Farming systems research (FSR) has come to prominence as a part of tropical agricultural research in the past decade or so. The main stimulus was the growing realization that small farmers are ‘economically rational’ and agricultural economists have been the leading agents in developing FSR ideas. Three broad aspects are distinguished: (1) FSR sensu stricto, the deep analysis of farming systems as they exist, which is essentially an academic activity, (2) OFR/FSP (‘on farm research with farming systems perspective’), a practical adjunct to research which seeks to test the socio-economic suitability of research ideas on-farm before recommending extension and (3) NFSD (‘new farming systems development’) which seeks to develop complex, radical change rather than the stepwise change characteristic of OFR/FSP. The technical components of NFSD are probably mostly available but the necessary transdisciplinary, synthetic thinking is not. Research on perennial plants in tropical agriculture has been rather neglected but there are signs of growing concern; they must be an important feature of any NFSD for the wetter areas.

The traditional management of cattle manure in a cropping system in the savanna zone of central Nigeria is discussed in conjunction with the agronomic benefits and problems of manure use. Nitrogen and phosphorus contents of the manure varied seasonally. On-farm trials showed that maize grain yields were about 1 t ha−1 more and weed growth 90% greater in manured than in non-manured areas. It is important to reduce the competition between crops and weeds if grain crops are to obtain the full benefit of manure in such cropping systems.

Pods of vegetable cowpea Vigna unguiculata Walp. cv. Dinner were harvested at various developmental stages and their biochemical components and other characteristics analysed in two years. Pod length, percentage dry matter and starch, fresh and dry weights and total yield of sugar and starch per unit area increased with age. The percentage total yield of sugars was greatest in pods aged between 11 and 13 days. Vitamin C, total acidity, crude fibre and crude protein percentage decreased with age. Content of minerals except iron also decreased with age of pods. Magnesium, phosphorus, potassium, manganese and copper contents were greater in 1977 than in 1979 but iron and calcium contents were smaller. The vegetable cowpea pods were a rich source of calcium, magnesium, potassium and iron. Pods harvested between 7 and 10 days after flowering were crisply tasty and high in nutrients and therefore nutritionally the most acceptable for consumption.

Improved groundnut production practices are compared with traditional methods. Improved sole crop production practices show significantly greater net returns per hectare than traditional methods but when other considerations such as the riskiness of the various enterprises are examined, the superiority of the improved sole crop technology becomes less clear-cut. A case is made for designing improved technologies involving crop mixtures.

The future evolutionary potential of pulses is determined by the nature and extent of the genetic variability in the primary gene pool. This is extensive in the major grain legumes, notably the groundnut, soyabean, Phaseolus and faba beans, and in the cowpea. It is less extensive in the cultivated lupins and this appears to be a serious limitation to their development as useful crops. The considerable development of isolating mechanisms between related species of legumes has restricted the development of the secondary gene pool. This is most developed in the genus Arachis, where section Arachis provides an extensive secondary gene pool for the groundnut. Tertiary gene pools are potentially quite extensive for many grain legumes but since most interspecific hybrids are inviable this resource would be difficult to exploit with present techniques. The development of sophisticated gene transfer techniques for grain legumes is inhibited by their lack of amenability to in vitro culture. The suggestion is made that genetic resources profiles could be constructed on the basis of an expansion of Harlan and de Wet's gene pool system. These could serve as a guide to the present state of germplasm collections, indicating their strengths and weaknesses, which would be useful in formulating future collection and evaluation strategies.

The potential for more intensive exploitation of such legumes as the winged bean and lupins undoubtedly exists. The reasons for past under-exploitation of the winged bean need to be determined.

Grain legumes have an assured future for good economic and nutritional reasons. More attention probably should be devoted to exploiting the legume-Rhizobium symbiosis, fundamental to the development of efficient and economic farming systems in the developing world.

The effects on the potato crop of the herbicides metribuzin, linuron and metobromuron, singly and in combination with each other and with hand weeding, were investigated and compared with cropped and uncropped weedy controls. Weed competition was determined by measuring weed dry weight. When the three herbicides were applied singly metribuzin gave the lowest weed dry weight, while the combination of metribuzin, metobromuron and hand weeding gave the lowest weed dry weight per unit area of all treatments in both seasons. However, the best potato yield was obtained from the combination of metribuzin and hand weeding. Metobromuron consistently reduced yield through reduction of tuber size irrespective of its effect on weed competition. Metribuzin was the best herbicide for the control of broad leaved weeds and many grasses.

Brassica carinata (an uncultivated species) was compared with other oilseed species already under cultivation in India, on irrigated and rainfed soils. B. carinata yielded very well in a wide range of environments partly because it had a large number of primary and secondary racemes. It also showed better environmental adaptation and substantial resistance to pests and disease.

Eighteen arabica coffee introductions from the USDA germplasm collection were planted at 23° S latitude in Brazil from 1977 to 1982 to assess their yield potential and frost hardiness, compared with the cultivar Catuai Amarelo which is extensively planted in Brazil. Nine of the introductions had similar yields to Catuai Amarelo. Erecta T966 and Harrar yielded as well as Catuai Amarelo and were also more frost hardy. Tall, early maturing coffee varieties showed the least frost injury.

Nine rice genotypes were classed as tolerant, moderately tolerant, susceptible and highly susceptible, depending on their growth retardation and the intensity of lime-induced iron chlorosis. All except genotypes IET 7972 and IET 7973 showed varying degreees of chlorosis and corresponding decreases in shoot dry matter production. Chlorosis was negatively correlated with the orthophenanthroline reactive Fe2+ iron content of the leaves, the concentration of which accounted for 82% of the variability in chlorosis. However, total iron concentration in the leaves and the Fe/Mn, Fe/Cu and K/Fe ratios were not significantly correlated with dry matter accumulation in the plants.