Rajneesh K. Agnihotri

Effect of lead and nickel toxicity on chlorophyll and proline content of Urd (Vigna mungo L.) seedlings

The effect of Pb and Ni on chlorophyll a, b, carotenoids and proline content of Black gram (Vigna mungo L.) seedlings were evaluated under 10, 50 and 100 µM concentration. These concentrations significantly affected chlorophyll, carotenoid and proline content of Black gram as compared to control. Pb and Ni at 10 µM concentration resulted in less significant effect on chlorophyll, a, b and carotenoids. Carotenoids were less affected compared to Chl a and b, while higher concentrations (50 and 100 µM) significantly reduced chlorophyll and carotenoid contents of the seedlings. However, the addition of nitrogen (5 mM) somehow minimized the effect of these heavy metals. Nitrogen increased the chlorophyll content of metal treated plants. The proline content of plants was increased under Pb and Ni treatments (10, 50 and 100 µM). In this case, the additional supply of nitrogen in the form of ammonium nitrate decreased proline content of plants treated with Pb and Ni.

Gas exchange variability and water use efficiency of thirty landraces of rice still under cultivation in Kumaun region of the Indian Central Himalaya

Gas exchange characteristics of thirty landraces of rice (Oryza sativa L.) along with an introduced variety VL-206 (recommended high yielding variety for rainfed uplands of the Indian Central Himalaya, ICH), grown in earthen pots and kept in the open at the Institute nursery at Kosi (1150m amsl, 79°38′10″E and 29°38′15″N) were studied. The photosynthetic rate (Pn) and other related parameters were found to vary considerably among landraces. Based on the comparison of Pn of landraces with that of VL-206, these were categorized into two groups: i) high (〉6.0 µmol m−2s−1), and ii) low (<6.0 µmol m−2s−1) Pn groups. Overall the landraces belonging to the high Pn group (Saurajubawan, Syaudhan and Taichin) which had higher stomatal conductance (gs), transpiration rate (E), water use efficiency (WUE), mesophyll efficiency (low Ci/gs ratio) and chlorophyll (Chl) content in comparison to landraces in the low Pn group. However, significant differences were not found in the intercellular CO2 concentration (Ci) between landraces belonging to the high and low Pn groups. Differences among landraces were found with regard to dark respiration; landraces with low Pn respired proportionately more of the carbon fixed than those of high Pn group. Based on the studied gas exchange characteristics Saurajubawan, Syaudhan and Taichin, local landraces of rice, may be identified as potential cultivars with high Pn and WUE.

Biochemical Changes in Seedlings of Brassica nigra Imposed by Iron and Manganese Induced Heavy Metals Stress

In present study, the seeds of Brassica nigra (variety 1021) were used to evaluate the effect of iron and manganese on different biochemical parameters. The effects of Fe and Mn were studied with regard to pigments composition (proline and carbohydrates contents) of black mustard seedlings under 50 μM, 100 μM and 200 μM concentrations. These concentrations significantly affected the growth of tested seedlings compared to control. Chlorophylls and carbohydrate content also increased at the lower concentrations of Fe and Mn. However, the additional supply of the 5 mM nitrogen in the form of Ca(NO3)2 in the nutrient medium somehow reduced the effect of these metals. On the application of nitrogen in the nutrient medium, Fe showed more promotary effect on chlorophylls, carotenoid and carbohydrates content in all concentrations (50 μM, 100 μM and 200 μM). Whereas, Mn exhibited increase in chlorophyll ‘a ’, carotenoid and carbohydrate content at 50 μM concentration but these contents significantly decreased at 100 μM and 200 μM concentrations, respectively; while chlorophyll ‘b ’and proline content decreased at all concentrations of the Mn.

Effect of Environmental Changes on Phenology and Reproductive Biology of Sida cordifolia with Special Reference to the Temperature and Relative Humidity

Impact of environmental factors (temperature and relative humidity) on phenology and reproductive biology of a medicinal plant Sida cordifoliaL.growing at district Agra was studied. The study revealed that phenological events (leaf fall, leaf renewal, flowering and fruiting) varied considerably with the fluctuations in temperature and relative humidity. Flowering was observed throughout the yearwith maximum in the months of FebruaryApril (11.8 �38.3∫C) and August-September (24.4-33.9∫C). Floral biology studies showed that pollen viability, pollenovule ratio and fruit -set percentage was greatly reduced with rise or fall in temperature and rela tive humidity. The maximum pollen fertility (71%), fruit set (70-90%) and pollen-ovule ratio (190:1) was recorded in the month of March when temperature was ranging between 15.1-32.6∫C with 22- 76% RH. With the fall in temperature in the month of January(6.8-17.9∫C) the pollen fertility was reduced to 52%. At the end of April 32.5 -45.3∫C with 16-43% RH, the plants under observation exhibited OriginalResearch Article