PRIMARY DIAGNOSIS OF STRENGTH RESISTANCE OF SOME TOMATO (Solanum Lycopersicum) VARIETIES BY PHYSIOLOGICAL METHODS

It is known that a number of physiological processes occur during the influence of stress factors on the plant organism. It is possible to study these processes with different diagnostic methods, to give preliminary information about the resistance of plants to salt and drought. In the study, we aimed to study the salt and drought tolerance of 6 tomato varieties using these methods - Sheker, Volgograd, Ilkin, Shahin, Zafar, Leyla. At the initial stage, we studied the parameters of water regime in the leaves, the total amount of water and the ability to retain water during the active vegetation of these varieties. One of the diagnostic methods used in the study of stress resistance is the study of changes in the amount of chlorophyll (a + b). Under the influence of stress factors, green plastids break down, which leads to a decrease in the amount of chlorophyll. However, the less the pigments change under the influence of stress, the more stable the samples are. The amount of chlorophyll (a + b) in Shahin tomato decreased by 4% in drought, 5% in saline environment, 8% in Leyla variety by drought and 7% in saline environment. According to the results obtained and water regime parameters (water holding capacity 9.1, 10.9 percent), Shahin and Leyla tomato varieties were evaluated as salt and drought tolerant varieties. According to the changes in chlorophyll (a + b), Zafar and Volgograd tomato varieties were rated as moderately drought-resistant, salt-tolerant, and Sheker, and Ilkin tomato varieties were rated as moderately resistant to both stresses. Water storage capacity in these varieties varies from 11.9 to 16.9 percent. In addition to studying the resistance of the studied tomato varieties to stressors, their resistance to sunstroke, hill rot, famoz fungus and leaf curl viral diseases was also assessed.Of them, Shahin, Leyla and Zafar varieties were found to be resistant to these diseases.