A three-year field experiment was undertaken to evaluate the effects of tillage methods on grain yield and yield components of wheat (Triticum aestivum) in continuous cropping. The experiment was conducted on a Ramjerd, fine, mixed, mesic, typic Calcixerepts soil. Wheat was sown: (1) after burning residues followed by conventional tillage, (2) after complete residue removal followed by conventional tillage, (3) after soil incorporation of residues followed by conventional tillage, (4) into untilled residues, (5) using chisel seeder after field irrigation, (6) using chisel seeder plus herbicide application, and (7) after disking. Residue burning and removal increased spikes per square metre, grain per spike, 1000-grain weight, grain yield and harvest index compared with other treatments. This was due primarily to weed interference and lack of uniform crop establishment in the presence of residues. Reduced tillage methods retained more residues on the soil surface, which provided unsuitable conditions for crop emergence and growth. The incorporation of residues led to a build up of carbon in the soil, with lower grain yields compared with residue burning and removal, but these yields were higher than those of chisel-seeded plots.

The concept of water productivity (WP) or ‘more crop per drop’ has been revived recently in international water debates. Its application has notably been extended from single crops to mixed farming systems, integrating both crops and livestock, with the wider objective of reducing poverty. Using evidence from the Ganga Basin, India, we discuss the relevance of this concept as a tool to guide interventions for livelihood improvement and poverty alleviation. We argue that WP studies would benefit from greater attention to the role of capitals, inequities and institutions. Firstly, it is crucial to acknowledge the heterogeneity of capitals and capabilities of farmers to make changes in their farming systems and practices and avoid one-fix-all interventions. Identifying pre-existing inequities in water access within and among communities will support better targeting of poor communities. WP interventions can either reinforce or reduce inter-household inequities within communities. We stress the need for assessment of institutional impacts of WP interventions on water access and development.

The main nutrient deficiency in Malawi is a chronic lack of nitrogen, which is found on all but a few soils. Phosphorus also becomes limiting quite rapidly on certain soil types as a result of permanent cultivation, but there has so far been little response to potash or lime. Incipient sulphur shortage is automatically corrected by the use of sulphate of ammonia and single superphosphate to correct the major deficiencies. Trace elements have not been widely tested. Samples of organic manure vary widely in moisture and nutrient content, and their nitrogen status is frequently low, so it is safest to consider manure as primarily a source of P, K and minor nutrients, and to supplement it with fertilizer nitrogen. It should be possible, with good cultivation of synthetic varieties and improved selections, to obtain maize yields of 15–20 bags/acre with fertilizer dressings of up to 80 lb/acre of the limiting nutrients.

There is wide variation in the morphological characteristics of sweet potato leaf tips which are acceptable as a vegetable for human consumption. Thus many cultivars are available from which further selections can be made for yield, palatability, tenderness, flavour, and nutritional quality. A list is given of some cultivars which combine a number of desirable traits.

Sixteen years' yield and growth data from an oil palm planting experiment, comparing 56, 110, 148 and 186 palms ha−1, and additional records from a progeny experiment, were used to study the effect of palm age and planting density on carbohydrates incorporated in total above-ground dry matter production per palm (TDMc) and its components: fruit bunch yield (Yc) and vegetative growth (VDMc). The canopy efficiency (e), the amount of carbohydrate incorporated in dry matter production per unit of absorbed radiation per hectare, decreased from the fifth to eighth year then levelled off, but increased once crown expansion was completed. The decrease in e paralleled the expansion of the intercepting leaf surface, and might therefore be linked to an increase in maintenance respiration losses. These losses were apparently not compensated for by an increase in photosynthetic production. The subsequent increase in e in older palms appears to have been due to improved light distribution as a result of an increase in light penetration. The effects of changing levels of light interception and distribution on e were more pronounced at higher density, and resulted in marked differences in changes of TDMc with age between densities. Corresponding differences occurred with Yc, so that the optimum density for current yield decreased until 12 to 13 years from planting, then markedly increased. These findings are discussed in relation to the measures which might be used to increase yield per unit area.

To improve the national average yield of potato in Ethiopia, which is very low as compared to its potential, factors that influence technical efficiency of potato production need to be determined. Therefore, the objective of this study was to investigate the determinants of technical efficiency using a cross-sectional data collected from 368 randomly selected potato producers in Northern Ethiopia using a multi-stage sampling technique. The study employed Cobb–Douglas stochastic frontier model to get farm-level technical efficiency scores. Tobit model and principal component analysis were used to determine the factors that influence technical efficiency of farm households. The results revealed that chemical fertiliser, seed potato, plot size and labour are statistically significant factors that affect potato yield. The average technical efficiency score was estimated to be 75%; and education, experience, off-farm income, household size, membership in a farmers’ association, use of irrigation water, extension contact, use of improved seed, access to product market and weak coordination of stakeholders’ were significant factors influencing technical efficiency. The findings of the study suggest that there is a need for government intervention to create strong market linkage between producers and buyers and to give appropriate training to agricultural extension agents.

