Genetic Evaluation of Seedling Heat Tolerance in Sorghum

Surface temperatures of tropical soils at planting time, where sorghum ( Sorghum bicolor ) is a traditional crop, can exceed 50°C for hours. Seedling heat tolerance is critical for adequate crop establishment in the semi-arid tropics. Improvement of seedlings heat tolerant genotypes would reduce crop losses due to sufficient plant populations. The objectives of this study were to estimate seedling tolerance to heat, determine individual parental contribution and estimate additive, dominance and epistatic effects for seedling tolerance. In our experiments, seedling heat tolerance termed heat tolerance index (HTI) was defined as a ratio of resumed coleoptile growth after a controlled heat shock, compared to normal growth. Genetic parameters of HTI were determined by crossing four lines with varying HTI, with three tester lines, and deriving F1, F2, F3, BC1 and BC11 families for generation means analysis. Line IS20969 from Egypt showed the highest HTI of 0.71, while 290R, an experimental line from the University of Nebraska was the lowest at 0.51. Additive and dominance effects contributed to coleoptile elongation under normal conditions, but only additive effects were significant in recovery growth. Epistatic effects were present in both conditions. General combining ability (GCA) effects for HTI were highly significant in both conditions, but specific combining ability effects were negligible. These results indicate that it is possible to improve seedling heat tolerance and, thus, improve sorghum variety and hybrid plant populations in tropical areas where hot soil temperatures occur.Les températures en surface des sols tropicaux au moment des semis, où le sorgho est une récolte traditionnelle, peuvent excéder 50°C pendant des heures. La tolérance de la chaleur des plantes est critique pour l'établissement adéquat de la culture dans les tropiques semi-arides. L'amélioration des génotypes résistants à la chaleur de plantes réduirait des pertes de récolte dues aux populations de plantes suffisantes. L'objectif de cette étude était d'estimer la tolérance des plantes a la chaleur, déterminer l'additif parental individuel de contribution et d'évaluation, la dominance et les effets épistatiques pour la tolérance des plantes en utilisant des analyses de moyens de génération des populations développées à partir de l'ensemble de détail de parents. Dans nos expériences, la tolérance de la chaleur des plantes l'index nommé de tolérance de la chaleur (HTI) a été définie comme rapport de croissance reprise de coléoptile après un choc commandé de la chaleur, comparé à la croissance normale. Des paramètres génétiques de HTI ont été déterminés en croisant quatre lignes de différents HTI avec trois lignes d'appareil de contrôle, et dérivant les familles F1, F2, F3, BC1 et BC11 pour la génération veut dire l'analyse. La ligne IS20969 d'Egypte a montré le plus haut HTI de 0.71 tandis que 290R, une ligne expérimentale de l'université du Nébraska, était la plus basse à 0.51. L'additif et les effets de dominance ont contribué à l'élongation de coléoptile dans des conditions normales, mais uniquement les effets additifs étaient significatifs dans la croissance de rétablissement. Les effets épistatiques étaient présents dans les deux conditions. Les effets de combinaison généraux de la capacité (GCA) pour HTI étaient fortement significatifs dans les deux conditions mais les effets de combinaison spécifiques de capacité étaient négligeables. Ces résultats indiquent qu'il est possible d'améliorer la tolérance de la chaleur pour des plantes améliores et d'améliorer ainsi la variété de sorgho et les populations de plantes hybrides dans des secteurs tropicaux avec de fortes températures de sol

Risk-Efficient Production Plans Under Alternative Measures of Income Expectations

Decision—making under uncertainty with income expectations conditioned on available information is contrasted with the standard risk modeling defini— tion of expectations as mean income. Two MOTAD models are specified, a traditional MOTAD and one employing an ARMA model to develop conditional expectations. The analysis indicates that income variability may be reduced by conditioning expectations on relevant information

