Agronomic Performance of Wheat Cultivars under Different Sowing Densities in Southern Brazil

Sowing density is one of the management techniques that most influence wheat crops. This management practice may affect the plant productive behavior, leading to changes in tillers growth, and also interferes with the plant architecture by influencing solar radiation uptake by the plant canopy, the production components and grain yield. This work aimed to assess the agronomic performance of two wheat cultivars (low tillering and high tillering) under influence of four sowing densities. The experiment was conducted in field conditions from July to November 2017. The experimental design consisted of randomized blocks with split-plots and five replicates. The factors consisted of two wheat cultivars in main plot (TBIO Sossego and TBIO Toruk), subjected to four different sowing densities as sub-plots (208; 312; 416 and 500 viable seeds m-2). Morphological characteristics, relative chlorophyll content, NDVI, production components and grain yield were evaluated. Among the assessed traits, only the stem diameter was affected by sowing density. The highest plant height, peduncle length and flag leaf length were found in cultivar Sossego, whereas the largest stem diameter was observed in cultivar Toruk. Relative chlorophyll content and NDVI were higher in cultivar Sossego. The agronomic performance of the cultivar Sossego was higher and exceeded the grain yield of Toruk at 673 kg ha-1. Suboptimal sowing densities promote a decrease in the productive performance of wheat and under conditions of rainfall limitation and genetic potential of reduced tillering while sowing densities above the recommended ones are more efficient.