Chloroplasts isolated from Vigna sinensis L, seedlings grown under cool íluorescent (control chloroplasts) and ultraviolet-B (UV-B)-enhanced íluorescent (UV chloroplasts) radiation, when incubated at 10, 20, 30 and 40 °C, showed large variations in the photosynthetic electron transport reactions. The overall electron transport activity in both control and UV chloroplasts incubated at 40 decreased rapidly. In contrast to this, at 30 the control chloroplasts got inactivated very rapidly during the 30 min of incubation while the UV chloroplasts showed high stability. A similar trend was also noticed at 20 “C. At 10 °C, although the rate of inactivation was slow, UV chloroplasts were more stable than control chloroplasts. A similar trend was noticed in photosystern (PS) 2 activity. In contrast to overall electron transport and PS2 reactions, PS 1 activity showed only marginal changes at all temperatures. The polypeptide profiles of chloroplasts exposed to UV-B iixadiation for 60 min at different temperatures revealed marked decreases in the level of the 23 and 33 kDa polypeptides in control chloroplasts while in UV chloroplasts these polypeptides were highly stable. In addition, UV chloroplasts contained several new polypeptides of both high and low molecular masses. The polypeptide partem indicated that higher photochemical activity of UV chloroplasts over the control chloroplasts could be due to stabilization of PS 2 core complexes by the new polypeptides induced under UV-B enhanced radiation.
Potential daily biomass production of jutě was calculated from the conversion of measured incident photosynthetic photon flux (PPF) during the jutě growing season (Apríl - August) of Indo-Bangladesh sub-continent and evaluating the average respirátory loss over the same period. Taking an average incident PPF of 39.87 mol(photon) m-2 d’*, the potential daily rate of dry matter production of 49.77 g m'2 was estimated with a photosynthetic efficiency of 1.25 g mol'^ Considering the daily production rate as proportional to the amount of radiant energy interception by the crop at different stages of growth, a maximum jutě biomass production capacity of 4.081 kg m'2 (40.81 t ha'*) was estimated. This value was little more than two times the average production obtained from the field experiment under similar conditions. Radiation use efficiency of a dosed jutě canopy (3.5 g MJ**), however, appears to háve reached that for any field crop.