Field experiments were carried out to study the effects of elemental sulphur on irrigated groundnut. The sulphur was applied at rates of 50, 100 or 150 kg ha−1, either at sowing, at flowering or in two equal splits at sowing and flowering. Shoot dry weight, total sulphur content of leaves, nodule number per plant and pod yield were all significantly increased by sulphur treatment, but nodule dry weight was unaffected. The greatest response lay at or below 50 kg ha−1 applied at sowing. There were no further increases in response above this level.

The distribution of dry matter among the fractions of cotton boll (the bur, the fibre and the seed) may have significant impact on fibre biomass per boll, and consequently on lint yield. Little is known on how cotton boll allocates available photosynthetic assimilates to its components. A two-year field study was conducted to ascertain the difference in boll dry matter production and partitioning among three cotton genotypes differing in boll size and lint percentage. The dynamics of dry matter production in all fractions of cotton boll against boll age followed a logistic pattern. The final dry weights of all components were largely due to the duration of dry matter exponential accumulation, and less correlated with the maximal rate of exponential accumulation. Partitioning biomass to the bur differed significantly among these genotypes at 10 days post-anthesis (DPA). The genotypic difference in partitioning biomass to the fibre was originally observed at 24 DPA in 2009, while in 2010, this was observed at 17 DPA. The genotypic difference emerged rather late for the seed ratio compared with the fibre ratio and the bur ratio, which was first observed at 45 DPA in 2009 and at 31 DPA in 2010. These results indicate that management practices may need to be applied to cotton plants prior to 31 DPA to ensure optimal boll size and partitioning. Large boll genotype MM-2 consistently maintained higher seed ratio and lower fibre ratio than two other genotypes (2870 and AX) due to more developing ovules in its boll. These differences contributed to significant difference in lint percentage and less difference in fibre mass per boll between MM-2 and 2870 and AX.

The parasitic weed striga had significantly greater effects on sorghum yield components than non-parasitic weeds. Grain reduction caused by striga amounted to 65% compared with 32% reduction caused by non-parasitic weeds. Comparable reductions were also manifest in straw yield, grains/head and plant height of sorghum. Early removal of striga (a week after its emergence), and thereafter at regular weekly intervals, may help to improve crop yields.

The effects of intercropping, mulching and staking on growth and yield of three tomato varieties were evaluated in four field trials in 1982 and 1983. Fruit yields of the improved varieties were significantly reduced by intercropping with okra but the yield of a local variety was unaffected. Though the yield of okra when grown with tomato varieties was less than that of a sole crop, the combined yield of the two crops in mixtures was more than the means of the species in monoculture. Relative Yield Totals (RYT) increased to maxima of about 1.42 and 1.39 when the local variety was grown with okra in 1982 and 1983 trials, respectively. Mulching and staking significantly increased vegetative growth, yield and yield components of the tomato plants. Mulched plants grew taller and had more branches and a greater number and weight of fruits than staked plants. Improved varieties responded better to mulching and staking than the local variety. Growing improved varieties of tomato in sole stands with proper mulching and staking is therefore recommended.

The unit for separating juice from which 5 to 10 kg of leaf protein could be made in a day has been modified so as to make it more efficient and more convenient to use.

