Abstract
ABSTRACT The salt stress caused by irrigation water with high concentration of salts stands out as one of the main limiting factors in agricultural production in the semiarid region of Northeastern Brazil. In this context, the objective of this study was to evaluate the photosynthetic pigments, the photochemical efficiency, and the growth of custard-apple irrigated with saline water and potassium doses. The research was carried out under field conditions in a randomized block design in a 2 × 5 factorial scheme, corresponding to two values of electrical conductivity of irrigation water - ECw (1.3 and 4.0 dS m-1) and five potassium doses (50, 75, 100, 125 and 150% of the recommendation). The dose referring to 100% corresponded to the application of 20 g of K2O per plant per year. ECw of 4.0 dS m-1 reduced the synthesis of chlorophyll a, total chlorophyll, and carotenoids in custard-apple, at 245 days after transplanting. Fertilization doses of 50 to 150% of the recommendation inhibited the synthesis of chlorophyll b and the absolute and relative growth rates in stem diameter of custard-apple plants irrigated with water of highest electrical conductivity. Reduction in the quantum efficiency of photosystem II in custard-apple cultivated under ECw of 4.0 dS m-1 is related to photoinhibitory damage to photosystem II. Potassium fertilization did not alleviate the stress caused by water salinity on the growth of custard-apple, during 151-245 days after transplantation.
Highlights
Belonging to the Annonaceae family, custard-apple (Annona squamosa L.) is a fruit appreciated fresh or as a sweet pulp and stands out as a source of vitamins A, B, C, E, and K1, antioxidant compounds, polyunsaturated fatty acids, and presence of essential minerals, preventing and fighting heart disease, diabetes, hyperthyroidism and cancer (Senthil & Silambarasan, 2015)
Comparing the plants grown under ECw of 4.0 dS m-1 to those irrigated with water salinity of 1.3 dS m-1, there was a reduction of 51.59% (2.43 mg g-1 FM)
Irrigation with water of 4.0 dS m-1 reduces the synthesis of chlorophyll a, total chlorophyll, and carotenoids in custardapple, at 245 days after transplanting
Summary
Belonging to the Annonaceae family, custard-apple (Annona squamosa L.) is a fruit appreciated fresh or as a sweet pulp and stands out as a source of vitamins A, B, C, E, and K1, antioxidant compounds, polyunsaturated fatty acids, and presence of essential minerals, preventing and fighting heart disease, diabetes, hyperthyroidism and cancer (Senthil & Silambarasan, 2015). The Northeast region of Brazil stands out with the largest national production, mainly in the states of Alagoas, Bahia, Ceará, and Pernambuco (Medeiros et al, 2014) This region commonly has high temperatures, low rainfall levels, irregular distribution of rains, and intense evaporation in most months of the year, which makes the practice of irrigation indispensable to ensure security in agricultural production (Lima et al, 2019). Custard-apple is a fruit tree sensitive to water salinity, with a reduction in photosynthetic efficiency and production under an electrical conductivity of 3.0 dS m-1 (Ferreira et al, 2021) In this context, the improvement of nutritional status with potassium fertilization in plants subjected to salt stress can be used as a tool to minimize oxidative cell damage, because K regulates growth and development through changes in physiological and biochemical attributes. Several studies suggest that an adequate supply of potassium may attenuate the negative effects of salinity on different crops, such as strawberry (Khayyat et al, 2009), melon (Gurgel et al, 2010), and West Indian cherry (Lima et al, 2019)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
