C. P. Malik

Effect of mixtalol on growth, yield and yield components of Indian mustard (Brassica juncea)

Mixtalol (a mixture of long chain aliphatic alcohols varying in chain length from C24 to C32) applied to Brassica juncea plants as foliar spray caused an increase in secondary and tertiary branching with consequent enhancement in seed yield through increased number of inflorescences and siliquae per plant. The percentage of immature siliquae and shattering of siliquae decreased with this treatment. Mixtalol increased total dry matter of plants, partitioning coefficient and harvest index. The contents of starch, protein and oil were also higher in seeds from Mixtalol treated plants.

Hormonal regulation of cotton fibre elongation in Gossypium arboreum L. in vitro and in vivo

Summary Changes in endogenous levels of IAA, GA3 and ABA during in vivo fibre growth of Gossypium arboreum L. cv. LD 230 revealed an overriding influence of ABA in restricting the rate of fibre elongation. No relationship between IAA levels and extent of fibre elongation was discernible. The fibre growth of unfertilized cotton ovules cultured in vitro was promoted by the application of fluridone, an inhibitor of ABA biosynthesis. Fluridone resulted in a marked reduction of ABA concomitant with an increase in IAA and GA3 levels of cultured cotton ovules. The relationship of ABA with IAA and gibberellin is shown to have regulatory influence in determining the extent of cotton fibre elongation.

Hormonal effects on tube elongation, 14CO2 fixation and phosphoenolpyruvate carboxylase activity in Amaryllis pollen: Promotion by abscisic acid

Abscisic acid promoted tube elongation, 14CO2 fixation and phosphoenolpyruvate carboxylase activity during in vitro germination of Amaryllis vittata Ait. pollen. Other growth regulators tested viz. indol-3yl-acetic acid, gibberellic acid, N6-benzyladenine and ethephon did not affect pollen tube elongation at 1 μg/ml concentration but inhibited it at 10 μg/ml. The case for abscisic acid as a growth promoter is argued.

Cyclic AMP-induced Elongation of Pollen Tubes in Tradescantia paludosa

Summary Cyclic AMP evoked early emergence of pollen tube, increased percentage of pollen germination and promoted pollen tube elongation in Tradescantia paludosa pollen. GA 3 and ABA were found to decrease and increase pollen tube length, respectively. The effect of combined treatments of cAMP, ABA, GA 3 and cycloheximide on pollen tube growth is described. This study unequivocally demonstrates the action of cyclic AMP and discusses its probable mode of action in pollen tube growth.

Triacylglycerol synthesis in developing kernels of groundnut as influenced by aliphatic alcohols

Abstract In developing groundnut ( Arachis hypogaea ) kernels, the most active period of lipid, chiefly triacylglycerol (TG) accumulation is between 15 and 35 days after podding (DAP). Between 5 and 15 DAP starch content was enhanced but declined thereafter up to maturity. With progressive development of kernels both phospholipids and free fatty acids decreased, whereas total glycerides continuously increased. At 15 DAP, [U- 14 C]fructose was incorporated into TG at a high rate. The incorporation of [1- 14 C]acetate into TG increased progressively during the active period of lipid accumulation. The rate of incorporation of the latter into TG was about three-fold greater than that of fructose. Addition of glycerol (0.5 mM) in the incubation medium stimulated lipid accumulation and is attributed to the limited availability of glycerol and other metabolites, especially during the active period of lipid accumulation in seed [15–35 DAP]. Foliar spray treatments with a mixture of aliphatic alcohols enhanced incorporation of [U- 14 C]fructose and [1- 14 C]acetate into TG of the developing kernels. The regulatory mechanisms involved in the stimulation of lipid accumulation are discussed.

Calcium-mediated changes in peroxidase and O-diphenol oxidase activities of cotton fibres (Gossypium spp.) and its possible relationship to ABA

This work is an investigation of the influence of ABA and calcium on soluble and wall-bound activities of peroxidase and O-diphenol oxidase of cotton fibres at the stages of primary and secondary wall development, during incubation of intact fibres for 3h at 28°C. ABA (10 μM) caused marked inhibition of enzyme activities in both the fractions, whereas calcium (1 mM) was promotory. The incorporation of 1 mM EGTA (a calcium chelator) and chlorpromazine (10 μg cm−3) (a calmodulin antagonist) resulted in decreased enzyme activities suggesting regulation of enzyme synthesis and/or secretion to the cell wall by calcium-calmodulin. As a general trend, the relative effect of Ca2+ on the activity of peroxidase in the wall was much greater than on the soluble activity, but this was not true of O-diphenol oxidase. It is inferred that ABA inhibits enzymic activities by inhibiting calmodulin synthesis or its mobilization to sites of action.

Effect of Salicylic Acid and Tannic Acid on Stomatal Aperture and some Enzyme Changes in Isolated Epidermal Peelings of Euphorbia hirta L.

Summary Exogenously added salicylic acid. (5–25 ppm) and tannic acid. (5–20 ppm) reduced stomatal aperture and caused complete closure in isolated epidermal peelings of Euphorbia hirta L. Studies on some enzyme activities revealed that both phenols drastically reduced the activity level of acid phosphatase and ATPase compared with the controls. The probable role of these phenols in stomata] mechanism is discussed.

Flowering pattern and pod development responses in a spreading type of groundnut (cv. M-13) to a monophenol and aliphatic alcohols mixture

Plants of spreading type of groundnut (Arachis hypogaea cv. M-13) were given foliar sprays separately with phenolic compound β-naphthol-1-amino, 4-sulphonate (50, 100, 150 μg/ml) and a mixture of aliphatic alcohols—C-24 to C-34 (1 μg/ml) at 30 and 37 days after flowering. In the treated plants, the total number of flowers produced per plant, number of flowers in the initial 3 weeks increased significantly. Both the compounds required lesser number of days for the production of initial 70 flowers as compared with control. With aliphatic alcohols several of the kernel and pod characters increased significantly over the control. Flowering in phase A showed a positive significant correlation with some of the yield characters though it was significantly negatively correlated with harvest index. The compounds were effective in inducing the establishment of early potential sinks and caused efficient mobilization of assimilates for a longer filling period in the pods.

Effect of carbon dioxide on lipid metabolism in Crotalaria juncea pollen suspension culture

Abstract The effect of carbon dioxide (1%) on the incorporation of [1- 14 C]acetate into polar and non-polar lipids was studied in the growing pollen tubes of Crotalaria juncea . Carbon dioxide stimulated the incorporation of 14 C into non-polar (except sterols) fractions and decreased the incorporation into polar (except phosphatidic acid) fractions. It is suggested that carbon dioxide could regulate membrane biosynthesis.

Cyclic-amp control of some oxido-reductases during pine pollen germination and tube growth

Abstract Cyclic-AMP markedly increased the activities of peroxidase, malate dehydrogenase and succinate dehydrogenase but not glucose-6-phosphate dehydrogenase. Using inhibitors of protein and RNA synthesis, it was found that a part of enzyme activity increase caused by cyclic-AMP required fresh protein synthesis. The question of specificity of enzyme induction by cyclic-AMP has been examined.