The objective of this study was to compare historical experimental and commercial yield data for sugarcane in order to determine the general level of disparity and assess the possibility of deriving a correction factor to adjust trial yields to realistic commercial levels. Over the 29-year comparison period, trial yields (fresh stalk weight) of sugarcane were significantly higher (p < 0.001) than commercial yields by approximately 30 t ha−1. Trial and commercial yield data were used to derive a correction factor of 0.7, which can be used to successfully correct trial yields to equivalent commercial levels at both the national and regional level; however, at the local (mill supply area) level different correction factors were derived. The degree of correlation between experimental and commercial yields was found to be greater in areas of higher yield potential, and it was also established that off-station trials were more representative of the commercial potential than on-station trials. The correction factor of 0.7 can therefore be used as a tool to adjust experimental sugarcane yields to indicate likely commercial levels, thereby improving the confidence of growers in taking up recommendations for the adoption of new varieties derived from trial yields.

Conflict is the most common cause of food insecurity. Foreign aid to countries emerging from conflict often allows a funded but brief window for the confirmation-testing and diffusion of agricultural innovation in affected areas. This paper asks the question: what lessons has agricultural research learned through its involvement in this process in countries emerging from conflict? Drawing on experience from Afghanistan and other countries, this paper documents some cases in which it has been possible to inject an element of simple hypothesis testing, often in farmer-managed trials, into post-conflict plans leading to useful lessons. Agricultural researchers need to be cognizant of this approach so that the practice becomes more widely used and lessons recorded for future use.

Greater yam (Dioscorea alata), a popular crop in India, is cultivated widely in Orissa state, India. In spite of the availability of several improved varieties, farmers preferred the local landraces. An investigation was carried out to identify whether the varietal preferences of yam farmers in two production systems, subsistence and commercial, were different. While the subsistence farmers demanded the yam varieties adaptable to a wide range of soils, the commercial farmers preferred the anthracnose-resistant cultivars. This study demonstrated that the farmers' varietal preferences were highly influenced by the production systems. Identifying the convergence/divergence of varietal preferences across production systems can help breeders to develop the high impact varieties.

Ecuadorean mashua (Tropaeolum tuberosum) germplasm has been found to be widely infected with the potyvirus Tropaeolum mosaic virus (TropMV). The objective of this research was to produce virus-tested (VT) germplasm to compare growth in vitro and in the field with virus-infected (V) germplasm. Twenty-three of 25 apical dome-derived clones tested free of virus based on bioassays using Nicotiana benthamiana and Chenopodium quinoa. In vitro-generated plant tissue was just as effective for determining VT status as greenhouse-generated plant tissue. Genotype rather than virus-infection status appeared to have a greater effect on in vitro proliferation. There were no differences in in vitro rooting among the genotypes or between the VT clones compared to the V clones, with at least 90% of the microcuttings rooting. However, rooted microcuttings of V clones were taller than rooted microcuttings of VT clones. Plants were readily re-established in a greenhouse at the USDA, Foreign Disease-Weed Science Research Unit at Fort Detrick, USA. In field experiment 1, ca. 75% of the plants survived field transplanting and VT plants of genotype 1147 had greater tuber weight (928 g) than V plants (235 g). In field experiment 2, plant mortality was high one month after field transplanting. Genotypes 1093 (59%) and 1141 (54%) had higher survival than genotype 1147 (44%); however, survival did not differ between the VT (46%) and V (59%) plants of all genotypes. No differences were noted in field performance for the three genotypes after 10 months of growth. Although overall tuber yield among the V, VT and VTR (reinfected-VT plants) did not differ, V plants produced big tubers that weighed more than those from VT plants. Thirty-three percent of the VT plants became reinfected and 42% of the V plants tested negative after 10 months in the field based on double-antibody-sandwich ELISA.

