Aspectos produtivos, morfofisiológicos e nutricionais de genótipos de capim-elefante de diferentes portes consorciados com cunhã

Abstract

This study aimed to evaluate productive, morphophysiological and nutritional aspects of elephant grass genotypes (Cenchrus purpureus Schum. Syn. Pennisetum purpureum Schum.), with different sizes, under monocropping and from their intercrops with the butterfly pea (Clitoria ternatea L.). Elephant B and IRI-381 (tall-sized genotypes), besides the dwarf Mott and Taiwan A-146 2.37 and the forage legume were assessed in 2019 and 2020. Greater annual herbage accumulation (P < 0.0001) was observed in the harvesting of Elephant B under monocropping (19.3 t ha-1 year-1). The greatest yield stability occurred in the ‘Mott + butterfly pea’ intercropping (σi2 = 0.10), while the Elephant B under monocropping was less stable (σi2 = 5.59). Greater butterfly pea’s competitiveness indexes were observed in the intercrops with dwarf Mott (3.31) and Taiwan A-146 2.37 (3.14). Forage harvested from Taiwan A-146 2.37 under monocropping and that one from its intercropping with the butterfly pea showed greater proportions (P < 0.0001) of true soluble protein (610 and 621 g kg-1 CP, respectively) and lower ones of acid detergent insoluble protein (41 and 43 g kg-1 CP, respectively). In the forage harvested from dwarf Mott and Taiwan A-146 2.37, under monocropping, there were greater (P = 0.0148) coefficients of in vitro digestible dry matter (755 and 745 g kg-1, respectively), while the forages obtained from the intercrops had lower digestibility. Greater coefficients of light extinction (0.47), leaf area index (3.82) and non-fiber carbohydrates content (NFC) (181 g kg-1 DM) were observed in the dwarf Mott canopies. Greater NFC content also was found in the forage obtained from the intercrops (178 g kg-1 DM). Elephant B, a tall-sized genotype, presents morphological traits that favor the forage production. Dwarf Mott and Taiwan A-146 2.37 show morphological characteristics that favor the forage nutritional value. Butterfly pea’s inclusion in the system improves the stability for herbage accumulation. Butterfly pea’s inclusion enhances the crude protein content with a great proportion of digestible proteins, and reduces the forage digestibility. Both the morphological composition and structural traits of the dwarf Mott favor the synthesis of non-fiber carbohydrates in the vegetal tissue. Butterfly pea’s inclusion into the system does not reduce the light-use efficiency by plants, neither reduces the penetration of photosynthetically active radiation until the canopy basis.