Effects of daylength and night temperature on the onset of flowering of selected cowpea cultivars have been investigated, using automatically controlled glasshouses at Reading. The results show close agreement with those from field trials in Nigeria, wherein low intensity incandescent lighting was used to extend the natural daylength. As the field technique has proved an effective screen for daylength insensitivity, future screening work in glasshouses can be for effects of night temperature on time to first flower and for day temperature on the rate of leaf senescence and components of seed yield. This integrated approach can accelerate the screening of cowpea cultivars for sensitivity to environmental factors over ranges characteristic of the low altitude, humid tropics.

Studies to determine the effect of planting unshelled pods, using groundnut varieties with different shell thicknesses, indicated that emergence and yield were suppressed by planting unshelled pods. Depth of sowing, and soaking pods in water prior to planting, had limited effects.

Bread wheat is grown under irrigation in Saudi Arabia. Since water resources are limited, any additional agricultural development must make use of sources of water that are less than ideal, for example, saline drainage water. A two year field study was conducted to compare the effects of irrigating bread wheat with normal water, with a 1: 1 mixture of normal water and drainage water, and with drainage water alone, at three levels of nitrogen fertilizer use. The mean electrical conductivity of the irrigation water was 2.6, 8.6 and 14.6 ds m−1, respectively, in the two seasons of the study. Irrigation with drainage water decreased yield and yield components but increased the protein content of the grain of the two wheat cultivars studied. Drainage water depressed straw yields more than it depressed the yield of grain. Nitrogen application increased yield and yield components in all the irrigation treatments, partially overcoming the adverse effects of the use of saline drainage water.

Efectos del agua salada y el nitrógeno en el trigo

A study conducted at Ibadan, Nigeria, showed that some community water supplies were slightly polluted by the pesticides applied on adjacent farms. There was also evidence of soil degradation as a result of agrochemical use, with differences in the physico-chemical properties of soils in fields where agrochemicals had been applied and in adjacent fields that had not been cultivated. Measures that can be taken to minimize some of the environmental dangers inherent in the application of agrochemicals are discussed.

In response to the current needs of humanity with regard to food production, environmental disasters and climate change, it is important to define (livestock) production systems and management practices that are both productive and ecologically sustainable. We qualitatively assessed advanced silvopastoral experiences in five ecologically and culturally distinct regions in Chiapas, Mexico, given their ability to provide key services: internal (productivity and productive resiliency) and external (climate change mitigation and biodiversity conservation). We propose 20 indicators that reflect management, resources, use of external inputs, availability of food, commercial products and animal feed and trees in grazing and forest areas. Sets of some indicators form criteria for dependence on external inputs, productive diversification with emphasis on food security, soil conservation, tree cover and landscape connectivity, among others. Indicators and thresholds were adjusted to critical (traffic light) levels, based on field data. Comparing the levels reached by the studied experiences, we found that most of the resulting services go hand in hand; so ‘win–win’ situations are possible to be achieved. The elements and practices that affect both internal and external services were explored. The red light critical points in each production unit were identified so that they could be attended. Experiences that presented higher levels in assessment criteria could serve as examples to enable the improvement of livestock systems under similar conditions. We propose this assessment as a tool for rapid intervention that can be widely applied to livestock systems, from conventional to organic or diversified, because of the criteria used. However, it can be more flexible, as new criteria can be added and thresholds can be adjusted for other types of production systems, always reflecting local and desired conditions. The proposed indicators can be also used as a basis for a quantitative agroecosystem assessment.

An experiment was carried out to determine the partitioning and accumulation of nitrogen in plant components, nitrogenase activity and their relationships with seed yield of a local cultivar of winged bean (Psophocarpus tetragonolobus (L.) DC.) grown on three support systems of 0, 1, and 2 m height under field conditions. Total nitrogen accumulation and nitrogen partitioning were determined throughout the growing season by measuring nitrogen content and concentration in above-ground plant tissues (leaves, stems, petioles and pods). Support heights of 1 and 2 m significantly increased total nitrogen accumulation in component parts of the plant, nitrogenase activity, nodulation, total dry matter accumulation and seed yield compared with the control. Plants grown on supports accumulated significantly higher leaf nitrogen at the vegetative stages and the contribution of seed nitrogen was also significantly higher compared with unsupported plants. Nitrogenase activity increased with onset of flowering but declined during the pod formation stage in plants grown on a support system. Unsupported plants showed higher nitrogenase activity prior to flowering possibly due to lack of photosynthate and, consequently, early senescence of leaves.

