Soil inoculation was tried in field experiments during two seasons using different concentrations and amounts of bacterial suspension and compared with direct seed inoculation of chemically protected and unprotected peanut seed. Soil inoculation gave significantly better results than direct inoculation of chemically protected or unprotected seed.

Large yields of high quality peanuts, which compared favourably with highly nitrogen-fertilized peanuts, were obtained after the application of relatively small amounts (10–40 gm.) of enriched peat inoculant in 5 litres of water per dunam (1/10 ha).

The hill ecosystem of Northeastern Himalayas is suitable for organic farming due to negligible use of fertilizer (<12 kg ha−1) and agrochemicals, abundance of organic manure, especially plant biomass, and favourable climatic conditions for diverse crops. For successful organic farming, efficient cropping systems and organic amendments are to be identified to sustain soil health on one hand and productivity and enhanced income on the other. The efficacy of three organic amendments, namely, farmyard manure (FYM), vermicompost (VC) and integrated nutrient source (INS; 50% recommended dose of nitrogen (N) through FYM + 50% N through VC) on performance of three-vegetable-based cropping systems, namely, maize + soybean (2:2 intercropping)–tomato, maize + soybean–potato and maize + soybean–French bean was evaluated for five consecutive years (2005–06 to 2009–10) under subtropical climate at Umiam, Meghalaya, India (950 m above sea level). All the organic amendments were applied on N equivalent basis and phosphorus (P) requirement was compensated through rock phosphate. The results revealed that the yield of vegetables, except root vegetables, was maximum with FYM as soil amendment. Total system productivity in terms of maize equivalent yield (MEY) was significantly higher under FYM followed by INS. Pooled analysis revealed that MEY was enhanced by 200 and 191% with continuous application of FYM and INS, respectively, over control (no manure). Maize + soybean–tomato system recorded the highest MEY (28.78 Mg ha−1; Mg – megagram) followed by maize + soybean–French bean (24.37 Mg ha−1). INS as organic amendment resulted in maximum improvement in soil organic carbon (SOC), available P and potassium (K), soil microbial biomass carbon and water holding capacity and was similar to those under FYM. The SOC concentration under INS (23.6 g kg−1), FYM (23.3 g kg−1) and VC (22.3 g kg−1) after five years of organic farming were 31.0, 29.4 and 23.8% higher than the initial and 26.2, 24.6 and 19.3% higher than those under control, respectively. The quality traits of tomato such as total soluble solids (5%), ascorbic acid (28.6 mg 100 g−1) and lycopene content (19.35 mg 100 g−1) were higher under FYM application than other amendments. The study indicated that FYM and INS are equally good as organic amendment and their continuous application not only improves soil health but also crop productivity. FYM application was also found to be cost effective as it resulted in a higher benefit: cost ratio (4.4:1) compared to other amendments irrespective of cropping sequences during transition to organic farming.

Seedling emergence and stand establishment of crops following the allelopathic crops are often affected. When the crops are grown in rotation, they are influenced by allelopathy of preceding crop. In this study, consisting of three independent experiments, allelopathic effect of tobacco, rich in several allelochemicals, on the subsequent maize and mungbean crops was investigated. In first experiment, maize and mungbean were sown in field previously occupied by tobacco or was fallow. In second experiment, maize and mungbean were planted in pots after the harvest of tobacco. Whereas in third experiment, maize and mungbean seeds were soaked in water or 2 and 4 mM nicotine and were then sown in soil-filled pots. Stand establishment, leaf emergence and growth of maize were significantly improved when grown after tobacco, whereas in mungbean these characters were suppressed when grown after tobacco. Likewise external application of nicotine improved the emergence uniformity, seedling dry weight and chlorophyll contents in maize and suppressed these parameters in mungbean. Tobacco allelopathy also increased the total soil nitrogen, zinc, iron, nicotine and total phenolics. Nicotine-induced change in chlorophyll contents and α-amylase activity seems the possible reason of differential response of maize and mungbean to tobacco allelopathy. When grown in rotation with tobacco, stand establishment and growth of maize were improved, whereas mungbean stand and growth were suppressed. In crux, allelopathic nature of the crops must be considered while making the crop rotations.

