| Abstrakt: |
Increased urban and suburban populations in the arid western United States have resulted inmorewater demand; however, water availability in the region has become limited because of inadequate precipitation. Recent droughts have led to restrictions on irrigating landscape plants. Garden rose (Rosa ×hybrida) is commonlyusedas flowering plants in residential landscapes, but its drought tolerance has not beenwidely studied. The objective of this studywas to determine the impact of reduced irrigation frequency on visual quality, plant growth, and physiology of five garden rose cultivars, including ChewPatout (Oso EasyVR Urban LegendVR), Meibenbino (Petite KnockOutVR), MEIRIFTDAY (Oso EasyVR Double Pink), Overedclimb (Cherry Frost™), and Radbeauty (Sitting Pretty™). Twenty-four plants of each rose cultivarwere established in a trial plot atUtah Agricultural Experiment StationGreenvilleResearch Farm (North Logan, UT,USA) in Summer 2021. Plantswere randomly assigned to one of three deficit irrigation treatments forwhich irrigation frequencieswere calculated using 80% reference evapotranspiration (ETO) (high),50%ETO (medium), and 20% ETO (low). The total volumes of irrigationwater applied to each plantwere 345.6, 172.8, and 43.2 L for the high, medium, and lowirrigation frequencies, respectively, during the deficit irrigation trial from12May to 30 Sep 2022.Root zoneswerewettedmore frequently as irrigation frequency increased fromlowto high irrigation frequencies. Decreased irrigation frequency increased the number of visiblywilted and damaged leaves on all rose cultivars. However, only 'Meibenbino' and 'MEIRIFTDAY' exhibited a reduction in overall appearance under decreased irrigation frequency. The relative growth indices of both 'Meibenbino' and 'MEIRIFTDAY' decreased by 6%, whereas the dryweights of their leaves decreased by 37% and 36%, respectively, as irrigation decreased fromhigh to lowfrequencies. Roses in this study appeared to decrease stomatal conductance up to 51% when irrigation decreased fromhigh to low frequencies, orwhen air temperature increased. 'Meibenbino' and 'MEIRIFTDAY' exhibited unacceptable overall appearance, growth reduction, and higher leaf-air temperature differences, and theywere less tolerant to reduced irrigation. Although the 'Radbeauty' maintained plant growth under the reduced irrigation frequency, the large leaf size led to amore visiblywilted appearance and the potential for heat stress, thus impairing visual quality. 'ChewPatout' and 'Overedclimb' weremost tolerant to deficit irrigation at 20% ETO andmaintained plant growthwith acceptable visual quality and lower leaf temperatureswhen they received one irrigation during the growing season. [ABSTRACT FROM AUTHOR] |
