Extrato de microalgas enriquecido com cálcio como atenuador da salinidade da água no crescimento e fisiologia de mudas de mamoeiro

Abstract

The present study evaluated the effect of microalgae extract enriched with calcium (EMa-Ca) in mitigating salt stress in Formosa papaya seedlings (Tainung-1 hybrid). The experiment was carried out in a greenhouse, using a 5x2 factorial scheme, with five levels of electrical conductivity of irrigation water (0.50; 1.10; 2.50; 3.90 and 4.50 dS m-1) and the application or not of EMa-Ca via fertigation. The growth variables evaluated were: plant height, number of leaves, stem diameter, leaf area and dry mass weight of the roots, aerial part and total. The physiological variables analyzed were: photosynthesis, transpiration, stomatal conductance and chlorophyll a, b and total indices. The results indicated that the salinity of irrigation water negatively affected the growth and physiology of papaya seedlings, reducing height, stem diameter, number of leaves, leaf area, photosynthesis, transpiration, stomatal conductance and chlorophyll indices. On the other hand, the application of EMa-Ca attenuated the negative effects of salinity, promoting a significant increase in height, stem diameter, number of leaves, leaf area, photosynthesis, transpiration, stomatal conductance and indices of chlorophyll. The interaction between salinity and EMa-Ca was significant for the variables dry mass of roots, shoots and total, with the absence of EMa-Ca resulting in a more pronounced reduction of these variables as salinity increased. In summary, the study demonstrates that the application of EMa-Ca (1.0 ml/L) is an effective strategy to improve vegetative development, gas exchange and chlorophyll indices of papaya seedlings under saline stress conditions.