The capacity of sorghum lines to germinate at high soil temperatures (above 40°C) is clearly related to the temperature sensitivity of embryo protein synthesis. The development and optimization of a simple laboratory technique based on this correlation for the rapid large-scale screening of sorghum lines is described. Embryo-containing half seeds are incubated in the presence of 14C-labelled amino acids at different temperatures and the resulting radio-labelled proteins extracted and bound to nitrocellulose discs for counting. The extent to which incorporation of 14C-label into proteins is inhibited by elevated temperatures can be used to predict the likely temperature sensitivity of a given line during germination.

Prolonged moisture stress and high vapour pressure deficits reduced the shoot water potential, shoot population density, rate of shoot extension and yield of clonal tea. The more drought susceptible Clone 6/8 had a lower shoot water potential, rate of shoot extension, number of shoots per unit area, rate of shoot regeneration and yield than the more tolerant Clones 31/8, 57/15 and 15/10 during the periods of low soil moisture, which coincided with high vapour pressure deficits. The changes in the shoot growth components could be used as an index of the suitability of different clones for different regimes of soil moisture and vapour pressure deficits.

Factores ambientales que afectan el rendimiento del té

Amorphophallus paeoniifolius, popularly known as elephant foot yam, is an important tropical tuber crop in India. Its modified stem (corm) is consumed as a vegetable after boiling, baking or frying. Mealybug (Rhizoecus amorphophalli), a soft-bodied insect, infests the corms both in storage and in the field. Though pesticides are effective in controlling mealybugs, they can be hazardous to human health and the environment. Two experiments, one in storage followed by one in the field, were conducted during 2009 and 2010 at the Regional Centre of Central Tuber Crops Research Institute, Dumuduma, Bhubaneswar, India, to determine the effect of six low cost and environmentally safe management practices on mealybug. In the absence of mealybug control measures, mealybug numbers increased by 4–5 times during the storage period. The pest affected the quality of the corms and reduced subsequent field establishment and crop growth. Salt (NaCl) solution (1000 ppm), cow urine, cow dung slurry (2 kg of cow dung in 1 litre of water) and clay slurry (1 kg of clay in 1 litre of water) treatments were effective in reducing mealybug numbers and the associated corm damage. However, availability of cow urine, cow dung and clay slurry limit their usage. Common salt is cheap, widely available and easy to use in treating the corms prior to storage. Relative to untreated corms, those treated with salt solution recorded greater emergence when field planted as well as producing plants with more vigorous growth.

The adaptation of extra short duration (ESD) pigeonpea (Cajanus cajan) genotypes to rainfed environments was studied on Alfisols and Vertisols at the ICRISAT Center between 1987 and 1989. Despite a slightly shorter crop duration, the grain yield of ESD genotypes was twice as large on Alfisols as on Vertisols. On both soil types, the rate of growth and grain yield were better in crops sown on time than in those where sowing was delayed. The population levels necessary to maximize yield varied among genotypes on Alfisols, where the grain yield of several ESD genotypes compared favourably with that of ICPL 87, a standard short duration genotype. However, none of the ESD genotypes yielded more than ICPL 87 on the Vertisols.

Shortened fallow periods lead to a decline in crop yields in traditional mixed-food crop fields in southern Cameroon. Farmers use no inputs such as fertilizers for crop production in these field types. Planted fallows with adapted tree species might sustain or increase crop production under those conditions, as found in other parts of Africa. Two-year-old calliandra tree fallows, with trees planted in alleys, clusters, equidistantly or around plot borders, were compared with two- and four to five-year-old natural fallows for their effect on groundnut, maize and cassava yields on eighteen farmer fields in southern Cameroon. Trial fields covered a wide range of soil and environmental conditions. The tree fallows had no significant effects on the yields of maize and cassava with the exception of the border planting, in which trees were not rigorously pruned back prior to cropping. Here, cassava tuber yields were reduced. Cassava tuber yields declined generally with decreasing planting distance to trees. The yield of groundnut, the most important crop in this field type, was adversely affected. However, maize grain yields were positively related to biomass produced by calliandra trees, notably on soils with pH over about 5.3. The data indicated that yields of all crops could be increased with higher plant densities, irrespective of fallow type. The tree fallows, with the exception of border planting, showed less adaptability than four to five-year-old natural fallows to sites with low crop yields, whereas no difference compared with two-year-old natural fallows was found.

