Factorial combinations of three daylengths (11, 12 and 15 h), warm and cool days (30° and 22° C) and warm and cool nights (18° and 10°C) were imposed on nodulated plants of three chickpea cultivars grown in pots in controlled environment growth cabinets. The treatments had large effects on growth, phenology and seed yield and no single environmental regime was optimal for all successive stages of development. Root growth and nodulation were extremely responsive to the environment experienced by the shoot. Conclusions are drawn on the potential contribution of these data to the development of empirical screening techniques suitable for large, segregating populations in field programmes devoted to the production of chickpea cultivars better adapted to their intended environments.

Essential features are described of a computer programme, written in F.A.S., for the evaluation of 1 : 1 and 4 : 1 confidence limits of expected ‘twenty-day’ totals of rainfall. The paper deals briefly with the availability and utility of the programme to agricultural research workers in Africa.

Changing the geometry of planting under irrigated conditions from the traditional pattern of regular rows (with plants equidistant from each other) into double rows (with plants arranged in row pairs) promoted plant competition. This resulted in a significant reduction in overall yield components of sorghum but a marked increase in shoot yields of striga. A better yield of sorghum was obtained in ridged plots than in flat plots, associated with less striga infestation and a slightly higher soil moisture content under the ridged plots.

Field irrigation is costly in arid regions, and over-fertilization of farmland can lead to high groundwater nitrate levels and significant environmental challenges. Integrative aquaculture and agriculture (IAA) systems allow the reuse of water and nutrients to offset production costs while promoting greater sustainability. The aim of this study was to test the effectiveness of an IAA system using treatments formed from one water source, groundwater (GRND) or fish pond effluent (EFF), and one chemical fertilizer regime, eliminated (ELIM) or historical (HIST). Treatments were applied to field plots of barley or cotton. There were typically positive effects of EFF applications on crop growth and yield relative to GRND applications under identical fertilizer regimes. However, GRND-HIST almost always outperformed EFF-ELIM, suggesting that substituting effluent irrigations for a historical fertilization regime without pond biosolid or reduced fertilizer applications could be detrimental to crop production.

Output:input ratios and apparent balances for nitrogen (N), phosphorus (P) and potassium (K) were measured in a rice-wheat system at Modipuram (29.4°N, 77.46°E, 237 m asl), India, under two planting densities (P1 = 200×200 mm for rice, 230 mm row spacing for wheat, and P2 = 200×100 mm for rice, 150 mm row spacing for wheat), and two levels of fertilizer NPK (100% F = recommended levels of fertilizer N, P and K for each crop, i.e. 120 kg N, 26 kg P and 33 kg K ha−1, and 150% F = 150% of the recommended levels) with and without 5 t ha−1 farmyard manure (M) to each crop. After two cycles of the rice-wheat rotation at a fixed site, N and K balances were negative for all treatments, but P balance was negative only in plots treated with P1 + 100% F treatment. The largest yield in the system, 15.7 t ha−1, was obtained in plots receiving P2 planting density with 150% F + M treatment, and the smallest (13 t ha−1) in plots of P1 planting density with 100% F treatment. In plots with the largest yield, total removal of NPK was 659 kg ha−1 (310 kg N, 62 kg P and 287 kg K ha−1), and in plots with the smallest yield, NPK removal was 411 kg ha−1 (188 kg N, 34 kg P and 189 kg K ha−1). At these nutrient uptakes, output:input ratios were 0.74 for N, 0.57 for P and 1.80 for K in plots receiving P2 + 150% F + M treatment, and 0.78 for N, 0.65 for P and 2.86 for K in plots receiving P1 + 100% F treatment.

