Following a survey of fertilizer use on farmers' barley fields in northern Syria and very positive results from barley fertilizer trials on ICARDA research stations, a programme of researcher managed trials on farmers' fields indicated considerable potential for yield increase from the use of nitrogen and phosphorus fertilizers across a range of environments. It was then necessary to test and demonstrate the effectiveness of fertilizers in farmers' hands. A researcher managed trial (RMT) and a farmer managed trial (FMT), with similar fertilizer treatments, were compared over the winter cropping season on each of 10 on-farm sites in 1987/88 and 20 sites in 1988/1989. Despite large differences in rainfall between the two seasons (means across sites, 422 mm in 1987/88 and 174 mm in 1988/89), yield responses to fertilizer were similar in both seasons, with only marginal yield differences between researcher and farmer managed trials. Crop sequence had no effect on the pattern of fertilizer response in either type of trial. Once the effectiveness of fertilizers had been tested in farmers' hands, demonstration trials were conducted in the following two years to transfer the technology to farmers in the barley growing areas of northern Syria.

Ensayos conducidos por agricultores e investigadores en Siria

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.

The results from a 33 and two 25 factorial fertilizer experiments are presented. N-deficiency limited female flower production, rate of bunch production, and yield; K-deficiency reduced the setting of flowers and yield; nuts were larger where P was applied. The results are interpreted in the light of foliar analyses, and the concept of independant critical levels of the major nutrients is challenged. It is suggested that yield is related to the ratios between foliar N and K, but that the K level should in turn be interpreted in the light of a balance between the monovalent and divalent cations. Female flower production and setting can be used as a ready field guide to nutrient requirements.

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.

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.

Fourteen on-farm sites used in barley fertilizer trials were retained for a second year and, without further fertilizer, sown with a mixed vetch/barley forage crop. Rainfall at the sites ranged from 149 to 451 mm, and linear regression on rainfall accounted for 76% of the variation in hay yield between the sites, with a greater rain-related increase in vetch than barley. Soil nitrogen and phosphorus content at planting time in the second year was significantly affected by the rate of fertilizer application in the previous year. Previous phosphate fertilization tended to increase hay yields, particularly at sites where levels of native available phosphate were poor. However, responses to residual fertilizer nitrogen were small and variable.

Respuesta al N y P residual en el norte de Siria

Land resources are scarce in Mauritius and to fulfil the export quota sugarcane (Saccharum hybrids) has to be grown in marginal areas which are not conducive to optimal growth. In order to increase overall productivity there is a need to breed and select sugarcane varieties specifically adapted to the extremely dry and extremely wet areas. In this study, 154 genotypes representing four families were planted in a randomized complete block design at two sites. The genotypes were replicated at the two sites and evaluated in the plant cane and first ratoon crops. Family × environment and genotype × environment interactions were determined using the mixed model analysis of variance. Significant differences between families, genotypes and environments were found in stalk height, stalk diameter, industrial recoverable sucrose % cane (IRSC) and cane yield per hectare in tonnes (TCH). The genotype × environment interaction was significant for stalk height, stalk number, stalk diameter, sucrose content, TCH, tonnes sugar per hectare (TSH) and kilobrix (parameter used for selection in the preliminary phase of the selection programme at the Mauritius Sugar Industry Research Institute) in both plant cane and first ratoon crops indicating that the relative performance of the genotypes is not consistent across the environments for these characters. The family × environment interaction was found to be significant for cane and sugar yields whereas it was not significant for field Brix in either the plant cane or the ratoon crops. This showed that, for the parameter Brix, the relative performance of the families is similar in both environments and there is no need to replicate in more than one environment. The environmental sensitivities measured with respect to sugar yield showed that families and genotypes with nearly equal means over all environments displayed inconsistent performances. Differences in the sensitivities of the different families and genotypes were observed and some of the family × environment and genotype × environment interactions could be ascribed to them. The results also suggest that mass selection could be more effective than family selection and selection for each specific environment is advisable.

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.

Under controlled environment conditions a semi-dwarf wheat, Mexico 120, was subjected to day temperatures of 32 and 27°C, with night temperatures of 21 or 16°C, which are similar to those occurring for a large part of the dry (winter) season of the Ord River valley area of northern Australia. Temperature differences imposed only during the 23 days between sowing and floral initiation produced effects which persisted throughout later growth, when all plants were grown under one temperature regime. The effects of temperature differences before floral initiation were greater than those of similar temperature differences imposed after ear emergence began. The maximum temperatures occurring even in the coolest months probably limit maximum potential grain yields in an environment similar to that of the Ord River valley.

