Performance of Dry-Seeded Rice Genotypes under Varied Soil Moisture Regimes and Foliar-Applied Hormones

Rajinder Pal; Gulshan Mahajan; Virender Sardana; Bavita Asthir; Bhagirath Singh Chauhan

doi:10.3390/plants9040539

Performance of Dry-Seeded Rice Genotypes under Varied Soil Moisture Regimes and Foliar-Applied Hormones

Plants (Basel). 2020 Apr 21;9(4):539. doi: 10.3390/plants9040539.

Authors

Rajinder Pal¹, Gulshan Mahajan^{1

2}, Virender Sardana¹, Bavita Asthir¹, Bhagirath Singh Chauhan²

Affiliations

¹ Department of Biochemistry, Punjab Agricultural University, Ludhiana 141004, Punjab, India.
² The Centre for Crop Science, Queensland Alliance for Agriculture and Food Innovation (QAAFI) and School of Agriculture and Food Sciences (SAFS), The University of Queensland, Gatton, Queensland 4343, Australia.

Abstract

Plant hormones influence various physiological processes during the growth and development of plants, but their critical roles in influencing yield and antioxidant activities in dry-seeded rice (DSR) have not been adequately explored. This study aims to analyze the performance and antioxidant activity of contrasting genotypes of DSR in response to soil moisture regimes and foliar-applied hormones. The study comprised sixteen treatments that were evaluated under field conditions as per split-plot design in three replications. Treatments comprised combinations of two soil moisture tension regimes (10 kPa and 20 kPa) and two genotypes (PR-111, non-stay-green type and PR-123, stay-green type) applied to the main plots and foliar application of three hormones (gibberellic acid (GA₃) 40 mg kg^-1, abscisic acid (ABA) 20 mg kg^-1, and cytokinin (CK) 40 mg kg^-1)) and a control (unsprayed) to subplots. The non-stay-green genotype (PR-111) resulted in 34.6% more grain yield (6.48 t ha^-1) than the stay-green genotype (PR-123) at the lower soil moisture tension regime (SMTR) (10 kPa) due to the increased number of filled grains per panicle and improvement in harvest index (HI). At the higher SMTR (20 kPa), the stay-green genotype (PR-123) produced 26.4% more grain yield (5.21 t ha^-1) than non-stay green genotype (4.12 t ha^-1) and showed enhanced superoxide dismutase (SOD) and peroxide dismutase (POD) activity that may have contributed in maintaining sink size through improved chlorophyll content. Grain yield (6.35 t ha^-1) with foliar-applied GA₃ (40 mg kg^-1) at SMTR of 10 kPa was higher by 12.2% and 24.0% than with foliar-applied ABA (20 mg kg^-1) and unsprayed treatments, respectively. Irrigation application at SMTR of 20 kPa and foliar application of ABA gave 24.1% higher grain yield (5.15 t ha^-1) than the unsprayed treatment, but it was similar to foliar-applied GA₃ and CK. This study implied that the stay-green genotype (PR-123) was more suitable under moisture stress conditions (20 kPa) in DSR, as it maintained sink size even under moisture stress conditions by improving dry matter translocation and enhancing SOD and POD activity. The study suggests the need to find out the endogenous level of these plant hormones in rice genotypes under a range of water regimes to develop high yielding and water use efficient genotypes of DSR.

Keywords: antioxidant activity; enzymatic activity; growth regulating substances; harvest index; leaf area index; oxidative defense mechanism; stay green genotypes; yield attributes.