Selection of soybean lines under biotic stresses and endophytic bacteria as an alleviating factor of drought during lentil cultivation

Abstract

Biotic and abiotic stresses are predicted to raise in the future scenario of agricultural production due to escalated climate change. Those factors are going to be responsible for increasing challenges in crop production, and can possibly lower grain yield worldwide. Consequently, plant exposition to a combination of both biotic and abiotic stresses is more likely to occur in the future. Higher incidence of stink bugs and drought stresses are common issues that pose an additional threat to soybean and lentil crop productions. In this scenario, breeding programs have a crucial role in developing tolerant lines to main pests. Due to the significant attack of stink bugs on soybeans, especially Euschistus heros, which can considerably compromise grain yield and seed quality, the development of superior lines is crucial. The selection based on positive correlations between grain yield and a higher number of pods and weight of seeds has demonstrated to be an important indicator of soybean resistance to stink bug attack. Twenty-three soybean F8 lines developed by the Soybean Breeding Program of Federal University of Uberlândia and four cultivars (Msoy 8527, UFUS Xavante, Msoy 8787, and UFUS Milionária) were evaluated during the growing season of 2015/2016 and 16 agronomic traits were accessed. The lines G1, G2, and G24 are very promising genotypes as they have shown valuable agronomic traits for stink bug resistance. Besides, another concern that can drastically impact crop yields is the occurrence of drought stress. An alternative to alleviate the negative effect of drought, other than genetic breeding, is the association of crop species with beneficial growth-promoting bacteria. Thus, the direct benefit of plant growth and tolerance to drought stress by bacterially produced phytohormones could minimize the negative effect of water scarcity on lentil production. A vegetative stage experiment was aimed to evaluate the performance of lentil plants during 25 day-long period of complete water withdrawal (terminal drought). Lentil seeds were inoculated with Methylobacterium at the time of planting by adding bacterial solution to half of the pots of the experiment. Through the analysis of morphological, biometrical, and physiological parameters, the positive effect of inoculated lentils was to a high extent a result of visibly improved plant vigor, plant growth, nutrient uptake (electrolyte content), as well as optimized water management parameters (WUE, LWL). Consequently, a sustainable growth enhancer of bacterial origin could lower the negative effect of drought on lentil cultivation. Thus, plant breeding and sustainable technologies together could minimize concerning issues in the agricultural scenario such as the high incidence of stink bugs in soybeans and drought stress in lentils.