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).

Little bag silage (LBS) is seen as a low-cost alternative suitable for resource-poor smallholders to alleviate dry-season feed constraints. Within a research project carried out by the International Center for Tropical Agriculture and partners in Honduras, LBS was tested and its use encouraged during farmer training and field days. The present study highlights the most relevant technological and socio-economic potential and constraints of LBS. Surveys and experimental results revealed great vulnerability of plastic bags to pests, particularly rodents, accompanied by high spoilage losses. The main constraints to wider adoption include availability of i) suitable and affordable plastic bags, and ii) appropriate chopping equipment and storage facilities on smallholder farms. LBS proved to be useful and could play an important role in participatory research and extension activities, as a demonstration, experimentation and learning tool that can be used to get small-scale silage novices started with a low-risk technology.

In 2004 and 2005 through field trials in over 2500 locations in several agroecological zones, 40 new cassava varieties were introduced in Nigeria. The trials were managed by scientists, extension workers and farmers. The aim in introducing these new varieties was to pre-emptively manage cassava mosaic disease, to avert an imminent threat from the Ugandan strain of the pathogen and prevent damage to the Nigerian cassava economy. From these trials, 10 new varieties were selected and officially released for high root yield, high dry matter content and acceptability for food, industry and livestock. Cassava root rot is a major source of yield loss in Nigeria, especially where farmers practice late harvest because they wait for a good price from the market before harvest and sales. This paper investigated how the 40 varieties together with three old improved varieties currently in farmers' fields during the formal trials responded to root rot disease. No absolutely resistant variety was found, indicating that early harvest (9–11 months after planting) is still the best way to reduce losses from root rot. Root rot is also significantly (p ≤ 0.05) influenced by genotype and environment interaction. Most root rot was recorded in the humid forest and the least was in the Sudan savanna agroecological zone. Using a rank-sum method, the 43 varieties were separated into highly resistant, resistant, moderately resistant, moderately susceptible, susceptible and highly susceptible classes.

Intensity of harvest in tea can be defined in terms of the number of leaves or axillary buds left behind after a shoot is harvested; we describe a simple method for measuring it. Application of the method in trials confirms that yield increases with more intense (harder) harvesting. Differences in intensity of harvest explain much of the variation in yield between different harvesting treatments, including semi-mechanical and mechanical harvesting methods. We recommend that measurements of intensity of harvest should be made routinely in experiments with tea.

The genotype × environment (GE) interaction analysis is fundamental in crop breeding programs to guide selection and for recommendation of high performing and stable genotypes for breeding objectives. This study aimed at quantifying the GE interaction effects and determines grain yield stability among winter bread wheat genotypes under rainfed conditions of Iran. Twenty-four winter wheat genotypes were evaluated under nine test locations using a randomized complete blocks design with four replications during three cropping seasons (2019–21). The additive main effects and multiplicative interaction (AMMI) model and several parametric and nonparametric stability statistics were applied for analysis of grain yield data collected from the experiments. AMMI analysis of variance for grain yield revealed significant effects (p < 0.01) for genotype, environment, and GE interaction. The environment was the main source of variation and accounted for 83.5% of the total yield variation, followed by GE (6.5%) and genotype (1.0%) effects. The AMMI biplot analysis indicated the genotypes G3, G23, G22, G10, and G19 as high yielding with stability performance across environments. Genotypes G14, G13, G20, and G9 showed large positive interaction with the environments featuring the highest rainfall during growing season, while genotypes G7, G6, and G21 had a large positive interaction with environments with low rainfall. Spearman’s rank correlation analysis revealed that the AMMI stability value, Shukla’s stability variance (σ2i), Wricke’s ecovalence (W2i), coefficient of determination (R2i), variance in regression deviations (S2di), and nonparametric statistic of S2(i) were not correlated with mean yield in tested genotypes, showing they are related to static/biological concept of stability. In contrast, the genotypic superiority index (Pi) and regression coefficient (bi) were significantly correlated (p < 0.01) with mean yield and corresponded to dynamic/agronomic concept of stability. These findings suggest that selection of genotypes should be considered based on selection objectives of using the various stability parameters described here. In conclusion, the selected genotypes in this study should be recommended as new cultivars or parental lines for grain yield and stability improvement under rainfed conditions of Iran or similar agro-ecologies.

