Physiology of ‘Paluma’ guava under irrigation with saline water and nitrogen fertilization

Abstract

The use of saline water in irrigation causes osmotic and toxic effects and nutritional imbalance in plants, leading to morphophysiological modifications in the leaves and compromising the production of photosynthetic pigments, which negatively reflects in the growth and development of the crops. Hence, this study aimed to evaluate the effect of irrigation water salinity on the content of photosynthetic pigments and leaf morphophysiology of guava seedlings cv. 'Paluma' under nitrogen (N) fertilization. A randomized block design was used, testing five levels of irrigation water electrical conductivityECw (0.3, 1.1, 1.9, 2.7, and 3.5 dS m -1 ) and four N doses (541.1, 773.0, 1,004.9, and 1,236.8 mg of N dm -3 of soil) in a 5 x 4 factorial scheme with three replicates and five plants per plot. The contents of photosynthetic pigments in the leaves of the guava seedlings cv. 'Paluma' were inhibited by the increase in irrigation water salinity at 190 days after emergence, and the salt stress was lessened with the N dose of 1,004.9 mg dm -3 up to an ECw level of 1.2 dS m -1 . Leaf morphophysiology of guava seedlings was not compromised by irrigation water salinity up to 1.5 dS m -1 , and the highest values were obtained in plants fertilized with 541.1 mg of N dm -3 . Key words: Psidium guajava L. Photosynthesis. Salinity and nitrogen. ResumoO uso de água salina na irrigação promove efeitos osmóticos, tóxicos e desbalanço nutricional nas plantas, causando modificações morfofisiológicas nas folhas e comprometimento na produção dos pigmentos fotossintéticos, refletindo negativamente no crescimento e desenvolvimento das culturas. Nesse sentido, objetivou-se com o presente trabalho avaliar o efeito da salinidade da água de irrigação no teor de pigmentos fotossintéticos e na morfofisiológica foliar de mudas de goiabeira cv. Paluma sob adubação nitrogenada. Usou-se a aleatorização em blocos, testando cinco níveis de condutividade elétrica da água de irrigação -CEa (0,3; 1,1; 1,9; 2,7 e 3,5 dS m

Water salinity and nitrogen fertilization in the production and quality of guava fruits

“…Souza et al (2017) evaluating the growth of phytomass production and the quality of 'Crioula' guava rootstock under salt stress (ECw of 0.3 to 3.5 dS m -1 ) verified that the irrigation with electrical conductivity of irrigation water above 0.3 dS m -1 adversely affected the formation of guava rootstocks. Silva et al (2017) analyzing the effects of irrigation water salinity (ECw ranging from 0.3 to 3.5 dS m -1 ) on photosynthetic pigment content and foliar morphophysiology of guava seedlings cv. Paluma, found that the photosynthetic pigments in guava seedlings cv.…”

Growth and gas exchanges in soursop under irrigation with saline water and nitrogen sources

“…Alternatives have been tested to mitigate the effects of salinity on plants, for instance, N fertilization in the guava crop using urea as N source (Silva et al, 2017). There are also studies about the attenuating action of calcium nitrate and potassium nitrate on the salt stress on the melon crop (Fernandes et al, 2010;Andrade Júnior et al, 2011).…”

Tolerance of precocious dwarf cashew clones to salt stress during rootstock formation stage

“…The excess of salts in water and/or soil causes imbalances in the chloroplast activities (decrease in the synthesis of 5-aminolevulinate acid, a precursor molecule of chlorophyll), inducing an increase in enzymatic activity, which results in degradation of the molecules of photosynthesizing pigments, such as chlorophyll b (Cavalcante et al, 2011). Silva et al (2017), studying the effects of irrigation water salinity (ECw: 0.3 to 3.5 dS m -1 ) on the contents of photosynthetic pigments and leaf morphophysiology of guava seedlings cv. 'Paluma' , concluded that chlorophyll b contents in the leaves were inhibited by the increase in irrigation water salinity.…”