Comportamento do maracujazeiro amarelo sob condições de estresse salino.

Abstract

The present study had as objective of studying the effects of different levels of salinity of irrigation water from germination to the crop of passion fruit (Passiflora edulis Sims. / flavicarpa Deg.). For the purpose, three experiments were carried out. In the first experiment, accomplished in greenhouse, the effects of 8 levels of salinity of the irrigation water - ECW (1.0; 2.0; 3.0; 4.0; 5.0; 6.0; 7.0 and 8.0 dS m"!) were studied on germination vigor and formation of seedling. In the second experiment, also accomplished under conditions of greenhouse, the growth, development and production of the crop under 5 levels of ECW (1.0; 2.0; 3.0; 4.0 and 5.0 dS m"1) utilising seedlings produced with respective water were appraised. In the third experiment conducted in field conditions, the effects of 5 levels of ECW (0.2; 2.0; 3.0; 4.0 and 5.0 dS m"1) utilising seedlings produced in normal conditions. The experimental design adopted for the three experiments was the completely randomized. In the preparation of the irrigation waters, for the first and second experiment, NaCl, CaCh.211:0 and MgCk6H;0 salts were utilised, maintaining the equivalent proportion of 7:2:1 among Na:Ca:Mg, respectively, while in the third experiment, NaCl was used in the preparation of the irrigation waters. The results obtained allow to conclude that during germination of the passion fruit plant, the salinity caused a delay, on an average of 5 days, the critical value of ECW being of the order of 4.43 dS m"1. The seedling's vigor decreased linearly with the increment of ECW, the root system being the most sensitive; the effects of the salinity intensified with the age of the plants, critical value being ECe s of 5.61 and 2.73 dS m"1, respectively, at 32 and 77 days after planting, with a mean decrease of 7.6%, for unit increment of ECe s above the respective critical value; in the growth stage and development, the salinity affected the vegetative development as well as the production under greenhouse conditions, the same of being true for field conditions. Based on the obtained results, it can be said that the water with ECW < 4.0 dS m"1 may be used in the production of seedlings of passion fruit, with good perspectives of growth recovery later in field and that the passion fruit plant is tolerant to the salinity during the germination and moderately tolerant to the salinity in the other phases.