REGULATED DEFICIT IRRIGATION AND DIFFERENT MULCH TYPES ON FRUIT QUALITY AND YIELD OF WATERMELON

ABSTRACT The objective of this work was to assess the pulp resistance, soluble solids and yield of watermelon fruits grown under different irrigation managements (determined by the ISAREG model) and mulches, and their interactions. After a survey carried out on local producers, two experiments were conducted, using a completely randomized block design in split-plot arrangement with four replications, in the Teaching, Research and Extension Unit (UEPE) of the Federal Institute of Ceara (IFCE), Jaguaribe-Apodi Irrigation District (DIJA), State of Ceara, Brazil. The treatments consisted of four irrigation managements in the plots, M1 (100% of the available-water capacity (AWC) of the soil), M2 (80%), M3 (60%) and M4 (average water depth used by local producers) and four mulch types in the sub-plots, without mulching (C0) with rice husk (C1), white plastic (C2) and black plastic (C3) as mulches. The results were subjected to analysis of variance, and significant results were subjected to regression (irrigation managements), average test (mulches) and trend graphs (interaction between the factors). The irrigation management practiced during the watermelon crop cycle by the local producers of the Irrigation District of Jaguaribe-Apodi (DIJA) in the State of Ceara, Brazil, is not appropriated, since they usually apply more water than the highest water depth determined by the ISAREG model (100% of the AWC). The plants grown under irrigation water depth of 365.20 mm (M1) and soils with mulches of rice husk or white plastic had the highest yields and fruits with better quality of soluble solids and pulp resistance.

摘要 本研究旨在评估不同灌溉管理（基于ISAREG模型制定）与覆盖方式下种植的西瓜果实的果肉坚实度、可溶性固形物含量及产量，并分析二者的交互作用。本研究在对当地种植户开展调研后，于巴西塞阿拉州雅瓜里贝-阿波迪灌区（DIJA）的塞阿拉联邦研究所（IFCE）教学、研究与推广单元（UEPE）设置两项试验，采用裂区设计的完全随机区组设计，设置4次重复。试验主区包含4种灌溉管理方式：M1（达到土壤100%有效持水量（available-water capacity, AWC））、M2（80%有效持水量）、M3（60%有效持水量）以及M4（当地种植户常规灌溉水深）；副区包含4种覆盖方式：无覆盖（C0）、稻壳覆盖（C1）、白色地膜覆盖（C2）与黑色地膜覆盖（C3）。试验数据采用方差分析进行处理，对显著结果分别开展回归分析（灌溉管理方式）、均值检验（覆盖方式）及趋势图绘制以分析两因子间的交互作用。结果表明，巴西塞阿拉州雅瓜里贝-阿波迪灌区当地种植户在西瓜全生育期采用的灌溉管理方式并不合理，其常规灌溉水深高于ISAREG模型确定的最大灌溉水深（即土壤100%有效持水量对应的灌溉量）。当灌溉水深为365.20 mm（对应M1处理）且采用稻壳或白色地膜覆盖时，西瓜产量最高，果实的可溶性固形物含量与果肉坚实度均表现更佳。