Tolerância de porta-enxertos de cítros à salinidade.

Abstract

The objective of this study was to evaluate the growth and tolerance to salinity of citrus genotypes (varieties and hybrid). The experiment was conducted under protected ambient (greenhouse) of the Centro de Tecnologia e de Recursos Naturais - CTRN of UFCG, located in Campina Grande, State Paraiba-BR, with geographical coordinates 7°15T8 " latitude "S" and 35°52'28 " longitude "W", at an altitude of 550 m. The treatments were composed of two factors, being five leveis of salinity of the irrigation water: SI - control (irrigation with tap water with electrical conductive ECW of 0.41 dS m"1); S2 - ECW of 1.0 dS m"1; S3 - ECW of 2.0 dS m"1; S4 - ECW of 3.0 dS m"1 and S5 - ECW 4.0 dS m"1 and 18 citrus genotypes (' 1 '-Tangerine comraon sunk (TSKC) x Citrange Troyer (CTTR) - 002; '2'- TSKC x Citrumelo Swingle (CTSW) - 019; '3' - TSKC x Citrangequat ' Thomasville (CTQT1439) - 004; '4' - TSKC x CTTR - 028; '5' - TSKC x CTTR - 029; '6' - TSKC x CTSW - 033; '7' - TSKC x CTSW - 064; '8' - TSKC x (CTQT1439) - 014; '9' - TSKC x Citrange Argentina (CTARG) - 015; '10' - TSKC x (CTQT1439) - 001; '11' - TSKC x CTSW - 031; '12' - TSKC x CTARG - 081; '13' - Tangerine Sunk of Florida (TSKFL) x CTTR - 008; '14' - TSKFL x CTTR - 036; '15' - TSKFL x Citrange C25 (CTC25) - 010; '16' - Rangpur Lemon 'Santa Cruz'; '17' - TSKFL x CTTR - 013; and '18' - TSKFL x Citrange C13 (CTC13) - 005. The experiment was conducted in randomized block design with five replications each constituted for four plants; the seeds were sown in pots (type tubets) of poliethylen of 288 mL of capacity using commercial substrate composed of vermiculite, pine bark and húmus during a period of 150 days. The saline water treatments were initiated at 60 days after sowing (DAS), being made periodic evaluations, from this date, of the number of leaves, plant height and stem diameter. In each period the relative xiii growth rate (RGR) was obtained, and at the end of the experiment by destructive analysis the leaf area, water content in leaves and dry matter of the plant were obtained which were used to accomplish the classification of the genotypes by the method of the relative growth. The genotypes of studied citrus may be classified in the following classes: a- Tolerant (T): '7', '11', '15', and '16'; b-Moderately Tolerant (MT): '2', '4', '9', '10', '13', '17' and '18'; c- Moderately Sensitive (MS): ' 1 ' , '3', '5', '8' and '12'; d-Sensitive: genotype '6'. The genotypes '9', '10', '11' and '16' may be indicated for the production of citrus rootstock under saline conditions. The tolerant genotypes resisted to salinity of 7.68 dS m"1 in the saturation extract of substrate.