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

Abstract

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.

Keywords

• Bhagwa
• Physiological Parameters
• Plant Growth Regulators
• Pomegranate