Abstract
Injury to turfgrass leaf segments was measured as percent electrolyte leakage as affected by the duration and level of imposed heat stress. Species differences in heat tolerance were most apparent when injury was monitored over time at 50°C, using leaf segments which were obtained from heat-hardened plants and immersed in distilled water during the stress treatment. Quantitative differences in heat tolerance in vitro were consistent with qualitative descriptions of drought resistance for most of the species tested.
Heat stress is detrimental for cool-season turfgrasses and is characterized symptomatically by a marked decrease in TQ in cool-season turfgrass species as a result of heat-induced leaf senescence. Heat-induced leaf senescence is associated with
Processed-kaolin particle films (PKPFs) are used commercially in large quantities on horticultural crops to repel insects, and reduce heat stress and solar injury of fruit. Our studies determined the effect of two processed-mineral particle film materials (kaolin and calcium carbonate), on whole plant carbon assimilation, water use efficiency, yield, mean fruit weight and quality in `Empire' apple [(Malus ×sylvestris (L.) Mill var. domestica (Borkh Mansf.))] over a four-year period. The application of a PKPF reduced canopy temperature, and probably reduced environmental stress, resulting in increased mean fruit weight and red color in two of the four years of the study. Whole canopy carbon assimilation studies indicated increased carbon assimilation only under conditions of high air temperature. The PKPF sprayed leaves also had reduced water use efficiency; likely due to increased stomatal conductance associated with reduced leaf temperature. Calcium carbonate had none of the positive effects of PKPF and reflected more photosynthetically active radiation (PAR) than the PKPF.
Abstract
Seedling leaf segments of 2 Cucumis melo L. cultivars were heated for 15 min at 50°C to observe the influence of duration of temperature conditioning on the acclimation and deacclimation of membrane thermostability. The percentage of injury was measured by the increase in solution conductivity due to electrolyte leakage from leaf segments. Leaves from seedlings held for 5 days at 15° had a higher percentage of injury following heat stress then those held 5 days at 35°. Acclimation for 2 to 4 hr at 35° was enough to reduce the percentage of injury to leaves from 15°-grown plants. Deacclimation for 8 hr at 15° increased the percentage of injury to leaves from plants grown at 35°. Heat injury regressed as a function of mean relative leaf-blade growth rate with temperature and leaf age with temperature yielded predictive regression equations suggesting leaf age is better as a predictor of membrane thermostability than is leaf growth rate.
were used to identify heat tolerance when planted in five environments in field experiments ( Table 1 , Supplemental Fig. 1). These genotypes were selected from preliminary evaluations of 3-week-old lettuce plants. Seedlings were exposed to heat stress
avoid water and heat stress under drought conditions ( Álvarez et al. 2009 ). For example, Mee et al. (2003 ) reported that native plants in the arid western United States, such as Artemisia tridentata Nutt. (big sagebrush) and Cercocarpus montanus
Influence of irrigation regime on growth of select field-grown tree species in a semiarid climate J. Environ. Hort. 27 134 138 Harlan, S.L. Brazel, A.J. Prashad, L. Stefanov, W.L. Larsen, L. 2006 Neighborhood microclimates and vulnerability to heat stress
overall turf quality of cool-season grasses during summer months is commonly referred to as summer stress. Summer stress can be broken down into two major components, heat stress and drought stress ( Huang et al., 1998a ; Jiang and Huang, 2000 , 2001b
than did BD (10.7 nodes). The heat stress treatments did not affect the number of vegetative nodes produced. Discussion Flower dry weight and flower abscission were most affected at the visible bud stage, which corresponds to stress treatments during
, Steyn WJ . 2014 . Response of Apple ( Malus domestica Borkh.) fruit peel photosystems to heat stress coupled with moderate photosynthetic active radiation at different fruit developmental stages . Scientia Hortic . 178 : 154 – 162 . https