Drought- and heat- resistance of garden plum (Prunus domestica L.) accessions and forms in the forest steppe of Ukraine

Abstract

Aim. To evaluate drought- and heat- resistance of garden plum (Prunus domestica L.) accessions and forms in the Central Forest-Steppe of Ukraine Results and Discussion. The study was carried out at L.P. Symyrenko Experimental Station of Pomology of the Institute of Horticulture of NAAS in 2018-2019. Fourteen accessions and 9 early-, mid- or late-ripening elite forms were studied. Recently, the climatic conditions in Ukraine have been characterized by an increase in the average annual temperature and unstable precipitation; there have often been periods without any precipitation. All these changes negatively affect the growth and development of plants. Analyzing the water-physical properties of different plum varieties, we measured the water content of leaf tissues. Most varieties had moderate water content ranging 55% (President) to 64.9% (Renklod Karbysheva). Record, Bluefri, Nenka, Oda and elite forms 7794, 12516, and 605 stood out, because the water content in their leaf tissues exceeded 60%. Investigation of the water balance in plum leaves revealed significant differences between varieties and hybrids. The water loss intensity varied. It was the lowest at all three exposures of leaves of forms 8087 and 9996 and variety Nenka (3.72-4.86, 9.53-11.06, and 14.90-15.61%, respectively). A high ability to retain water was also intrinsic to varieties Yantarnaya Mlievskaya (6.39%, 11.33%, 15.66%, Oda (7.21%, 12.84%, 18.48%), Dobra (7.73%, 13.66%, 19.58%), and Tophit (8.07%, 13.57%, 18.45%). The greatest loss of water of 19.21% and 20.56% after 2 hours was recorded in form 7794 and varietys Renklod Karbysheva. Conclusions. The studied plum varieties and forms have been categorized according to water-physical indicators and drought resistance into the following groups: highly resistant (Nenka, 8087, 9996); resistant (Oda, Yantarnaya Mlievskaya, Dobra, Tophit); medium resistant (Herman, Stanley, Record, Blufri, 9605, 7756, 8124, 8143); lowly resistant (Zamanchyva, 8110). Renklod Karbysheva and elite form 7794 were the least resistant. The highest heat resistance was recorded for varieties Nenka, Oda, Stenley, Record and elite forms 12516, 8124, and 7794, in which the damage to leaves was 10-15%. The lowest heat resistance was seen in variety President and elite form 8143, in which the damage to leaves was 75%. In the other accessions and forms, this parameter ranged within 20-50% of the total leaf area, corresponding to medium heat resistance.