Production possibility frontiers contribute much to an economic evaluation of yield advantages from intercropping. The difficulty with estimating a production frontier empirically from experimental data is one of ascertaining that the fitted curve corresponds with the frontier. This problem has been overcome by deriving the frontier from a priori knowledge of the biological processes that determine the outcome in intercropping. The hyperbolic relationship between biomass yield and plant density, and the parameters that characterize the degree of intra-and inter-specific competition in intercropping are used in this paper to derive production possibility frontiers. The method is illustrated with data from three intercropping studies. A brief review of the two main methods used by researchers to evaluate the results of intercropping, and their limitations, is also presented.

In tropical legume-grass swards random core sampling recovered too few nodules to be a useful method. Core sampling of individual plants with a 5·0 cm. Stace tube showed similar changes in nodulation as total root excavation. However, the nodule distribution was different on the root systems of the two species studied, Desmodium uncinatum and Phaseolus atropurpureus. Nodule weights per plant on these species were much higher than any previously recorded in the literature. The direct contribution from nodule decay to the total end-of-season nitrogen release was estimated and shown to be small, approximately 14 per cent for D. uncinatum and 8 per cent for P. atropurpureus.

Length and weight of pigeonpea roots were measured weekly in different soil layers and compared with estimates obtained from a root simulation model using daily climatic data, soil physico-chemical properties and dry matter allocation to roots. Daily moisture content and temperature at different soil depths were well simulated using sub-routines from the CERES-Maize model. Daily allocation of dry matter to roots was calculated from logistic functions fitted to the growth data for shoots and roots. Although root length and weight tended to be underestimated by the model, regressions between measured and simulated root growth were highly significant so that the model could, with a few modifications, be used to predict root system development.

On-farm trials were conducted for seven years in north-west Syria to investigate the use of land left fallow after a barley crop to grow feed legumes for small ruminants. Common vetch (Vicia sativa), forage peas (Pisum sativum) and common chickling (Lathyrus sativus), with and without applied phosphate fertilizer, were grown in rotation with barley and a barley-fallow rotation was used as a control.

Vetch was preferable for grazing whereas chickling yielded more grain and straw and had a higher harvest index. Both species showed substantial responses to phosphate fertilizer. Yields of subsequent barley crops were slightly lower after unfertilized feed legumes than after fallow but after fertilized feed legumes, barley yields were higher than after fallow. The milk production of ewes and liveweight gains of lambs grazing vetch, chickling and common land were similar.

The project showed how results from on-farm research can modify on-station research objectives and identify questions for further on-station research.

White yam (Dioscorea rotundata) is a major root crop grown throughout West Africa but one of the major factors that limits its production is the availability of good quality planting material. This paper described the results of farmer-managed demonstration plots established in 2012 and 2013 designed to promote the Adapted Yam Minisett Technique (AYMT) in Nigeria. The AYMT was developed between 2005 and 2008 to produce quality seed yam tubers at a cost that is viable for small-scale farmers. Since its development the agronomic performance of AYMT has not been explored across a large sample of farmers, and neither has there been any attempt to explore possible varietal effects although farmers have often alluded to this. This papers seeks to address these gaps in the literature and the results suggest that the AYMT does succeed in producing seed yams of the required size and the economic returns are also good. Results also suggest that there is a varietal affect with AYMT, including a significant interaction with pesticide treatment; the first time this has been demonstrated.

Theaflavins contribute to astringency and brightness while thearubigins contribute to colour and mouth feel of black tea. Green leaf flavan-3-ols influence levels and distribution of theaflavins and thearubigins in black tea and are black tea quality precursor compounds. Caffeine also contributes to tea quality. Although location of production and nitrogenous fertilizer rates influence black tea quality, it is not known if the variations arise from the levels and distribution of the precursor compounds in green leaf or other factors. The variations and distribution of the flavan-3-ols and caffeine in young green leaves of clone TRFK 6/8 due to nitrogen fertiliser rates in seven locations within Eastern Africa were evaluated. Green leaf comprising two leaves and a bud were harvested from each plot, and subjected to HPLC analysis for caffeine, total polyphenol, dihydroxyflavan-3-ols, trihydroxyflavan-3-ols, ratios of trihydroxyflavan-3-ols to dihydroxyflavan-3-ols and total catechins levels. Results were subjected to statistical analysis using split plot design, with locations as main treatments and nitrogen rates as the sub-treatment. Caffeine and flavan-3-ols levels changed (p ≤ 0.05) with location of production, demonstrating that even with use of same cultivar and similar agronomic management quality of tea from one location cannot be replicated in another location. Caffeine levels increased (p ≤ 0.05) with rise in nitrogen fertilizer rate in all locations, but the extent depended on location. Total polyphenols and individual flavan-3-ols showed an inverse quadratic response, except EGCG that linearly decreased (p ≤ 0.05) in some locations, due to increasing rates of nitrogen fertilizer. Similar responses in the black tea quality parameters had been observed in previous studies. The black tea quality results were therefore directly influenced by the green leaf precursor compound patterns. Region specific nitrogenous fertilizer rates need development to ensure high tea quality.

