Growth of ungrafted and grafted citrus rootstocks under saline water irrigation

Abstract

Growth of citrus genotypes under salinity during the plant formation was assessed. The experimental design consisted of a randomized block design with three replications in a greenhouse. Five salinity levels (0.8; 1.6; 2.4; 3.2; and 4.0 dS m-1) of irrigation water were applied to 12 genotypes (citrus varieties and hybrids from crossings involving Citrus and Poncirus) of citrus rootstocks, ungrafted and grafted with ‘Tahiti’ lime and ‘Star Ruby’ grapefruit. The irrigation with saline water was started at 60 days after sowing. Plants were initially grown in polyethylene tubes of 288 ml, and were transplanted to plastic bags, filled with commercial substrate after five months. The stem diameter, stem height and number of leaves on ungrafted rootstocks and scion-rootstock combinations were evaluated every 30 days. Data were assessed by analysis of variance by the 'F' test. Regression analyses were performed for quantitative variables (salinity) and means were compared at 5% of probability for qualitative factors (rootstocks and scions combinations) by Scott-Knott and Tukey tests. Citrus growth was reduced by salinity. The hybrid between Sunki of Florida mandarin (TSKFL) and citrange C25 (CTC25) - 010 and ‘Troyer’ citrange had greater growth compared to ungrafted. ‘Rangpur’ lime under ‘Tahiti’ lime is the most indicated combination for irrigation with saline water. Key words: Citrus spp., salt stress, rootstocks, varieties and hybrids, water quality, salinity, seedlings.