The experiment was carried out in three crop cycles as plant cane, first ratoon, and second ratoon at five locations on Florida muck soils (histosols) to evaluate the genotypes, test locations, and identify the superior and stable sugarcane genotypes. There were 13 sugarcane genotypes along with three commercial cultivars as checks included in this study. Five locations were considered as environments to analyze genotype-by-environment interaction (GEI) in 13 genotypes in three crop cycles. The sugarcane genotypes were planted in a randomized complete block design with six replications at each location. Performance was measured by the traits of sucrose yield tons per hectare (SY) and commercial recoverable sugar (CRS) in kilograms of sugar per ton of cane. The data were subjected to genotype main effects and genotype × environment interaction (GGE) analyses. The results showed significant effects for genotype (G), locations (E), and G × E (genotype × environment interaction) with respect to both traits. The GGE biplot analysis showed that the sugarcane genotype CP 12-1417 was high yielding and stable in terms of sucrose yield. The most discriminating and non-representative locations were Knight Farm (KN) for both SY and CRS. For sucrose yield only, the most discriminating and non-representative locations were Knight Farm (KN), Duda and Sons, Inc. USSC, Area 5 (A5), and Okeelanta (OK).

The growth and nitrogen yield of Stylosanthes guyanensis undersown with upland rice were negatively related to level of urea application at Khon Kaen, north-east Thailand. In the absence of applied urea the nitrogen yield of rice monoculture was 3·3 gm./m.2 whilst the addition of stylo increased nitrogen yield of the association to 9·6 gm./m.2 Stylo was initially dominated by rice but exploited environmental growth factors more effectively in the latter part of the growing season, accentuating competition for water and phosphorus. Simultaneous stylo and rice sowing reduced rice grain yield by 12 per cent, the greatest reduction occurring at a low level of urea application, mainly due to abortion of spikelets after panicle exsertion.

Reports that an Indonesian soyabean (Glycine max) line (TGm737p) shows greater seed storage longevity than an American cultivar (Bossier), and that the cross between them (TG×536–02D) is intermediate between the two parents in this regard, were investigated by growing all three genotypes under identical conditions (30°C/20°C, 12 h d-1 photoperiod) in a plastics house. Seeds were harvested when moisture content had declined naturally to 14–15% (wet basis), and then stored hermetically at five different moisture contents at 40°C. Analyses of the resultant seed survival curves revealed that the seed lot constant Ki (a measure of potential longevity) was greatest in TGm737p and least in cv. Bossier, the cross being much closer to the American parent in this regard. The negative logarithmic relation between σ (standard deviation of the frequency distribution of seed deaths in time) and moisture content did not differ (p > 0.10) among the three genotypes. Moreover, this relation was close to that predicted by earlier results for four different genotypes. Similarly, there was no significant difference (p > 0.25) among genotypes in the negative semi-logarithmic relation between σ and seed equilibrium relative humidity (rh): the regression slope was equivalent to a doubling of longevity for each 8.0% reduction in rh. Finally, comparison of the negative logarithmic relation between absolute longevity (50% viability period) and seed moisture content confirmed that TGm737p showed greatest longevity (p > 0.005), but failed to show a difference in absolute longevity between cv. Bossier and the cross (p > 0.25). The results confirm that the seed viability equation of Ellis and Roberts (1980a, b) provides a framework within which the seed longevity of different genotypes can be compared. They suggest too that there is considerable doubt as to whether or not the greater potential longevity of the Indonesian line TGm737p has been incorporated successfully into the cross TG×536–02D.

Longevidad de la semilla de soja

The effects of date of planting and soil mulching on cowpea growth and yield were investigated for three years during the middle part of the minor season in Sierra Leone. Mulching at 8 tons/ha conserved more soil moisture than other mulch rates, with greatest difference in the top 15 cm of soil, especially during drier periods. Plant height, pod number and seed yield of cowpea planted in September were significantly greater than from other planting dates whether mulch was applied or not. The beneficial effects of mulching at 8 tons/ha on cowpea growth and yield were more dramatic when the crop received an average weekly rainfall of 100 mm before 50% flowering.

Internal and external factors affecting the germination of seeds of six common East African weeds were studied by sowing the seeds in each of 13 different treatments chosen to provide a wide range of different germination environments. The results indicate how germination is regulated in each of these species and provide the basic information necessary for further field studies.

