Abstract
ABSTRACT: The aim of this study was to investigate the effect of heat stress on 12 bean genotypes through the analysis of their reproductive biology in terms of flowering, pollen viability, meiotic behavior, and production. Plants were grown in a climate chamber at 25-20 °C (day and night) and at a high temperature treatment 37-26 °C (day and night) from the vegetative (V4) development stage to physiological maturity. The experimental design was 2 × 12 factorial arrangement with six replications and the factors consisted of heat treatments and genotypes. In three replications, the number of newly opened flowers was checked daily. At physiological maturity, the following traits were evaluated: percentage of pod set, number of pods, number of viable seeds, number of aborted seeds, 100 seed weight, and seed yield (g per plant). The other three replications were used to collect flowers to create slides to study viability of the pollen grain and analyze the meiotic behavior. The heat treatment factor significantly affected the following traits: total number of pollen grains, number of flowers, number of pods, pod set, number of viable seeds, 100 seed weight, and seed yield. The raised temperature reduced these variables, except for percentage of pod set, and increased meiotic irregularities. The mean values regarding seed yield were 16.39 g per plant for the control treatment and 7.46 g per plant under high temperature. IAC Imperador, FT Nobre, Perola, BRS Estilo, and IAC Diplomata stood out for higher bean seed yield under increased temperature.
Highlights
In Latin America and in Africa, dry bean (Phaseolus vulgaris L.) production is highly vulnerable to the effects of climate change, mainly higher temperatures and drought
This study investigated the effects of stress caused by high temperature on 12 bean genotypes, studying their reproductive biology through monitoring flower production, analysis of pollen grain viability, meiotic behavior, and pod set, as well as their yield potentials
The influence of high temperature on the total number of pollen grains assessed was observed when the germination technique was used in relation to the staining technique
Summary
In Latin America and in Africa, dry bean (Phaseolus vulgaris L.) production is highly vulnerable to the effects of climate change, mainly higher temperatures and drought. Recent studies on climate modeling suggest that over the decades, higher temperature will be the main threat to bean production with possible drastic reductions in planted area by 2050 (CGIAR, 2015). Hatfield and Prueger (2015) emphasize that the effect of extreme temperatures on plant development has not been treated as the main effect during the pollination phase and that plants exposure to heat in this phase has considerable impact on yield for all plant species. The authors reported that yield reduction was caused by abscission of flower buds, flowers, and newly formed pods and by failure to fertilize. Monterroso and Wien (1990) verified that the pre-fertilization period is more sensitive to heat stress, causing roughly 82 % of abscission of newly formed pods The authors reported that yield reduction was caused by abscission of flower buds, flowers, and newly formed pods and by failure to fertilize. Monterroso and Wien (1990) verified that the pre-fertilization period is more sensitive to heat stress, causing roughly 82 % of abscission of newly formed pods
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