Chilling Injury in Mature Leaves of Rice. II. Varietal Differences in the Response to Interactions Between Low Temperature and Light Measured by Chlorophyll Fluorescence at 77k and the Quantum Yield of Photosynthesis

Abstract

Characteristics of photosynthetic CO2 exchange and 77K chlorophyll fluorescence in attached and detached leaves of rice were used to examine differences between five varieties exposed to a combination of bright light and low temperature. Preliminary studies established that attached leaves of varieties did not differ in the light dependence of photosynthesis at CO2 saturation or fluorescence properties when grown in full sunlight and measured under comparable conditions. All varieties showed a depression in maximum photosynthetic rate, but not in quantum yield or chlorophyll fluorescence when examined in the late afternoon after a period of active photosynthesis in air at 25°C. Attached leaves of all varieties showed depression of the maximum rate of photosynthesis and of quantum yield as well as an increase in Fo and a decrease in Fv/Fm of chlorophyll fluorescence at 77K following horizontal exposure to bright light in air at 25°. Similar results were obtained with detached leaves exposed to bright light while floating on water at 25°C. The rate of photosynthetic CO2 fixation in air as a function of temperature was examined in attached leaves of two representative varieties, Japonica-like cv. Hungarian- 1, and Indica-derived cv. IR-8. The former was capable to rates of photosynthesis at 10°C which were twice those of the latter, although the rates at 25°C were similar in both varieties. When detached leaves of five varieties of rice were floated on water at 10°C while exposed to 700 �mol photons m-2 s-1 of white light, consistent differences in the response of quantum yield, light and CO2 saturated O2 evolion and 77K fluorescence properties were found. Exposure to bright light at low temperature exaggerated the effects of bright light on these parameters, and larger effects were found in the Indica-derived varieties than in Japonica-like cv. Hungarian-1. These treatments at 10°C did not influence the extent of increase in Fo, but led to a greater decline in Fv/Fm of 77K chlorophyll fluorescence compared with treatments at 25°C. Varieties in which there was a larger decline in Fv/Fm showed slower recovery of variable fluorescence in the dark at 25°C, and especially at 10°C. These responses to in vitro treatments seem capable of distinguishing varieties such as cvv. Hungarian-1 and Er Bai Ai, which are believed to be more chilling tolerant by other criteria, from chilling sensitive varieties such as Gui Chao-2 and IR-8. Even though there is potential for application of these methods in screening programs, there is little evidence that the lesions in primary photosynthetic processes indicated by these methods are significant determinants of photosynthesis under field conditions.

Chilling Injury in Mature Leaves of Rice. I. Varietal Differences in the Effects of Chilling on Canopy Photosynthesis Under Simulated 'Dry Cold Dew Wind' Conditions Experienced in South-East China

“…As noted elsewhere, the maximum rates of light and C02 saturated photosynthesis of all rice varieties tested are higher in the morning than in the evening (Huang et al 1989). The range and extent of this variation is damped during chilling, suggesting it, too, may be related to soluble sugar accumulation.…”

“…Previous studies of the temperature responses of instantaneous leaf photosynthesis in air indicate that Indica and Japonica derived varieties do not differ in relative rate over the range 20-30°C (Evans and Bush 1985;Huang et al 1989). That is, the differences in canopy photosynthesis on chilling are not due to intrinsic differences between varieties in their temperature response.…”

“…Casual observation showed more horizontal leaf architecture in cv. Hungarian-1 than other varieties, indicative of interactions between light and low temperature in rice which are explored in the subsequent paper (Huang et al 1989). Changes in these parameters seem to be of secondary importance compared with the direct association between soluble sugar retention in leaves and the inhibition of photosynthesis in rice during simulated dry cold dew wind conditions.…”

“…The major objective of the research reported here was to determine if temperature and light regimes, comparable with those experienced by rice plants in the field during DCDW events, affected photosynthetic COz fixation in mature leaves. A second objective was to determine if varietal differences in the interactions between bright light and low temperature, on photosynthetic capacity and efficiency in vitro (Huang et al 1989), were responsible for, or correlated with, differences in photosynthetic response in air at the canopy level during DCDW events. In the process of the present studies we have been obliged to consider the additional implications of chilling on root function and carbohydrate utilisation recognised in earlier studies (Lin and Tarn 1979;Wang et al 1980;McWilliam et al 1982).…”

Evaluation of chilling sensitivity in different rice varieties. Relationship between screening procedures applied during germination and vegetative growth

“…In rice, numerous cold-screening procedures have been applied at various stages of development, from germination to maturity (Sasaki, 1974 ;Li & Rutger, 1980;Kaw & Kush, 1985Khan et al ., 1986 ;Shahi & Khush, 1986 ;Nagamine & Nakagahra, 1990;Nagato et al, 1992 ;Sthapit, 1992 ;Sthapit & Wilson, 1992) . Among the quantitative assays, the chlorophyll fluorescence has retained more attention (Smillie et al ., 1988 ;Huang et al ., 1989 ;Sthapit et al ., 1995) . Majumder et al .…”