Topdressing of N fertilizer, whenever leaf greenness, as measured by Chlorophyllmeter (SPAD), falls below the threshold value can be used for site-specific N management in wheat cultivation. Herein, a field experiment was conducted to analyse the effect of SPAD-based N management on wheat productivity and N use efficiency during the dry season of 2010/11 and 2011/12 on acid lateritic soil of eastern India. The experiment had 12 treatments, with nine treatments combining three SPAD thresholds (38, 40 and 42) and three N levels (15, 25 and 35 kg N ha−1) as real time N management (RTNM), one fixed time N management (FTNM), one farmers’ fertilizer practise (FFP) and control (Zero N), with three replications. The grain yield of RTNM ranged from 90 to 113% as that of FTNM, but using considerably less N. Maintaining SPAD threshold of 40 up to heading stage by topdressing 25 kg N ha−1 at each time (N25S40) caused the highest grain yield (4483 kg ha−1). While saving 22.5 kg N ha−1 (18.8%), N25S40 increased agronomic N use efficiency by 58.5%, nitrogen recovery efficiency by 15.1% and partial factor productivity of applied N by 26.4% when compared with conventional fertilizer recommendations (i.e. FTNM). The SPAD-based N management strategy was found very promising in efficiently managing N fertilizer in wheat for improving wheat productivity and N use efficiency.

A field experiment was carried out to compare the performance of 18 accessions of jackbean from different origins. Plant development and phenology, final plant biomass, and seed yield and its components were evaluated. Flowering time ranged from 56 to 109 days after sowing. Bush and climbing types were identified and differences in seed yield were recorded, the largest yield occurring in a mid-season flowering accession. It was concluded that more material should be screened since germplasm introduction appears to be a promising route to larger jackbean yields in Yucatan

Many farmers are intensifying production systems by applying greater amounts of inorganic fertilizers, irrigation and pesticides, especially to cash crops. Such intensified systems, even though economically profitable in the short run, may not be sustainable. This paper analyses the economics and sustainability of an intensified rainfed rice-based system in Ilocos Norte, Philippines. Farmers use high levels of inorganic fertilizers for cash crops such as sweet pepper, garlic and tomato. Although these crops generate high levels of income, the high input systems may not be sustainable in the long run due to adverse on-site and off-site effects. Preliminary estimates of total factor productivity that include on-site effects only, display no clear time trend. However, negative externalities created by high nitrate contamination of groundwater and high rates of pesticide usage could make the system unsustainable by adversely affecting human health and the environment.

Using a qualitative case study design, a demonstration farm approach implemented in northern Patagonia, Argentina, was assessed to examine differences in perceptions between participating stakeholder groups regarding their roles and how these affect the collaboration process. Moreover, differences in stakeholder perceptions regarding positive impacts and constraints of the implemented innovation (supplemental feeding of small ruminants) were assessed, as one exemplary innovation to improve low-external-input pastoral livestock systems. Three cases of demonstration farm projects were selected and a total of 31 semi-structured and narrative interviews were carried out with participating livestock keepers, extension workers and scientists. Together with information gained by employing visual tools and participant observation, data was analysed using qualitative content analysis. Results reveal that major decisions regarding the collaboration process were taken by scientists in advance, hence, livestock keepers' participation was used to meet predetermined objectives, which is characteristic to the concept of functional participation. While scientists seemed to transfer the control principles of on-station research to the on-farm situation, extension workers recognised the need for replacing teaching by the aim of creating learning opportunities. Here, incongruences in role understanding indicate an overall lack of joint role definition and the need of balancing power differences. Livestock keepers' perceptions of the supplemental feeding strategy highlight substantial management constraints for implementation, which were not recognised by scientists and extension workers, nor were they captured by the monitoring system implemented. We recommend furnishing the demonstration farm approach with principles, methods and tools of collaborative learning, to create a change in actors' understanding of roles and to induce a shift towards increased transdisciplinarity.

A field experiment was conducted on sandy loam soil at Hisar, India during the autumn seasons 1984–85 and 1985–86 to study root characters, evapotranspiration, water use efficiency, moisture extraction pattern and plant water relations of rape genotypes under varying irrigation schedules. Root volume and dry weight increased, while tap root and lateral root lengths decreased with irrigation. Increased irrigation frequency increased evapotranspiration but decreased water use efficiency. The relative water content and osmotic potential of the leaves increased with more frequent irrigation, but plant water retention capacity decreased. There were genotypic differences between the characters examined.

Diurnal variations in soil temperature were measured under tea plants with different kinds of mulches. During the early years after planting temperatures differed, depending on the type of mulch and its heat absorptivity. Black plastic and stone chippings showed the greatest diurnal variations, but the variations disappeared in all treatments when there was a ≥ 60% canopy. Tea plants themselves modify soil temperatures, which could affect growth and yield in places where soil temperatures are generally lower.

Four isolates of Azolla pinnata collected from Bangkok, Bangladesh, Vietnam and India grew well when used in paddy fields both before and after transplanting with rice varieties of different heights and times to maturity. Azolla increased plant height, tillering, 1000-grain weight, grain and straw yields, nitrogen concentration and uptake, and soil fertility.

