Studies on the Photosynthetic Tissues in the the Leaves of Cereal Crops : VII. Effect of temperature on mesophyll structure of leaves in wheat and rice

Abstract

Effect of temperature was investigated on structure of the wheat mesophyll consisting of the longitudinally elongated arm-pa1isade cells (TP-type cells) and the rice mesophyll consisting of the transversely elongated arm-palisade cel1s (TP-type ce11s). In the first experiment, anatomical observations were made of the third leaf blades of wheat grown at day/night temperatures of 9/9O°C, 17/12°C, 24/19°C and 32/27°C.the results obtained were as follows. 1) The longest leaf blades were formed at 24/19°C whereas the maximal values of leaf blade width, mesophyll thickness and interveinal distance were gained at 17/12°C. 2) Surface/volume ratio of the LP-type cells increased with increasing temperature, as a result of increase in number of protubctfances and decrease in diameter of protuberances 3) So far as the unit leaf area was concerned, the number of mesophyll cells and the total cell surface area increased with increasing temperature. In the second experiment, anatomical observations were made of the lOth leaf blades of rice grown at temperatures of 17/12°C, 24/19°C and 30/25°C. The results obtained were as follows :1) The shortest leaf blades and the thickest mesophyll were formed at 17/12°C. 2) The number of protuberances developed by TP-type cell decreased with increasing temperature. The longest protuberances were formed at 17/12°C. 3) When the unit leaf arca was taken into consideration, the number of mesophyll cells and the total cell surface area increased at 17/12°C. Changes in mesophyll structure with increasing temperature from 17/12°C to 24/19°C were larger than those with increasing temperature from 24/19°C to 30/25°C. From the results of these expeliments, it may be concluded that the wheat leaves grown at higher temperatures and the rice leaves grown at low tempelature (17/12°C) have a mesophyl1 structure like as sun leaves.