Suplementação foliar com zinco como estratégia para atenuar os efeitos de déficit hídrico em soja (Glycine max L.)

Abstract

The global population grows exponentially and with it the need to increase food production. Within this context, soy production will play a fundamental role, since soy is the main source of vegetable protein in the world. However, the main environmental factor that negatively affects the productivity of several crops, including soybeans, is the water deficit. Management strategies such as mineral supplementation have been identified as a way to minimize the harmful effects of water deficit. Thus, the objective was to evaluate the viability of supplementation with the micronutrient Zn in attenuating the deleterious effects caused by the low water content in soybean (Glycine max L.). For this, an experiment was carried out with a completely randomized design, in a 2x4 factorial scheme, with 5 replications. The factors of variation were two water conditions (irrigated and water deficit) and four doses/sources of Zn (300 mg Zn L-1

and with 600 mg Zn L-1

, using ZnO as a source; 300 mg Zn L-1

sulfate of zinc PA and water in MOCK treatment). Collections were carried out to assess biometric, biochemical and photosynthetic parameters during the period of maximum stress and 5 days after rehydration. In addition to production components at the end of the experiment. The water deficit reduced the growth parameters (height, number of leaves, and nodes) in the period of maximum stress and production, and supplementation with Zn was not enough to minimize such reductions. After rehydration, supplementation is also not sufficient for a faster recovery of the plants. Even so, some biochemical changes in the supplemented plants drew attention. As the proline content in the period of maximum stress was about 6 times higher in the roots of plants treated with 600 mg Zn L-1 when compared to irrigated plants of the same treatment. The ZnSO4 source promoted a greater accumulation of sugars in plant roots under water deficit conditions in the period of maximum stress, mainly soluble sugars. In all options and Zn source, as leaves of irrigated plants, lower MDA and H2O2 content compared to those underwater deficit, except for those that were supplemented with 600 mg Zn L-1

, which did not differ from those supplied with water. Thus, in general, it can be observed that soybean plants under water deficit seek a strategy to minimize the effects of water stress against different doses and sources of applied Zn. Despite this, growth and production were compromised, which can be explained by the severity of the stress caused and that, probably, in a less severe drought event, supplementation with Zn can be beneficial to the plants.