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THE INHIBITION OF POLYMERIZATION OF GLUCOSE IN CARBOHYDRATE UNDER CU STRESS IN VIGNA RADIATA

RAFIA AZMAT^* AND SANA RIAZ¹

Abstract: This study was planned to explore the effect of Cu on polymerization of glucose into carbohydrate under Cu stress in seedlings of 15 day old Vigna radiata in relation with photosynthetic pigments. Copper is an important trace metal in carbohydrate metabolism, it effects on the sugar contents when in excess. The interaction of Cu with photo-inhibitory and sugar metabolism showed a direct relation in between carbohydrate metabolism and photosynthesis. A decrease in glucose contents may be attributed with Cu toxicity which inhibits the fixation of CO₂ that in turns related with formation of first organic complex. A drastic decrease in carbohydrate contents may be related with Cu interference in polymerization of glucose into carbohydrates. Relative growth rate (RGR) and leaf mass ratio (LMR) of stressed plants were significantly lower than that of control plants. Copper was shown to restrain the growth of the seedlings as it is most important immobile micronutrient that inhibits new root growth.  A radical disorder in soluble reducing and non reducing sugars like, glucose, sucrose, total soluble sugars and carbohydrate with decrease in chloroplast pigments can be associated with reduction in leaf photosynthesis and also growth reduction is more likely due to a reduction in whole plant leaf area. Reduced leaf expansion with reduced photosynthetic activity may be related with fewer K contents in seedlings which play a crucial role in leaf expansion.
 

^*Department of Chemistry, University Karachi, Karachi-75270, Pakistan.

¹Jinnah University for Women Karachi 74600 Pakistan