The effect of grass mulch on groundnut yield and shelling percentage has been studied at three locations in the Gambia. Yield increases have been mainly attributed to physical factors but residual increases were found for only one year after application. Mulching gave rise to significant increases in exchangeable soil potassium, in percentage potassium in the plant at harvest and in total potassium uptake by the plant. In the absence of response to potassium fertilizer, increased uptake was ascribed to luxury consumption. It was suggested that reduced shelling percentage from mulched plots was due to potassium-calcium antagonism.

In cotton–wheat cropping system of Pakistan, wheat (Triticum aestivum L.) is harvested in late April; however, the optimum sowing time of Bt cotton is mid-March. This indicates a time difference of 4–6 weeks between the harvest of wheat and cotton sowing. It is hypothesized that this overlapping period may be managed by transplanting cotton seedlings (30–45 days old) in late April, after the harvest of wheat due to better performance of already established seedlings. To this end, this study was conducted to evaluate the allometric traits and fiber quality of transplanted Bt cotton after harvesting wheat in the cotton–wheat cropping system. The Bt cotton–wheat cropping systems were flat sown wheat (FSW)–conventionally tilled cotton, FSW–zero tilled cotton, ridge sown wheat–ridge transplanted cotton using 30- and 45-days-old seedlings, and bed sown wheat (BSW)–bed transplanted cotton (BTC) also using 30- and 45-days-old seedlings. The study was conducted at Vehari and Multan in Punjab, Pakistan. Bt cotton in BSW–BTC with 45-days-old seedlings showed better performance for allometric (leaf area index; (LAI), net assimilation rate; (NAR), and crop growth rate; (CGR)), seed cotton yield, and fiber traits (fiber uniformity, fiber length, fiber strength, and fiber fineness) in comparison to other treatments. Most of the fiber quality traits were positively correlated with allometric traits and biological yield (dry matter yield at maturity) at both locations, except correlations of CGR and LAI with fiber fineness and fiber length and NAR with fiber length. As plant growth and fiber quality of transplanted cotton was significantly higher than conventionally grown cotton, our data indicate transplanting is an interesting management practice for improving productivity in wheat–cotton cropping systems.

ANOVA, one of the most common statistical methods applied in agronomy, offers a variety of results we can report when analyzing designed experiments. The focus, of course, is on treatment means, but what should we report to characterize precision? Should we choose treatment standard deviations (SDs) or standard errors of the mean or standard errors of the difference (SEDs)? We discuss why treatment raw SDs should not be reported as the result of ANOVA, and point out that most of the time it is SEDs that should be provided.

In arid and semiarid winter crop growing regions of southern Australia, low rainfall, high evaporation, and low soil moisture storage are the limiting factors for crop production. In this region canola (Brassica napus L.) is principally grown in rotation with wheat and pasture species. Some field studies have indicated Indian mustard (Brassica juncea L.) to be more drought tolerant than canola and therefore considered to be better adapted than canola to short season environments. A field experiment was conducted at Wagga Wagga in NSW to determine the effect of two soil moisture regimes on water use efficiency, harvest index, seed and oil quality of cv. Oasis of Indian mustard and cv. Skipton of canola. Significant year × stress and species × stress interaction effects were observed for grain yield, harvest index, seed weight, biomass water productivity, and grain water productivity. Irrigation during the post flowering period resulted in 50% and 200% increases in canola grain yield in the first year (year with higher in-crop water) and the second year (year with low in-crop water), respectively. For mustard, these values were 7% and 45%, respectively. Stressed mustard resulted in higher grain yield than stressed canola while irrigated canola performed better than irrigated mustard. High mustard biomass production resulted in lowering its harvest index. Generally, the biomass water productivity of mustard was higher than that of canola. Grain yield-based water productivity of stressed mustard was higher than that of stressed canola while irrigated canola had higher water productivity than irrigated mustard. When rainfall and actual evapotranspiration drop below some thresholds, mustard becomes a favourable crop. Generally, effects due to the water treatments (stressed v irrigated) were much larger than the differences due to species.

Weedy rice species exhibit differential competitive ability and cause significant losses to rice yield. The present study was conducted to evaluate the competing ability of weedy rice accessions collected from foothills of eastern Himalayas and coastal Odisha grown in the presence of cultivated indica rice var. Swarna. The competitive ability of Swarna and weedy rices were estimated on the basis of (i) Swarna yield reduction under different durations of competition with weedy rice; and (ii) nutrient uptake by Swarna and weedy rice in competitive environment. There was significant yield reduction (18%) when competition was allowed until 6 weeks after emergence (WAE) compared to competition until 2 WAE, which was due to vigorous growth of weedy rice at early vegetative stage. The biomass accumulation and tiller number of weedy rice were significantly higher compared to Swarna. Odisha weedy rice accession recorded about 18, 57 and 24% higher N, P and K uptake, respectively, than Swarna. The highest yield reduction (22%) in Swarna was recorded when grown with OA1 and the lowest impact (7.7%) was recorded with AA2. As conclusion, management practices should be implemented within 2–4 weeks of emergence considering 5–10% acceptable yield loss of Swarna, and grain yield of cultivated rice was reduced significantly by high N and K uptake by weedy rice under a competitive environment.