Grass pea (Lathyrus sativus L.) has a Mediterranean origin and was spread to Western Europe, Africa and South Asia. Over time, this grain legume crop has become important in South Asia, where it is often affected by waterlogging at germination. Therefore, varieties with waterlogging tolerance of seeds at germination are needed. This study evaluated waterlogging tolerance in a grass pea diversity panel. First, morpho-agronomic traits of 53 grass pea genotypes from 7 diverse countries (Afghanistan, Australia, Bangladesh, Cyprus, Ethiopia, Greece and Pakistan) were measured in a glasshouse. Seeds of the collection were then sown into waterlogged soil for 6 days and is subsequently drained for 8 days. Finally, representative genotypes from each country of origin of the three survival patterns (described below) were then tested to identify the effect of seed priming on germination and seedling growth in waterlogged soil. Canonical analysis of six traits (seed weight, pod length, pod width, flowering time, time to maturity and seedling survival) showed that genotypes from Bangladesh and Ethiopia were similar. There was a significant variation amongst genotypes in waterlogging tolerance. Genotypes from Bangladesh and Ethiopia showed the highest percent seedling survival (54% and 47%), with an ability to germinate under waterlogging and then maintain growth from the first day of draining to the final sampling (Pattern 1). In contrast, genotypes from other origins either germinated during waterlogging, but did not survive during drainage (Pattern 2) or failed to germinate and had low seedling survival during waterlogging and drainage (Pattern 3). Priming seeds reduced seedling survival in grass pea. Despite Mediterranean origin, specific ecotypes of grass pea with greater waterlogging tolerance under warm wet conditions have been favoured in Bangladesh and Ethiopia where adaptation to extreme precipitation events at germination and seedling survival upon soil drainage is critical for successful crops.

The productivity of seven multiple rice-cropping systems, utilizing a short-duration cultivar under irrigation, were assessed over 5 years. Systems of one, two and three crops a year were compared. Multiple cropping reduced grain yield, panicles m-2, total dry matter and nitrogen uptake per crop. However, the unfertilized three-crop-per-year system averaged 9·1 t grain, 17·1 t DM and 126 kg N ha-1 per annum, without showing a long term decline in productivity. Recovery and utilization of nitrogen fertilizer were generally low compared to other experiments, and were highest for the early dry season cropping period.

The macadamia nut is the only commercial food crop indigenous to Australia. It originated along the fringes of rainforests, only becoming an important internationally traded crop in the late 20th century. Australia is now the main centre of production, following a lead set by Hawai'i. The crop is also important in Central America and southern Africa. The majority of recent research reported in the literature on the physiology and water relations of macadamia has been undertaken in Australia. Macadamia is a tall evergreen tree in which vegetative growth occurs in a series of flushes. Mild water stress suppresses growth, but compensatory growth occurs on re-watering. Flowers form on hardened wood within the leaf canopy. Floral initiation occurs in late autumn, with flowering in the following spring. Flowering is profuse but only 5–10% of the flowers set fruit and less than 1% of the flowers reach maturity as fruits due largely to premature abscission. High temperatures (>30 °C) can contribute to the shedding of fruit. It takes about 12 months from floral initiation to the completion of harvest. Macadamia root systems are described as relatively shallow and spreading. The taproot can extend to depths of >1.2 m, with a dense matt of fibrous roots in the top 0.4 m. Proteoid rootlets are also present. Stomata are only found on the abaxial surface of the leaf. Macadamia has several attributes that help to explain its apparent tolerance to periodic dry conditions as found in its native habitat. These include leaves with xeromorphic adaptations, stomatal closure without concurrent changes in leaf water potential and an efficient water transport system. There has only been one serious attempt to measure the actual water use of macadamia. Most irrigation experiments have been poorly planned and/or the outcomes were inconclusive. Nut yields are cyclical and highly variable, making it difficult to establish cause and effect. It is not yet possible to say with evidence where and when irrigation is worthwhile.

The composition and control of the grass weed flora of India and Pakistan are discussed, and the losses caused by the weeds are reviewed. The most important perennial weeds are Cynodon dactylon and Sorghum halepense and the most important annual weeds Echinochloa crusgalli and E. colona in the summer (kharif) crops and wild oats (Avena spp.) and Phalaris minor in the winter (rabi) crops. Losses caused by these weeds can be considerably reduced by the use of selective herbicides but these may be too expensive for many farmers. The problems and control of Phalaris minor are considered in detail.

The objective of this paper is to identify the major factors responsible for the differences in transpiration rate (T) between stands of groundnut grown at three row spacings on stored water in central India. A method of analysis is developed to distinguish between the impact on transpiration of ground cover (which varied threefold between spacings) and of root:shoot ratio, which was substantially greater in the wider row spacings. When the soil was wet, both T and the canopy conductance, gc, were approximately proportional to the fraction (f) of incident radiation intercepted by foliage. But when the soil water content decreased below a threshold value, T/f and gc/f decreased because of an increase in stomatal resistance. Stomatal closure in response to soil water stress occurred sooner in the denser stands, partly because of more rapid depletion of soil water. A second contributory factor was that the sparser stands (which had a relatively large root:shoot ratio) had a greater capacity to keep stomata open as the soil water deficit increased.

