Produção de porta-enxerto de goiabeira com águas de diferentes salinidades e adubação potássica.

Abstract

Considering the socioeconomic importance of the guava crop, especially for the northeastern region of Brazil where there is limited availability of good quality water, the need arises for the use of saline waters for agricultural production, implying the need to develop strategies that can their use. In this sense, the research was carried out to evaluate the effects of different doses of potassium combined with waters of different salt levels in the production of seedlings for guava rootstock. The experiment was carried out in a greenhouse at the Agrifood Science and Technology Center of the Federal University of Campina Grande, Pombal - PB. The experimental design was a randomized complete block design, in a 5 x 4 factorial scheme, with the treatments referring to five levels of electrical conductivity of the irrigation water (CEw = 0,3; 1,1; 1,9; 2,7 and 3,5 dS m-1) in interaction with four doses of potassium (70, 100, 130 and 160% K) and the recommended dose of 100% K (726 mg K dm-3 substrate) for guava seedlings and four repetitions, each plot consisting of two useful plants. The treatments were started at 40 days after emergence of the seedlings (DAE). The rootstocks were evaluated at 120 and 225 DAE, through plant height, stem diameter, number of leaves and leaf area; in the period from 60 to 225 DAE, absolute and relative growth rates were measured for plant height and, at 225 DAE, the specific leaf area, stem dry matter, leaves, root dry matter, shoot, total ratio root/shoot, leaf area ratio and Dickson quality index. Irrigation with CEw water of up to 1,9 dS m-1 allowed the formation of a guava rootstock cv. Paluma with acceptable reduction in its growth; potassium dose of 798,6 mg of K dm-3 substrate promoted the highest growth in height of the guava rootstock cv. Paluma at 120 days after the emergency; increasing doses of K did not attenuate the harmful effects of the salts on guava rootstocks cv. Paluma; dose of 508,2 mg of K dm-3 of substrate favors the accumulation of dry phytomass of cv. Paluma at 225 DAE; irrigation with CEw water 1,9 dS m-1 promotes a 10% acceptable reduction on the phytomass production and quality of guava rootstocks cv. Paluma; there was no significant interaction (salt x doses of K) on the studied variables.