Effect of growth hormones i.e., GA3 and kinetin and heavy metali.e., Pb(NO3)2 on the seedlings of Cucumis sativus L.

Effect of growth hormones i.e., kinetin and gibberellic acid as wellas heavy metal i.e., Pb(NO3)2 were studied pertaining to external andinternal morphology of Cucumis sativus L. Moreover, thehistomorphology of leaf was also studied. The following concentrationsof growth hormones i.e., 40 ppm kinetin, 200 ppm GA3 and heavy metali.e., 100 ppm Pb(NO3)2 and 200 ppm Pb(NO3)2 were appliedindividually. In combinations, they were 40 ppm kinetin, 100 ppmPb(NO3)2, 40 ppm kinetin + 200 ppm Pb(NO3)2, 200 ppm GA3+100 ppmPb(NO3)2 and 200 ppm GA3+200 ppm Pb(NO3)2. In the externalmorphology, applied kinetin revealed reduction in the length ofinternode and petiole, which was accompanied by expansion indiameter. Furthermore, it increased the fresh and dry weight. AppliedGA3 registered increase in length and inhibition in diameter anddecrease in fresh and dry weight. Application of Pb(NO3)2 treatmentsshowed decrease in length as well as in fresh and dry weight, whichwas accompanied by some expansion in diameter. The results of mixeddoses of Pb(NO3)2 with kinetin and GA3 were more or less similar asobserved in individual doses of kinetin and GA3. In the leaf, freshand dry weight, leaf area and number of leaves were increased withkinetin. Contrarily Pb(NO3)2 treatments revealed inhibition in freshand dry weight and leaf area. Moreover, number of stomata/mm2,stomatal index and %age of open stomata showed increase with kinetin.In the internal morphology of internodes, the epidermis, corticalcollenchyma and parenchyma, cambial region, xylary region and pithshowed increase with kinetin and decrease with GA3. In the petiole,the epidermis, collenchymatous hypodermis and xylary elementsshowed expansion with kinetin and Pb(NO3)2 treatments, whileinhibition was observed with GA3. In the case of leaf, width ofepidermal cells, size and number of mesophyll cells and width of xylemelements revealed increase with kinetin, while rest of the treatmentsshowed no significant effect.