Physiological and Fluorescence Reaction of Four Rice Genotypes to Exogenous Application of IAA and Kinetin under Drought Stress

Abstract

To assess the effects of IAA and Kinetin plant growth regulators in order to improve the drought tolerance in rice seedlings (Oryza sativa L.), a factorial experiment was carried out based on complete randomized design with three replications. The experimental factors included different rice genotypes ['Gharib', 'Khazar',], drought stress from 1 to 4 code of the Vergara coding system and control (normal irrigation) and growth regulators in three levels (IAA and Kinetin through foliar spraying and non-application as control). The results indicated, under normal irrigation condition together with IAA application, 'IR83750' rice genotype had the highest number of tillers and leaf greenness, with mean of 18.27 and 49.46, respectively. The highest amount of leaf relative water content (95.11%) was related to 'Sepidrood'. Under drought stress condition, the highest electrolyte leakage (36.59%) was observed in 'Gharib'. In drought condition, the highest leaf drying score was related to 'Gharib' in both years, but the highest score of leaf rolling index (9) was observed in 'Gharib' and 'Khazar'. The present findings showed that drought stress had harmful effects in all examined genotypes and the impact in susceptible genotypes ('Gharib' and 'Khazar') was more than 'IR83750' and 'Sepidrood'. Application of growth regulators (IAA and Kin) improved growth conditions for of all genotypes. Therefore, using tolerant genotypes along with growth regulators can improve the rice growth traits.

A manipulative interplay between positive and negative regulators of phytohormones: A way forward for improving drought tolerance in plants

“…Accordingly, Bagheri et al (2019) reported an increase in the number of leaves and yield components of wheat by priming with indole acetic acid (IAA), an auxin precusor compound. Similarly, Salehifar et al (2017) also reported a higher growth rate and DT in rice genotypes treated with IAA. In tobacco, auxin was shown to facilitate lateral root growth development under DS (Wang et al, 2018).…”

Foliar Growth Regulator Sprays Induced Tolerance to Combined Heat Stress by Enhancing Physiological and Biochemical Responses in Rice

“…Four plant hormones were used, and the characteristics of each active ingredient sprayed in this study are mentioned in Supplementary Table 1. The concentrations of the foliar growth regulators used were as follows: (i) auxins (1-Naphthaleneacetic acid: NAA) at 5 × 10 −5 M; (ii) gibberellins (Gibberellic acid: GA3) at 5 × 10 −5 M; (iii) cytokinins (Trans-Zeatin) at 1 × 10 −5 M; and (iv) brassinosteroids [Spirostan-6-one, 3,5-dihydroxy-, (3b,5a,25R)] at 5 × 10 −5 M. These concentrations were selected since they showed a positive response and increased plant tolerance to heat stress (Zahir et al, 2001;Wen et al, 2010;El-Bassiony et al, 2012;Salehifar et al, 2017). Rice plants without any plant growth regulator sprays were only treated with distilled water.…”

Effects of Variations in Hormonal Treatments Upon In vitro Regeneration Potential in Embryo Explants of Arenga pinnata

“…Numerous studies have been established to illustrate the production of tissue culture from either the basal stem [9] and fruit [1,11] utilizing various PGRs such as 6-benzylaminopurine (BAP), 2, 4-Dichlorophenoxyacetic acid (2,4-D) and KN related to multipurpose benefits from sugar palm. The current study therefore uses a mixture of KN and IAA as PGRs to evaluate the growth of sugar palm from fruit as an explant.…”

“…The study indicated that pigeon pea treated with IAA 10mm in pre-treatment (87.67±0.33 cm) had a significance difference with respect to control (68.00±0.58 cm) in terms of plant height [8]. Another studies on application of KN and IAA in a field study to improve the drought stress tolerance in four rice genotypes (Gharib', 'Khazar', 'Sepidrood' and 'IR83750-131-1'('IR83750')) showed manipulation of amount used for IAA and KN are vital in developing the optimum drought tolerance ratio where highest percentage of relative water content (RWC) in "Sepidrood" (51.26% and 50.19% treated in IAA and KN respectively) and lowest electrolyte leakage (EL) with (25.79% and 27.59% treated in IAA and KN respectively) [9]. Hence, the aim of this study is to determine the optimum combination of KN and IAA on sugar palm culture and the response towards the hormone combination.…”