Crescimento, fisiologia e produção de palma forrageira sob regimes hídricos e adubação orgânica.

Abstract

The forage cactus stands out as one of the plants with the greatest potential for biomass production and cultivation expansion in the Brazilian semiarid region, but there are still few studies addressing the issues of improving the management of recently used varieties, such as those resistant to carmine mealybug, especially in relation to irrigation and fertilization using alternative organic sources. The present work aimed to evaluate the growth, physiological and productive aspects of the Orelha de Elefante Mexicana (Opuntia stricta (Haw.) Haw.) and the Negro Michoacan (Opuntia atropes Rose) forage cactus varieties fertilized with biomass ash and bovine manure in rainfed and irrigated systems. The experiment was conducted under field conditions at the Ignacio Hernán Salcedo Experimental Station of the National Institute of the Semiarid in the municipality of Campina Grande-PB, during the period from November/2019 to November/2020. The treatments were arranged in randomized blocks, in a 2 × 2 × 5 factorial scheme, consisting of two water regimes (rainfed and irrigated), two doses of bovine manure (0 and 33.3 Mg ha-1), five doses of biomass ash (0; 1.3; 2.6; 3.9 and 5.2 Mg ha-1) and three repetitions, totaling 60 experimental units for each variety of forage cactus. Growth characteristics evaluated: plant height and length, number, length, width and thickness of primary, secondary, tertiary and quaternary cladodes; physiological characteristics: internal carbon concentration (ci), transpiration (E), stomatal conductance (gs), CO2 uptake rate (A), momentary water use efficiency (EmUA), intrinsic water use efficiency (EiUA) and instantaneous carboxylation efficiency (EiC); and production characteristics: green matter productivity (GMP), dry matter content (DM), dry matter productivity (DMP), plant water accumulation (ACA), water use efficiency (WUE), sheep feeding capacity (CSO), cow feeding capacity (CSV), and mortality rate (TM). The data was subjected to exploratory factor analysis (AF) with multivariate statistics. Irrigation, bovine manure and biomass ash significantly influenced the growth, physiology and production variables of the two forage cactus varieties analyzed, except for secondary cladode length, internal carbon concentration, transpiration and mortality rate in the Negro Michoacan variety. The treatment that allowed greater productivity of green matter for the forage cactus Orelha de Elefante Mexicana (257.9 Mg ha-1) was associated with irrigation and fertilization with cattle manure. For the cultivation of this variety under rainfed conditions, the application of 33.3 Mg ha-1 of bovine manure is recommended. The maximum yield obtained for the Negro Michoacan variety occurred through irrigation and organic fertilization with cattle manure and 1.3 Mg ha-1 of biomass ash. Under rainfed conditions, it is recommended to apply 33.3 Mg ha-1 of cattle manure and 3.9 Mg ha-1 of biomass ash.