Shifting agriculture is an ancient basis for maintaining soil fertility but pressures of population have caused it to give place in most countries to rotations and bare fallows which, in turn, have had to be reduced or modified. Research on various measures to shorten the duration of fallows and increase their effectiveness is reviewed. These measures include the use of organic manures and inorganic fertilizers, green manuring, mulches and the growing of legumes and grasses, which are discussed in relation to their effects on the soil and on crop yields. The increasing use of the factorially-designed experiment is recognized as a major contributor to this research.

A tied ridge system of hand cultivation has been practised successfully in parts of Tanzania for many years. Equipment to mechanize this system was devised and constructed by the National Institute for Agricultural Engineering, U.K., particularly for use in areas of marginal rainfall where water conservation is essential. Agronomic trials with this equipment were carried out on three soil types in Northern Tanzania. Records from resistance units showed much better penetration of rainfall under tied ridges than under flat cultivation. Corresponding yield responses in maize were only obtained when the increase in available water made an appreciable difference to conditions of water stress at the time of tasselling and silking. Weeding operations using a ridging body achieved a satisfactory control. After a few modifications to the equipment, especially the incorporation of a small tine to rip the bottom of the basins to improve infiltration, the system of cultivation based on ripping, ridging and tieing proved to be an adequate alternative to ploughing and harrowing for seed bed preparation, and a much more efficient method of water conservation.

In a field experiment initiated in the 1972/73 rabi season (November–March) on an acidic soil in the western Himalayas of India, continuous cropping for 25 years with nitrogen fertilizer alone reduced the grain yields of maize (Zea mays) and wheat (Triticum aestivum) to almost zero. Based on five-year moving average values, the application of 100% NP resulted in a reduction of grain yields of maize and wheat crops by 67 and 19% respectively during 1994 to1998 compared with 1973 to 1977. The crops did not respond to K application during the initial years of cropping, but a significant reduction in crop yields was observed in the absence of K after five years of continuous cropping. With the integrated use of chemical fertilizers (100% NPK) and farmyard manure, the pooled grain yields of 25 years were about 4600 and 3300 kg ha−1 for maize and wheat respectively. Corresponding yields with the use of chemical fertilizers and lime (100% NPK + lime) were 4000 and 3100 kg ha−1 respectively. The use of nitrogenous fertilizer alone aggravated the problem of soil acidity by lowering the pH from 5.8 to 4.7 after 25 years. In almost all the treatments, the organic carbon content increased: a marginal decrease occurred in the 100% N and control plots. Even under optimum application rates, the available N and K status decreased with time. Again with the exception of the control plots, the contents of the Diphenyl Triamine Penta Acetic Acid-extractable micronutrients were sufficiently high for the crops in all the treatments. The available sulphur decreased with the use of di-ammonium phosphate as the P source, which drastically reduced the yields of both crops. In the N-alone treatment the weed flora also changed with the change in soil environment. There is a need to review fertilizer recommendations in this region of India.

Pearl millet [Pennisetum glaucum (L.) R. Br.] is grown as a forage, cover and grain crop in Brazil. Historically, forage production has the most important use, but during the last 30 years, the use as a cover crop in no-till soybean [Glycine max (L.) Merrill] production systems has expanded greatly and is currently used on over 5 million ha. Grain production as livestock feed is presently of minor importance but expanding. This review cites 125 references and documents pearl millet research conducted in Brazil which is largely published in Portuguese. The review addresses recommended pearl millet production practices for different uses, including stand establishment, row spacing and plant population, fertiliser and pest management, and the use of pearl millet in rotation and as a cover crop between soybean or maize (Zea mays L.) production to reduce crop losses from nematode infestation. It is concluded that greater research investment in crop improvement, fertiliser and pest management, nematode management, and forage/grain utilisation is needed to fully take advantage of pearl millet to meet feed, food and soil improvement needs in Brazil. In addition, creation of a database on pearl millet production, marketing and utilisation to assist farmers and grain merchandisers, and increased extension programming on pearl millet production is needed.

