Water Conditions And Proline Content In Shade And Sun Plants

Abstract

Different parameters of the water conditions (Water content, water saturation deficit, osmotic pressure of the cell sap and partial osmotic pressure due to sugars), chlorophyll and proline contents were investigated in sun and shade plants of Sesbania sesban, Ocimum basilicum and Chenopodium murale. The total chlorophyll content per unit fr. wt. is higher in shade than in sun plants. In shade, a considerable decrease of chlorophyll a/b ratio is observed in Sesbania and Chenopodium; but this ratio increases slightly in Ocimum. The different parameters measured exhibit a wide difference in sun and shade plants. The diurnal march of the proline content, water saturation deficit and the osmotic pressure show almost the same trend; being low before sunrise and increasing by the progress of the day. Their march is a mirror image of that of the water content of the photosynthesizing organs. The partial osmotic pressure due to sugars contributes more to the total osmotic pressure of the cell sap than electrolytes in sun and shade. The rise of the osmotic pressure at midday and afternoon hours is mainly due to the rise of the partial osmotic pressue of the sugars, particularly in sun plants.