TY  - BOOK
AU  - Nair D B
AU  - Annamalainathan K
AU  - Jacob J
TI  - Partial shading is beneficial in Hevea during summer
PB  - Placrosym XIV, 2000, Hyderabad, India : Programme and Abstracts.p.67
KW  - Hevea
KW  - Shading
N2  - Nursery level performance of Hevea at different shade levels and in open sunlight were evaluated at Rubber Research Institute of Indias farm, Kottayam. The observations were carried out in one year old polybag grown clones of RRII 105, RRIM 600, GT-1 and PR 255 under open sunlight (unshaded plants) and at 30;and 70;shade. Drought stress was imposed by with holding water for fifteen days in the month of March. Biomass production leaf area per plant, chlorophyll content and chlorophyll a/b ratio were estimated and measurement of net photosynthesis and chllorophyll fluorescence parameters were taken in respective ambient growth light conditions. Higher increase in plant height, internode length and leaf area was observed in the plants growing under shaded condition than the open sun grown plants. The open grown plants had more chlorophyll a and less total chlorophyll. Clones RRII 105 and RRIM 600 exhibited higher photosynthetic rates than GT1 and PR 255 at 30;shade. However, 70;shade resulted in greater inhibition of photosynthesis (25;) and loss of biomass (11;) inspite of a large increase (36;) in total leaf area per plant compared to open. Similarly drought and high light affected the in vivo quantum yield of PSII (Fv/Fm) in the drought than the fully irrigated plants. In drought stressed plants Fv/Fm was inhibited both in open sunlight and at 30;shade indicating that high light aggravated the harmful effects of drought on PSII activity. The studies clearly indicated that high light is an additional stress to plants experiencing drought stress and shading from full sun helped Hevea plants to alleviate photo inhibition in extreme water deficit situation
ER  -