Navita Ghai

Translocation of metabolites in pigeonpea (Cajanus cajan L.) under the influence of mineral nutrients

Mineral nutrient sources viz., CaCl2 (0.01% and 0.02%), KNO3 (0.5% and 1%), MgCl2 (0.1% and 0.2%) and urea (1% and 2%) were applied as foliar application to pigeonpea varieties (PAU 881 and AL 201) at green floral bud stage of inflorescence to study their effect on the level of various metabolites viz., total soluble sugars, total starch, total free amino acids and total soluble proteins in leaves and their subsequent accumulation in developing seeds. It was observed that mineral nutrients caused greater accumulation of different metabolites in developing seeds (sink) which may be attributed to enhanced translocation of these metabolites from source to sink tissues as evident from their decline in leaf tissues (source) thereby strengthening the source-sink relationship in pigeonpea. Urea application @ 2% increased accumulation of metabolites in mature seeds by 27.71 (PAU 881) and 25.25% (AL 201) in case of total soluble sugars, 11.19 (PAU 881) and 11.33%(AL 201) in case of total starch, 38.23 (PAU 881) and 39.41% (AL 201) total free amino acids and 10.72 (PAU 881) and 8.66% (AL 201) of total soluble proteins as compared to their respective controls.

Variations in morpho-physiological and yield attributes of kabuli chickpea genotypes in relation to seed size

Present study was undertaken with three categories of seed size of Kabuli chickpea genotypes. Leaf characteristics, viz., number of leaves, leaf area, leaf area index, and specific leaf weight were high in large-seeded category genotypes than other two seed size category genotypes during reproductive phase of plant growth and development. Photosynthetic rate, biomass accumulation was also higher in large-seeded category. Phenological parameters such as days to flower initiation and days to pod initiation were earlier in large-seeded category genotypes, while pods maturity was late in large-seeded category than in medium-and small-seeded category. However, mean number of flowers plant−1 was higher in medium-seeded category than in small-and large-seeded categories. Yield contributing parameters at harvest viz., per cent filled pods, number of seeds plant−1, number of pods plant−1, 100-seed weight, partitioning coefficient, harvest index and yield were greatly affected by seed sizes. On the basis of varietal differences, small-seeded genotypes GLK 26155 and BG 1053, and medium-seeded genotypes GLK 26164 and GLK 25121 had higher biomass, per cent filled pods, number of pods plant−1, Per cent pod set, 100-seed weight, partitioning coefficient and yield plant−1, while in large-seeded category, genotypes GLK 28119 and GLK 28126 showed higher biomass, per cent filled pods, per cent pod set, 100-seed weight, partitioning coefficient, harvest index and yield plant−1. Large-seeded genotypes showed higher Per cent filled pods, 100-seed weight, Per cent pod set and partitioning coefficient, followed by medium-and small-seeded genotypes, but the differences were non-significant.

Homobrassinolide-Induced Thermotolerance in Brassica Species

The Brassica crop encounters high temperatures during harvest leading to fruit shattering. Early sowing of the crop may help in overcoming this problem. However, the early sown crop may be exposed to high temperature during seedling stage, and high soil temperature may cause profound modification of growth and metabolic processes in young seedlings. Growth regulators have widely been used for acquisition of thermotolerance in a variety of crops, so efficacy of homobrassinolide (HBR) in inducing thermotolerance was tested in different cultivars of Brassica, namely RL-1359 (Brassica juncea), PBR-210 (Brassica juncea), and PC-5 (Brassica carinata). Application of homobrassinolide HBR at 0.1 and 0.2 μg ml−1 as pretreatment to four-day-old Brassica seedlings before exposing them to lethal temperatures increased the values of the following characteristics: seedling length, vigor index of seedlings, total soluble sugar content, and enzymatic activities, and caused remarkable reduction in relative injury of membranes measured by electrolyte leakage. Separation of proteins through SDS-PAGE revealed the accumulation of some new proteins in HBR-treated seedlings. Activities of enzymes peroxidase and invertase increased remarkably, whereas catalase showed a reduction in activity. The scavenging of reactive oxygen species like H2O2 and superoxide ions by antioxidant enzymes plays a key role in imparting thermotolerance. Thus high peroxidase activity, high invertase activity, and low electrolyte leakage of membranes could be directly linked with enhanced tolerance to heat-induced oxidative damage and could be involved in the processes leading to acclimation during heat stress. These features could be exploited to improve thermotolerance of crop plants by suitable breeding strategies.