Fisiologia e produção do coqueiro (Cocos nucifera, L.) submetido a irrigação e fertirrigação no Nordeste Paraense.

Abstract

The coconut tree is one of the most relevant fruit trees for tropical regions due to its high economic importance, responsible for generating various products, both in natura and industrialized. In Brazil, coconut production is distributed throughout the national territory, with the most prominent states being the north and northeast regions. Pará has a rainy and less rainy season throughout the year, which requires the use of irrigation, as the plants experience a water deficit, which generates significant losses in productivity. The irrigation system can define the minimum amount of water that must be used for an economically viable and sustainable production. The objective of the study was to evaluate the influence of different fractions of reference evapotranspiration (ET0) and potassium doses on the physiological, physicochemical responses of coconut water, productivity, phenology and economy in the implanted system. The experiment was carried out at the Reunidas Sococo farm, Santa Isabel do Pará-PA. A randomized block design was used in a 5 x 5 factorial scheme, with 25 treatments and three replications (5 fractions of ET0 = S/A; 50%; 100%; 150% and 200% and 5 doses of KCl = 2, 50; 3.75; 5.00; 7.50 and 10.00 kg of KCl plant-1 year-1). A fixed irrigation shift was used for the irrigation depths and fertirrigation was applied weekly. Gas exchange evaluations were carried out 3 times in the year 2020. Fruit harvests were carried out every 21 days in the period 2020 and 2021 for further physical-chemical and productivity analyses. The phenology was evaluated monthly and the economic viability was carried out in the two years of the experiment. Data were submitted to quantitative and qualitative analysis applying analysis of variance. It is understood, therefore, that the plants maintained different behaviors for gas exchange, considering the climatic conditions as the main interference factors for the ecophysiology of the coconut tree. The results of the physical-chemical analyses, potassium doses and irrigation depths maintained values within the standards established by current legislation in Brazil. In productivity and efficiency of water use, in the two years of study, the effectiveness of the implanted system was shown, with greater production of water and fruits in 2021. The phenology stood out according to the ideal application depth of irrigation and fertigation. Thus, it is concluded that the doses of 5.00 and 7.50 kg of potassium and the depths of 100% and 150% of ET0, provided greater productivity, better vegetative development of the plants and were economically viable.