Ten wheat and six barley genotypes were tested for their response to soil salinity regimes varying from 0 to 16 mmhos cm−1. Barley showed remarkable resistance to salt stress, linked to its capability to resist efflux of potassium ions from the plant system. Both crops showed substantial yield reductions at 12 mmhos cm−1, but barley still outyielded wheat by over 50%. There were significant interactions between salinity levels and genotypes in wheat but not in barley.The wheat variety Sonalika showed poor salt tolerance. The implications of these findings in breeding salt-tolerant varieties are discussed.

A two year field study designed to investigate the effect of spacing on yield of two cowpea cultivars in the savanna and forest zones of Nigeria showed that cowpea yields were larger in the savanna than in the forest zone at all spacings employed. Inter-row spacing wider than 60 cm and intra-row spacing closer than 10 cm could be used for improved seed yield in the savanna zone, while 60 × 20 cm (83 333 plants ha−1) would be optimum for cowpea production in the forest zone.

Instruments and techniques are described for measuring the interception of light by the canopy of a crop, the CO2 exchange of individual leaves, leaf extension rate, and root distribution. Suitable systems for recording are also reviewed. Names and addresses of manufacturers are cited for a few representative models.

The yield and gross returns (Rs/ha) were studied over two years in three experiments on intercropping in corn and sorghum. Paired-row planting recorded 8 to 12% and 44% higher yield in corn and sorghum respectively over conventional equidistant planting at the same plant populations. Additional gross returns due to intercropping ranged from 24 to 76% in corn (1975–76 winter) and 4 to 56% in corn and 15 to 75% in sorghum (1976 rainy season) compared to pure crops. Intercropping was beneficial, particularly in the limited cropping periods of this semi-arid tropical zone.

The response of chickpea to irrigation and phosphorus was studied at Kharagpur in Eastern India. Irrigation scheduling was based on the ratio between irrigation water applied and cumulative pan evaporation (ID/CPE), and had little effect on dry matter accumulation. Increasing the frequency and amount of irrigation reduced the number and dry weight of nodules per plant, which increased to a maximum 70 days after sowing and then declined. Irrigation significantly reduced grain yield as a result of excessive vegetative growth at the expense of pod formation. Application of phosphorus promoted nodulation and increased both nodule dry weight and the concentration of N, P and K in grain and stover. Uptake of N, P and K by the crop was also increased.

Seeds can deteriorate rapidly under high heat and humidity, making it challenging and potentially costly to store orthodox seeds effectively in the tropics, thereby affecting agriculture development. This work explores the effectiveness of novel, low-cost technologies for storing seeds in warm, humid, resource-constrained environments, focusing on maintaining the viability of seeds already dry prior to storage. Seeds of okra (Abelmoschus esculentus (L.) Moench), sorghum (Sorghum bicolor (L.) Moench), and velvet bean (Mucuna pruriens (L.) DC) were kept for 12 months under roofed, outdoor screened porches. Seed moisture content prior to treatment was 6, 9, and 12% for okra, sorghum, and velvet bean, respectively. Treatments, replicated four times at each of two locations (USA [Florida] and Thailand), were technology suites involving vacuum drawn on glass jars with a modified bicycle pump, vacuum drawn on polyethylene bags with an electric vacuum sealing machine, desiccant (calcium oxide powder or zeolite Drying Beads® at a 2:1 ratio, by weight, of seeds to desiccant) in glass jars, and nontreated seeds in paper bags. Ambient temperature and humidity were variable and high, reaching over 35 °C and 83%, respectively, at both locations. Under these conditions, okra and sorghum germination percentages (across locations) without treatment declined from over 90% initially to 30 and 0%, respectively, by month 12. Both vacuum treatments and calcium oxide maintained high germination of okra (≈ 80%) and velvet bean seeds (nearly 100%) across locations. Glass, however, was superior to polyethylene in maintaining vacuum and stabilizing the moisture content of okra and sorghum seeds. Only zeolite reduced seed moisture below initial values, drying seeds to ultradry levels of <5%. With zeolite, sorghum germination stayed near 70% over time, while okra and velvet bean germination fell to <40 and <20%, respectively, by month 12, suggesting that, with the beads kept with dry seeds in storage rather than removing the beads after reaching a target level of seed moisture, the 2:1 ratio of seed-to-bead weight was too high for seeds that are sensitive to ultralow moisture. Findings have practical implications for inexpensive household- or community-level seed storage to deliver development impact.

