised on research and experimental Stations in the developing countries. The need for extensive agronomic experiments to be sited on small farmers' fields is emphasized. This method has been quite widely used with annual crops, but could with advantage be more generally adopted in perennial crops. Some of the advantages of this approach in agronomic investigations are illustrated by examples from work carried out in East Africa.

Mechanical disintegration seems to be the most effective way of damaging the cells in potato tubers so that their juice can be expressed. If disintegration is too intense the pulp is intractable; a grater makes a uniform pulp with suitable texture. With existing continuous equipment it is necessary to press in two stages to get to 40% dry matter and further batch pressing is needed to get to 50%, but experience suggests it should be possible to make a press that would press to > 50% in one operation. Much less energy is needed to press out water rather than evaporate it, but about one-sixth of the tuber dry matter and more than one-half of the N is in the juice.

Seven maize cultivars and seven soyabean cultivars were grown in monocultures, and in all possible 49 mixtures of maize and soyabean, at two locations to assess the intercropping advantages of mixtures. On average, intercrops produced 6% more dry matter and 17.5% more protein than the monocultures of maize, the most productive component. Both the dry matter and protein yields of intercrops were closely correlated with the yield of the maize component, but not with that of the soyabean component, indicating that there was no need for a specific breeding programme for maize to be used in intercropping systems. Although the average intercropping advantage, the monoculture yields of maize cultivars and, to a lesser extent, the monoculture yields of soyabean cultivars differed between locations, there was no evidence that the yield of various intercrop combinations differed between locations.

No natural population of Rhizobium japonicum specific for soyabeans (Glycine max L.) could be found in any soil type in Israel. A crop of 5450 kg seed/ha was obtained in a field of sandy soil, inoculated with commercial granular inoculant, by maintaining soil at a moisture level near to field capacity during the growing season. In another field, on heavy soil inoculated with different strains of R. japonicum, the highest yield was obtained with strain 31-SM, a mutant derived from strain 61A75. Nitrogen fixation, as measured by the acetylene reduction method, was highest with strain 31-SM. Under local conditions soyabean plants snowed 100% nodulation when inoculated by the slurry method, by granular inoculant or by spraying bacteria into the furrow.

Twenty-five cultivars of soyabean (Glycine max (L.) Merr.), differing in their origin, crop duration and seed size, were planted four times at bi-weekly intervals during the major rainy season at Ibadan, Nigeria and harvested at optimum maturity or two weeks later. Delayed harvest and intense rainfall during pod maturation were essential for selecting for resistance to field weathering, but 2 weeks' delay enabled susceptible and resistant cultivars to be identified. Percentage of infected seed had the highest correlation with potential germination at harvest (r=−0·869**) but may not be a suitable criterion for use in a screening programme. An alternative would be to screen cultivars for resistance to weathering on the basis of seed size and the proportion of smooth and clean seed, since these characters were highly correlated to potential germination (r=−0·562** and 0·632** respectively).

In nine breeding trials with cocoa in Ghana the experimental trees were interplanted with temporary trees of a standard variety as ‘calibrators’. The calibrators were removed after 2–2½ years before there was strong competition with the permanent trees. Trunk diameters of the calibrators were used as covariates in analyses of trunk size and yield of dry cocoa up to 7 years after planting, giving reductions in standard errors of differences between progenies of up to 25% in analyses of size and 15% in analyses of yield.

Recommendations of crop varieties are usually done on the basis of grain yield. However, there are other important traits related to quality and agronomy that need to be considered. This study has clearly shown that grain yield is often not related to some important traits of the crop. Under such circumstances, selection based on yield can lead to the loss of these important characters. Recent research has also indicated the need for a multi-trait approach to recommending crop varieties. However, such approaches, as suggested in the literature, are subjective and do not have a sufficient statistical basis. This study proposes a methodology for varietal recommendations by taking account of all important traits. It is a multivariate approach considered to be an improvement on the univariate method previously proposed. Data from rice varieties of 3, 3½ and 4½ month maturity groups, cultivated across diverse environments, over two seasons in Sri Lanka were used to illustrate the proposed methodology. The results suggest that the new method will be appropriate for taking in to account all important traits along with yield.

