Search

Start Over Coverage 430-436

1. Gas-exchange characteristics, leaf water potential and chlorophyll a fluorescence in oil palm (Elaeis guineensis Jacq.) seedlings under water stress and recovery

Creator:
Suresh, K., Nagamani, C., Ramachandrudu, K., and Mathur, R. K.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, Elaeis guineensis, photosynthesis, photosystem II, stomatal conductance, and transpiration
Language:
Multiple languages
Description:
The gas-exchange characteristics, leaf water potential and chlorophyll (Chl) a fluorescence of oil palm (Elaeis guineensis Jacq.) seedlings subjected to water stress and recovery were investigated in a greenhouse experiment. At 24 days after imposition of stress, leaf water potential in water-stressed seedlings was doubled compared to that of control and there was a drastic decline in gas-exchange parameters viz. photosynthesis, transpiration, and stomatal conductance. Water stress did not irreversibly affect gas-exchange parameters and quantum efficiency of photosystem II, as seedlings exhibited total recovery of photosynthetic apparatus by 12th day of rehydration. These findings indicate that oil palm exhibits physiological plasticity to water stress during the seedling stage. and K. Suresh ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Photosynthesis and ultrastructure of photosynthetic apparatus in tomato leaves under elevated temperature

Creator:
Zhang, J., Jiang, X. D., Li, T. L., and Cao, X. J.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, chloroplasty, rajčata, photosynthesis, chloroplasts, tomatoes, gas exchange, heat stress, Lycopersicon esculentum L, photosynthetic apparatus, microstructure, 2, and 581
Language:
Multiple languages
Description:
The microstructure of leaves and ultrastructure of chloroplasts were examined in tomato (Lycopersicon esculentum L.) plants treated with elevated temperature. Plants were exposed to 35°C for 30 d after florescence. The plants grown continuously under 25°C served as controls. Compared with the controls, the net photosynthetic rate (PN) in stressed plants decreased significantly. Stomatal conductance, intercellular CO2 concentrations, the rate of transpiration, and the limitation of stomatal conductance showed that the decrease in PN was caused mainly by nonstomatal restrictions. Meanwhile, stomata density increased significantly in the stressed plants. The stomata status of opening and closing became disorganized with a prolonged 35°C exposure. The damage of chloroplast membrane occurred earlier and was more serious in the plants under elevated temperature. At the same time, the thylakoids were loosely distributed with lesser grana, but the number of lipid droplets increased in chloroplasts. The number of starch grains in chloroplasts increased first and then decreased. In addition, the length of the main nerve in leaves increased and the main vein showed distortion in the plants stressed by 35°C. An increase was observed in the number of cells on the abaxial side of the main vein and these cells were overly congregated. The thickness of a vertical section became thinner in the stressed leaves. The cells of the upper epidermis thinned, and the ratio of palisade tissue to spongy tissue decreased. Generally, the photosynthetic apparatus of tomato changed significantly and the changed chloroplast ultrastructure might be one of the important reasons that caused the decrease of PN under 35°C., J. Zhang, X. D. Jiang, T. L. Li, X. J. Cao., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public