The response of rice to Azolla was similar to that obtained by applying 60 kg N ha−1 as urea in three split applications. The different Azolla isolates differed in their growth, N2-fixation and response to rice crops and soil fertility. All these characteristics were better in the isolates from Bangkok and Vietnam than in those from Bangladesh and India. Azolla growth and N2-fixation were better with short rice varieties (IR-36, Ratna and Kalinga-II) than with Mahsuri, a tall rice variety, but Mahsuri, having a longer growing season, showed a better response to Azolla.

Understanding the genetic variability, heritability and genetic advance (GA) of traits in any plant population is an important pre-requisite for variety development. The objectives of the study were to assess the level of genetic variability among vegetative growth traits and yield, assess the relationship among the growth traits and yield and predict GA for the most heritable traits among Robusta coffee full-sib families. The trial was established in June 2009 at the experimental fields of the Cocoa Research Institute of Ghana with 62 full-sib families planted in a randomized complete block design with six replications. Significant (p < 0.05) variation was observed among the full-sib families evaluated for all traits, except for span (canopy diameter). Span and number of laterals were genetically correlated (p < 0.001) with cumulative yield (2013–2017), with span being the vegetative growth trait most strongly related to cumulative yield (rg = 0.60, p < 0.001). The most heritable vegetative growth and yield traits were, respectively, number of laterals (H2 = 0.59) and cumulative yield (H2 = 0.41). The top 10 families (BP40, BP41, BP9, BP36, BP34, BP28, BP37, BP14, BP4 and BP10) in terms of cumulative yield are proposed for multi-location evaluation and possible release as hybrids for coffee farmers in Ghana.

Taichung (Native) No. 1 rice was grown under controlled conditions with a basic temperature regime of 30°C by day and 20°C by night. Periods of 2, 4 and 12 hours at 15°C (59°F) were imposed during darkness for the first or second 40 days, or for the first 80 days after sowing. Floral initiation was delayed by cool periods of 2 hours at night or longer, and delay from this cause was always accompanied by reduced grain yields, resulting from fewer spikelets per panicle or increased tiller sterility. This effect was not overcome when the cool periods ceased after floral initiation. Cool periods longer than 4 hours had a greater effect when they were given in the first 40 days.

At Pantnagar, India, linear response in maize to nitrogen application was observed up to 150 kg. of N/ha. with some of the most promising hybrids and composites released by the All India Co-ordinated Maize Improvement Programme. Increase in grain yield, and total nitrogen accumulation in grain, were substantially more in Ganga 2 than in the local cultivar or the composites, at higher rates of N application. In absolute terms, the local cultivar accumulated more nitrogen in its grain, but the relative amounts declined at higher rates of N application. Among the yield components influencing ultimate grain yield, barrenness exerted a negative influence on grain yield through the number of cobs per plot. Among cob characters, such as thousand grain weight and number of grains per cob, the former exerted a substantial influence on grain yield.

Application of dimecron to cowpea plants increased grain yield, its effect being more pronounced in widely spaced plants and those planted in March. Dimecron increased grain yield by encouraging greater leaf area development, by increasing the number of flowering inflorescences and the number of pods set per inflorescence, and by decreasing the number of shrivelled pods. March planting encouraged greater dry matter production than January and May planting. Dimecron application decreased the number of Ootheca beningseni, reduced the proportion of leaf damaged by these insects, and reduced the number of plants infested with aphids and Acidodis larvae.

Ecoregional research has the potential to help address some of the huge challenges facing agriculture in developing countries by developing technologies that work under different agro-ecological conditions, and the processes by which these technologies can be adapted to work in other areas with similar conditions. The CGIAR system has been developing ecoregional research as a new paradigm for over a decade. In this paper we evaluate one of the most ambitious of these initiatives called the Benchmark Area Approach (BAA) pioneered by the International Institute of Tropical Agriculture. We evaluate the BAA against nine good practice criteria for ecoregional research and finding that the approach is delivering, or has the potential to deliver, on all nine. Many of the lessons learnt from this evaluation will be relevant to current and future attempts to undertake co-ordinated multi-locational research for development.

Experiments in Tanzania have shown that green gram planted one week before bulrush millet produced a complimentary protein energy balance optimal for a cereal–legume diet. Grain yields were increased due to additive intercropping (by 13%) and replacement intercropping (27%). Green gram plants were more competitive than bulrush millet plants at the seedling stage but were overpowered in later growth stages.

The effects of plant population on yield and its components were investigated in three experiments in 1969, 1970 and 1971. Increasing populations from 9000 to 36,000 plants/ha. increased yield linearly. The number of tubers produced per plant was not affected by population, but an increase in plant density decreased average tuber weights. Increasing sett weight from 203 to 608 gm increased tuber yields/ha. and the number of tubers per plant but did not affect average tuber weights in two experiments. In 1971 compound fertilizers increased yield up to the highest rates of 90 kg./ha. each of N, P2O5 and K2O respectively.