Gypsum application and irrigation increased yield in early maturing groundnut genotypes in experiments using line source and conventional irrigation. Response to gypsum varied with genotype; with some gypsum increased yields at all water application rates, in some genotypes there was no response, while with others gypsum increased yield in drought conditions.

In a separate study of the effect of gypsum and drought on pod initiation and development in three groundnut genotypes, gypsum did not greatly influence pod initiation when adequate irrigation was applied, but was beneficial when water was withheld during pod set and again during pod filling. Crops where the combination of gypsum and genotype were most advantageous in the first drought period subsequently grew more slowly so that there were no final differences in response to gypsum. Cultivar EC 76446(292) had a higher requirement for gypsum and was more susceptible to drought than the other two genotypes.

The aim of this work was to test the performance of a shrimp-tomato culture system (STCS) in an arid-semiarid region (Sonora, Mexico) and to evaluate the water quality variables and phytoplankton variation of shrimp effluent and that water returning from the tomato module culture. The field study was conducted using groundwater and consisted of three circular tanks that were used for shrimp (Litopenaeus vannamei) farming and were coupled to one culture module of tomato plants (Lycopersicon esculentum). The shrimp effluent was used to irrigate the tomato plants. The yield was 11.1±0.2 kg shrimp per tank (3.9±2.0 ton ha−1) and 33.3 kg tomatoes per 45 plants (36.1±2.3 ton ha−1). During the culture, the concentrations of nutrients were (mg L−1): total N-ammonia, <0.001–0.848; N-nitrite, <0.001–1.45; N-nitrate, 5.2–172.2; dissolved reactive-P, <0.005–0.343. A total of 35 taxa belonging to three different algal classes were observed: Chlorophyta (87 to 98%), Bacilliariophyta (2 to 9%) and Cyanophyta (0–3%). This STCS allowed us to harvest the equivalent of 3.9 ton ha−1 of shrimp and 36.3 ton ha−1 of tomatoes, with a water consumption of 2.1 m3 per kg harvested of both products.

Insects cause serious problems during the storage of cassava chips, when quality may be reduced and significant quantities of the product consumed. The major species naturally infesting chips were Rhizopertha dominica, Lasioderma serricorne and Araecerus fasciculatus. Infestation occurs during the sun-drying process, and up to 16% reduction in chip weight due to insect feeding was recorded after 2 months storage. Chips that had not received any pre-drying storage, but contained salt as a preservative, were infested by fewer insects than chips without salt. The poorest quality chips had significantly more insects than better quality ones.

Fluid-drilling is the term used to describe sowing seed in a liquid carrier. Elliot (1966) used a tractor-mounted fluid drill designed by the National Institute of Agricultural Engineering to sow normal seed into killed grassland, and a similar but modified drill was subsequently used at the National Vegetable Research Station to sow pre-germinated vegetable seeds (Gurrah et al., 1974; Gurrah, 1975). It then became necessary for compact and economical experiments to be carried out, both on and off the Station, creating a requirement for a small, portable, easily operated, hand-powered drill of simple and robust construction (Gurrah, 1975). Such a drill was built in 1975 and is described in this paper.

The introduction of appropriate crop rotations is known to be beneficial in many farming systems. One feature of rotations is that it takes a valuable length of time for the advantage of the rotation to take effect. In long-term rotation trials, the observations from the same plot over years are correlated; ignoring such correlations may affect the precision of the estimates of rotation effects. We examined five covariance structures between the plot errors over time to assess the effect of correlations on the standard errors of rotation means and rotation x cycle combination (interaction) means on wheat yields using eight years of data from six two-phase rotations with wheat. Based on wheat yield data from the four cycles of the rotations considered, the compound symmetry covariance structure (constant correlation) between plot errors arising over alternate years gave more efficient estimates of rotation means compared with the other four covariance structures.