Fertilizer nitrogen (N) management in any region following standard general recommendations discount the fact that crop response to N varies between sites and seasons. To devise field-specific N management in wheat at jointing stage (Feekes 6 growth stage) using atLeaf meter and leaf colour chart (LCC), eight field experiments were conducted in three wheat seasons during 2017–2020 in the West Delta of Egypt. In the first two seasons, four experiments consisted of treatments with a range of fertilizer N application levels from 0 to 320 kg N ha−1. Monitoring atLeaf and LCC measurements at Feekes 6 growth stage in plots with different yield potentials allowed formulation of different criteria to apply field-specific and crop need-based fertilizer N doses. In the four experiments conducted in the third season in 2019/20, different field-specific N management strategies formulated in 2017/18 and 2018/19 wheat seasons were evaluated. In the atLeaf-based fertilizer N management experiment, prescriptive application of 40 kg N ha−1 at 10 days after seeding (DAS) and 60 kg N ha−1 at 30 DAS followed by application of an adjustable dose at Feekes 6 stage computed by multiplying the difference of atLeaf measurements of the test plot and the N-sufficient plot with 42.25 (as derived from the functional model developed in this study), resulted in grain yield similar or higher to that obtained by following the standard treatment. The LCC-based strategy to apply field-specific fertilizer N at Feekes 6 stage consisted of applying 150, 100 or 0 kg N ha−1 based on LCC shade equal to or less than 4, between 4 and 5 or equal to or more than 5, respectively. Both atLeaf- and LCC-based fertilizer N management strategies not only recorded the highest grain yield levels but also resulted in higher use efficiency with 57–60 kg N ha−1 in average less fertilizer use than the standard treatment.

Seedling vigor is important to help ensure good crop establishment. In direct-seeded rice, this is particularly relevant when soil conditions are marginal. In Asia, about one third of the area of rainfed rice is situated on unfavorable soils, many of which are low in plant available P. In such environments, as farmers tend to have few resources, options to overcome poor crop establishment should be low cost and preferably seed-based. The P content of seed depends on genotype and can be augmented by soaking seeds in a P-containing solution prior to seeding (P-priming). In addition, the presence of the Pup1 quantitative trait locus can reportedly confer tolerance to low soil P availability. We tested combinations of seed priming (unprimed control, water priming, P-priming), and inherent seed P concentrations in contrasting rice genotypes (DJ123, Sadri Tor Misri), and two near isogenic sister lines of IR74 with (+Pup1) and without (−Pup1) the Pup1 QTL. Treatment effects on germination were studied in Petri dishes, while seedling growth and P accumulation were assessed using pots with P deficient soil. Germination was less than 75% in seeds with low seed P content. Seed priming with both water and P enhanced germination and seedling growth. In plants growing from high P seeds, water priming outperformed P-priming. In Sadri Tor Misri with low seed P, we observed a tendency for better performance in some parameters when P-primed. While the presence of the Pup1 QTL in IR74 increased shoot biomass and total root length, these effects could be further enhanced by water priming. Combining genetic and seed management approaches may contribute to improved rice establishment in P deficient soils but its effectiveness depends on genotype and seed attributes.

At its International Centres Week in October 2000 (ICW2000), the Consultative Group on International Agricultural Research (CGIAR) adopted a new Vision and Strategy. This paper is about Plank 4 of the CGIAR's Vision and Strategy which calls for the adoption, in collaboration with national and regional partners, of a regional approach to research planning, priority setting and implementation. Given the poverty and impact focus of international public goods research, both national agricultural research systems (NARS) and the CGIAR have advantages in pursuing a regional approach as a component of their respective activities. For the NARS in the region, this means seeking advantages at the regional level that they could not derive solely from a national-level approach. For the CGIAR, this means seeking complementary gains that it could not achieve exclusively through a global or ecoregional approach. These mutual advantages open the door for partnerships in regional research between NARS and their regional organizations, and the CGIAR. The paper highlights the advantages as well as risks and limitations of a regional approach to research. Since ICW2000, all regional and sub-regional organizations and CGIAR Centres have taken action to facilitate consultation processes that could eventually lead to the establishment of a regional approach to research for the CGIAR and NARS. The paper notes some emerging lessons, and takes a forward look.

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.

In agricultural innovation, the success of widely used technologies is often assumed to have been inevitable. Conversely, the blame for the failure of new technologies that researchers, policy makers and extensionists consider superior to existing solutions is often placed on farmers. However, these assumptions can be challenged by taking a social-constructivist view of on-farm innovation to examine how and why farmers made sense of new technologies and how this sensemaking shaped their use of these technologies over time. The present study took such an approach in its analysis of Australian woolgrowers’ adoption, abandonment, implementation and use of new wool-testing technologies that highlighted the social and dynamic nature of innovation on-farm. On-farm innovation in this case was an evolving, dynamic process that changed over time as woolgrowers made sense of new technologies. The primary message to agricultural innovation researchers, technology developers, policy makers and extensionists is that successful on-farm innovation requires the active, ongoing engagement of industry participants. In order to engage industry participants in the innovation process, sensemakers’ personal identity frames and social context, and how these interpretation frameworks relate to the new technology need to be understood.

