The response of plant canopy to radiation as Normalised – Difference Vegetation Index (NDVI), and Chlorophyll and nitrogen content in large cardamom (Amomum subulatum Roxb.) were studied under agroforestry systems at three elevations in the Sikkim Himalaya. Large Cardamom is a high-value, low-volume, non-perishable and perennial cash crop grown as understorey in agroforestry system. N2-fixing alder (Alnus nepalensis D. Don) or mixed species plantations serve as shade trees. Reduction in photosyn-thetically active radiation under the shade compared to open was substantial, 39% reaching the cardamom under Alnus and 50% under mixed tree species. Chlorophyll a, total chlorophyll and nitrogen of large cardamom were always higher under Alnus trees than under mixed tree species. Total chlorophyll and chlorophyll a contents of large cardamom leaf and NDVI varied significantly between plantation types and altitudes. Nitrogen content of leaf showed positive relation with total chlorophyll and chlorophyll a indicating enhanced productivity of large-cardamom under Alnus due to nitrogen fixation.
