Elevated UV-B radiation (12.2 kJ m -2 d -1 ) as against the ambient level of 10 kJ m -2 d -1 affected flowering, productivity and biomass partitioning of green gram [Vigna radiata (L.) Wilczek cv. KM-2]. UV-B stress delayed flowering initiation and achievement of 50 % flowering, reduced flower retention by 25 %, potential yield by 18 % and all yield attributes such as pod number (25 %), pod mass (41 %), seed number (32 %) and seed mass (45 %). Harvest index and shelling percentage were also reduced by 31 and 7 %, respectively. Application of triadimefon (20 mg dm -3 ) to unstressed plants accelerated flowering and enhanced flower retention (21 %), potential yield (15 %) and yield attributes (7 to 44 %). The partitioning of biomass between plant parts also showed improvement over the control plants. In UV-Bstressed plants, triadimefon treatment compensated the inhibitions to varying extents.

Supply of aqueous solution of triadimefon (20 mg dm -3 ) to unstressed green gram plants increased the contents of soluble proteins, amino acids, nitrate and nitrite, and the activity of nitrate reductase in the leaves and nitrate reductase in nodules. The nitrogenase activity in nodules and roots was also increased. Number and fresh mass of nodules and their nitrate and nitrite contents were also higher than those of the controls. In contrast, the UV-B stress (12.2 kJ m -2 d -1 ) suppressed nodulation and nitrogen metabolism in leaves and roots compared to plants under natural UV-B (10 kJ m -2 d -1 ). Triadimefon-treated plants did not show such severe inhibitions after exposure to elevated UV-B. Thus triadimefon increased their tolerance to UV-B stress.

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Callus induction was tried with leaf explants (third leaf from top of canopy) harvested from in situ control and supplementary UV-B irradiated (UV-B = 2 hours daily @ 12.2 kJ m-2 d-1; ambient = 10 kJ m-2 d-1) three varieties of green gram viz. CO-8, NVL-585 and VAMBAN-2 to study their viability for germplam conservation. Callus induction occurred both in control and UV-B stressed NVL-585 leaf explants. VAMBAN-2 both in unstressed and UV-B stressed conditions did not initiate callus. Only control leaf explants from CO-8 proliferated callus. Callus of UV-B irradiated NVL-585 weighed less (51.28 %) than control. Parenchyma cells were smaller in callus inducted from in situ UV-B exposed NVL-585 leaf explants. The leaf explants from UV-B stressed NVL-585 varieties of green gram responded to in vitro callus proliferation making them fit for germplasm conservation for cultivating in UV-B elevated environment.Int J ApplSci Biotechnol, Vol 4(1): 82-91

International audienceA new species of Tetrastigma, Tetrastigma tamilnadense, from Western and Eastern Ghats of Tamil Nadu is described and illustrated. It differs from its allied species, Tetrastigma leucostaphylum and Tetrastigma sulcatum, in leaflet size and shape, pubescence of young vegetative parts and flowers, size and rind of berries, and seed shape