Relações hídricas do mamoeiro, cv. tainung 1, com aplicação de antitraspirantes foliares

Abstract

The cultivation of papaya stands out in terms of economic importance in Brazil, which has maintained its position as the second world producer in the last two decades. However, researches have been paying attention to records of reduction of planted areas and fruit production drops, mainly due to changes in environmental conditions. Among the biggest challenges in this scenario is the use of irrigation efficiently to optimize the efficiency of water use without reducing crop productivity. For this, techniques must be explored for all crops of great economic importance and sensitivity to water deficit. Currently, a technique that is being studied is the foliar application of antiperspirants that form a particle film, such as hydrated aluminum silicates (kaolin). These attenuate the effect of excess solar radiation, reducing leaf temperature and water loss through transpiration. This work aimed to evaluate the aspects of the water-soil-plant relationship in the cultivation of papaya, cv. Tainung 1, under application of kaolin-based foliar antiperspirants. The experiment was carried out at Embrapa Cassava e Fruticultura, with the papaya crop, cv. Tainung 1, cultivated in drainage lysimeters following a completely randomized design, with four replications. Plants in the flowering and fruiting phase were sprayed with Kaolin and Surround WP syrups at concentrations of 0, 3 and 5%. Absolute growth rate, gas exchange, leaf chlorophyll index, leaf temperature, chlorophyll fluorescence, soil water balance and sap flow were evaluated. The sap flow was measured by the heat pulse method. The results showed that the use of foliar antiperspirant does not influence papaya growth. Stomatal conductance, as well as transpiration and CO2 assimilation were not influenced by the use of foliar antiperspirant at different concentrations. However, the time of evaluations and their respective air DPV influenced the stomatal conductance and leaf temperature of the papaya tree. With the exception of Kc in plants sprayed with Surround WP, the water balance in the soil cultivated with papaya was not influenced by the use of foliar antiperspirants. The crop evapotranspiration, in the monitored period, ranged from 8.24 to 9.57 mm. The sap flow was higher in papaya plants sprayed with Surround WP at 5% concentration. The action of the foliar antiperspirants Kaolim and Surround WP as a thermal conditioner for the papaya crop was not verified.