Maturation of peas in cool temperatures (mean 17.5°C) at Dalang Maidan, Lahaul (in the Himalayas) led to the development of larger seeds in comparison to those of the same varieties which had matured in warmer temperatures (mean 24.5°C) at Delhi, India. The larger seeds from Lahaul, when sown at Delhi, gave rise to taller plants which came into flower earlier compared with those from the seeds matured at Delhi. Significant location ′ variety interactions were recorded for germination and plant height. Inherent variation in days to flowering could have been a major factor in these interactions. These data are of direct importance to breeders using seeds developed at more than a single location if environmental conditions differ appreciably.

A late-maturing, high-yielding maize released for the Burundi highlands was rejected by subsistence farmers. Analysis of this variety in terms of the local cropping system shows that it offers no advantage over earlier maturing varieties when whole-system biological and economic yield and Land Equivalent Ratios are examined, while farmer risk is apparently substantially increased. The value of incorporating a ‘farming systems’ approach into national commodity research programmes in developing countries is demonstrated.

In field trials a population of 61,700 maize plants/ha produced higher total dry matter and grain yields than the conventional 36,000 plants/ha. There was no difference in yields with inter-row spacings of 45, 60 or 90 cm, regardless of population levels. Weed suppression was increased by the higher population even though the entire experimental area was treated with herbicides. In one of three years perennial sedge and annual weed growth started 4–5 weeks after herbicide application, under which conditions row spacing had a greater effect and weed growth was significantly less with 45 or 60 cm maize rows than at 90 cm.

This paper uses survey results to show how one group of small scale farmers in Santa Cruz, Bolivia, were able to mechanize annual cropping despite a farming systems diagnosis which indicated that this was not a viable development path. It attempts to identify the underlying causes of farmer success and diagnosis failure.

Two tropical and one temperate genotypes of maize were grown during the cool dry winter seasons in northern Nigeria. The tall tropical genotypes produced a greater leaf area index and more above-ground dry matter, and so had a higher crop growth rate, than the dwarf temperate genotype. However, the early flowering temperate genotype yielded more grain than the late flowering tropical genotypes. Although the initial low winter temperatures prolonged the preflowering growth period in the tropical genotypes, the terminal high temperatures hastened maturity and were associated with poor grain filling.

Maíz de temporada seca en Nigeria

A grazing management study involving the new white clover cultivar Osceola grown in association with Bahiagrass cv. Pensacola was conducted on wet and dry sites with and without pesticide/herbicide treatment. A combination of heavy grazing pressure and a short deferment period before grazing during the summer and autumn resulted in the largest soil seed reserves and seedling recruitment by the white clover component. However, maximum survival of plants was recorded from a combination of a short deferment period and moderate grazing pressure.

A slight increase in plant survival and seedling recruitment was shown on the wet site. Survival potential was least in pasture treated with pesticide and herbicide. Heavy grazing pressure and short deferment periods appear essential for the survival of the clover component. Annual seedling recruitment from soil seed reserves was the primary mechanism of white clover survival from spring to spring in pasture associations based on tropical bahiagrass.

Rice is the staple crop of Guinea Bissau, and its production system is based on human labor with very limited possibility of mechanization, particularly in the Mangrove ecosystem. Due to this and to the low possibilities of controlling environment parameters, such as water level and availability, the genetic resistance to extreme abiotic factors was identified as a key point for increasing yields quantity and stability. Among the ample genetic material available in the country, no purification activities were carried out in the past decades. This led to the cultivation of mixtures or ecotypes and not to uniform varieties, with consequent issue related to cultivation and milling. On 103 samples collected, only on about 50% of ecotypes, the purification was carried out as the remaining half was too much variable. The purification ended with less than 20% of material considered stable and uniform varieties. Moreover, the program adopted a bottom-up approach for collection and variety conservation to drive the program and improve the genetic material.

