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

Abstract

Canopy temperature and incident photosynthetically active radiation were measured in experimental rice plots in Guangzhou, South China, during conditions which approximated those of the 'dry cold dew wind', a chilling phenomenon which is responsible for substantial yield reduction in rice. These field conditions were then reproduced in controlled environment photosynthetic measurement chambers. Mature plants of five varieties of rice were arranged to simulate a canopy in these chambers which was then exposed to a 3-day chilling treatment (21°C day/lO°C night) 14 days after anthesis. Canopy photosynthesis was measured before, during and after the chilling period. A Japonica-like cultivar, Hungarian-1 from Central Europe, and an Indica-like cultivar, Lemont from Texas, were markedly less sensitive to a chilling-dependent reduction in photosynthesis than were cultivars Gui Chao-2, Er Bai Ai and IR-8 from South-East China and The Philippines. The extent of chilling-dependent reduction in photosynthesis was greater if roots of plants in the simulated canopy were allowed to track air temperature at night. This led to a 5-7°C differential between root and air temperature in the morning and was associated with a midday depression of photosynthesis in all varieties. If root temperature was kept at 20°C during the day and night and air temperature controlled at 21°C day/ 10°C night, the effects of chilling on photosynthesis were much less pronounced.These changes in canopy photosynthesis following chilling treatments were correlated with changes in leaf level parameters. The level of soluble sugars and starch in leaves was found to remain high during the first cool night and to increase further during the next day. In cultivars which showed pronounced inhibition of canopy photosynthesis throughout the chilling treatment (Gui Chao-2, IR-8), soluble sugars remained at high levels until temperatures were returned to control values. In the less sensitive cultivar, Hungarian-1, soluble sugars declined throughout the chilling treatment. These results suggest inhibition of photosynthesis may be associated with sugar retention in leaves of rice at low temperatures, and imply differences between cultivars in this response. Other photosynthetic parameters monitored included the maximum rate of light and COz saturated photosynthesis, the quantum yield of photosynthesis, and FO and F,IF, of chlorophyll fluorescence at 77K. Surprisingly, Hungarian-1, the cultivar which showed least impairment of canopy photosynthesis showed greater reduction in quantum yield and larger changes in fluorescence parameters during the chilling treatments. These changes were readily reversible and may be related to the more horizontal leaf habit of this cultivar compared with the more vertical orientation of leaves in the other cultivars. These observations imply that assimilate regulation of photosynthetic metabolism, rather than light dependent damage to primary photosynthetic processes, underlies low temperature effects on yield of rice during grain fill...

Differences in photosynthetic characteristics and accumulation of osmoprotectants in saplings of evergreen plants grown inside and outside a glasshouse during the winter season

“…For example, B. rugulosa contained more soluble saccharides and showed larger reduction in P N . This finding is supported by Huang et al (1989) who reported high content of soluble sugars and inhibition of photosynthesis at low temperature in rice leaves. On the other hand, high photosynthetic activity was associated with high proline content ( Fig.…”

Balance in the source – sink system: a factor in crop productivity

“…Balance between sources and sinks can be upset when photosynthesis increases without a corresponding increase in import or when overall im port into sinks decreases without a comparable decrease in photosynthesis. In some cases photosynthesis may change (Huang et al, 1989b and references cited therein) while in other cases a change in partitioning among sinks may allow export to continue even though import into some sinks is inhibited (Fondy and Geiger, 1980). Experience tells us that adaptations exist which allow plants to restore and maintain the critical metabolic equilibrium between sources and sinks (Wardlaw, 1985).…”

“…Experience tells us that adaptations exist which allow plants to restore and maintain the critical metabolic equilibrium between sources and sinks (Wardlaw, 1985). For example, when source-sink balance is upset by hindered export, photosynthesis acclimation usually is seen only after a lag of a day or two (Mayoral et al, 1985;Plaut et al, 1987;Bagnall et al, 1988;Huang et al, 1989b). Physiological processes in leaves can respond rather quickly to some environmental changes; for instance, alterations in the pattern of the daily light regime, transient changes in irradiance caused by sun flecks or passing clouds (Pearcy, 1990), and onset of some forms of stress such as leaf water deficit.…”

Growth and photosynthesis of Gossypium hirsutum L at high photon flux densities: effects of soil temperatures and nocturnal air temperatures

“…Various short-term experiments have revealed that low temperatures can lead to considerable accumulations of carbohydrates in source leaves, which could potentially result in a feedback inhibition of photosynthesis (Azcon-Bieto, 1983;Paul et al, 1990;Stitt, 1991;Brüggemann et al, 1992 (Huang et al, 1989). Marked and sustained increases in carbohydrates were also found in cotton plants exposed for 4 d to low air temperatures (20 °C) during the light period (Königer and Winter, 1992 Winter and Königer, 1991) resulted in decreases in leaf turgor pressure.…”

“…Little is known about the effects of different temperatures during the dark period on photosynthesis and growth of plants, since in most experiments temperatures were changed simultaneously during the light and dark period (eg Downton and Slatyer, 1972;Huang et al, 1989;Schleppi et al, 1990;Zollinger and Kells, 1991). Those experiments in which the temperature during the dark period was changed independently of the light period suggested that the night temperatures might have a significant impact on plant growth.…”