A large body of evidence demonstrates the agronomic superiority of maize hybrids over open-pollinated varieties (OPVs) in intensive monoculture. However, comparisons of the performance of hybrids and OPVs in agroforestry systems are scarce. In this study, the performance of four maize hybrids and four OPVs is compared in sole crop and under mature trees. Experiments were conducted on-farm during four seasons in Bugesera, Rwanda and two seasons in Meki, Ethiopia. Two tree species were selected in Bugesera (Grevillea robusta and Senna spectabilis) and one in Meki (Acacia tortilis), and three farms were selected for each tree species, each including two plots with almost identical trees in their centre and two plots without tree. In Bugusera, grain yield was higher for hybrids (2 Mg ha−1) than for OPVs (1.5 Mg ha−1), and the presence of trees reduced the harvest index more in OPVs than in hybrids. In this region, the estimated reduction in grain yield due to the presence of trees was 0.9 and 1.1 Mg ha−1 in hybrids and OPVs, respectively, while estimated reduction in biomass was 1.5 and 1.7 Mg ha−1, respectively. In Meki, the grain yield of OPVs (2.08 Mg ha−1) and hybrids (2.04 Mg ha−1) did not differ and the presence of trees reduced their grain yields in the same manner. Our results showed that hybrids yielded more than OPVs under G. robusta and S. spectabilis in Bugesera but performed equally well under A. tortilis in Meki. We conclude that agroforestry farmers could benefit from growing hybrids in the equatorial savannahs of Rwanda, but that the choice between hybrid and OPV in equatorial savannahs of Ethiopia can simply be based on other factors such as seed costs and availability.

The objective of this study was to evaluate morphogenetic and structural characteristics of Guinea grass pastures subjected to two grazing frequencies (90 and 95% light interception) and two post-grazing heights (30 and 50 cm), during the rainy season and dry year. The leaf appearance rate varied only in the summer, the grazing pastures managed at 90/50 (light interception/post-grazing height) presented higher values in the leaf appearance rate (0.440 leaf/tiller.day), compared with those managed at 90/30 (0.275 leaf/tiller.day) and 95/50 (0.228 leaf/tiller.day), respectively. In the winter/beginning of the spring, pastures managed at 90/30 (0.03 cm/tiller.day) presented lower stem elongation rate in comparison with those managed at 90/50 (0.19 cm/tiller.day) and 95/30 (0.16 cm/tiller.day). Management strategies do not compromise the tissue flow in tillers and, consequently, can be utilized for the management of Guinea grass.

A long-term field experiment was conducted to determine the effects of indigo (Indigofera tinctoria) on the productivity of rainfed lowland rice-based cropping systems: rice–tomato, rice–tobacco or soyabean, rice–maize, and rice–garlic. Indigo was grown as an intercrop during the dry season and incorporated as green manure for wet season rice. Dry season crop yields were generally not affected by the indigo intercrop but indigo green manure had a positive effect on rice yields. At the same level of nitrogen (N) inputs, indigo-N produced higher yields than urea-N which may be due to high inorganic N losses.

A long-term field study was conducted from 1979 to 1985 in the Karnal district of Haryana, India to evaluate the effect of three rates of gypsum (0, 5.2 and 10.4 kg ha−1) on the performance of five grasses (Diplachne fusca, Panicum laevifolium, P. antidotale, Chloris gayana and Cynodon maritimus) on an extremely sodic soil with an initial pH of 10.6 and an exchangeable sodium percentage (ESP) of 94. Diplachne, Chloris and Cynodon usually gave their maximum yield in the second year of planting, P. antidotale in the third year and P. laevifolium in the fourth year. The results showed that Chloris can be recommended for such situations as it maintains a higher productivity over a longer period than the other grasses. Alternatively P. antidotale and P. laevifolium can be planted in association with Diplachne to provide a steady forage supply for a long time. Increasing doses of gypsum resulted in decreases in soil pH, exchangeable sodium and ESP and increases in calcium, magnesium, organic carbon and the infiltration rate of soil.