This research sought to link Andean soil knowledge and farmer categorization of soil fertility to soil science characterization of soils, and use these to understand the impacts of phosphorus (P) fertilization of legumes using rock phosphate and soluble P fertilizer in 17 smallholder-managed sites with varying soil properties. We found that farmer high/low categorization of soils corresponded to soil P fertility and distance from farmer dwellings. Measures of soil P fertility also were inversely related to mycorrhizal colonization of vetch roots and directly related to the potential for P release by legume residues (C:P ratio). However, particular soil properties (texture and calcium phosphate pools) were better in explaining the response of legume biological nitrogen fixation to P addition, with maximal impacts in low-clay soils and soils with low calcium phosphates, as assessed with a dilute HCl extraction. In these conducive contexts, legume BNF increased 67 and 150% for RP and TSP, respectively (p < 0.05), with similar increases in biomass P stocks that showed promise for soil regeneration. In low-P fields, added P increased potential P release from legume residues via lower C:P ratios (p < 0.05). Percent cover of soil increased from 35% in the control to 45 and 55% with RP and TSP (p < 0.05), which shows potential for reduced erosion risk under P fertilization of legumes. We discuss results with respect to the integration of local farmer knowledge systems with exogenous scientific knowledge.

Rationally higher population density is crucial for seeking a balance that meets lodging resistance and maximizes seed yield in mechanized direct-seeded winter canola. In this study, a split-plot experiment with two cultivars (Huayouza9 and Zhongshuang11) and eleven planting densities (12–105 plants m-2) was conducted in a two-season field experiment to evaluate the high planting density in this cropping system and improve its production efficiency. Seed yield noticeably increased in planting density up to 80 plants m-2 in Zhongshuang11 (2187 kg hm-2) and 60 plants m-2 in Huayouza9 (2943 kg hm-2). The seed yield of Huayouza9 did not differ significantly from the local target seed yield. Higher plant density curtailed the luxurious vegetative growth of individual canola plants at the density of no less than 60–80 plants m-2, and high seed yield was derived from the increased ratio of main raceme and branch seed weight in winter canola. An increase in plant densities contributed to the reinforced sunlight interception at the pod-filling stage, providing a larger canopy photosynthetic area for the rapid growth of more canola pods at higher densities (60–105 plants m-2). Lodging resistance and breaking resistance decreased sharply with the plant density increasing from 12 to 60 plants m-2 while remaining almost steady as it further increased from 60 to 105 plants m-2 for Huayouza9 and Zhongshuang11. Hence, the population density of 60 plants m-2 reached a balance between lodging resistance and maximized seed yield in mechanized direct-seeded winter canola in China.

In Coffea arabica, there is a small genetic distance between wild and bred genotypes. However, coffee genotypes express differential acclimation to multiple drought cycles, allowing them to successfully deal with water-limiting conditions. We hypothesized that bred coffee cultivars have a plant structure less sensitive to drought than wild genotypes. Plant and leaf architecture were analyzed over the coffee strata of two cultivars (Iapar 59 and Catuaí 99) and two wild Ethiopia accessions (‘E083’ and ‘E027’) grown under rainfed conditions and irrigation. During two consecutive productive years, evaluations were taken at leaf and berry expansion (BE1 and BE2) and harvest (BH1 and BH2) phenophases. The plant canopy was divided into up to four strata of 40 cm of thickness. Topological and geometric coding of coffee trees was performed in three botanical scales – metamers, branches, and plants in multiscale tree graphs (MTGs), following the VPlants modeling platform. Leaf and branch area per plant increased with tree structure development, being always significantly higher in irrigated than in rainfed plants over all phenophases. The individual leaf area was the least sensitive to water regime in Catuaí 99, while the 2nd order axis elevation – angle in relation to horizontal plane, ranging from 0° to 90° – of bred cultivars was less sensitive to drought than in ‘E083’. This finding partially corroborated our hypothesis that orchestrated reprograming of leaf/branch responses over the vertical plant profile were less sensitive to water availability in cultivars than in wild accessions. Leaves of 2nd to 4th-order branching were roughly plagiophile, while the 1st-order leaves were classified as extremophiles. When the coffee leaves were planophile, irrespective of genotype, this pattern was found at the lowest, 1st plant stratum, and the newest developed 4th stratum. Such responses were not obligatorily related to water regime, similar to branch elevation – with exception of ‘E083’, very sensitive to drought. Taken together, our data suggest that the leaf and branch elevations in C. arabica were more influenced by light distribution through the canopy profile – i.e., self-shading – than by water availability.

The developmental and scientific impacts of research carried out intermittently over a thirty year period on the tea crop (Camellia sinensis) in southern Tanzania are reported. It is an attempt to demonstrate to questioning donors that research can contribute, in many ways, to the alleviation of poverty in developing countries. During Phase I (1966–1972) the work was funded in large part by the UK Department for International Development (DFID), as it is now known, with the support of the tea industry in East Africa. During Phase II (1985–1991) a regional study in eastern Africa was largely funded by DFID with local field experimentation in Tanzania paid for by tea growers. In Phase III (1992–1997) the work was funded almost entirely by a consortium of commercial producers.

