Sensitivity of leaflet growth rate to drought predicts yield in common bean (Phaseolus vulgaris)

Although drought limits yield by decreasing photosynthesis and therefore biomass accumulation, biomass is not the strongest predictor of yield under drought in common beans (Phaseolus vulgaris L.). Instead, resource partitioning from pod walls into seeds is a stronger correlate. Our aim was to determine whether growth rates of developing leaflets and pods, as independent indicators of sink strength, predict resource partitioning into seeds. Using 20 field-grown genotypes, we paired biomass, yield, and resource partitioning data with leaflet and pod growth rates under well-watered and droughted conditions. We hypothesised that genotypes with faster growing leaflets and pods under drought would fill seeds better. However, we found that leaflet and pod growth rates did not predict partitioning to seeds; rather, sensitivity of leaflet growth rate to drought was a good predictor of yield reduction. Further, plants with rapidly growing leaves under well-watered conditions were most vulnerable to decreases in leaflet growth rate under drought. This suggests that lines that inherited a conservative growth strategy were better able to maintain yield by allocating resources to seeds. Our findings indicate that inherent sensitivity of leaflet growth rate to drought may be used as a predictor of partitioning and yield in common beans.

Humic Acid and Biofertilizer Applications Enhanced Pod and Cocoa Bean Production during the Dry Season at Kaliwining Plantation, Jember, East Java, Indonesia

Cocoa (Theobroma cacao L.) is an important crop in Indonesia, but many farmers still face problem in improving bean production. This research aimed to evaluate the effect of humic acid and biofertilizer applications on pod growth and yield of cocoa. The research was conducted at Kaliwining Plantation managed by Indonesian Coffee and Cocoa Research Institute at Jember District, East Java, Indonesia from June 2017 to February 2018. The experiment used mature tree of Sulawesi from one clone. Treatment used were humic acid at level of 0, 1000, 2000, 3000 and 4000 ppm in combination with biofertilizer at level of 0, 500, 1000, 1500 and 2000 ppm that were applied through soil and foliar respectively. Results of this experiment showed that there was an interaction between humic acid and biofertilizer on beans number per plant and photosynthesis rate. Plants treated with 1000 ppm humic acid produced the highest number of small cherelle. Biofertilizer applied at 1500 ppm increased cherelle number, healthy cherelle, number of young pods, number of harvested pods, bean weight per plant and bean yield. The combination of 1000 ppm humic acid and 1500 ppm biofertilizer increased bean production by 39.7%. The high bean production was in line with the high photosynthetic rate. Thus, humic acid and biofertilizer applications could be a way to increase cocoa bean production in this area.

Drought sensitivity of leaflet growth, biomass accumulation, and resource partitioning predicts yield in common bean

ABSTRACTWhile drought limits yield largely by its impact on photosynthesis and therefore biomass accumulation, biomass is not the strongest predictor of yield under drought. Instead, resource partitioning efficiency, measured by how much total pod weight is contained in seeds at maturity (Pod Harvest Index), is the stronger correlate in Phaseolus vulgaris. Using 20 field-grown genotypes, we expanded on this finding by pairing yield and resource partitioning data with growth rates of leaflets and pods. We hypothesized that genotypes which decreased partitioning and yield most under drought would also have strongest decreases in growth rates. We found that while neither leaflet nor pod growth rates correlated with seed yield or partitioning, impacts to leaflet growth rates under drought correlate with impacts to yield and partitioning. As expected, biomass production correlated with yield, yet correlations between the decreases to these two traits under drought were even stronger. This suggests that while biomass contributes to yield, biomass sensitivity to drought is a stronger predictor. Lastly, under drought, genotypes may achieve similar canopy biomass yet different yields, which can be explained by higher or lower partitioning efficiencies. Our findings suggest that inherent sensitivity to drought may be used as a predictor of yield.HIGHLIGHTIn common bean, higher biomass accumulation under drought alone does not guarantee higher yield, as maintenance of higher growth rates and partitioning processes act as an additional requirement.