We investigated the occurrence and status of the leaf folder Cnaphalocrocis ruralis (Walker) (Lepidoptera: Crambidae) in accessions of Erianthus spp. maintained as a part of the world germplasm collection at the Research Center of ICAR-Sugarcane Breeding Institute, Kannur, Kerala State, India. The nature, pattern, extent and year-to-year variation in damage were examined and accessions categorized based on relative incidence. The larvae of C. ruralis caused characteristic injury by feeding on chlorophyll bearing tissues leading to the formation of white and transparent streaks on the leaf blade. The grown-up larvae folded the leaf longitudinally with the adaxial surface inside the fold and exposing the abaxial surface, the edges being held in place by bands of silk thread at regular intervals. The length of leaf folds varied from 2.6 to 27.0 cm with a mean of 9.1 cm, which roughly constituted 7.3% of the mean length of the leaf blade. Leaf length, leaf width and leaf area were not correlated with either the leaf fold length or the number of webs. However, the leaf fold length was positively correlated with the number of webs. Attack rates (infestation rate) on cane basis (up to 69.0%) were generally higher than the damage rates (intensity) on leaf basis (up to 50.0%); infestation index ranged between 0.0 and 13.7%. Correlations between infestation rate and intensity varied among the three study years. Non-parametric analysis indicated significant differences among the three years for percent of infested canes and infestation index but not percent of damaged leaves. All accessions showed C. ruralis incidence in at least one experimental year, indicating that none of the accessions tested was immune to its attack. When all 74 accessions were considered on the basis of infestation index, 85.1% were placed in low and moderate categories and only 14.9% in high incidence category. Within the accessions of Erianthus spp., leaf area was not related to infestation rate of cane or damage rate of leaves but positively related to infestation index. The dynamics of the leaf folder in the predominantly paddy ecosystem were discussed in the light of its first occurrence in Erianthus spp. accessions in India and the world.

The objective of the study was to characterize small-scale dairy production systems to identify the technological preferences according to the farmer and farm characteristics and to analyze the importance and role of the information communication technologies (ICTs) in the dissemination of information related to management and livestock activities. To collect the data, a survey was applied to 170 small-scale dairy farmers from central Mexico. To characterize the farms, a factor analysis (FA) and cluster analysis (CA) were performed. To compare and identify differences between groups, a Kruskal–Wallis test was conducted. Four factors that explain 70.93% of the accumulated variance were identified; these factors explain the use of technology, production characteristics, social connections, and use of ICTs. The cluster analysis identified four groups. Group 1 was integrated by farmers with more experience and the largest farms. Group 2 had higher studies and use of ICTs. Group 3 was formed by young farmers but had a low use of technology. Group 4 contained older farmers with a low use of technology. The young farmers with higher studies have begun to incorporate ICTs into their daily activities on the farm, as observed in Group 2. Smartphones were the most used and were considered important by the farmers of the four groups, since they enable interaction with other farmers and the dissemination of topics of interest related with the farm. In conclusion, four group of farmers were differentiated; therefore, different extension approaches should be implemented to take into account the preferences and the technologies considered most important for each group. The ICTs are emerging technologies among small-scale dairy farmers to communicate information related to livestock management, mainly by young farmers with studies of secondary, as observed in Group 2.