Throughout this period, despite political and economic uncertainties in Tanzania, the close contact with industry meant that the results of the research were exploited to commercial advantage whenever circumstances allowed. These interventions enabled productivity on a unit area basis to rise over time and companies to remain profitable. More recently major investments in new projects have taken place in southern Tanzania, again supported by the results of the research. All of this has led to the creation of new jobs and to continuity of employment in rural areas that have few other sources of paid work. The financial return on the research investment, although very difficult to quantify with precision, has been immense.

The science has not been neglected either. Over the same period more than 30 refereed papers have been published in the international scientific literature. These cover such topics as the responses of tea to climate and weather, including drought and irrigation. Scientists have also been trained in modern research techniques. In addition there have been ancillary benefits including the introduction of technical and management training programmes for staff in the tea industry. Frustration has been caused by the lack of continuity in funding due to changes in policies, and in the priority research topics, even within one donor organization, which have often put the work at risk. Ingenuity, patience and commitment have all been pre-requisites to ensure that the research continued.

The partnership with industry has been beneficial to all the stakeholders. It has led directly to the creation of the new, commercially managed Tea Research Institute of Tanzania serving both small- and large-scale producers throughout the country. Researchers, with the support of the tea industry and in partnership with the Tanzanian Government and DFID, can continue to play a significant role in the fight against poverty. Research for development is a continuing process: it can be successful.

Attention is drawn to the large annual fluctuations of clove yields in Zanzibar and Pemba which appear to result from a synchronization of clove production by trees. Linear regression analyses are presented which show that in years of peak production tree yield is often correlated with tree canopy area and that when trees yield in two consecutive years, yield in the second year is usually negatively correlated with yield in the first year; equations including both variables often leave considerable variation in yield unaccounted for. It is suggested that some of the year to year variation in tree yield may result from an environmental stimulus affecting clove bud differentiation.

Two early maturing semi-tall (120–130 cm) rice varieties, Kalinga-3 (85 days duration) and Banaprabha (95 days duration), were compared in pure and mixed crop stands under intermediate deepwater conditions (15–50 cm) with a modern late maturing (170 days duration) semi-dwarf (100 cm) variety, CR 1016. Parallel line seeding of CR 1016 and Kalinga-3 or Banaprabha in alternate rows (1:1 ratio) 20 cm apart yielded 19% more grain than a pure crop of CR 1016 alone. Mixed crop planting in a 1:2 or 2:1 ratio or with reduced inter-rovv spacing gave no additional yield advantage. Mixed row cropping prevented lodging in early varieties, whereas monocrops of the same varieties were partially lodged and showed some premature seed germination. The better and more stable yields obtained from such mixed cropping could be beneficial to resource poor farmers growing rice in conditions of excess water.

Low levels of phosphorus limit the yield of pearl millet (Pennisetum glaucum) grown on acid sandy soils of the West African Sahel. The application of phosphorus and the recycling of millet residues produces large increases in the total dry matter and grain yields of millet but little is known about the effects of these amendments on the by-products of millet fields which include weeds and millet leaves at harvest. Phosphorus applied at 13 kg ha−1 as single superphosphate and millet residues applied at 500 or 2000 kg ha−1 as a mulch or as the ash from 2000 kg millet residues ha−1 that had been burned, increased dry matter yields of millet leaves and weeds leading to large increments in the total in vitro metabolizable energy harvested per unit area. These increases in dry matter production were only accompanied by minor decreases in the concentration of crude protein. The increased availability of millet by-products should be taken into account when evaluating the effects of phosphorus and crop residue application on the economy and sustainability of agro-pastoral farming systems in the West African Sahel.

The environmental conditions and test duration in rainfall simulators have been major constraints to find reliable differences in preharvest sprouting (PHS) among wheat cultivars. This study aimed to elucidate the temperature conditions and degree-days (DD) that enable higher discrimination of genotypes in a PHS test. Thirteen genotypes with different degrees of PHS (BR 18, BRS 220, CD 104, CD 105, CD 108, CD 114, CD 116, Frontana, IPR 085, IPR 128, IPR 136, OR1 and Safira) were evaluated in a rainfall simulator, during four years, conducting two trials per year. The tests were carried on 20 spikes per cultivar, kept in a vertical position on Styrofoam plates, spaced 10 cm between rows and 5 cm within the row. The air temperature data were recorded on a thermograph and the DD were calculated from the mean daily air temperature assuming a base temperature of 4 °C. The Falling Number (FN) parameter and germination percentage (GP) data were averaged for each test. The temperatures (minimum, mean and maximum) and the DD were regressed and correlated with FN and GP. Any increase in the minimum and mean air temperature and accumulated DD decreased FN values and increased GP. Higher genotypic discrimination was achieved at an average air temperature of 21.5 °C and 35 DD. These values can be used as reference to set simulated rain testing condition for screening genotype for PHS based on FN or pericarp rupture of grains.

