Water regimes on soil covered with plastic film mulch and relationships with soil water availability, yield, and water use efficiency of papaya trees

Abstract

Plastic film mulches have the potential to be used in papaya production, mainly aiming to reduce water application in semi-arid regions. However, there is a lack of technical information and the need to introduce mulching practices in papaya orchards. The objective of this work was to evaluate the effects of plastic film mulch and irrigation depths on soil water availability (SWA), stomatal conductance, leaf temperature, and agronomic traits of papaya trees. The study was carried out during 2018 and 2019 in Jaíba city, located northern Minas Gerais state, in the Brazilian semi-arid region. The experiment was a split plot design, with soil cover conditions assigned to the plots (bare soil and mulched soil) and water replenishment levels to subplots (25%, 50%, 75%, 100% and 125% of crop evapotranspiration [ETc]). Plants were drip irrigated with water replenishments based on climate data. Soil moisture was measured along time and agronomic and physiological characteristics of papaya trees, as well. Water tensions were higher in treatments with lower water replenishments. Results showed that the increase in irrigation depth favors leaf-area growth rate, stomatal conductance, yield, and water footprint of papaya. The use of mulch together with the increase in water replenishment levels contributes for maintenance of the soil water content between the upper limit of SWA and 75%SWA. The use black plastic mulching with drip irrigation in medium-textured soil saves up to 152 L of water per Kg of fruit, and increase productivity up to 34% by replenishing the crop evapotranspiration every irrigation event. The use of black plastic as ground cover is technically feasible for keeping soil water availability above 75% by irrigation supply of at least 75% of ETc on sand-clay-loam soil.