Red pea (Lathyrus cicera L.) is an underutilized protein crop with broad adaptability. Intercrops of red pea with winter cereals have not been studied. A two years field study was conducted with the objective to determine the productivity of intercropping systems of red pea with barley (Hordeum vulgare L.) and triticale (xTriticosecale Wittmack) in two seeding ratios (60:40 and 80:20). Growth rate, dry matter yield, protein content and yield were determined. Several indices were used to evaluate the intercropping systems and analyse competition and interrelationships between mixture components. Growth rate of cereals was lower in the mixtures than in the monocrops. Dry matter yield were the highest in barley monocrop and its intercrop with red pea at 60:40 seeding ratio. Red pea monocrop showed the highest crude protein concentration followed by its intercrops. The land equivalent ratio, relative crowding coefficient (K), actual yield loss (AYL) and system productivity index values were greater for the red pea-barley 60:40 mixture, indicating an advantage of intercropping. The partial K, aggressivity, competitive ratio and partial AYL values indicated red pea as the dominated species in the intercrops. The highest monetary advantage value was recorded for the red pea-barley mixture (60:40). The results indicate that red pea-barley mixture (60:40) was the most productive and produced better forage quality and thus could be adopted by the farmers as alternative option for forage production.

The effect of the field application of chlormequat on the growth, yield and seed oil content of Brassica juncea grown under irrigated and rainfed conditions was evaluated for three consecutive crop seasons. Foliar application at the flower initiation stage increased the number of primary branches, number and length of siliquae, weight of seeds and seed oil content. Chlormequat (50 AS) applied at 80 ml ha−1 increased seed yield by more than 50%. The increase was greater in unirrigated crops.

Response to potassium fertilization was tested, over a two-year period, in 24 experimental fields, predominantly in coarse-textured soils. Only two fields showed significant yield increases. Potassium availability was estimated on the basis of (a) the free energy (ΔF) of potassium exchange for calcium and magnesium, (b) the proportion of potassium in total exchangeable cations, and (c) soluble potassium extraction in correlation with the potassium content of the plants. Woodruff's method (ΔF) yielded the best agreement (correlation coefficient r = 0·77). ΔF values showed a sufficient supply of available potassium, which may have accounted for the lack of response to fertilization.

Breeding for drought tolerance using novel genetic resources possessing relevant agronomic and adaptive traits is a key to enhance productivity and food security in wheat growing areas. Herein, the main objectives were (i) to use a combination scoring index (multiple scoring index, (MSI)) for selection of durum wheat genotypes under different drought stress intensities (SIs) (ii) to examine repeatability of the scoring index through bootstrap re-sample method, and (iii) to study the relationship of MSI with some drought-adaptive traits. Sixteen durum wheat genotypes were grown under rainfed and irrigated conditions during three cropping seasons (2012–2015), resulting in different drought SIs, that is, mild (SI < 0.3), moderate (0.3 < SI < 0.6), and severe (SI > 0.6). The average grain yields among test environments varied between 708 and 3631 kg ha−1. The validation of the methodology of scoring index was confirmed by the correlation coefficients between score indices and their original values across different drought SIs. According to MSI, the genotypes G16, G1, and G3 had the best combination of high productivity and high resilience to mild, moderate, and severe drought stress conditions, respectively. These results indicated that the ranking of genotypes varied among different drought SIs, which support the high potential of durum wheat for adaptation to different drought stress conditions. Based on the bootstrap samples, non-repeatable correlations were observed between the estimates of MSI from different levels of stress. The significant correlation between MSI with grain yield and 1000-kernel weight (TKW) under severe drought condition provides evidence that MSI ultimately be considered as a tool for effective selection of drought-tolerant genotypes. The MSI selected genotypes based on high productivity and resilience, to each level of drought SI, and favorable adaptive traits useful for breeding.

Cropping systems research to improve the productivity of an acid upland rice and maize-based farming system is described and evaluations by co-operating farmers are presented. Farmers rejected introduced patterns. The cropping choices of non-cooperating farmers are described in terms of cost–benefits and the reasons underlying their decisions. An approach that combines an understanding of farmers' systems in order to conduct focused research on the weak points of such systems, together with an evaluation of farmer technology and adaptation, may be more effective than researcher-designed, farmer-implemented cropping pattern trials.