Abstract
ABSTRACT Drought stress is a limitation for the agricultural production, having as a primary effect the reduction of plant gas exchanges, and the continuity of its incidence results in a lower yield. This study aimed to evaluate the photosynthetic responses and the soybean yield, concerning the seed inoculation and foliar spray with Azospirillum brasilense and plant regulator containing auxin, gibberellin and cytokinin. A randomized complete block design was used under greenhouse conditions, with five treatments: four under drought stress (control, seed inoculation and foliar spray with A. brasilense and plant regulator) and one irrigated treatment. The soil gravimetric moisture, relative water content, CO2 net assimilation rate, apparent quantum efficiency, light compensation point and grain yield were evaluated. The water deficiency reduced the relative water content by 76.96 % and the soybean gas exchanges by 860.43 %, in the drought stress control. However, when using A. brasilense or plant regulator, the reduction of these values was mitigated, with maximum reductions of 52.40 % in the relative water content and 361.99 % in the gas exchanges. Thus, the mitigation of these effects was directly correlated with the grains yielded by plants, where the use of foliar spray with A. brasilense or plant regulator presented averages 19 % higher than the drought stress control. The applications of foliar spray with A. brasilense and plant regulator mitigate the effects of drought stress on the soybean photosynthesis and culminate in lower yield losses.
Highlights
Soybean occupies a prominent place among worldwide commodities
This study aimed to evaluate the photosynthetic and productive responses of soybean seeds inoculated with A. brasilense, as well as foliar spray with A. brasilense and plant regulator containing auxin, gibberellin and cytokinin, under induced severe drought stress
The treatments were represented by irrigated and non-irrigated controls, seed inoculation with A. brasilense, foliar spray with A. brasilense and foliar spraying with auxin, gibberellin and cytokinin (AX + GA + CK)
Summary
Soybean occupies a prominent place among worldwide commodities. Drought stress periods are one of the factors that limit the crop yield, mainly when they affect the reproductive stage, due to the abortion of leaves and reproductive structures, lower grain filling and accelerated senescence (Vieira et al 2013). The soybean crop has a water demand that varies from 450 mm to 800 mm during its cycle, with a greater need between flowering and grain filling (Souza et al 2016). In order to tolerate drought stress, the plants developed adaptive strategies to reduce losses in low water availability resulted by.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call