Little bag silage (LBS) is seen as a low-cost alternative suitable for resource-poor smallholders to alleviate dry-season feed constraints. Within a research project carried out by the International Center for Tropical Agriculture and partners in Honduras, LBS was tested and its use encouraged during farmer training and field days. The present study highlights the most relevant technological and socio-economic potential and constraints of LBS. Surveys and experimental results revealed great vulnerability of plastic bags to pests, particularly rodents, accompanied by high spoilage losses. The main constraints to wider adoption include availability of i) suitable and affordable plastic bags, and ii) appropriate chopping equipment and storage facilities on smallholder farms. LBS proved to be useful and could play an important role in participatory research and extension activities, as a demonstration, experimentation and learning tool that can be used to get small-scale silage novices started with a low-risk technology.

Traditional cultivars of arabica coffee (Coffea arabica) are susceptible to coffee leaf rust (CLR, Hemileia vastatrix) and coffee berry disease (CBD, Colletotrichum kahawae). CLR is of worldwide importance, while CBD is still restricted to Africa. Host resistances present in C. canephora to both destructive diseases have been successfully introgressed into C. arabica, after several decades of breeding and selection notably in Brazil, Colombia, India and for CBD resistance in East Africa. CLR resistant cultivars have since been grown on hundreds of thousands of hectares in Latin America and elsewhere, while CBD (and CLR) resistant cultivars are now increasingly being planted in East and South Eastern Africa. They contribute to ecologically sustainable coffee production and to considerable socio-economic benefits for the coffee growers. Nevertheless, some representatives of the international coffee trade continue to be sceptical about the cup quality of these modern cultivars. This paper presents an overview of the considerable amount of scientific evidence accumulated over the years showing that, with all environmental factors at optimum level, disease-resistant cultivars can produce quality coffees as good as those from the best traditional varieties.

Daily courses of leaf gas exchange and leaf water potential (Ψleaf) of green dwarf coconut palm (Cocos nucifera) were measured in irrigated plantations on the wet coastal plateau and in a dry semi-arid area of northeast Brazil. At both sites, significant correlations were obtained between stomatal conductance (gs) and vapour pressure deficit (VPDair), Ψleaf and VPDair, leaf transpiration (E) and gs, and E-Ψleaf. Despite these similar relationships between sites, stronger correlations involving gs-VPDair and E-Ψleaf were found at the semi-arid site, where whole-plant hydraulic conductance (gp) was correlated significantly with VPDair. In addition, at the semi-arid site, only, the net photosynthesis (PN) was not correlated with E and Ψleaf, and the intrinsic water use efficiency (WUEi) was disconnected from VPDair and Ψleaf. The different behaviour of leaf gas exchange and Ψleaf between sites was probably caused by low gs in response to high VPDair at the semi-arid site. Our results indicate potential for significant alterations in the pattern of leaf gas exchange during future climatic changes with increasing temperature and concomitant increases in VPDair. The atmospheric water stress will probably reinforce the strength of connection among water relation variables (E, Ψleaf, gs, gp, and VPDair), but it will disrupt the linear relationship between net CO2 assimilation and leaf water relations such as PN-E, PN-Ψleaf, WUEi-VPDair and WUEi-Ψleaf.

The present study evaluated the pest constraints of an innovative crop management system in Cameroon involving conservation tillage and direct seeding mulch-based strategies. We hypothesized that the presence of mulch (i) would support a higher density of phytophagous arthropods particularly millipedes as well as pathogenic fungi that cause severe damage to cotton seedlings and (ii) would reduce early aphid infestations. The impact of two cover-crop mulches Calopogonium mucunoides and Brachiaria ruziziensis on the vigour of seedling cotton stands and arthropod damage was assessed in two independent field experiments conducted in 2001 and 2002 respectively. In both experiments the presence of mulch negatively affected cotton seedling stand by 13–14% compared to non-mulched plots and the proportion of damaged seedlings was higher in mulched than in non-mulched plots supporting the hypothesis that mulch favoured soil pest damage. In both experiments insecticidal seed dressing increased the seedling stand and the number of dead millipedes collected and fungicide had little or no effect on seedling stand and vigour. It was however observed in 2002 that the fungicide seed dressing had a positive effect on seedling stand in non-mulched plots but not in mulched plots suggesting that fungi may have been naturally inhibited by B. ruziziensis mulch. The dynamics of aphid colonization was not influenced by the presence of mulch. In 2001 taller seedlings were found in mulched than non-mulched plots probably due to greater water and nutrient availability in C. mucunoides-mulched plots than in non-mulched plots.

