Publication Date:
1993-03-01
Description:
The concentration and mass of nitrogen (N) were followed seasonally in leaves of 26 trees species of Central Himalaya: 11 evergreen species with about 1-year leaf life-span and 15 deciduous species. Like the deciduous species, the leaves of these evergreen species start senescing and losing mass in the year of formation. Species with higher N status retranslocated a larger proportion of leaf N prior to leaf abscission than the species with less favourable N status. The percentage of N mass in the leaf that was retranslocated during senescence ranged from 32.7 to 75.3%, but none of the species with N concentration less than 2.5% in mature leaves retranslocated more than 60% of N. Compared with evergreen species, on average the deciduous species showed higher N concentration in mature leaves (3.2 vs. 2.5%), higher proportion of leaf mass loss during senescence (31.6 vs. 26.2%), and greater proportion of retranslocated N mass from leaves (57.1 vs. 51.8%). With regard to the N-use efficiency the two groups of species were not clearly different. The dependence of deciduous species on retranslocated N mass for leaf growth during the dry period of the premonsoon season was greater than that of the evergreen species, which showed partial dependence on the soil N pool for new leaf formation.
Print ISSN:
0045-5067
Electronic ISSN:
1208-6037
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