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.

With increasing land-use pressure in semi-arid, dryland Middle Eastern agriculture, fallow-based cereal production has given way to cropping intensification, including legume-based rotations along with conservation tillage and on-farm straw disposal. Such agronomic developments can only be biologically and economically assessed in multi-year trials. Thus, this 10-year study examined the influence of tillage systems (conventional and shallow or conservation) and variable stubble management, including compost application, on yields of barley and vetch grown in rotation. Barley yielded higher with compost applied every two or four years than with burning or soil-incorporating the straw and stubble. Barley straw and grain yields were generally higher with the mouldboard plough. Similarly with vetch, treatments involving compost application yielded significantly higher than burning or incorporating the straw and stubble. Despite yearly differences between crop yields, the pattern of treatment differences was consistent. Thus, the cereal–vetch rotation system is sustainable, while excess straw could be used as compost with benefit to the crop. Though there was no clear advantage of the shallow conservation-type tillage, the energy costs are less, thus indicating its possible advantage over conventional deep tillage in such rotational cropping systems

Rice, pigeonpea and rice + pigeonpea systems (in the row proportions of 1:2 and 2:5) were compared. Soil water depletion and percolation were determined during selected dry spells and yields ascertained after harvest. The mean evapotranspiration rates of rice, pigeonpea, rice + pigeonpea (1:2) and rice + pigeonpea (2:5) were 0.28, 0.79, 0.40 and 0.35 cm d−1, respectively, during a dry spell around 60 days after sowing. In general low rainfall intensity and frequent dry spells in the growing season increased pigeonpea yield but depressed that of rice. Intercropping thus ensured yield stability and hence the profitability of the system as a whole.

Plant breeding makes genetic gains over years, so growing newer varieties generally provides greater benefits than growing older ones. However, in low-altitude districts of Nepal, a few rice varieties covered 75% of the rice area and were more than 20 years old (first paper in this series). We test here if this slow rate of adoption of new varieties could be accelerated using a participatory method, Informal Research and Development (IRD), where packets of seeds of new rice varieties are widely distributed to many farmers. From 2008 to 2011, over 117 000 IRD packets were distributed in 18 districts of the Nepal Terai, including over 70 000 of three released varieties from a client-oriented breeding (COB) programme in Nepal. The IRD significantly increased the adoption of the three COB varieties. The benefits obtained by farmers in a single growing season equal the costs of IRD, if for every 75 kits distributed an additional 1 ha is grown. This assumes that the new varieties produce a 10% increase in yield (lower than that evidenced in their release proposals). On an average, fewer than three IRD kits were distributed for each hectare of a new variety grown by farmers in 2011. Furthermore, the effectiveness of IRD could be increased 1.2 to 2.7 fold (depending on the COB variety) if the IRD distribution were to be restricted to the region where the variety was most accepted. The best comparison of IRD with extension by the conventional system was their popularity compared with similar-aged varieties that had been promoted in the two systems. The adoption of three COB varieties was about twicethat of three varieties from the National Rice Research Programme (NRRP) that were closest in release date to the COB varieties. Unlike cost effectiveness assessed by hectares grown per IRD kit distributed, this comparison can only indicate efficacy because, as well as extension method, many factors influenced the adoption rates of the COB and NRRP varieties. The costs of IRD are small, both relative to the cost of breeding new varieties and to the benefits gained; so it is one of the simplest and most cost-effective interventions to increase agricultural productivity.

Simple methods are proposed for measuring the relative importance of grain and fodder produced jointly from maize fields in four zones in northern Pakistan. These methods suggest that the joint production of grain and fodder from maize is important in all four zones and that fodder accounts for between one-third and one-half of the total value of the crop. The relative value of fodder production is particularly high in two of the zones (the irrigated mid-altitude Swat Valley and the rainfed low altitude Islamabad District), both characterized by a high ratio of animal numbers:maize area. The results suggest that maize research and extension recommendations that do not take into consideration the fact that farmers produce maize for fodder as well as grain will often not be accepted by farmers.

Experiments in Brazil have shown that a sorghum-pulse (cowpea or common bean) intercrop system yielded more grain than the monocrop system and produced a Land Equivalent Ratio (LER) greater than 1.00 even though rainfall was limited. Sorghum competed less than maize with the associated pulse when Competitive Ratios (CR) were considered. In cowpeas, CR values were correlated positively with the number of pods and seeds plant−1. The two crops in the intercrop systems were responsive to fertilizer application. Thus, improved management (i.e. fertilizer usage) was appropriate without the loss of the advantageous effects realized from intercropping.

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.

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.

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.

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.