An on-farm study was conducted from 2009 to 2012 with communities in the Manjawira, Mpingu and Zidyana Extension Planning Areas in the Ntcheu, Lilongwe and Nkhotakota districts of central Malawi. The aim of the study was to evaluate the effects of the principles (no-tillage and mulching) and components (fertilization and weeding) of conservation agriculture (CA) on crop productivity and weeds, and the interactions between principles and components, and to suggest strategies for introducing CA to smallholder farmers. The treatments consisted of tillage, fertilizer application, residues management and weed control strategies. While combined analysis showed that mulching is as effective as tillage in controlling weeds, the interaction between site and treatment revealed that in the more humid environment of Zidyana, weed dry matter obtained under no-tillage and residues plus fertilizer (NT+F+R) was 0.6 mg ha−1 lower than under CP+F. Results suggest that about 6.0 mg ha−1 of mulch is required to have a similar effect as tillage in controlling weeds. Fertilizer had an overriding effect on maize yield, regardless of tillage and crop residue management. Mulching was beneficial over tillage in the drier environment of Manjawira, where maize yield obtained under NT+F+R was 1.2 mg ha−1 greater than under CP+F. Our results show that the introduction of no tillage has benefits only if it is accompanied by fertilizer application, retention of crop residues as surface mulch, and improved weed control. Increasing availability and accessibility of inputs (fertilizers and herbicides) to farmers is critical for adoption of CA at scale in Malawi.

On-farm participatory varietal selection (PVS) trials are often of two types: mother trials (with all of the entries) and baby trials (each having one, or very few of the entries from the mother trials). We conducted PVS trials on 17 wheat varieties in 12 villages of four districts of Bangladesh over three years but the data were highly unbalanced. Both quantitative and qualitative traits were measured in the on-farm trials. The factors in the trials were both fixed effects (varieties and districts) and random (years and farmers). We used the residual or restricted maximum likelihood (REML) analysis for the mixed model for quantitative traits. For qualitative data on farmers' perceptions, logistic regression procedures were used that are equally applicable to balanced and unbalanced data sets. The REML analysis provided adjusted mean values for quantitative traits for all the varieties, for the mother and baby trials separately, using the data from all years and all locations. It identified varieties BAW 1006 and BAW 1008 that yielded 19–30% more than the control Kanchan and also had a higher 1000-grain weight, were at least as early to flower and had a high overall ranking by farmers in the mother trials. The logistic regression analysis of perception data agreed with the results of the REML analysis as these varieties were most preferred by farmers for grain yield, earlier maturity and better chapatti making quality. The less labour-intensive method of recording qualitative perceptions can usefully replace actual yield measurements, particularly when validated by other participatory measures such as intended and actual adoption. In 2005, BAW 1006 was released as BARI Gom 23 or Bijoy and BAW 1008 as BARI Gom 24 or Prodip for the whole of Bangladesh. The validity of the results of the REML analysis was confirmed by the high early adoption trends of the identified varieties. Since REML is an effective analysis for unbalanced PVS trial data using a mixed model, its wider use by researchers would increase the value of the PVS process.

