Estratégias de irrigação para o coqueiro-anão-verde: análise produtiva e econômica sob diferentes lâminas de irrigação em Santa Isabel do Pará - PA.

Abstract

The coconut palm (Cocos nucifera L.) is a perennial fruit palm of great global socioeconomic importance due to the diversity of products and byproducts derived from it. In Brazil, the North region stands out as one of the main producers, with Pará ranking third nationally in green dwarf coconut production, especially in the Northeast of Pará. Aiming to increase production and mitigate water deficits during the dry season, the use of irrigation systems has expanded for various fruit species. Interest in coconut irrigation has also emerged, as prolonged water scarcity can compromise productivity, given the sensitivity of the green dwarf coconut palm to water deficits. Irrigation management based on crop evapotranspiration is an excellent water resource management tool; however, irrigation practices are still incipient, resulting in wasted water and economic resources. Thus, this study aimed to evaluate the influence of different irrigation depths on production parameters, fruit yield, and water productivity in terms of fruits and coconut water, as well as the economic viability of producing dwarf coconut palms under these depths. The experiment was conducted at the Reunidas Sococo Farm, in the municipality of Santa Izabel do Pará, Pará, between 2023 and 2025, in a randomized complete block design with four treatments and six blocks. The treatments corresponded to the application of four water depths based on fractions of coconut palm evapotranspiration (Dryland, 50% ETc, 100% ETc, and 125% ETc). The plants were irrigated daily during the less rainy season by a micro-sprinkler system, with one emitter per plant. Productivity was monitored every 21 days with 24 replicates, with assessments of fruit number, fruit weight, and fruit water volume. Additionally, the leaf water potential of plants subjected to treatments was evaluated in experimental campaigns conducted during the rainy and less rainy seasons using a Scholander pressure pump. Finally, water productivity was calculated in terms of number of fruits and accumulated water volume throughout the period for each treatment. All statistical analyses were performed at a significance level of p < 0.05. The results showed that the leaf water potential of irrigated plants differed significantly from that of the dryland treatment in the pre-morning period, but there were no significant differences during the day in the less rainy season, while during the rainy season there were no differences between treatments at any of the analyzed time points. There were significant differences in production parameters and fruit yield, demonstrating that the irrigated treatments, especially 125% ETc, were superior to the dryland treatment, demonstrating an 11.89% increase in fruit mass, 15.1% in fruit water volume, 14.7% in fruit water mass, and 32.1% in fruit yield. Water productivity was significant only for fruit production, demonstrating the superiority of the irrigated treatments; however, it did not differ for water volume. In the economic analysis, all treatments demonstrated viability over a 12-year planning horizon, with the irrigated treatments standing out, as they proved more resilient to potential project risks. The 125% ETc management regime was the most significant and robust to pessimistic scenarios.