STUDY OF WATER REGIME OF APPLE VARIETIES IN SUMMER PERIOD RELATIVE TO THEIR DROUGHT HARDINESS AND HEAT RESISTANCE
The resistance of apple varieties to unfavorable conditions of the environment is one of the basic characteristics which determine their commercial and production value and economical efficiency in the cultivation areas. Lately, extremely high air temperatures on the background of a long drought in summer have become more frequent that leads to plant oppression. The degree of resistance to water loss and overheating greatly varies in apple varieties. In connection with this water loss and wilting effect on water regime of apple varieties in summer has been studied in the laboratory conditions. Basic indices of water regime have been studied: water content, water loss and turgor restoration. The majority of apple varieties are characterized by drought resistance. “Yubilar” shows high drought and heat resistance. This variety is characterized by less water loss and high ability to restore turgor. Moderate heat resistance was observed in the following varieties: “Antonovka obyknovennaya”, “Bolotovskoye’, “Melba”, “Orlik”, “Orlovim”, Sinap orlovskiy” and “Wealthy”. Low heat resistance was observed in “Imrus”.