Water stress is one of the main environmental stress conditions that adversely affect growth and yield of crops. Sulphydryl (-SH) compounds have been reported to induce tolerance to abiotic stress conditions. A two-year (2010 and 2011) experiment was conducted at Bikaner, Rajasthan, India to test whether the exogenous applications of thiourea (500, 750 and 1000 mg L−1) and thioglycolic acid (200, 300 and 400 mg L−1) as a foliar spray would alleviate deleterious effects of water stress on clusterbean (Cyamopsis tetragonoloba L.). The -SH-treated plants showed higher membrane stability index, photosynthetic pigment content, photosynthetic capacity and antioxidant enzyme activities and lower lipid peroxidation compared with untreated plants. Compared with untreated plants, the -SH-treated plants had 11–18, 18–30, 17–57, 25–47, 14–22% higher membrane stability index, total chlorophyll content, antioxidant enzyme activities, net photosynthetic rate and seed yield, respectively; whereas the malondialdehyde content was 10–19% lower. These data suggest that under water deficit stress, exogenous -SH compound application improves photosynthesis by increasing photosynthetic pigment, protects plants against oxidative damage by scavenging reactive oxygen species and minimizing lipid peroxidation by elevated antioxidant enzyme activities. These results indicated the role of -SH compounds in diminishing the negative effects of water deficit on clusterbean and suggest that -SH compounds could be used as a potential bioregulator to improve plant growth and yield under water deficit conditions.

Simulation models for many crops are often simple, empirical equations that lack generality across different locations or different levels of abiotic stress making them difficult to apply by independent researchers. The objective of this paper is to describe and demonstrate a user-oriented model ‘BAMGRO’ for an underutilized crop, bambara groundnut with enough detail to be general across locations and genotypes but not so complex that independent users cannot apply it to their own situations. The model consists of different sub-modules that deal specifically with weather (thermal time), crop growth (canopy development, biomass production and yield), temperature (heat and cold stress), photoperiod (daylength control of phenology and reproductive development) and soil water (drought stress). The model predictions are achieved by defining genotype (i.e. cultivar) input files, daily weather parameters and soil characteristics. The model achieves a good fit between observed and predicted data for leaf area index (Nash and Sutcliffe (N-S), 0.80–0.84; mean absolute error (MAE) with maximum less than ± 0.50) for tested genotypes. Pod yield simulation correlated well with measured values (N-S 0.73–0.87; MAE ± 16 g m−2). Available soil moisture content correlated well with the observed data for a field site in Botswana indicating successful performance of the soil water module.

A technique to better ensure reliable nodulation of pot-grown, P. vulgaris plants with cultured strains of Rhizobium is described. Nodulation, dinitrogen fixation (acetylene reduction) activity and growth of 28-day-old plants were all stimulated markedly when seeds had been inoculated with cultured Rhizobium phaseoli suspended in alginate gel (Agrigel) rather than in sucrose solution. Nodulation attributes of plants inoculated with R. phaseoli strain RCR 3644 which had been sub-cultured repeatedly on yeast mannitol agar slopes were consistently inferior to those recorded for the same strain but recently cultured from a freeze-dried sample. Some of the potential problems with open pot culture of nodule-dependent legumes are discussed.

Differences in the age at which okra pods were harvested (4, 7, 10 or 13 days after pod set) had no effect on vegetative growth or pod yield, but pods harvested more than seven days after pod set were of poorer quality. The reduction in pod quality arose mainly from an increase in crude fibre and a reduction in the moisture, crude protein and ash content of older pods.

We demonstrated experimentally that Sufetula, a root-mining insect, has a depressive effect on coconut yields on peat soils. The impact of the pest resulted in a shortfall in earnings that warranted taking control measures. We considered control methods suitable for rehabilitating infested mature coconut plantings and for preserving young coconut plantings. Currently, cultural control is the only effective method. It involves eliminating all identified shelters for the adult insect, i.e. fern cover and heaps of coconut waste (dry fronds and husks). The aim is to achieve totally bare soil, with moss cover that does not attract the pest, or planted with an unattractive intercrop such as pineapple.

In 1963 and 1964 a total of 290 cotton trials, 78 groundnut trials and 51 finger millet trials were conducted on small farms in Uganda to determine the effects and profitability of applying ammonium sulphate and single superphosphate under local conditions. The organization and methods of these trials are described and their results discussed. Ammonium sulphate gave highly significant increases in millet and cotton yields, whilst superphosphate produced similar results on groundnuts but was less effective on cotton and unprofitable on millet. Recommendations are made for groundnuts and millet, but a further season's results are thought necessary before recommending fertilizer treatments for cotton. Soil and leaf samples were taken from the trials and analysed, and relevant agronomic field data were recorded. The correlations of these factors with trial yields and responses are discussed. In general, soil and leaf analyses have been disappointing in assessing responses to fertilizers, but these responses tend to be greater where better farming is practised.

