Injury to ‘Prelude’ and ‘Manhattan II’ perennial ryegrass (Lolium perenne L.) was measured as percentage of electrolyte leakage from leaf segments after stress to determine the influence of prestress growth temperature and poststress temperature on heat tolerance. The temperature required to cause 50% cell solute efflux was 59.5°C for ‘Prelude’ and 56.5° for ‘Manhattan II’, when measured immediately after stress treatment. However, electrolyte leakage increased with time after termination of stress. When measured 24 hr after termination of stress, 52° caused 50% cell solute efflux from leaf segments of both cultivars. Injury levels 44 hr after 30 min at 50° were ≈ 12% and 89% when incubated at poststress temperatures of 7° and 35°, respectively. Incubation temperature following a 55° treatment did not affect electrolyte leakage rate in either cultivar. Greater injury occurred in both cultivars when grown at 25° than at 41°.
al., 2008 ). Heat tolerance is a complex trait that varies with the severity of stress and plant growth stage. Therefore, there is a need to identify heat-tolerant carrot germplasm with stable growth and yield under high temperature at various stages
the present-day transition zone ( National Assessment Synthesis Team, 2000 ). Thus, understanding the mechanisms of heat tolerance is increasingly important for turfgrass breeders and managers. Cellular membranes, which are selectively permeable
Heat stress on field grown Phaseolus lunatus (lima bean) can have a significant influence on yield. Lima bean crops grown in Delaware typically yield less pounds per acre than the same cultivars grown in California. Part of this effect may be due to extreme heat conditions or fluctuations during Delaware's summers, which can affect blossom and pod set. Our purpose was to analyze the heat tolerance of various cultivars of P. lunatus using quick bioassays and to establish a relationship to yield in greenhouse temperature trials. Two assays were used. The first, a hypocotyl extension assay, consisted of a treatment of germinated seedlings at 25, 35, or 42 for 2 h and observations of hypocotyl extension at 72 and 96 h posttemperature treatments. Three cultivars [`Fordhook' 1072 (heat-sensitive), `Jackson Wonder' (heat-tolerant), and `Early Thorogreen' (heat tolerant)] were analyzed. Initial results indicated that `Jackson Wonder' and `Early Thorogreen' are capable of surviving the 42C heat shock, but `Fordhook 1072' is not. In the second assay, we measured electrical conductivity of a solution containing hypocotyl sections following incubation at various temperatures (R1). Tissue samples then were boiled and conductivity was measured again (R2). The ratios of R1/R2 × 100 were determined as percent injury. Preliminary data suggests that `Jackson Wonder' is more heat-tolerant in this assay than `Fordhook 1072'. Subsequent experiments will analyze the induction of specific heat shock proteins as a function of cultivar-specific heat tolerance.
[ Trifolium repens ( Li et al., 2019 )]. Sitosterol reinforces the stabilization of liquid-disordered membranes in plants exposed to heat stress ( Dufourc, 2008 ). Sitosterol content correlated positively to heat tolerance of hard fescue, as demonstrated by
activities were associated with the differences in heat tolerance of turfgrasses and indicated a positive correlation between chlorophyll content and the antioxidant enzymes and a negative correlation between membrane injury index and the antioxidant enzymes
xanthophyll) led to decreased membrane permeability and protected the plants against heat damage ( Havaux et al., 1996 ). The association of antioxidant effects of carotenoids with improved heat tolerance in cool-season grass species is not yet well
leaves ( Ecke et al., 2004 ). However, the effects of high temperatures on poinsettia morphology have not been adequately studied. Heat tolerance can be improved by genetic selection as well as by the use of exogenous regulators, which aid in the
). Physiological disorders have an important G × E interaction that breeders must take into considerations when designing breeding strategies to improve heat tolerance in lettuce ( Jenni and Hayes, 2010 ; Jenni and Yan, 2009 ). The genetic basis of heat tolerance
measuring electrolyte leakage from leaves of plants at different temperatures. Several studies have indicated that CMT is effective in detecting genetic differences with regard to heat tolerance among several crops ( Islam et al., 2014 ; Kumar et al., 2012