Abstract
The great challenge of breeding programs focused on tolerance to water stress is the precise, in large scale, and automated phenotyping. Therefore, the objective of this study was to assess whether the controlled conditions of SITIS Automated Phenotyping Platform and the protocol used are suitable for discriminating cultivars of common bean and soybean for tolerance to this stress. Two experiments were carried out in randomized block design, in a split plot scheme, with four replications. The main plots had five water regimes, applied after flowering: daily replacement of 100 (control), 80, 60, 40, and 20% of water evapotranspired in control. The subplots consisted of two common bean cultivars (BRS Pontal and BRS Perola) in the 1st experiment, and two soybean cultivars (MG/BR 46 Conquista and BR-16) in the 2nd one. In each species, the first cultivar is more tolerant to water stress, and the second one is more susceptible. It is possible to use the SITIS Platform and the proposed protocol to evaluate common bean and soybean cultivars for tolerance to water stress. The common bean cultivars evaluated were more sensitive to this stress than soybeans. The best water status of cultivars BRS Pontal and MG/BR 46 Conquista under water stress confirmed their greater tolerance.
Highlights
Water deficiency is the environmental factor that affects the crop yield the most
Well-watered condition was maintained until the flowering stages R6 and R2, for the common bean and soybean, respectively, when water restriction was applied by daily replacement of 20%, 40%, 60%, and 80% of water evapotranspired at the well-watered treatment
We evaluated the grain yield per plant, the number of pods per plant, the number of grains per pod, 100-grain weight and evapotranspiration after R6 and R2 stages, for the common bean and soybean, respectively
Summary
Water deficiency is the environmental factor that affects the crop yield the most. It affects various physiological factors of plants, among them the photosynthesis, the mobilization of carbohydrate, and the symbiotic fixation of atmospheric nitrogen. Decline in nitrogen (N) fixation with the water deficit in the soil causes reductions in soybean productivity due to inadequate availability of N for the production of protein, which is critical for the production of grains. With the decrease in the amount of soil water, the N2 fixed by soybean decreases, even before other physiological processes are compromised. Protein synthesis, amino acid metabolism, and cell growth are among the most altered processes in soybean nodules under drought stress (GIL-QUINTANA et al, 2013)
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