The response of wheat to the application of different rates of nitrogen (N), phosphorus (P), potassium (K), and sulfur (S) under balanced fertilization on different soil types and agroecologies has not been well studied in Ethiopia. Therefore, the objectives of this study were to (1) determine soil-specific responses of wheat to N, P, K, and S under balanced fertilization; (2) quantify agroecology-specific N, P, K, and S response of wheat under balanced fertilization; and (3) determine nutrient use efficiency of wheat on different soil types under balanced fertilization. Trials were conducted on farmers’ fields across 24 locations covering 4 soil types and 5 agroecological zones (AEZs) from 2013 to 2017. The mean grain yields of wheat significantly varied with applied N and P fertilizer rates with soil types and AEZs. With balanced application of other nutrients, the optimum N rates for wheat were 138 kg N ha−1 on Cambisols and Luvisols, 92 kg N ha−1 on Vertisols, and 176 kg N ha−1 on Nitisols, while the optimum P rate was 20 kg P ha−1 on Cambisols and Vertisols. The nutrient dose–response curve did not reveal consistent pattern for K and S applications on all soil types. The agronomic efficiency of wheat decreased with increasing rates N and P on all soil types. The highest agronomic efficiency of N (15.8 kg grain kg−1 applied N) was recorded with application of 92 kg N ha−1 on Vertisols, while the highest agronomic efficiency of P (49 kg grain kg−1 applied P) was achieved with application of 10 kg P ha−1 on Cambisols. We conclude that applications of 92–138 kg N ha−1, 20 kg P ha−1, 18 kg K ha−1, and 10 kg S ha−1 under balanced application of zinc and boron could be recommended depending on soil type for wheat production in the study areas.

The introduction of forage or hay crops into fallow land represents a means of increasing feed supplies for small ruminants in north Africa and west Asia. Such fallows lie between zones planted with food crops and traditional grazing areas. Mixtures of vetch with barley, oats or triticale, and peas with barley, were cut at the 10% flowering, 100% flowering (100F) and full pod (FP) stages of the legume component. Effects of crop maturity, weather conditions and cutting height on yield, the chemical composition of the standing crop and re-growth were measured. Barley–vetch mixtures yielded 8147 kg dry matter ha−1 of standing crop at the FP stage in 1983 but only 2283 kg dry matter ha−1 in 1984 under drought conditions. Hay yields were 4377 and 1640 kg dry matter ha−1, respectively. The highest yielding mixture, grown in 1983, was oat–vetch which yielded 8670 kg dry matter ha−1 of standing crop and 4285 kg dry matter ha−1 of hay at the FP stage. Cutting at the 100F or FP stage maximized dry matter yield and minimized the risk of rainfall prolonging hay making. Rain caused slight damage to some hays cut at early stages of maturity. Voluntary intakes and digestibilities of field-cured hays were determined. The voluntary intakes of triticale–vetch hay at the FP stage and all barley–pea hays were low compared with other hays. Hays contained sufficient estimated metabolizable energy (ME) for use in sheep diets during pregnancy and middle or late lactation. ME values averaged 9.2 megajoules per kg dry matter in both 1983 and 1984.