The amount of starch in branches of Coffea arabica L. was studied by means of a method of visual scoring. In cropping branches, the variation in starch level was greatly, but not completely, determined by the growth of the crop. More knowledge of the formation and distribution of the products of photosynthesis is needed before a satisfactory explanation can be offered. Starch levels in non-cropping branches were higher than those in the cropping branches, but followed the same pattern of fluctuation. In general, translocation of starch occurred rapidly throughout the tree but some exceptions to this rule were found.

The possibility of growing grasses of higher quality than tall fescue (Festuca arundinacea) in a continental climate with cold winters, hot summers and low precipitation was investigated with and without irrigation at Taigu, Shanxi, China. Tall fescue was compared with perennial ryegrass (Lolium perenne), meadow fescue (Festuca pratensis) and a perennial ryegrass × meadow fescue hybrid cultivar in field swards, managed by cutting, during the year of sowing and in the three subsequent years. Tall fescue persisted satisfactorily throughout the experiment, even without irrigation. With irrigation, the other three grasses persisted satisfactorily to the end of the second harvest year and fairly satisfactorily to the end of the third harvest year. Without irrigation, the other three grasses had incomplete ground cover in the second harvest year and did not recover from the third winter.

Four tillage treatments were applied to soil on which wheat was to be sown in 1988/89 after pastures of two annual medics, Medicago rigidula and M. polymorpha, had been established in 1987/88. Germination of the medics was monitored in the following year (1989/90) when halfof each plot was sprayed to prevent further seed set. M. polymorpha produced more seed in 1987/88 and three times more regenerated seedlings in 1989/90 than M. rigidula. Regeneration and winter herbage yields of both medic species were least after deep ploughing. Seedling numbers were less in 1990/91 than in the previous year but seedling numbers of M. polymorpha were sufficient to sustain the cereal-pasture rotation except after deep ploughing. Both medics germinated promptly soon after the first effective rains in December 1989, but the first germination in 1990/91 was on 24 November, with three subsequent germinations, the last in early February. About half (40 to 50%) of pods remained in the top 5 cm of soil, except after deep ploughing when only 28% remained near the top. The seeds in the top layer lost their hard-seededness more rapidly than those buried more deeply. M. polymorpha was softer seeded than M. rigidula. The results suggest that deep ploughing, as commonly used in west Asia and north Africa, is unsatisfactory for cereal-pasture rotations.

Regeneración de alfalfa en Siria

The quality of bean pods was influenced to a large degree by the variety, season of planting and the precise time of harvesting. The varieties Tenderette, Executive and Bush Blue Lake 274 were outstanding in their concentrated yield and pod quality. The development of seeds in the pods was faster in beans planted during the spring than in the autumn. Thickening of the pods during ripening was more rapid in the autumn than in the spring season. Outstanding differences were found between varieties with regard to the speed of seed development during pod ripening. As opposed to the outstanding differences between varieties with regard to quality characteristics, the differences with regard to yield were generally small and without economic importance.

A technology for improving the productivity of short fallows using herbaceous legumes as cover crops was evaluated with farmers in the forest and savannah transition zones of Ghana. Legumes were relayed in maize 5–8 weeks after planting maize, depending on the legume species. An economic analysis of the technology compared with natural fallow over two cropping seasons (2001–2002) showed that the legume fallows were more profitable under the scenarios tested. Farmer assessment of the biological performance of the technology revealed the benefits of weed suppression and soil moisture conservation potential of the legume biomass as well as an improvement in the yield of the succeeding maize crop. However, farmers realized that planting legumes at close spacing and weeding before and after relaying are essential in the development of an appreciable biomass cover. The technology is suitable for farmers of all strata, in several major ecological zones of Ghana, and for planting on land with poorly secured tenure. However, at least two years of tenancy is required for the landless to derive some benefits from the legume fallow.

The possibility of producing herbage of higher quality than that of tall fescue (Festuca arundinacea) in a continental climate with cold winters, hot summers and low precipitation was investigated, with and without irrigation, at Taigu, Shanxi, China. Tall fescue was compared with perennial ryegrass (Lolium perenne), meadow fescue (Festuca pratensis) and perennial ryegrass × meadow fescue in field swards, managed by cutting, during the year of sowing and in the three subsequent years. Perennial ryegrass yielded well in the year of sowing, but was low yielding subsequently; perennial ryegrass × meadow fescue yielded well in the year of sowing and in the following year. Both of these grasses had high rates of leaf appearance and extension and a high proportion of cell content in the dry matter. Tall fescue yielded well, but was low in proportion of cell content.