Under rainforest vegetation, the central Amazonian Ferralsols are characterized by relatively high availability of N in relation to other nutrients. After forest clearing, several tree crops also have not shown yield responses to N fertilizer. To elucidate the mechanisms of this apparent N sufficiency, the mineralization of soil N was measured under three tree crops and a leguminous cover crop (Pueraria phaseoloides) in a multi-strata agroforestry system at two fertilizer input levels on a Xanthic Ferralsol in central Amazonia. In situ incubations of topsoil (0–10 cm) were carried out using the buried-bag method on five occasions over ten months. The highest mineralization rates were found under the cover crop, intermediate rates under rubber trees (Hevea brasiliensis) where the soil was also covered by the cover crop, and lowest rates under peach palm (Bactris gasipaes) and cupuaçu (Theobroma grandiflorum) with no cover crop. The increased N mineralization under the cover crop was due to more total N in the soil, higher soil moisture and, presumably, a larger pool of readily mineralizable soil N compared with the soil under the tree crops. Other fertility parameters also differed significantly between sampling positions within the plots, but this had no major influence on net N mineralization. Also, the input of NPK fertilizer and dolomite had no significant influence on N mineralization, indicating that N mineralization was not nutrient-limited. High total N mineralization rates in the soil (approximately 350 kg ha−1 a−1 at 0–10 cm depth) explained earlier observations of nitrate leaching into the subsoil under multi-strata agroforestry at this site. Considering the spatial patterns of N mineralization with maximum values under the cover crop, the exploration of the soil volume by crop roots should be maximized to increase the uptake of mineralized soil N by the crops and reduce nitrate leaching. Appropriate measures are narrow tree spacing, use of annual and semi-perennial intercrops and encouragement of the lateral root development of the trees. In addition, the mineralization of soil N close to the tree crops can be influenced through the management of the cover crop. In view of the high total N mineralization rates in the system and unclear yield responses of tree crops to N fertilizer, the application of N fertilizer to tree crops with well-developed root systems and a well-managed cover crop may often be unnecessary on this soil type. This may facilitate the further development of tree crop agriculture in the region.

When differences are observed between genotypes in their response to low temperatures at germination, it has been generally assumed these are purely genetic. Laboratory experiments were carried out to evaluate the effects of physiological age on the temperature responses of 13 rice genotypes from Bangladesh in order to clarify whether (a) differences in seed germination at low temperature represented genetic differences or differences in the physiological state of the particular seed lot used and (b) whether genotype performance at higher temperatures was indicative of performance at lower temperatures. A higher initial seed moisture content (mc) was associated with lower initial viability (Ki). The base temperature for germination differed by less than 1 °C between genotypes. Seeds remaining ungerminated at low temperatures usually germinated when transferred to 21 °C. The thermal time requirement to reach t50 (θ) differed widely between genotypes. Lower optimum temperatures for germination were associated with lower thermal time requirements. Ageing seeds for 24 hours at 24 % mc and 45 °C significantly reduced final germination on a thermal gradient table at all temperatures below 20.8 °C in genotype BR29 but only below 16.5 °C in BR11. The rates of germination (seeds d−1) of aged seeds were also lower at all temperatures. Germination of high quality seeds of four genotypes were compared at 21 °C and 11 °C both before and after ageing (at 24 % mc and 45 °C). Ageing consistently reduced the rates of germination at both 21 °C and 11 °C. Increased ageing time progressively reduced the rate of germination of all seed lots at both temperatures. The rates of germination at 11 °C and 21 °C were positively and significantly (p < 0.01) related to final germination at the lower temperature of 11 °C. These results demonstrate that seed physiological quality as well as genotype might influence the final germination and rate of germination of rice genotypes at low temperatures. This information will be useful for breeders involved in selection of lines suitable for growing in cooler seasons.

The nutritive value and yield of forage legumes and barley harvested as immature herbage, hay and straw were measured in two experiments. The voluntary feed intake of peas at all stages of maturity and immature herbage from woollypod vetch was substantially lower than that of common vetch and chickling. At each stage of maturity barley was less digestible than all the forages except immature peas. Despite exceptionally cold weather in February/March 1985, yields of common vetch were higher in 1984/85 than in 1985/86 when there was less rain. Peas yielded the most hay, and chickling yielded less seed and straw than common vetch, peas and barley. Yields of digestible dry matter from straw and seed exceeded those from hay but protein yield at the two stages was similar. Mechanical baling substantially reduced the yields of baled hay but these losses would be reduced to less than 10% if the residues were grazed.

