Tolerância de genótipos de porta-enxertos de citros em condições de estresse salino.

Abstract

The adaptive capacity of plants allows the selection of genotypes, which are tolerant and able to produce economically acceptable earnings, when using saline water for irrigation. The aim of this study was to assess the salinity tolerance of genotypes (varieties and hybrids) of rootstocks, considering the growth of plants; alterations of gas exchange, the biomass of plants and classification of genotypes regarding the degrees of salinity tolerance. The experiment was conducted in a greenhouse (vivarium) at UFCG, Campina Grande, PB, adopting a randomized block design with three repetitions, combining three salinity leveis of irrigation water - CEa (0.5, 2.4 and 4.0 dS nf'), analyzed in two by two factorial, (0.5 and 2.4 dS m" ), evaluated in period I, from 60 to 135 days after seeding (0.5 and 4.0 dS m~') and in period II, from 136 to 210 days after seeding and eleven genotypes of rootstocks (LCSTC (G5); TSKC x TRENG 256 (G6); TSKC x (TR x LCR) -059 (G9); TSKFL x CTTR - 013 (G13); TSKC x TRENG - 264ÍG16); TSKC x CTTR - 025 (G17); LVK - 10 (G25); TSKFL x C T T R - 0 17 (G12); CTSW (G18) ; TSKFL x LRM - 017 (G22) and LVK x LCR ( G15). The plants were grown in tubes with volumetric capacity of 288 mL, the experimental unit consisted of 15 useful plants of each genotype, in experimental units. Were performed evaluations of growth, physiological, and of biomass genotypes regarding the classification of degrees of salinity tolerance. Statistical analysis were performed by the program SISVAR, by analysis of variance thru the F test, until 1% probability and comparison of average factors of salinity leveis and genotypes was performed by the xvin Scott-Knott test (p <0.05). Thus, it appears that the salinity of the water causes a reduction in plant growth, negative physiological changes in gas exchange and decrease in rates of biomass of rootstock plants. The genotypes of rootstocks TSKFL x CTTR- 017 (G12) and TSKFL x LRM - 017 (G22) were tolerant to growth variables as well as the relative growth rates corresponding to these variables; were also tolerant, the variables of gas exchange and leaf of dry biomass and relative yield of total biomass, then such genotypes can be recommended for use in saline stress conditions. The genotypes of rootstock TSKFL x CTTR - 013 (G13) and CTSW - (G18) were sensitive to growth variables and dry biomass and the genotype of rootstock TSKC x (TR x LCR) - 059 (G9) was sensitive to variables of gas exchange and dry biomass and the genotypes of rootstock LCSTC (G5) and LVK x LCR (G15), did not survive to saline stress with electrical conductivity of 4.0 dS m" .