Trials on cotton in Uganda show that four DDT sprays give substantial increases in yields and a reduction in percentage of stained cotton. Benefits were obtained from early ploughing prior to sowing and there were positive interactions between time of ploughing and spraying. Fertilizer applications of superphosphate and sulphate of ammonia generally produced marginal benefits but more cotton was obtained from fertilized plots if they were sprayed, though not if unsprayed. The effect of fertilizer on the pest complex was slight, though one pest appeared to be attracted to lush fertilized cotton. Spraying gave excellent control of bollworms and mirids.

Leucaena leucocephala is cultivated at close spacings that do not permit intercropping. This has been a discouraging factor for small landholders who need regular income to establish leucaena plantations and benefit from the rapidly expanding market for wood. Therefore, on-farm experiments were conducted near Bhadrachalam, Khammam district, Andhra Pradesh, India, from August 2001 to January 2006, to study the effect of reducing tree density and modifying tree geometry on the growth of leucaena and productivity of intercrops. The inter-row spacing of 1.3 m in farmers' practice was increased up to 13 m to examine whether wide-row planting and grouping of certain rows would facilitate extended intercropping without sacrificing wood yield. Tree density treatments tried were 1.3 × 1.3 m, 3 × 0.75 m, 3 × 1 m, 5 × 0.8 m and 3 × 2 m which gives densities of 5919, 4444, 3333, 2500 and 1666 trees ha−1, respectively. Tree geometry treatments tested were 7 × 1 m paired row spacing (7 × 1 PR), 10 × 1 m triple row spacing (10 × 1 TR), and 13 × 1 m four rows (13 × 1 FR) with a constant tree population of 2500 trees ha−1. Cowpea (Vigna unguiculata) was the intercrop. While changes in tree density affected diameter at breast height (DBH) significantly, modification of tree geometry did not affect tree height and DBH. Marketable wood and dry biomass productivity was highest with 3 × 0.75 m spacing, and reducing tree density and alteration of tree geometry reduced the biomass considerably. In 2001, 2002 and 2003 seasons, respectively, tree spacing at 3 m produced mean yields of 97, 23 and 11% of the sole crop cowpea yield whereas modified tree geometry treatments produced mean yields of 97, 61 and 20% of sole crop yield. The widest spacing (13 × 1 FR) recorded 95, 73 and 30% of the sole crop yields during 2001, 2002 and 2003, respectively. Net returns from intercropping of leucaena in 3 × 0.75 m spacing was 36% higher than that of the farmers' practice. Although wider tree geometry treatments recorded lower net returns, they provided higher intercrop yields and returns in the first two years of plantation establishment. Therefore, it can be concluded that in regions where annual rainfall is around 1000 mm, leucaena can be planted at a spacing of 3 × 0.75 m for improving intercrop performance, higher tree productivity and returns.

A fluorescent-dye technique has been developed to measure root length of field crops. Roots are washed from soil samples, stained for about 30 min in a solution of fluorescein diacetate in acetone, washed, spread out on a tension table and photographed under UV light. Lengths of fluorescent roots recorded on the photograph are estimated by line intersection. The method is quick, simple, inexpensive and largely eliminates the usual time-consuming, tedious process of hand-sorting live roots from organic debris. Whereas all the roots of young laboratory-grown plants take up the dye, some older roots of field-grown crops do not fluoresce. Data indicate that the method may also give information on root diameter.

Experiments were conducted across 2 years to determine the effect of harvesting methods – combine harvester and hand harvesting – and harvest time during ripening on milling quality of long grain rice grown in the rainfed lowland ecosystem in Cambodia. Head rice yield (HRY) was highest when rice was harvested 25 days after flowering and decreased with delay in harvesting at 35 and 45 days after flowering. This was accompanied by a general decline in grain moisture content at harvest, although it was still high at 24–25% at 35 days after flowering. The decline in HRY was associated with increases in fissured grain percentage observed immediately after harvest. Hand harvesting produced 2–6% higher HRY than combine harvesting. Fissured grain in hand harvested crops was lower in year 1, but was similar to combine harvested crops in year 2. Both hand and combine harvested crops were sun-dried but rough rice harvested by combine was dried on plastic sheet and this may have contributed to reduction in HRY. Maximum HRY percentage was only about 44% and the factors contributing to this low HRY were discussed. Harvesting time and methods had no significant effect on grain yield, but the field grain loss during the harvesting operation was 2–5% higher in combine than hand harvesting.