The leaching of boron, studied after high rates of application under different management practices, indicated that leaching was rapid and that the presence of cover crops was likely to reduce the immediate availability of boron to the main crops.

The conservation of genetic resources is discussed in relation to the stages in the evolution of crop plants. Strategies for the collection and conservation of wild species, landraces and advanced cultivars are considered in relation to the pratical needs of plant breeders and other users.

The occurrence of chalkiness has decreased in new hybrid rice cultivars in China. As both chalkiness occurrence and starch granule size are associated with the biosynthesis of starch, we hypothesized that there may be a correlation between chalkiness occurrence and starch granule size, and this may partially explain the decreased chalkiness occurrence in the new hybrid rice cultivars. To test this hypothesis, a field experiment was conducted over eight environments (two years × four sowing dates) with two hybrid rice cultivars: one recently developed with low chalkiness occurrence, Jingliangyou 1468 (JLY1468) and a relatively older cultivar with high chalkiness occurrence, Liangyoupeijiu (LYPJ). Results showed that JLY1468 had a higher cumulative distribution of large-diameter (7.51–19.50 μm) starch granules and a lower grain weight of milled rice compared to LYPJ. As a consequence, mean and relative starch granule diameters were 6% and 21% higher in JLY1468 than in LYPJ, respectively. Although both the chalky grain rate and chalkiness degree were negatively correlated with mean and relative starch granule diameter, they were more closely correlated with the relative granule diameter. These results support our hypothesis regarding the relationship between chalkiness occurrence and starch granule size and suggest that the relative starch granule diameter is a relevant parameter in understanding the occurrence of chalkiness in hybrid rice.

The aim of this study was to compare the effects of cowpea green manure and inorganic nitrogen (N) fertilizers on yields of winter wheat and soil emissions of nitrous oxide (N2O). The comparisons included cowpea grown solely as green manure where all biomass was terminated at maturity by tillage, summer fallow treatments with 90 kg N ha−1 as urea (90-N), and no fertilization (control) at planting of winter wheat. Fluxes of N2O were measured by closed chamber methods after soil incorporation of cowpea in autumn (October–November) and harvesting of winter wheat in summer (June–August). Growth and yields of winter wheat and N concentrations in grain and straw were also measured. Cowpea produced 9.5 Mg ha−1 shoot biomass with 253 kg N ha−1 at termination. Although soil moisture was favorable for denitrification after soil incorporation of cowpea biomass, low concentrations of soil mineral N restricted emissions of N2O from cowpea treatment. However, increased concentrations of soil mineral N and large rainfall-induced emissions were recorded from the cowpea treatment during summer. Growth of winter wheat, yield, and grain N concentrations were lowest in response to cowpea treatment and highest in 90-N treatment. In conclusion, late terminated cowpea may reduce yield of winter wheat and increase emissions of N2O outside of wheat growing seasons due to poor synchronization of N mineralization from cowpea biomass with N-demand of winter wheat.

Since 1970 the University College of North Wales, in co-operation with the Saudi Arabian Ministry of Agriculture and Water, has been investigating the potential for forage production in all-year-round irrigated conditions in Saudi Arabia, and the principal results of the first 4 years of field experiments are discussed. Both temperate and tropical annual forages as well as perennial species were tested, and generally produced high yields with high nutritional value. Fertilizer responses and different management practices were evaluated and their relevance to the development of systems of forage production are discussed.

The cotton-wheat double-cropping system is widely used in the Yellow River Valley of China, but whether and how different planting patterns within cotton-wheat double-cropping systems impact heat and light use efficiency have not been well documented. A field experiment investigated the effects of the cropping system on crop productivity and the capture and use efficiency of heat and light in two fields differing in soil fertility. Three planting patterns, namely cotton intercropped with wheat (CIW), cotton directly seeded after wheat (CDW), and cotton transplanted after wheat (CTW), as well as one cotton monoculture (CM) system were used. Cotton-wheat double cropping significantly increased crop productivity and land equivalent ratios relative to the CM system in both fields. As a result of increased growing degree days (GDD), intercepted photosynthetically active radiation (IPAR), and photothermal product (PTP), the capture of light and heat in the double-cropping systems was compared with that in the CM system in both fields. With improved resource capture, the double-cropping systems exhibited a higher light and heat use efficiency according to thermal product efficiency, solar energy use efficiency (Eu), radiation use efficiency (RUE), and PTP use efficiency (PTPU). The cotton lint yield and biomass were not significantly correlated with RUE across cropping patterns, indicating that RUE does not limit cotton production. Among the double-cropping treatments, CDW had the lowest GDD, IPAR, and PTP values but the highest heat and light resource use efficiency and highest overall resource use efficiency. This good performance was even more obvious in the high-fertility field. Therefore, we encourage the expanded use of CDW in the Yellow River Valley, especially in fields with high fertility, given the high productivity and resource use efficiency of this system. Moreover, the use of agronomic practices involving a reasonably close planting density, optimized irrigation and nutrient supply, and the application of new short-season varieties of cotton or wheat can potentially enhance CDW crop yields and productivity.