Abstract
This study aimed to evaluate the relationship among traits related to yield and nutritive value of alfalfa genotypes grown under deficit and full irrigation conditions. Seventy-seven alfalfa genotypes were evaluated in two different cuts, the first one with full irrigation, and the second, with water deficit. A randomized block design with three replications was used. The evaluated traits were vigor, plant height, dry matter biomass, stem-to-leaf ratio, dry matter percentage, leaf and stem protein contents, in vitro dry matter digestibility, neutral detergent fiber, acid detergent fiber, and lignin. Significant interaction between genotypes and environments was reported for vigor, plant height, and lignin. The correlation between traits and path analysis of dry matter biomass was performed for each cut, aiming to identify auxiliary traits for indirect selection. Water availability did not alter the phenotypic and genotypic correlations, only their magnitudes. Regardless of the environment, plant height is one of the most promising traits for the selection of alfalfa genotypes with higher dry matter biomass since it showed a high direct effect in the same sense of its phenotypic correlations. However, the coefficient of determination obtained by the model applied to full irrigation was higher than that of the water-deficit environment, indicating the importance of variables not included in this study in the determination of alfalfa dry matter biomass under dry conditions.
Highlights
Alfalfa (Medicago sativa L.) is one of the most important forage plants in temperate climate countries (ANNICCHIARICO et al, 2015; FERREIRA et al, 2008), either by the range of explored area, or by its interesting traits, such as high productivity and protein content, which guarantees the culture the possibility of using in the feeding of specialized dairy herds, with excellent results in milk production (COMERON t al., 2015)
This study aimed to evaluate the relationship among traits related to yield and nutritive value of alfalfa genotypes grown under deficit and full irrigation conditions
The factors that limit the use of alfalfa in productive systems are related to the lack of knowledge of cultivation techniques and the low availability of cultivars adapted to tropical conditions (BOTREL et al, 2001; FERREIRA; VILELA, 2015)
Summary
Alfalfa (Medicago sativa L.) is one of the most important forage plants in temperate climate countries (ANNICCHIARICO et al, 2015; FERREIRA et al, 2008), either by the range of explored area, or by its interesting traits, such as high productivity and protein content, which guarantees the culture the possibility of using in the feeding of specialized dairy herds, with excellent results in milk production (COMERON t al., 2015). The factors that limit the use of alfalfa in productive systems are related to the lack of knowledge of cultivation techniques and the low availability of cultivars adapted to tropical conditions (BOTREL et al., 2001; FERREIRA; VILELA, 2015). Several studies related to alfalfa drought tolerance have been developed in recent years. Zhang et al (2017) investigated the genetic diversity and phenotypic variation for drought tolerance in alfalfa germplasm; Archad et al (2017) examined the response of transgenic alfalfa plants that super expressed the miR156 microRNA from drought tolerance; Molor et al (2016) performed a comparative analysis of morphological and physiological parameters and selection of droughttolerant cultivars; Qiao-li et al (2015) performed proteomic analysis to evaluate drought stress on seedlings; and Zhang et al (2015) identified molecular markers related to drought resistance and water-use efficiency Several studies related to alfalfa drought tolerance have been developed in recent years. Zhang et al (2017) investigated the genetic diversity and phenotypic variation for drought tolerance in alfalfa germplasm; Archad et al (2017) examined the response of transgenic alfalfa plants that super expressed the miR156 microRNA from drought tolerance; Molor et al (2016) performed a comparative analysis of morphological and physiological parameters and selection of droughttolerant cultivars; Qiao-li et al (2015) performed proteomic analysis to evaluate drought stress on seedlings; and Zhang et al (2015) identified molecular markers related to drought resistance and water-use efficiency
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