Pearl millet/cowpea cropping system yields and soil nutrient levels

Pearl millet [Penisetum glaucum (L.) R.Br.] and cowpea [Vigna unguiculata (L.) Walp] are important crops in traditional bush-fallow production systems in West Africa. Human population growth is forcing producers to consider alternative cropping systems and fertilizer application to meet food needs, by continuous, intercrop and rotational cropping systems on pearl millet and cowpea grain and stover yield, and maintaining soft nutrient levels. A long-term cropping system study with nitrogen applications of zero 20 and 40 kg ha-1 was initiated at the Cinzana Research Station near Segou, Mali in 1990. The field had a leached tropical ferruginous (Ustalf) soil. Nitrogen fertilizer application increased pearl millet and stover yield linearly per year, but had no effect on cowpea. Rotation with cowpea increased pearl millet grain yield by 17 to 31% each year between 1991 and 1995, but had little effect on cowpea yield. Intercropping reduced yield of both crops every year, but the Land Equivalent Ration indicated a 14 % average increase in land use efficiency. After four years, soil of plots with the different cropping systems had similar levels of nutrients, except for phosphorous which was higher in continuous cowpea plots. Soil of plots with all cropping systems had lower level of pH, K, Ca, Mg and cation exchange capacity than fallow plots, indicating that all cropping systems were mining soil of nutrients. This research indicates that nitrogen fertilizer application up to 40 kg/ha and crop rotation with cowpea increase pearl millet grain and stover yield.Le mil [Penisetum glaucum (L.) R. Br.] et le niebe [Vigna unguculata (L.) Walp] sont des cultures importantes dans les systemes traditionnels en Afrique de l'Ouest. La croissance demographique pousse les Producteurs a considerer d'autres systemes alternatifs de culture et l'utilisation des engrais chimiques pour satisfaire les besoins alimentaires et maintenir le statut des elements nutritifs du sol. L'objectif de cette etude etait de determiner les effects des systemes de monoculture et de rotation sur la production de grains et de biomasse du mil et du niebe et le niveau des elements nutritifs du sol. Une etude du stem de culture de longue duree avec l'apport de zero, 20 et 40 kg/hectare a ete initiee a la Station de Recherche Agronomique de Cinzana non loin de Segou au Mali en 1990. La parcelle experimentale etait un sol du type "Sols ferrugimeux tropicaux lessives". L'application de l'engrai azote a augmente le rendement grain et de biomasse du mil de facon lineaire chaque annee, mais n'a eu aucun effet sur la production du niebe. L'association du niebe au mil a reduit le rendement des deux cultures chaque annee, mais le rapport de la surface equivalente a indique une augmentation moyenne de 14% de l'efficacite d'utilisation de la terre. Apres quatre annees de culture, les sols des parcelles portant les differents systemes de culture avaient des niveaux similaires d'elements nutritifs, a l'exception du phosphore qui etait plus eleve dans les parcelles de monoculture du niebe. Les sols des parcelles de tous les systemes de culture avaient des niveaux de pH, K, Ca, Mg et la capacite d'echange cationique plus bas que ceux de la jachere, indiquant ainsi que tous les systemes de culture etudies minaient les sol de ses elements nutritifs. Cette etude montre que l'appliation de l'azote a la dose de 40 kg/hectare et la rotation avec le niebe augmente le rendement grain et de bimasse du mil

Adaptability and Reliability of Yield for Four Bell Pepper Cultivars Across Three Southeastern States

(Capsicum annuum L.) cultivars were evaluated for yield (total weight of marketable fruit) performance over 41 environments as combinations of 3 years, three planting dates, and seven locations across North Carolina, South Carolina, and Georgia. Cultural practices, including trickle irrigation and double rows planted on blackplastic- covered beds, were uniform across all environments, except for fertilization, which was adjusted at each location based on soil tests. Comparing production over 3 years between the mountain location and the Coastal Plain location in North Carolina, yields were lower on the Coastal Plain. Spring plantings provided higher yields than summer plantings at both locations. Yield increases were obtained from hybrid cultivars over that of the open-pollinated (OP) standard [‘Keystone Resistant Giant #3’ (KRG#3)] in the summer planting in the mountains compared to the Tidewater Coastal Plain. Across the three-state region, hybrid cultivar yields were higher than those of the OP cultivar for the second spring planting date in 1986 and 1987. Although the hybrid yields were higher than that of the OP standard, the hybrid ‘Skipper’ yielded less than the other hybrids (‘Gator Belle’ and ‘Hybelle’). ‘Gator Belle’ generally out-yielded ‘Hybelle’ at all locations, except in Fletcher, N.C. This difference may be related to the relative sensitivity of these two cultivars to temperature extremes, rather than soil or geographic factors, because there was a tendency for ‘Hybelle’ yields to exceed ‘Gator Belle’ in the earliest planting date. Based on the reliability index, the chance of outperforming KRG#3 (the standard) was 85% for ‘Hybelle’, 80% for ‘Gator Belle’, but only 67% for ‘Skipper’