Effect of different chemical and seasons on gas exchange parameters, phytohormones, and chlorophyll content in tissue culture plants of Pomegranate (Punica granatum L.) cv. Bhagwa

Little is known about rate of photosynthesis, transpiration, stomatal conductance, intrinsic water use efficiency, endogenous phytohormones (Gibberellic acid and Indole acetic acid) concomitant with leaf chlorophyll content during flowering and fruiting stages in pomegranate. As a result, a study was conducted to determine the function of various chemicals, such as Nitrobenzene (NB) at 1.0, 1.5, and 2.0 ml plant-1, Cycocel (CCC) at 500, 1000, and 1500 ppm plant-1, Uracil 25 and 50 ppm plant-1, CCC1000 ppm + Uracil 25 ppm plant-1, CCC 1500 ppm + Uracil 50 ppm plant-1, along with control at ICAR - Indian Institute of Horticultural Research (IIHR), Bengaluru, during the flowering and fruit set stages during two seasons, namely ambe bahar (January–February 2016) and hastha bahar (September–October 2016-17). Applications of Uracil 50 ppm plant-1, Uracil 25 ppm plant-1 and nitrobenzene 1.5 ml plant-1 at flowering stage resulted in highest rate of photosynthesis (16.48 µmol m-2 s-1), transpiration (7.69 mmol m-2 s-1) and stomatal conductance (0.44 mol m-2 s-1). Foliar spray of Nitrobenzene 1.5 ml plant-1, cycocel 1000 ppm plant-1 + Uracil 25 ppm plant-1 in conjunction with application of nitrobenzene 1.0 ml plant-1 registered highest rate of photosynthesis (12.55 µmol m-2 s-1), transpiration (6.19 mmol m-2 s-1) and stomatal conductance (0.19 mol m-2 s-1) at fruit set stage. Application of Uracil 50 ppm plant-1 resulted in higher levels of endogenous IAA content (394.3 ng g-1 FW and 885.3 ng g-1 FW), lower levels of GA3 content (110.7 ng g-1 FW and 144.0 ng g-1 FW), and highest total chlorophyll content (3.14 mg g-1 and 1.99 mg g-1) in the leaves at both flowering and fruit set stages. With application of cycocel 1500 ppm plant-1 at flowering and fruit set stages, highest photosynthetic rate (17.67 µmol m-2 s-1 and 15.71 µmol m-2 s-1), transpiration rate (7.68 mmol m-2 s-1 and 6.13 mmol m-2 s-1) and higher levels of endogenous IAA (946.7 ng g-1 FW and 633.0 ng g-1 FW) were registered respectively. Following application of cycocel 1500 ppm plant-1 and 500 ppm plant?1 at both flowering and fruit set stages, lower endogenous GA3 (163.3 ng g-1 FW and 276.0 ng g-1 FW) were observed. At flowering stage, cycocel 1000 ppm plant-1 + Uracil 25 ppm plant-1 recorded the highest total chlorophyll content (2.35 mg g-1). During flowering period, cycocel 1500 ppm plant-1 application resulted in the highest stomatal conductance (0.57 mol m-2 s-1). Application of cycocel 1500 ppm plant-1 + Uracil 50 ppm plant-1 resulted in the highest stomatal conductance (0.38 mol m-2 s-1) at fruit set stage.

Effect of exogenous gibberellin on endogenous hormone and ginkgolide content in Ginkgo leaves

Ginkgolide is one of the important secondary metabolites of Ginkgo biloba. The synthesis of plant secondary metabolites is influenced by exogenous phytohormones. In this study, ten-year-old ginkgo grafted seedlings were used as the test material, and the effects of 0, 2, 4, 6, 8, and 10 mmol L–1 gibberellin (GA3) on endogenous indole acetic acid (IAA), abscisic acid (ABA), GA3, and ginkgolide contents in ginkgo leaves were investigated. Results showed that exogenous GA3 treatment inhibited endogenous GA3, changed the contents of endogenous IAA and ABA in ginkgo leaves, and affected the accumulation of secondary metabolite ginkgolides. Among the given concentrations, the 4 mmol L–1 GA3 treatment could remarkably increase ginkgolide content. We found that the best harvesting period of ginkgo leaves were in late August and late September, in which the content of ginkgolides was the highest.

Effect of Auxins and Associated Metabolic Changes on Cuttings of Hybrid Aspen

In the present study, an attempt was made to induce rooting from single-node cuttings of hybrid aspen (Populus tremula L. ×P. tremuloides Michx.) with different concentrations of IAA, IBA and NAA during rooting. Among the three auxins used, NAA showed more effective induction on rooting as compared to IAA and IBA at the whole level. Thereafter, NAA was used further in experiments for anatomical and biochemical investigation. The results showed that it took 12 days from the differentiation of primordium to the appearance of young adventitious roots with NAA application. It was found that endogenous IAA, ZR and GA3 levels increased, but ABA decreased in cuttings with 0.54 mM NAA treatment. In contrast to the endogenous IAA level, NAA had negative effect on IAA-oxidase (IAAO) activity. Similarly, the decreased peroxidase (POD) activity, consistent with down-regulation of expressed levels of POD1 and POD2, was observed in NAA-treated cuttings. Whereas, NAA resulted in a higher activity in polyphenol oxidase (PPO) compared to the control cuttings. Collectively, the study highlighted that 0.54 mM NAA is efficient on rooting in hybrid aspen, and its effect on metabolic changes during rooting is discussed, which provide valuable information for propagating hybrid aspen.