A 4-year investigation of the effects of sowing date on three types of groundnut showed that the earlier the sowing date, the later was kernel initiation and kernel maturity. Early sowing resulted in a high pod yield, oil content and iodine number, but reduced the shelling percentage. The leaf area index ranged from 3·0 to 5·0, the highest value being obtained with early sowing and with non-upright bunch varieties.

Twenty one accessions of yam bean (Pachyrhizus Rich. ex DC.) were tested in yield trials under short day conditions in Tonga, South Pacific. Fresh weight tuber yields ranged from 5.3 to 72.0 t ha−1, dry matter content from 8.0 to 20.8% and dry matter yields from 1.20 to 8.57 t ha−1. Crude protein content of peeled tubers varied between 5.1 and 9.8% of dry matter, yielding 71–540 kg ha−1 of crude protein. Varietal variation in leaf defoliation by the rose beetle, Adoretus versutus Har., was noted.

Agricultural extension requires close communication with farmers, and researchers must consider farmers’ perspectives on crop management. Farmers tend to take into account the canopy appearance when they decide on fertilizer application, and this is often neglected in crop management recommendations by researchers. Our objectives were to dissect the growth characteristics that farmers implicitly account for in nutrient management of tropical rice. Farmer participatory trials were conducted in irrigated and rainfed lowlands in the Philippines during the wet seasons of 2014, 2015, and 2016. Each year, 30 participating farmers made decisions on fertilizer management for plots with different seedling ages and planting densities. These treatments greatly changed the canopy appearance, and affected farmer decisions on nitrogen (N) management, particularly in the first year. We found that plant height and leaf greenness were the major determinants of their decisions in irrigated lowlands. Under rainfed conditions, the risk of drought made farmers focus on tillering rather than plant elongation and leaf color during early growth stages, and on canopy cover and plant elongation during later stages. Across years and water regimes, farmers applied 78% more N than researchers without generally increasing grain yield. Since crop diagnosis is a key for successful management by farmers, guidelines for efficient nutrient management should include numerical targets for the traits emphasized by farmers. That will help farmers better understand their crops, and the guidelines will be more user-friendly than providing only a fertilizer application prescription.

Bud removal of the cuttings at underground level has been claimed by cassava growers in Thailand as a method to increase cassava yield. This practise should be tested experimentally to explain the reason for yield increase. The objective of this study was to investigate the effects of bud removal and cutting length on storage root yield and starch content of three cassava varieties. Field experiment was conducted in a split–split plot design with four replications in 2010 and 2011, under rainfed conditions. Three cassava varieties (KU50, RY9 and HB60) were assigned as main plot. Two cutting lengths (15 cm and 30 cm) were assigned as sub plots, and two treatments of buds (buds cut and not cut) were assigned as sub–sub plots. The buds on the cuttings that were inserted into the soil were removed. In 2010, the plants from 15-cm long cuttings subjected to bud removal had higher fresh storage root yield (88.4 Mg ha−1) than did plants from 30-cm long cuttings subjected to bud removal (75.8 Mg ha−1). Cutting of buds also had higher fresh storage root yield (89.1 Mg ha−1) than did non bud-cutting (75.0 Mg ha−1). KU50 had the highest fresh storage root yield (91.4 Mg ha−1), dry root yield (48.4 Mg ha−1) and starch yield (20.1 Mg ha−1). Cutting length of 15 cm had higher starch concentration in storage roots (25.6%) than did cutting length of 30 cm (24.2%). HB60 had the highest starch concentration (27.0%) among cassava varieties tested. The data in 2011 were similar to the data in 2010. The responses of varieties to bud removal and cutting length are discussed.

The response of germination and early seedling growth to levels of salinity (0, 50, 100, 150, 200 and 250 mM NaCl) were examined in single seed lots of ten modern rice genotypes. Unaged and deteriorated rice seeds were germinated in rolled paper towels and in Petri dishes. Initial seed quality, final germination, germination rate and early seedling growth were assessed. The samples of the rice genotypes differed in their initial seed quality (measured in terms of Ki). The effect of deterioration varied depending upon the initial seed quality and the severity of the treatment imposed. Ageing (using the technique of controlled deterioration, CD) for up to 24 h had no effect on final germination levels. Although CD for 30 h only reduced final germination slightly, ageing for 36 or 48 h reduced it greatly. Controlled deterioration for 36 h or longer reduced the final length and the rate of extension of both the plumule and radicle. Combining information about germination in salt solution with that about seed quality enabled a distinction to be made between varieties which performed poorly because they were genetically salt-susceptible from those which germinated poorly due to poor seed quality. It is argued that the seed vigour of seed lots used in genotype evaluation should be assessed in order to avoid discarding potentially useful genotypes because of poor physiological seed quality.

