Seventeen clones of C4 grass Miscanthus spp. collected from different climatic regions and elevations of Taiwan were transplanted in pots. 15-16 months after collection the plants received 0, 1, and 2 g of nitrogen fertiliser (N0, N1, and N2, respectively) per pot. All the measurements were done 10-12 d after N application. The relationships between net photosynthetic rate (PN) and photon flux density (PFD) showed a saturated curve, with PFD saturation at about 1 000 µmol m-2 s-1. The ranges of PFD saturated PN (Psat) for all the tested clones with N0, N1, and N2 were 8-16, 11-18, and 12-21 µmol m-2 s-1, respectively. The clones from southern Taiwan, a tropical region, showed the highest Psat, followed by the clones from northern Taiwan, a subtropical region, while those from mountainous area showed the lowest Psat. The clones collected from southern Taiwan showed the highest frequency of stomata on the adaxial surface, and those collected from the high mountainous area showed the lowest frequency. Also the adaxial surface of leaves from the higher mountainous area had more wax deposited than the leaves from the lowland. Thus the low Psat in mountain clones is limited by both stomatal and non-stomatal factors. Further, the lower leaf conductance and different epidermal characteristics of mountain clones might prevent excessive loss of heat through transpiration and provide production against ultraviolet-B radiation. and J. H. Weng, F. H. Hsu.
Growth characteristics such as leaf area, fresh and dry mass, and shoot length, and physiological parameters such as photosynthetic and transpiration rates, stomatal conductance, and water use efficiency were reduced by blister blight significantly more in a susceptible tea clone TES-34 than in a tolerant clone SA-6. Also the contents of total sugars, nitrogen, amino acids, proteins, polyphenols, and catechin were reduced more in diseased plant leaves. However, the reduction was more prominent in susceptible than in tolerant clone. Among the different hybrids of tea, Assam hybrid UPASI-3 was highly susceptible to blister blight followed by Cambod UPASI-27 and China UPASI-9. Similarly, tea seedling cv. Caline was highly susceptible to blister blight when compared to tea clone UPASI-3. Susceptibility of tea cultivars to blister blight infection is connected with many physical barriers including leaf area, shoot length, moisture contents, and other physiological and biochemical parameters. and R. Premkumar, P. Ponmurugan, S. Manian.
Partitioning of 14C-labelled photosynthates to various parts of un-pruned tea clones TV1 and TV25 was assessed in vivo by exposing maintenance leaves to 14CO2 at monthly intervals throughout the year. The plants from shoot apex to root tip were divided into twelve components to assess the allocation and retention of 14C-photosynthates by the maintenance foliage. Out of the total photosynthates produced by the maintenance leaves, only 11.08 % was allocated to the commercially useful harvestable two and a bud shoots which is accepted as the harvest index of tea. The photosynthetically active maintenance leaves retained 19.05 % while 24.56 % was distributed to the branches. The bottom and the top parts of the trunk utilized 7.44 and 7.21 %, respectively. The thick roots at the base of the trunk, medium sized roots, pencil size roots, and feeder roots imported 7.28, 7.72, 7.65, and 8.01 % of 14C assimilates, respectively. Except retention by leaves, all the plant parts of vigorous clone TV25 required higher percentage of assimilates than TV1. The mean quantities of net photosynthates utilized by the stem and the roots were 69.37 and 30.63 %, respectively. and T. S. Barman, J. K. Saikia.