RELATIONSHIP BETWEEN LEAF NITROGEN AND PHOTOSYNTHETIC CHARACTERISTICSIN BRASSICA-JUNCEA AND BRASSICA-CAMPESTRIS

The relationship between leaf nitrogen content (N) versus photosynthet ic rate (PN) and other associated parameters was examined in Brassica juncea, cv. Pusa Bold and B. campestris, cv. Pusa Kalyani. Leaf N, spe cific leaf weight (SLW), leaf area and PN were significantly higher in B. juncea, while the chlorophyll content was significantly lower comp ared to Brassica campestris. A significant positive correlation was ob tained between leaf N content and photosynthetic rate in both species. Similarly, SLW was also positively related with leaf N content. Brass ica juncea showed higher photosynthetic nitrogen use efficiency (PNUE) than B. campestris. Leaf N and PNUE were negatively associated. This was attributed to a low investment of N in photosynthesis related reac tions and/or partitioning of N towards compounds functionally unrelate d to photosynthesis. This attribution is further supported by the nega tive relationship obtained between SLW and PNUE.