Abstract
The objective of this study was to evaluate the levels of chlorophyll and agronomic performance of Bt and non-Bt soybeans. For the evaluation we used the chlorophyll meter (SPAD-502), which was collected randomly in the upper third (TS), middle third (TM) and lower thirds (TI). Evaluations were performed at 7, 14, 21, 28, 35, 42, 49, 56, 63, and 70 days after emergence (DAE). Used the randomized experimental design in a split plot design (2 x 3 x 10) with four replicates for analysis of chlorophyll content and factorial 2 x 2 (two cultivars and two regions) with four replications for the factors of production. For the region of Dourados, the highest chlorophyll levels were presented to 42 DAE for soybeans Bt and non-Bt, the TS and TI, for TM at 42 DAE for soybeans Bt and non-Bt to 35 DAE. In Douradina the highest levels of chlorophyll were for soybean at 28 DAE Bt and non Bt at 49 DAE in the lower third. For TM and TS cultivars Bt and non-Bt had higher chlorophyll content at 35 DAE. From the results obtained, it can be concluded that the Bt technology did not influence the chlorophyll content of soybean, the two cultivars showed similar levels, with higher concentrations in the middle third of the plants in the two regions studied. For agronomic attributes, plant height, first pod height, number of pods per plant and yield, Bt soybeans had higher values compared to non-Bt soybeans in two environmental studies.
Highlights
Soybean [Glycine max (L.) Merrill] is a major crop exotic Brazilian agribusiness, with great economic importance in grain exports and its derivatives, and has advantages such as higher yield potential and greater uniformity morphological and phenological, which facilitate crop management (Neves et al, 2013; Antunes et al, 2012)
For the region of Dourados, the highest chlorophyll levels were presented to 42 days after emergence (DAE) for soybeans Bt and non-Bt, the TS and TI, for TM at 42 DAE for soybeans Bt and non-Bt to 35 DAE
It can be concluded that the Bt technology did not influence the chlorophyll content of soybean, the two cultivars showed similar levels, with higher concentrations in the middle third of the plants in the two regions studied
Summary
Soybean [Glycine max (L.) Merrill] is a major crop exotic Brazilian agribusiness, with great economic importance in grain exports and its derivatives, and has advantages such as higher yield potential and greater uniformity morphological and phenological, which facilitate crop management (Neves et al, 2013; Antunes et al, 2012). Despite the great advances in technology Bt represents to world agriculture, their adoption in some regions may be affected positively or negatively, depending on the characteristics of each locality (Barros & Degrande, 2012). Soybean yield is defined by the interaction of the plant with the environment and management (Pereira et al, 2011), high yields are only obtained when such conditions are favorable, at all stages of crop growth.
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