Four genotypes of ‘desi’ and two of ‘kabuli’ chickpea (Cicer arietinum) were sown at six locations in Australia on various dates between 1986 and 1988, giving 22 combinations of site and sowing date with diverse photothermal environments. Times from sowing to first flowering (f) varied from 30 to 162 d, mean pre-flowering temperatures from 10.8° to 29.3°C and mean photoperiods from 11.3 to 15.6 h d−1. There was no evidence that any observation had been obtained in photoperiods shorter than the ceiling photoperiod (Pcc) or longer than the critical photoperiod (Pc). This suggests that, in typical agricultural environments, chickpea crops experience photoperiods (P) which should satisfy the condition Pcce < P < Pc. In one ‘kabuli’ and two ‘desi’ genotypes, 1/f was influenced by both temperature and photoperiod. The coefficient of determination (R2) for a linear, additive rate of development model ranged from 0.74 to 0.80, with no significant difference in either temperature sensitivity or photoperiod sensitivity among these three genotypes. In the remaining three genotypes, no significant response to temperature was detected between 10.8° and 29.2°C, so rate of progress to flowering was influenced solely by photoperiod. There was no significant difference in the sensitivity of 1/f to P among these three genotypes. The linear, additive rate model found here to be so satisfactory as a predictive tool for phenology, is also shown to have much wider general application.

Predicción del liempo de floración

This paper assesses farmer adoption of rice varieties and new genotypes introduced through participatory varietal selection (PVS) in villages which represent submergence- and drought/submergence-prone villages in eastern Uttar Pradesh, India. It focuses on the involvement of women farmers in participatory research for screening improved varieties for areas which suffer from abiotic stresses. It further assesses the impact on the decision-making authority (or women's empowerment) on rice varietal choice, seed acquisition and disposal, and crop management after participating in PVS trials. It suggests strategies to empower women farmers in making sound and timely decisions on farm-related matters and to enhance their roles in accelerating the adoption of new varieties.

In sub-Saharan Africa (SSA), rainfed agriculture is the dominant source of food production. Over the past 50 years much agronomic crop research has been undertaken, and the results of such work are used in formulating recommendations for farmers. However, since rainfall is highly variable across seasons the outcomes of such research will depend upon the rainfall characteristics of the seasons during which the work was undertaken. A major constraint that is faced by such research is the length of time for which studies could be continued, typically ranging between three and five years. This begs the question as to what extent the research was able to ‘sample’ the natural longer-term season-to-season rainfall variability. Without knowledge of the full implications of weather variability on the performance of innovations being recommended, farmers cannot be properly advised about the possible weather-induced risks that they may face over time. To overcome this constraint, crop growth simulation models such as the Agricultural Production Systems Simulator (APSIM) can be used as an integral part of field-based agronomic studies. When driven by long-term daily weather data (30+ years), such models can provide weather-induced risk estimates for a wide range of crop, soil and water management innovations for the major rainfed crops of SSA. Where access to long-term weather data is not possible, weather generators such as MarkSim can be used. This study demonstrates the value of such tools in climate risk analyses and assesses the value of the outputs in the context of a high potential maize production area in Kenya. MarkSim generated weather data is shown to provide a satisfactory approximation of recorded weather data at hand, and the output of 50 years of APSIM simulations demonstrate maize yield responses to plant population, weed control and nitrogen (N) fertilizer use that correspond well with results reported in the literature. Weather-induced risk is shown to have important effects on the rates of return ($ per $ invested) to N-fertilizer use which, across seasons and rates of N-application, ranged from 1.1 to 6.2. Similarly, rates of return to weed control and to planting at contrasting populations were also affected by seasonal variations in weather, but were always so high as to not constitute a risk for small-scale farmers. An analysis investigating the relative importance of temperature, radiation and water availability in contributing to weather-induced risk at different maize growth stages corresponded well with crop physiological studies reported in the literature.

