Drought resistance of English roses varieties in the conditions of the Right-bank Forest-Steppe of Ukraine

Abstract

Purpose. To study the drought resistance of plants of English roses varieties. Methods. Field, anatomical, biometric. The drought resistance of plants in the field was assessed according to S. S. Pyatnitsky 6-point scale (1961). The number of stomata per unit area of the leaf blade was determined using a JSM-6700F scanning electron microscope (JEOL, Tokyo, Japan). Results. The drought resistance of plants of English rose varieties was investigated both in the field and laboratory conditions. According to visual observations, during periods with a low level of moisture supply, leaf turgor did not decrease; therefore, the field drought resistance of all varieties was estimated at 5 points. According to the parameters of stomatal density per unit of leaf area, varieties that have the maximum and minimum values of this indicator were identified. Conclusions. It was found that all studied varieties of English roses from the collection of the State Dendrological Park “Alexandria” of the National Academy of Sciences of Ukraine are quite drought-resistant in the field. But they differed significantly in the density of stomata per unit area. The largest average number of stomata per 0.5 mm2 (163.67±7.93 pcs.) was recorded in the variety ‘Alan Titchmarsh’, the lowest (47.67±1.94) – in ‘Charles Austin’. Comparison of data on leaf morphology of English roses and stomata density showed that varieties with smaller leaf sizes (‘Cottage Rose’, ‘Fisherman Friend’, ‘Noble Antony’, ‘Crocus Rose’) have a greater number of stomata per unit area, which indicates their high drought resistance. The data obtained from field and laboratory studies will be taken into account in the formation of recommendations on the use of roses for landscaping urban areas, where plants may find themselves in more extreme conditions than in an arboretum.