In a 20 plot experiment with central composite second-order rotatable design, basal non-chlorophyllous sections of “D” leaves of Sugarloaf pineapples were sampled at harvest and analysed for N, P, K. Maximum yield of 17·8 tons per acre of good quality Sugarloaf pineapples and maximum fruit length of 27·4 cm. were associated with the nutrient combination of 36–42–32 lb/acre N P K applied at 4, 6, 11 and 12 months. The nutrient levels in the basal sections of “D” leaves corresponding to maximum fruit yield were 0·35–0·40% N; 0·04% P; 0·44% K; K/P 11·2–11·5: 1. K/P ratio for maximum fruit length was 10·4–11·5: 1. N/K ratio was associated with lodging.

A wide variety of training activites has been carried out related to farming systems research (FSR). The majority have had one or more of the following objectives: to introduce the farming systems perspective, to teach new research methods, and to promote the institutionalization of FSR. Many of these objectives are important, but FSR training is not usefully seen as a separate field of endeavour. The goals of FSR training will be better served by reconsidering the roles of universities, national research institutions, and international institutions.

The poor fertility of sandy Sahelian soils remains one of the major constraints to pearl millet (Pennisetum glaucum) production in West Africa. On-farm trials under farmers' management were conducted in two rainfall zones of Niger in 1996 and 1997 to evaluate the risk characteristics of six soil fertility restoration options. Stochastic dominance analysis was used to compare the fertilizer treatments tested. Results showed that the farmers' traditional method (no fertilizer control), Tahoua phosphate rock (PRT) alone applied at 13 kg P ha−1 broadcast, and a combination of PRT broadcast at 13 kg P ha−1 and single super phosphate (SSP) hill-placed at 4 kg P ha−1 had the most desirable risk characteristics and were acceptable to risk averse decision-makers in both rainfall zones. At current input–output price ratios, most fertilizer-using farmers would choose the combination of PRT broadcast and SSP hill-placed. If the availability of SSP was limited, some farmers would use PRT alone. The demand for risk efficient alternatives could significantly increase if farmers could bear less than half the fertilizer costs at the current output price, although further research is required to say if a fertilizer subsidy could be justified on broader economic or social grounds.

Dry matter production and partitioning in old clonal tea bushes pruned and maintained at different heights were investigated. New tissues (leaves, new branches and small roots) consti- tuted a small fraction of the total dry matter in all bushes pruned and initially maintained at 70, 40, 25 and 10 cm high, 36 months after pruning. Leaf/frame dry matter ratio was larger and the shoot/root and frame/root ratios were smaller in the bushes initially maintained at 10 cm than in the bushes maintained at other heights. Yields per unit area of the plucking surface were greatest in the smallest bushes initially maintained at 10 cm in 42 months of recording but on the basis of the available space they were greatest in the large bushes initially maintained at 70 cm.

Nursery trials have shown that carbamate fungicides containing zinc or manganese are effective against Helminthosporium heveae. The addition of a wetting or sticking agent did not improve control, and in one test significantly reduced it.

Monthly and annual totals for the Penman estimate of potential evaporation have been reliably determined, for periods varying from 7 to 11 years, at 14 East African observatories. At each site, these annual and monthly totals are normally distributed, with coefficients of variation of the order of 5 and 10 per cent, respectively. Meteorological stations established for the sole purpose of supporting evaporation surveys should therefore be relocated at 5- or 6-year intervals so as to derive maximum benefit from the valuable instruments. The results of these variability analyses were applied in the evaluation of confidence limits for monthly and annual potential evaporation rates, and reference is made to recent compilations of such limits for 137 sites in Kenya and Tanzania.

Poultry manure (PM) has been shown to boost crop productivity. However, little is known about its favorable interactions with wood biochar (B) on sweet potato (Ipomoea batatas L.) growth and yield, and soil qualities. Hence, a 2-year field trial was conducted in the southwest Nigeria at two locations (Owo – site A and Obasooto – site B) to co-apply PM and wood B as soil amendments to boost sweet potato productivity and soil quality. The experiment consisted of a 3 × 4 factorial layout with three replications. PM and B significantly reduced soil bulk density and improved porosity and moisture content with their rate of application when compared to the control. As PM and B applications increased from 0 to 10.0 t ha−1 and 0 to 30.0 t ha−1, respectively, soil chemical properties and sweet potato growth and tuber yield increased. Co-application of 10.0 t ha−1 PM and 30.0 t ha−1 B increased tuber yield by 220% compared to treatments without PM or B. Significant synergistic interactions between PM and B were observed for all parameters. In comparison with other treatments, co-applying PM and B to sweet potato soils is a viable sustainable option for increasing sweet potato productivity and soil sustainability.