In an on-station agroforestry experiment conducted in south-west Niger, the effects of seven windbreak species and of a soil mulch made from crop residue on wind erosion and pearl millet (Pennisetum glaucum) production were monitored. Within a distance of 20 m, strips of the perennial grass, Andropogon gayanus, reduced total annual soil flux by 6–55% and hedges of Bauhinia rufescens 2 m in height reduced soil flux by 47–77% compared with unsheltered control plots. No significant overall windbreak effect on millet stover and grain yields was found. In contrast, erosion reduction and yield increases due to mulch application were highly significant. Soil mulch is a promising alternative to complex windbreak–millet cropping systems in regions where direct economic benefits for farmers are not ensured by windbreaks.

Apparatus was built to screen sorghum and pearl millet for seedling emergence through a hot soil surface. Seeds were sown in soil in long clay pots arranged in a steel water tank so that the top 7 cm of the pots was above the water level. The soil in the pots was heated with infra-red lamps fitted to a frame above the tank. By adjusting the height of the frame the temperature of the soil could be changed. The system allows emerging plumules to be subjected to high soil temperatures (up to 50°C) but without water stress. Both crops exhibited genotypic differences in emergence.

Sweet potato virus disease (SPVD) causes strap-shaped leaves, vein-clearing, puckering, chlorosis and stunting in susceptible sweet potato varieties and yields are much reduced. To investigate the tolerance of genotypes and obtain a better appraisal of yield loss caused by SPVD, eight sweet potato varieties showing symptoms of SPVD were studied for two years in an area where SPVD is severe. Two varieties, although showing symptoms, were tolerant of the disease; their yields were not significantly depressed by SPVD. Among the remaining six varieties, storage root fresh yields were reduced by 56–90% in plants showing SPVD symptoms. Marketable yields, as well as total and marketable numbers of storage roots were similarly depressed by SPVD in the less tolerant varieties. Significant correlations were found between disease severity rating and yield reduction among cultivars.

The effect of variations in the relative sowing time and density of component crops in a maize/cowpea intercrop were examined in two experiments. In the first experiment, maize and cowpea were sown together, and either 10 or 21 days before or after each other. Maize yield was reduced when sown at the same time or after cowpea; intercrop cowpea yields were less than sole cowpea yields at all sowings. In the second experiment, maize densities of 35, 50 and 70 × 103 plants ha−1 were combined with cowpea densities of 70, 100 and 140 × 103 plants ha−1. Increasing the density of either crop in the mixture resulted in increases in total yield. Maize reduced cowpea yields more than the effect of cowpea on maize yields. In terms of LER and total seed protein yield, there was no advantage of either staggered sowings over simultaneous sowing or of the various intercrop density combinations, except between the lowest and the highest densities of either maize or cowpea. The LERs appeared to follow the trends in cowpea yields and total seed protein yields the trends in maize yields.

This paper addresses the current and future contributions of plant genetic resources and plant improvement to sustainable agriculture with reference to the activities of the International Center for Agricultural Research in the Dry Areas (ICARDA) in association with national programmes in West Asia and North Africa. These regions constitute the primary centres of diversity of crops such as wheat, barley, chickpea and lentil. Genetic erosion is being curtailed by germplasm collection and preservation. Selection for low-input cultivars of barley is conducted under low input conditions, and new cultivars of lentil and barley are often intentionally heterogeneous to stabilize their performance in dry rainfed areas. The importance of genetic differences in the cultivars on subsequent crops in the rotation and on straw quality for livestock is under study. Insect pests and diseases contribute to yield instability. Because of the potential adverse impact of pesticides on the fragile ecosystems of the region, integrated control strategies based on agronomic management, host plant resistance, biological control agents and strategic use of selective insecticides are being developed.