Artemisia herba-alba Asso has been successfully cultivated in the Tunisian arid zone. However, information regarding the effects of the harvest frequency on its biomass and essential oil yields is very limited. In this study, the effects of three different frequencies of harvesting the upper half of the A. herba-alba plant tuft were compared. The harvest treatments were: harvesting the same individual plants at the flowering stage annually; harvesting the same individual plants at the full vegetative growth stage annually and harvesting the same individual plants every six months. Statistical analyses indicated that all properties studied were affected by the harvest frequency. Essential oil yield, depended both on the dry biomass and its essential oil content, and was significantly higher from plants harvested annually at the flowering stage than the other two treatments. The composition of the β- and α-thujone-rich oils did not vary throughout the experimental period.

Prime lamb live weight response to lime application on pasture was measured in a grazing experiment in the high rainfall zone of the southwestern slopes of New South Wales, Australia. The pastures were limed every 6 years over 15 years. First cross South African Meat Merino lambs were used as test animals. Pre- and post-grazing pasture dry matter (DM) yield, botanical composition, feed quality and lamb live weight were monitored over 12 weeks in 2007. Results showed that liming significantly increased pasture DM yield of high quality species and improved overall pasture quality due to increased digestibility and metabolic energy content. As a result, the limed perennial and annual pastures carried 24.0% (3.6 lambs ha−1) and 29.0% (4.4 lambs ha−1) more stock than the unlimed perennial and annual pastures, respectively. Averaged across pasture types, the limed pastures produced 30.6% (131 kg ha−1) more lamb live weight gain than the unlimed pastures over 12 weeks. The live weight gain varied between grazing cycles depending on the availability of feed-on-offer and feed quality, which were closely related to the rainfall pattern. The perennial pastures did not show any advantage in animal production over annual pastures during the experimental period due to lack of moisture in the deep soil profile because of severe drought in the previous year. More seasons with normal or above average rainfall are needed to compare animal production on perennial pastures and annual pastures to investigate the advantage of perennial pastures in animal production.

The results of research on the water relations and irrigation need of banana are collated and summarised in an attempt to link fundamental studies on crop physiology to irrigation practices. Background information on the ecology of the banana and crop development processes, with emphasis on root growth and water uptake, is presented, followed by reviews of the influence of water stress on gas exchange (stomatal conductance, photosynthesis and transpiration), crop water use, and yield. Emphasis is placed on research that has international relevance and, where appropriate, three geographical areas (the tropics, subtropics and Mediterranean climates) are considered. Although roots can extend to depths of 1.0–1.5 m, the ‘effective’ depth of rooting is usually taken to be 0–0.40 m, sometimes extending to 0.60 m. Stomatal conductance is a sensitive measure of soil water availability and plant water status, whilst transpiration rates can be limited by dry air (saturation deficits >2.0 kPa). In the subtropics, there are seasonal differences in the crop coefficient (Kc) with values ranging from 0.6 in the winter months to about 1.0 Epan in the summer. It is difficult to draw generic conclusions with wide applicability from the irrigation experiments as they were reported. All the components of marketable yield can be enhanced by irrigation whilst applying insufficient water delays crop development. Annual yield responses to irrigation are variable, but water use efficiencies of 40 kg ha−1 mm−1 (fresh fruit/water applied) have been achieved in the tropics and subtropics (and elsewhere up to 80 kg ha−1 mm−1 with ‘partial’ replacement of the soil water deficit). To ensure large yields of (marketable) fruit, soil water deficits must be kept low (Ψm > −20 kPa at 0.2 m depth). In the subtropics, this means irrigation intervals should not exceed 2–3 d during the summer. The cooling effect of irrigation with micro-sprinklers on the soil and pseudostem temperatures, compared with drippers, can delay crop development and reduce annual yields by 30%. There is some (limited) evidence that the presence of the B genome contributes to drought tolerance. Yield response factors to irrigation for different growth stages have yet to be confirmed. Opportunities to improve the water productivity of the many, diverse banana cultivars need to be explored further.