A random sample of 13 uniformity trials was examined in terms of sensitivity to choice of block size and orientation. Five trials were classified as insensitive and eight as sensitive. Trials insensitive to blocking choices showed little variation in experimental error for various sizes, shapes and orientations of blocks, but those sensitive to blocking choices showed considerable, sometimes drastic, effects of such choices. There was often an objectionable degree of inflation of experimental error due to large or improperly oriented blocks. It is proposed that the routine analysis of field experiments based on block designs be modified to reveal cases in which ineffective blocks have been used on sensitive sites.

A breeding programme involving the progeny testing of small East African Zebu cattle for improved growth rates is described and an assessment made of environmental and genetic improvements which have occurred over a ten-year period. Evidence is presented to justify continuing the programme, but suggestions are made to modify it in order to speed up the testing period and also to make more use of genetically superior stock.

Repeatability estimates of milk yield and length of lactation of local, ½ Anglo-Nubian × local and ¾ Anglo-Nubian × local cross-bred goats were calculated. There were highly significant differences in the effect of dams on milk yields for the third, fourth and fifth lactations for local goats, when considered together. No significant differences were found for the first two lactations. For the ½ Anglo-Nubian cross-bred goats significant differences were also found for the first and second lactations, but not for the third lactation. No significant differences were found for the two lactations in the case of the ¾ Anglo-Nubian cross-bred goats. The effect of lactation periods were not significant for the three types of goats. The mean repeatability estimates for local goats were 0·47, 0·42 for ½ Anglo-Nubian and 0·54 for ¾ Anglo-Nubian cross-bred goats, which were comparable to those reported for cattle. The between-dam effect was highly significant when three lengths of lactations were combined in local goats, and the interval between lactations were also significant, but these two effects were not significant for the ½ Anglo-Nubian and ¾ Anglo-Nubian cross-bred goats. The estimates of repeatability for length of lactation averaged 0·29 for local goats, 0·17 for ½ Anglo-Nubian and 0·53 for ¾ Anglo-Nubian cross-bred goats. The correlation coefficients between milk yield and length of lactation were positive and statistically significant for all the three types of goats, ranging from 0·59 to 0·93. The similarity of the genetics of goats to those of cattle and sheep is mentioned.

Considering straw resource utilization and air pollution prevention, straw return has been commonly practiced in China. However, the practicability of plenty straw return in an emerging maize–rice rotation and their effects on soil C and N pools have not been extensively investigated. This study has been conducted to examine the effects of straw return on soil nutrients, soil functional C and N fractions, and then to figure out their relationships with yield and N use efficiency. Two treatments of straw return (S2Nck) and without straw return (S0Nck) were compared in 3-year field experiment, and subplots without N application were added in their respective plots in the third year. The results showed that, relative to the control (S0Nck), straw return significantly increased soil mineralized nitrogen (Nmin), available P, and exchange K content by 11.7%, 41.1%, and 17.4% averaged across 3-year experiments, respectively. Straw return substantially increased soil dissolved organic C, microbial biomass C, and microbial biomass N content by 73.0%, 25.2%, and 36.8%, respectively. Furthermore, straw return markedly increased C and N retention in particulate organic matter in microaggregates (iPOM) and mineral associated organic matter within microaggregates (intra-SC), but significantly reduced in free mineral associated organic matter (free-SC) fraction. The structural equation modeling analysis showed that yield and the partial factor productivity of N were positively correlated with labile and slow soil C and N fractions. Consequently, straw incorporation significantly increased grain yields of maize by 14.7% and rice by 15.1%. The annual potential reduction proportion in fertilizer-N induced by straw return was estimated to be 25.7% in the third year. This study suggests that the incorporation of straws is an effective way to enhance soil nutrients and regulate soil C and N pools to improve crop production and has the potential to reduce N fertilizer application under maize–rice rotation in subtropical regions.