Produtos comerciais como atenuantes do estresse hídrico na cultura do milho.

Abstract

Corn is one of the most expressive crops in Brazilian and world agribusiness due to its versatility of use, both in human and animal feed. In the Brazilian semi-arid region, corn productivity is still low compared to other regions of the country, due to the non-adoption of new production technologies and mainly due to the water deficit. In this work, the objective was to evaluate the potential of commercial products in the attenuation of the water deficit in the corn crop through their effects on gas exchange, growth, production and grain quality. The research was carried out in the field, at the Experimental Farm of the CCTA/UFCG, using a randomized block design, in subdivided plots in space, with a 6 ⨯ 2 factorial scheme, with the treatments consisting of the use of five commercial products (No. Nema + Azokop, Biobaci, Azokop, Arbolina and CoMO Max ) plus the control treatment and application of two irrigation depths (100% and 50% ETc). In plants, gas exchange, water use efficiency, leaf area index, plant height, stem diameter, leaf nitrogen content, weight of 1.000 grains, ear weight, grain yield were evaluated. The dependent variables were submitted to analysis of variance and test of means (LSD) at the 5% probability level. Under conditions of adequate water supply (100% of ETc), products containing plant growth-promoting bacteria or Co+Mo increased the photosynthetic rate of hybrid corn K9555VIP3. Under severe water restriction (50% of ETc), the tested products did not affect the photosynthesis of the crop. The growth in height and diameter of hybrid corn K9555VIP3 were not affected by the tested products, neither under water restriction nor under adequate water supply. However, the arboline product increased the leaf area index. Products containing plant growth promoting bacteria; especially No-Nema (Bacillus amyloliquefaciens) + Azokop (Azospirillum brasiliensis) and Biobaci (Bacillus subtilis) promoted improvement in corn nitrogen nutrition with the increase in total N content. The tested products did not interfere with corn productivity, when grown under adequate water supply. When cultivated under severe water restriction, Biobaci+Nonema and Azokop products can reduce productivity losses due to water deficit.