The drought tolerance of tea clones in Kenya can be improved by grafting onto appropriate rootstocks, with more susceptible clones showing greater improvement. It appears that drought may have distinct effects on rootstock and scion, with rootstock performance correlated with xylem water potential, while scion performance was correlated with stomatal conductance. Drought tolerance is not the only requirement for a rootstock under Kenyan conditions, however, and the most tolerant rootstocks do not necessarily give the greatest overall yield increase when non-drought years are included.

Variabilities in total yield, marketable yield and components of yield (tuber numbers and mean tuber weights) were studied in six sweet potato cultivars over two seasons, in crops harvested at two dates. Yield variability was high, particularly in marketable tubers, and was related to either or both components of yield. High-yielding cultivars had lower variabilities and the commercial cultivar 049 the lowest. The contribution of yield components to variability in total yield was evaluated and sources of yield variation were attributed to planting material, tuber development and season.

Nodulated plants of three USA cultivars of lentil (Lens culinaris) were grown in controlled environment cabinets. They were given either 20 or 80 ppm inorganic nitrogen and experienced a mean temperature of 12.3° C during the vegetative period, i.e. until 73–77 days after sowing. Factorial combinations of above- (29°/11° C) and below-average (23°/8° C) day/night temperatures were then imposed, to give four mean temperatures within the range of 16.6° to 21.1° C until reproductive maturity. Post-flowering vegetative dry-matter production and seed yields were dominated by treatment effects on the initiation and growth of branches. Warmer temperatures accelerated progress towards maturity, limited branching and restricted dry-matter production; at a mean temperature of 20° C plants were almost barren. The implications of these and previous data to lentil crop production and to the use of controlled environments in lentil breeding programmes are discussed.

Effective flowering time in Gossypium hirsutum cotton plants was studied with the aim of enhancing decision making on the best varieties to plant according to the planting date under rainfed cropping conditions. Trials were conducted at two sites in a cotton-growing area of Benin in 2002 and 2003. A split-split plot design with three replicates was used to compare 10 cotton varieties, with different growth cycle lengths and morphology, at three stand densities (42 000, 125 000, 167 000 plants ha−1) and two planting dates (standard planting in June and late planting). The flowering period was characterized by the mean first flower opening date (FF), which is an indicator of flowering earliness, and by the opening date of the last flower giving rise to a first-position boll on fruiting branches (LFP1). Effective flowering time (EFT) was calculated as the difference between LFP1 and FF. EFTs differed markedly in the 10 cotton varieties tested and this parameter could not be predicted on the basis of flowering earliness. Late planting and high planting rates delayed first-flower opening, accelerated last-boll development and reduced the effective flowering time. This latter factor should be taken into account in cotton breeding programmes so that varieties adapted to local rainfall constraints can be recommended to growers while also enhancing crop management sequences.

Soybean (Glycine max) is a major cash crop in the savannas of Nigeria although productivity is typically constrained by poor soil fertility. The objective of this research was to determine the interactive effect of N and P on soybean productivity in the northern Guinea and Sudan savannas of northeast Nigeria. Experiments were conducted using locally adapted early and late maturing cultivars. Two rates of N and three rates of P fertilizer were also compared at both sites over two years. At both sites, pods plant−1 and seed yield were higher in 2006 than in 2007, possibly due to better rainfall distribution in 2006. Nitrogen fertilizer had no significant effect on seed yield or pods plant−1. Application of P fertilizer increased pods plant−1 by 40–66%. Averaged across site and year, seed yield with no P was 1057.2 kg ha−1 while yield with 20 and 40 kg ha−1 P were 1941.0 kg ha−1 and 2371.5 kg ha−1, respectively. No significant interaction effect between N and P fertilizer on seed yield and pods plant−1 was observed. The late maturing cultivar yielded less than the earlier maturity group cultivar in 2007 likely due to moisture stress. For optimum seed yield 40 kg of P fertilizer ha−1 is recommended for soybean production in both locations. Our results suggest that N fertilizer is not critical for soybean production in this area.

Seven plant populations, ranging from 24,000 to 73,000 plants/ha of the maize variety White Composite, were established in four growing seasons between 1976 and 1978 by varying row width and number of plants per hill. Soil water profiles, leaf and soil water potentials, and leaf resistances were monitored. The results indicated a close link between these parameters, number of plants per hill and overall plant populations. Grain yield increased with increasing plant populations during the early growing season but dropped beyond 54,000 plant/ha (spaced two plants per hill at 60x60 cm) during the late season, due to adverse plant water status.

Winter wheat seeds were grown on compressed soil (a) with and without smearing, (b) with surface horizontal or at 45°, and (c) with and without a sand cover. Germination was not affected. At a soil suction of 0·1 bar, root penetration of the horizontal surface was decreased by smearing and by absence of an overburden; on a surface of 45° smearing had very little effect. As a general summary of the limited information, root penetration is decreased by 50 per cent for a ten-fold increase in suction above 0·1 bar; the effect of smearing is equivalent to a five-fold increase; and the effect of slope is equivalent to a four-fold decrease.

