Kamaljit KaurGurkarman Singh2022-02-102022-02-102021Gurkarman Singh (2021). Comparative studies on carbon and nitrogen metabolism in spring maize and teosinte. (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810182004The present investigation was undertaken to study comparative studies on carbon and nitrogen metabolism in spring maize and teosinte. For this study, two genotypes of maize viz., PMH-2 (relatively susceptible to heat stress), PMH-10 (relatively tolerant to heat stress) and a wild relative teosinte were taken into consideration. The content of sugars and the activities of carbohydrate and nitrogen metabolizing enzymes were determined in shoots and roots of seedlings. Heat stress increased the total soluble sugars and sucrose content in roots and shoots of PMH-10 and teosinte seedlings while it decreased in those of PMH-2 seedlings at 8 DSG stage. The roots of teosinte seedlings showed unaffected sucrose hydrolysing enzymatic activities. Sucrose synthetase (cleavage) activity of PMH-10 seedlings appeared to be mainly responsible for sucrose breakdown under stress conditions. In shoots of both maize and teosinte seedlings sucrose was primarily metabloised by sucrose synthetase (cleavage) activity. Sucrose phosphate synthetase activity was induced in PMH-2 and PMH-10 seedlings only while such induction was not observed in those of teosinte under stress conditions. In general, a parallel increase in GOGAT, GS and GDH activities in teosinte and PMH-10 seedlings corresponded to the increased total soluble protein content in their roots and shoots under heat stress. A decrease in the activities of above enzymes in PMH-2 seedlings corresponded to their decreased total soluble protein contentEnglishThesis