Seleção de genótipos de algodoeiro herbáceo para tolerância ao estresse salino

Abstract

In order to select cotton genotypes for salinity tolerance, three experiments were carried out in a greenhouse. In the first, 63 genotypes under two salinity levels: 4.0 and 8.0 dS.m^-1. The plants were conducted in bags of 1 L, containing properly corrected and fertilized soil. Each treatment was repeated three times. The plants were collected 33 days after germination (DAG) and taken to dry in stove at 40 Celsius degrees for 48 hours to obtain the total dry matter. (MST). With this variable, the percentage losses were calculated in relation to the control for each one of the genotypes tested. Then, the genotypes were classified according to the % Loss obtained: between 0 to 20, Tolerant (T); 20 to 40, Moderately Tolerant (MT); 40 to 60, Moderately Susceptible (MS); and, above 60, Susceptible (S). Of the 63 genotypes tested, twenty were selected for the second experiment, those with the lowest % Loss. The installation and conduction methodology was similar to experiment 1, except to the tested salinity levels, wich were 4.0 and 10.0 dS.m^-1. Of the 20 genotypes tested, five were selected for the third experiment, those with the lowest % Loss. The installation and conduction methodology do third experiment was also similar to experiment 1, except to the salinity levels tested wich were 4.0 and 12.0 dS.m^-1. In the end, the genotype that presented the lowest % Loss was the cultivar BRS Antares.