Cotton–wheat is an important cropping system in South Asia. Introduction of BT cotton has caused the time conflict between sowing of BT cotton and wheat harvest in this cropping system. Wheat is harvested in late April but the best planting time of BT cotton is mid-March, which indicates a time conflict of 30–45 days between two crops in the region. However, this conflict can be managed by raising the cotton nursery and transplanting 30–45 days old seedlings in the field after wheat harvest. This two years field study was conducted to assess the economic feasibility of transplanting BT cotton in BT cotton–wheat cropping system at two locations (Multan, Vehari) in the cotton belt of Punjab, Pakistan. The BT cotton–wheat cropping systems included in the study were; flat sown wheat (FSW) – zero-tilled cotton (ZTC), FSW – conventional-tilled cotton (CTC), ridge sown wheat (RSW) – ridge-transplanted cotton (RTC) (30 days old seedlings), RSW – RTC (45 days old seedlings), bed sown wheat (BSW) – bed-transplanted cotton (BTC) (30 days old seedlings) and BSW – BTC (45 days old seedlings). BSW produced more grain yield than RSW and FSW during both years at both locations. Likewise, BTC (45 days old seedlings) had higher production at both sites during both years. The overall productivity of BT cotton–wheat, in terms of net income, benefit: cost ratio and marginal rate of returns, was the maximum from transplanting 45 days old cotton seedlings on beds after BSW during both years at both sites. Sowing cotton as ZTC following FSW was the least productive cropping system. In conclusion, transplanting 45 days seedlings of BT cotton on beds during late April after harvest of BSW wheat may be opted to manage the time conflict and improve the productivity of BT cotton–wheat cropping system in Punjab, Pakistan.

The results of research on the water relations and irrigation requirements of the mango fruit tree are collated. The stages of development (including roots) are summarised, followed by reviews of plant water relations, water requirements, water productivity and water management. This long-lived tree is well adapted to a wide range of tropical and subtropical environments. In the low-latitude tropics, flowering is initiated after a period of water stress (at least six weeks duration) and is ended by rain or irrigation. In the high-latitude tropics and subtropics, flower buds are initiated during the cool winter months (<15 °C). Less than 1% of the flowers that set fruit reach maturity. Roots can reach depths of 5 m. Stomata occur mainly on the lower (abaxial) leaf surface. They are sensitive to dry air, closing as the saturation deficit increases (from 0.5 to 4.0 kPa). In humid tropical areas, the mean seasonal potential evapotranspiration rates (ETc) average 4–5 mm d−1, with peak rates of 5–6 mm d−1. The crop coefficient (Kc) varies between 0.65 and 1.05. Water productivities are in the range 3–6 kg (fresh fruit) m−3 (irrigation). Micro-sprinklers and drip irrigation are the preferred methods of irrigation. The trend towards greater intensification of production will impact on the water relations and irrigation needs of mango and provide a focus for future research.

Cotton–wheat (CW) is an important cropping system in South Asia. Wheat yields under a conventional CW system are generally lower compared to a rice–wheat system due to delayed seeding. Relay seeding of wheat can help timely sowing, capturing residual soil moisture of last irrigation to cotton, and increase the productivity and profitability of CW system. The field experiment included two Bt-cotton genotypes having different canopy cover (RCH 776 and MRC 7017), two types of relay seeders (RSs) for cotton planted at 67.5-cm and 101-cm row spacing and four types of relay seeding methods (manual broadcast, strip rotor (SR) and zero-till double disc and conventional till). Relay planting of wheat allowed one additional boll picking, which increased seed cotton yield by 12% compared with conventional tillage wheat. Cotton genotypes and RSs had no effect on emergence and yield of wheat. The RSs with SR and zero till double disc furrow openers performed better in terms of wheat emergence and grain yield compared to zero-till tine openers. Under relay seeding, wheat sowing was advanced by 31 days, which increased grain yield by 18.8% compared with conventional tillage practice. Net returns from the CW system with relay seeding of wheat were higher by US$ 311 to 425 ha−1 compared with the conventional CW system.

Instruments and techniques are reviewed for measuring the content and potential of water in the soil, the water potential and solute potential of plant tissue, and the diffusive resistance of leaves. Emphasis is placed on difficulties encountered in the field and in the interpretation of measurements. References are given to recent technical papers and reviews dealing with the principles and construction of individual instruments.

Reducing the leaf areas of different maize hybrids at the time of female flowering resulted in a reduction of up to 70–90 g/plant of grain yield, with a parallel deterioration in the health of the stalk pith (due to infection by Fusarium sp.) and an increase in lodging. However, beyond a certain limit defoliation caused a loss in fertilization and a further decline in grain yield, which was accompanied by an improvement in the health of the pith and less lodging. There were considerable differences in the reactions of six genotypes to the defoliation treatments.

Sorghum landraces from contrasting districts of northern Nigeria were grown during the 1990 rainy season to describe their physiological and morphological features. Changes in their dry matter production and yield could be predicted from thermal time to flowering (based on response to a fixed daylength) and partitioning indices. Many other morphological and physiological features, such as light-extinction coefficient, light-use efficiency, plant height, leaf area and leaf number, were either stable or varied systematically with time to flowering. Grain yields of early maturing lines were limited by low light interception from flowering to physiological maturity and those of later maturing lines by highly site-specific drought stress.