|Author:||Zhao, Ming ; Ding, ZaiSong ; Ishhill, R. ; Chen, Li ; Zhang, Xu|
|Book Group Author:||NA|
A study was conducted in 1999 to investigate the response of non-photochemical chlorophyll fluorescence quenching (qN) and its components in maize hybrids Nongda108, H2 and DK789, and inbred lines I1, P178, I2 and HuangC to drought and shade stresses. The treatments were: control (watering 3 times a week, and soil moisture kept at 85-90%); DD, the frequency and quantity of watering were decreased to a quarter of the control, during the time of 40 days from the 6th expanded leaf stage to the grain filling period, at a soil water content of 70-75%; DR, the frequency and quantity of watering were decreased to a quarter of the control during the time of 20 days from the 6th expanded leaf stage to the 12th expanded leaf stage, with a soil water content similar to that of DD; SS, the plants were shaded with a black gauze so that a quarter of the light intensity in the control was maintained; and SR, plants were kept under shade during the time of 20 days from the 6th leaf expanded stage to the 12th leaf expanded stage. Drought and shade treatments markedly increased qN and qNmax at the maximum and stable stage, respectively, and decreased the quantum yield of photosystem II photochemistry. Results showed that the ratio of qNs to qNmax corresponded to the severity of stresses, and varied between the different treatments were similar to that of the relative decrease of plant dry matter weight. Drought and shade affected to a certain degree the time (T) and rate (R) of qN to reach the maximum or stable stage (TqNmax, RqNmax, TqNs and RqNs, respectively). The most important parameter, RqNs, was lowest in the severe drought and shade treatments (DD and SS), and low in the treatments recovering from drought and shade conditions (DR and SR), and highest in the control. The changes in the RqNs were almost identical with that of the plant dry matter weight. The shade treatments mainly increased the energy-dependent quenching, but drought mainly increased the quenching related to state transitions.
|Pages:||59 - 62|
|Journal:||Acta Agronomica Sinica|
chlorophyll, crop growth stage, drought, drought resistance,hybrids, irrigation, maize, photosynthesis, photosystem II, plant waterrelations, shade, soil water, stress, stress response, water stress, Zeamays, Zea, Poaceae, Cyperales, monocotyledons, angiosperms,Spermatophyta, plants, eukaryotes, carbon assimilation, carbon dioxidefixation, corn, drought tolerance, soil moisture, watering, Field Crops(FF005) (New March 2000), Plant Physiology and Biochemistry (FF060),Plant Water Relations (FF062), Plant Production (FF100), EnvironmentalTolerance of Plants (FF900), Soil Water Management (Irrigation andDrainage) (JJ800) (Revised June 2002) [formerly Soil Water Management]