Agriculture research often focuses on a technical problem. However, the most effective researchers usually intuit that this entry point is not sufficient to make themselves useful to farmers and nudge systems. Yet non-technical work frequently goes undocumented leaving many of the drivers of success unstudied. This paper attempts to understand the factors that contributed to the wide utilization of native crop varieties and species that were being promoted by the Ecuadorian National Agriculture Research Institution. The results show that what really made a difference in farmers' lives and the overall food system was increasing farmers' knowledge and capacity to produce quality seeds, promoting the consumption of these crops to national consumers, and linking farmers to outside groups. As a result, over a period of five years three case studies on three different farmer groups showed adoption rates of new varieties of between 20–50% and that they were able to produce approximately 7.5% of the annual demand for quinoa and lupin seed in Ecuador, from a starting point of virtually nothing. The research shows that the added value of a research institution might not be known at the beginning of the intervention, but rather will emerge over time through dialogue and negotiation based on systematic understanding of the context. Therefore, an appropriate stance for external organizations is to begin with an awareness of the existing assets of a specific farmer group and provide options that can be leveraged by local communities.

Four-year-old seedlings of twenty-eight hybrid progenies were infected with the Ghanaian swollen-shoot virus strain A, but all were too severely affected to be of practical value in combating the disease. Sensitivity was assessed by comparison with uninoculated controls; reduction in crop and in growth and deterioration of canopy were correlated. The Amelonado × Amazon crosses were no more sensitive than the better inter-Amazon progenies. The rapid decline of the infected trees may have been partly due to infection coinciding with the slowing down of vegetative growth as cropping commenced.

Suitable fertilization is crucial for the sustainability of rice production and for the potential mitigation of global warming. The effects of fertilization on porewater nutrients and greenhouse-gas fluxes in cropland, however, remain poorly known. We studied the effects of no fertilization (control), standard fertilization and double fertilization on the concentrations of porewater nutrients, greenhouse-gas fluxes and emissions, and rice yield in a subtropical paddy in southeastern China. Double fertilization increased dissolved NH4+ in porewater. Mean CO2 and CH4 emissions were 13.5% and 7.4%, and 20.4% and 39.5% higher for the standard and double fertilizations, respectively, than the control. N2O depositions in soils were 61% and 101% higher for the standard and double fertilizations, respectively, than the control. The total global warming potentials (GWPs) for all emissions were 14.1% and 10.8% higher for the standard and double fertilizations, respectively than the control, with increasing contribution of CH4 with fertilization and a CO2 contribution > 85%. The total GWPs per unit yield were significantly higher for the standard and double fertilizations than the control by 7.3% and 10.9%, respectively. The two levels of fertilization did not significantly increase rice yield. Prior long-term fertilization in the paddy (about 20 years with annual doses of 95 kg N ha−1, 70 kg P2O5 ha−1 and 70 kg K2O ha−1) might have prevented these fertilizations from increasing the yield. However, fertilizations increased greenhouse-gas emissions. This situation is common in paddy fields in subtropical China, suggesting a saturation of soil nutrients and the necessity to review current fertilization management. These areas likely suffer from unnecessary nutrient leaching and excessive greenhouse-gas emissions. These results provide a scientific basis for continued research to identify an easy and optimal fertilization management solution.

Premature wilting and death of groundnut plants in Northern Nigeria was caused mainly by termites excavating the xylem tissue of the root. Lepidopterous larvae which damaged the crown of the plant were a less common cause. Occasional wilted plants had discoloured vascular systems from which Pythium myriotylum was consistently isolated. Wilting was also caused by mechanical damage inflicted during weeding operations. Complete severance or blockage of the water-conducting tissue of the primary root did not result in immediate death of plants, because the pods and pegs were able to absorb sufficient moisture to maintain the leaves above permanent wilting point until the onset of the dry season.

Significant differences were found between 20 chickpea cultivars and four locations in respect of the concentration of protein in the seeds. Cultivar x location interactions were also significant. The average protein concentration among cultivars varied from 18.5 to 23.2% and among locations from 18.3 to 22.7%. Correlations between seed protein concentration and seed yield and seed size were very small. Protein concentration was influenced by available nitrogen in the soil.

Aluminium toxicity is an important abiotic factor limiting the growth and yield of oat plants (Avena sativa L.) and other cultivated species. The objectives of this study were to evaluate the response of oat cultivars at the reproductive stage to aluminium under acid soil conditions and to compare with the responses observed at seedling stage under hydroponic conditions. In the soil, the damage to the above-ground part of the plant was estimated by the morphological response to aluminium, shoot length, shoot dry mass and plant height and, to the below-ground part of the plant as the length of roots and root dry mass. In hydroponics, the primary root regrowth was used to define the level of tolerance. The comparison of the results obtained in acid soil with those obtained in hydroponics demonstrated that both conditions produced essentially the same responses. The use of hydroponic solution can be a valuable tool for phenotyping large populations, especially useful for breeding programmes located in regions were aluminium is not present at toxic levels in the soil.