Variation of Thermal Time, Phyllochron and Plastochron in Passion Fruit Plants With Irrigation Depth and Hydrogel

The passion fruit demands water for its growth and production. Water management is relevant in regions characterized by low rainfall indices, such as semi-arid regions. In this direction, the use of hydrogel in the soil allows the water that is supplied through irrigation to be better utilized by the plants, reducing leach losses. The objective of this experiment was to evaluate the influence of hydrogel in soil cultivated with passion fruit and irrigated to various water depths on the thermal time of the phenological stages, phyllochron and plastochron of the plants. Treatments were distributed in randomized blocks in a 2 × 5 factorial arrangement, referring to the soil without and with hydrogel and raising the irrigation depth from 60% to 70%, 80%, 90% and 100% of crop evapotranspiration in four replications. The thermal requirements of the phenological phases and of the whole plant cycle, phyllochron of the main stem and the productive branches, and plastochron were evaluated. Increasing the irrigation depth from 60% to 100% reduced the total thermal time values from 3,811.8 to 2,401.3 °C day and from 3,707.8 to 2,628.7 °C day in the soil without and with hydrogel, respectively. The thermal time of the phenological phases and the phyllochron of the main stem and productive branches of the passion fruit were stimulated by an increase in irrigation depth.