Palma forrageira fertirrigada no semiárido brasileiro: estimativa meta-analítica da produtividade, estado nutricional e composição bromatológica.

Abstract

The objective of this study was to evaluate forage cactus varieties grown under different levels of reference evapotranspiration (ETo) replacement in the Brazilian semi-arid region, obtaining preliminary meta-analytical information and crop productivity predictability, as well as quantifying components of nutritional status and bromatological composition of crop production. The estimation of productivity gain was performed using systematic review and meta-analysis. To determine the nutritional status and bromatological composition, a randomized field experiment was carried out in a 3x5 factorial scheme, with three forage cactus varieties (Baiana, Miúda and Orelha de Elefante Mexicana) and five reference evapotranspiration replacement levels (25, 50, 75, 100 and 125% of ETo) with three replicates. Macronutrients, N, P, K, Ca, Mg and S, and Cu, Fe, Mn, Zn, Cl, Na and B were evaluated, as well as dry matter, mineral, crude protein, ethereal extract, fibers insoluble in neutral and acid detergents, total and non-fibrous carbohydrates. It was found that irrigated forage palm crops promoted a productivity increase of 53.54 t ha-1 year-1 when compared to rainfed crops. The soil water replacement level of 75% of ETo provided a better balance between nutrients in the cladodes of the ‘Baiana’ and ‘Miúda’ forage cactus varieties. The ‘Orelha de Elefante Mexicana’ variety had a better nutritional balance with 100 and 125% ETo replacement levels. The replacement levels of 100 and 125% of the ETo promoted a high accumulation of Na+ and Cl- ions in the cladodes of the forage cactus varieties. Among the varieties, the ‘Orelha de Elefante Mexicana’ had a greater capacity for nutrient accumulation, followed by ‘Baiana’ and ‘Miúda’, respectively. It was verified that the ‘Baiana’ variety obtained higher levels of crude protein and acid detergent insoluble fibers with 85% ETo replacement. The ‘Miúda’ variety accumulated higher content of dry matter and insoluble fibers in neutral detergent, requiring a 60% replacement of ETo. The ‘Orelha de Elefante Mexicana’ variety had higher accumulation of mineral matter and production of non-fibrous carbohydrates, being recommended 90% replacement of ETo for its maximum performance.