The grass Leptocloa fusca is very useful on salt-affected soils as it can tolerate extremely saline and alkaline conditions, Since its growth is not affected by gypsum application, planting with Leptochloa is a good biological method for the reclamation of alkaline soils. It is also well adapted to the waterlogging encountered on saline and alkaline soils, and improves the soil's physical, chemical and biological properties so that within two or three years many commercial and forage crops can be grown. Leptochloa excretes salts through specialized glands and is therefore reasonably palatable to farm animals. Because of its vigorous growth on alkaline soils it does not allow satisfactory growth of companion trees, especially in the initial years of soil reclamation.

Photosynthesis and biomass production by millet (Pennisetum glaucum) and taro (Colocasia esculenta) grown under baobab (Adansonia digitata) and néré (Parkia biglobosa) was studied at Nobéré (Burkina Faso) with the aim of optimising parkland systems productivity. Millet yielded the highest biomass under Baobab and the lowest biomass was recorded in the zone close to the tree trunk of néré. In contrast, the biomass of taro was higher in heavy shaded zones under néré and the zone close to baobab's trunk. The two crops showed an increasing trend of photosynthesis rate (PN) from tree trunk to the open area. However, the increase in the PN of taro from tree trunk to the open field was lower compared to that of millet. By increasing its leaf area index (LAI) under shade, taro displayed higher biomass production under tree compared to the open area while an opposite trend was observed in millet. The high millet biomass production under baobab could be explained by light availability and the reduction of temperature under shade compared to the open field. The adaptation of taro to shade by increasing its LAI and thus avoiding drastic reduction in PN under shade resulted in better biomass production under heavy shade. Therefore, it was concluded that by replacing millet with taro under dense tree crowns the productivity of agroforestry parkland systems could be increased.

Over an eight-year period, harvesting methods based on simple mechanical aids (blade and shear) were evaluated against hand harvesting on mature morphologically contrasting tea clones in Southern Tanzania. The effects of shear step height (5–32 mm) and the harvest interval (1.8–4.2 phyllochrons) were also examined. Except in the year following pruning, large annual yields (5.7–7.9 t dry tea ha−1) were obtained by hand harvesting at intervals of two phyllochrons. For clones K35 (large shoots) and T207 (small shoots), the mean harvested shoot weights were equivalent to three unfurled leaves and a terminal bud. The proportions of broken shoots (40–48 %) and coarse material (4–6 %) were both relatively high. Using a blade resulted in similar yields to hand harvesting from K35 but larger yields from T207 (+13 %). The yield increase from clone T207 was associated with the harvest of more shoots and heavier shoots, smaller increases in canopy height, and a higher proportion (7–9 %) of coarse material compared to hand harvesting. On bushes, which had been harvested by hand for two years following pruning, using flat shears (no step) supported on the tea canopy resulted, over a three year period, in yields 8–14 % less than those obtained by hand harvesting and, for clone K35, a reduction in the leaf area index to below 5. The development of a larger leaf area index is made possible by adding a step to the shear. However, since annual yields were reduced by 40–50 kg ha−1 per mm increase in step height, the step should be the minimum necessary to maintain long-term bush productivity. As mean shoot weights following shear harvesting were about 13 % below those obtained by hand harvesting, there is scope, when using shears, to extend the harvest interval from 2 to 2.5 phyllochrons.

Upland rice (Oryza sativa L., UR) could be an option under soybean–maize crop rotation system. However, the recommended row spacing for UR (0.30 m) is shorter than that recommended for soybean and corn (0.40 m), limiting the use of UR in this rotation. We hypothesize that cultivar adaptation to wider than recommended row spacing and local environmental conditions harbour significant potential for overcoming the yield constraints of wider row spacing. We evaluated the row spacing effects on rice grain yield and their components in UR cultivars grown under different water deficit conditions. The experiments were designed as a randomized block in a split–split-plot scheme with sites (the cities of Santo Antônio de Goiás, Porangatu and Formoso) as main plots, row spacing (0.25, 0.35, 0.45 and 0.55 m) as the subplots and UR cultivars (one old and two modern genotypes) as the sub-subplots. We found that, in the less stressful environments, the modern cultivars, BRSMG Curinga and BRS Primavera, presented the highest grain yield. By contrast, in environments with moderate to intense water stress, the traditional cultivar, Douradão, presented the best performance, regardless of row spacing used. We conclude that UR is a viable option for soybean–maize rotation systems, as the UR cultivars tested presented no noticeable yield losses when sown with the same row spacing used for soybean and maize crops (0.40 m). In terms of impact, it can lead to an increase in UR cropped area in Brazil, and decrease in dependence on flooded rice harvested in the south of the country.