CHANGES IN PHOTOSYNTHETIC PIGMENT CONTENTS AND SPAD INDEX IN RELATION TO WATERLOGGING IN SUGARCANE

Waterlogging is a major abiotic factor in tropics and subtropics India affecting plant productivity by creating anoxia, aerial rooting, mineral deficiency and toxicity, physiological and biochemical alterations. In present study, an effort was made to evaluate changes in photosynthetic pigments, chlorophyll a (Chl a), chlorophyll b (Chl b), total Chl (Chl a+Chl b), carotenoids (CAR), the ratio of Chl a and Chl b (Chl a/b) and total Chl/CAR ratio and Soil plant analysis development (SPAD) index in plants grown under waterlogged conditions (WL) along with untreated control (C) using four sugarcane cultivars; CoLk 94184, BO 91, CoS 767 and CoJ 64. The results obtained indicated variation in Chl a, b, total Chl contents (mg/g fresh wt.) among different cultivars and relatively less in waterlogged plants. Chl ranged between 1.277-2.300 (mean: 1.949 in control) and 1.057- 2.150 (mean: 1.716 in waterlogged), Chl b, 0.319- 0.607 (mean: 0.518) in control and 0.290- 0.571 (mean: 0.453) in waterlogged plants, respectively. Chl a/b ratio is slightly higher in waterlogged (3.640-3.957, mean: 3.794) as compared to control (3.610-3.997, mean: 3.789) plants except in CoJ 64, while total Chl/ CAR ratio was comparatively lesser in waterlogged plants as compared to untreated control. SPAD index was relatively higher in control (30.1 - 35.3, mean: 34.0) than waterlogged plants (22.4-34.1, mean: 29.6) similar to destructive analysis of chlorophyll contents. Carotenoids contents ranged from 0.477- 0.787 in control and 0.467-0.797 mg/g fresh wt in waterlogging treatment; BO91 and CoS767 cultivars showed slightly higher value in waterlogged. Correlation among different attributes indicated significant positive relationship except chlorophyll a/b ratio showing negative association. Cultivar CoJ 64 showed highest decrease in Chl a/b, total Chl/CAR ratio and CAR contents reflecting highly sensitive to waterlogging stress as compared to other cultivars studied.