The potential for using sorghum and millet crop residues as fodder was studied in southeastern Botswana. This region is characterized by low, unevenly distributed rainfall and shallow sandy soils. There were significant differences among cultivars for grain and stover yield, digestibility, crude protein, and mineral content, but no species advantage. Stover from all entries was adequate for cattle maintenance in in vitro dry matter digestibility (IVDMD) and most of the minerals tested, but crude protein and phosphorus levels did not always meet the minimum requirement. The deficient phosphorus levels were compounded by high calcium levels. This mineral imbalance could lead to bone abnormalities and reduced fertility in livestock.

Sorghum hybrids and varieties show similar responses to changing environment, with constant relative yield increases from the hybrids over a wide range of conditions due almost entirely to more florets and grains per plant and per hectare. Carbohydrate production of the leaves of good varieties is probably not much in excess of requirements for filling the grain. The extra spikelet number of the hybrid, increases in photosynthetic area and probably increased photosynthetic efficiency together enable the extra grains be filled. There is also an advantage in size and activity of the root system. The yield increase is strongly buffered against environmental fluctuations. The fact that hybrids can increase over a wide range of farming conditions should result in big increases in production simply by changing from varieties to hybrids, as is already happening in several countries.

Shoot population densities, stages of development (that is, the number of leaves per shoot) and shoot mass were recorded on an irrigation × fertilizer experiment at the Ngwazi Tea Research Unit in Southern Tanzania from 1986 to 1990. Over this period the mean basal shoot population density increased from about 310 to 560 m−2, with peaks of over 850 m−2 in high-input plots. Large fertilizer application rates increased both the total number of shoots per unit area and the proportion that were actively growing. By contrast, the main effect of water stress was to delay the peak shoot population density from the warm-dry season until the early rains without affecting the annual mean. Overall, between 20 and 60% of the harvested shoots were dormant, depending on season and fertilizer application rate. Of the active shoots harvested, about two thirds had two leaves and a terminal bud whilst the remainder were split almost equally between shoots with one or three leaves. The fresh mass of individual shoots was linearly related to the number of leaves, with the slope of the line (0.16–0.35 g leaf−1) largely dependent on the season and irrigation treatment. The dry matter content of shoots varied in the range 19–30%, and was primarily determined by the season. The dry matter content was also affected by the treatments and was decreased by irrigation in the dry season and by fertilizer in the wet season. Alternative models for predicting annual yields (based on the components of yield) and seasonal yield variations (based on dry matter production and partitioning) are discussed.

Densidad de poblacióon tamaño y masa de los brotes de té

Growth of the sunflower cultivar Peredovic was examined when exposed to periodic severe moisture stress, with and without soil drench application of CCG at the two-leaf stage. The experiment was conducted in sand culture under partly controlled environment conditions. Morphological and physiological measurements were made throughout the growing period. Amongst the responses to CCC were increased stem and petiole width, and decreased length of internodes, head diameter and photosynthetic area. Moisture stress reduced photosynthetic area and the root/shoot ratio. Both CCC and moisture stress increased the number of stomata per unit area.

A field experiment was conducted to study the effect of leaf stripping, de-tasselling and topping on the yield of maize and finger millet in a maize/finger millet intercropping system at Lumle in Nepal. De-tasselling of maize before pollen shedding reduced the number of barren plants, and increased test weight and grain yield but de-tasselling after pollination had no significant effect. Defoliation of maize by removal of leaves below and above the ear, or by topping 30 days after 50% silking, had no effect on either maize grain yield or on that of the relay planted finger millet. This contradicts the hypothesis that increased light penetration due to reduced shading improves the yield of millet under maize.

Upland rice and Stylosanthes guyanensis were sown simultaneously in pure and mixed culture at varying densities at Na Pheng, central Laos. Vegetative growth of the rice was negatively related to stylo density over the range o to 81 stylo plants/m.2 Rice grain yield varied from 98·4 gm./m.2 in monoculture to 63·4 gm./m.2 when grown with 81 stylo plants/m.2 Rice was more competitive than stylo, but stylo growth was relatively independent of rice density over the range 20 to 120 rice plants/m.2