Produtividade e desenvolvimento de pitaya sob diferentes combinações de adubação e seletividade de herbicida

Abstract

The Hylocereus costaricensis, commonly known as pitaya, is an exotic fruit native to Tropical America, with great potential to diversify rural properties due to its high rusticity and tolerance to abiotic factors. Despite this potential, the crop is still in the early stages of adaptation in several regions, requiring further research to optimize production systems under local conditions. Two studies were carried out at the Center for Engineering and Agricultural Sciences (CECA-UFAL) with the aim of evaluating the agronomic performance of red pitaya. The first study investigated the impact of different nutrients (N, P, and K) on plant growth and yield. A randomized complete block design (RCBD) with four replications was used to test seven nutrient combinations (N, P, K, NP, NK, PK, NPK) and a control treatment in H. costaricensis (var. Costa Rica). The second study, also established under an RCBD with seven replications, evaluated the effect of different fertilizer types (chemical, organic, chemical + organic combination, and control) on the performance of the same pitaya variety. In both experiments, plants and fruits were assessed for several parameters, including cladode greenness index, main cladode height, number of cladodes, cladode length and circumference, fresh and dry mass of different plant parts, nutrient content in plant tissues, as well as fruit circumference, length, and width, °Brix, fresh fruit weight, pulp and peel weight, dry pulp and peel weight, and nutrient content in pulp and peel. A third study, conducted at the same research center, evaluated the selectivity of different herbicides in two pitaya varieties (Costa Rica and Branca Comum) and assessed phytotoxicity levels. The experiment was conducted with two Hylocereus species and six herbicide treatments (isoxaflutole, flumioxazin, imazapic, sulfentrazone, oxyfluorfen, and a control), with four replications, totaling 48 plots. After herbicide application, evaluations included phytotoxicity, number of shoots per plant, mean cladode length, cladode diameter, greenness index, total fresh mass, fresh mass per cladode, and dry mass of secondary cladodes. For all three studies, the data were subjected to analysis of variance, and means were compared using the Scott-Knott test (p < 0.05). The results demonstrated that nitrogen, either applied alone or in association with phosphorus and/or potassium, enhanced vegetative growth, whereas PK and NP combinations positively influenced fruit traits. Yield was favored by NP, NPK, PK, and P treatments, highlighting the importance of balanced fertilization. The combination of chemical and organic fertilizers promoted greater plant growth, resulting in fruits with more favorable characteristics, such as increased width, circumference, soluble solids content, and weight. The highest productivity indices were observed under combined (chemical + organic) and chemical fertilization, confirming the efficiency of these nutritional strategies to maximize pitaya yield. Overall, the order of macronutrient accumulation in plants and fruits was K > N > P, confirming the high potassium requirement of this crop. Furthermore, the active ingredients isoxaflutole, flumioxazin, imazapic, sulfentrazone, and oxyfluorfen showed no phytotoxicity in 12-month- old plants up to 100 cm in height, although they caused injuries in young tissues with new shoots. Keywords: Hylocereus; Nutrition; Fruit growing; Cactaceae; Herbicide management.