engleski

Impact of Different Seed Priming Techniques on Germination and Seedling Performance of Common Bean Under Water Deficit Conditions

Achieving rapid and uniform seedling emergence is a key point for crop performance especially under adverse environmental conditions [1]. Several authors [2], [3] have reported that seed priming treatments could accelerate germination and seed emergence and produce more vigorous plants particularly under abiotic stress. Most frequently used seed priming methods are hydropriming (seed soaking in pure water) and osmopriming (soaking seeds in osmotic solution with low water potential, such as polyethylene glycol (PEG), mannitol, sorbitol, KCl, KNO3, K3PO4, CaCl2 etc. [4]. The aim of this study was to investigate whether hydropriming and osmopriming increase tolerance to water deficit stress in seedlings of main Croatian common bean landraces. Four most frequent Croatian common bean landraces ; 'Biser'’, ‘'Zelenčec'’, ‘'Trešnjevac'’ and ‘'Zlatni trešnjevac'’ [5] were included in this research. Total number of 40 seeds per genotype was used in this research, of which 8 seeds per genotype were treated with different priming treatments: • d H2O, during 4 h • 1.5% KNO3, during 12 h • 15 mM CaCl2, during 3 h • 2% H2O2, during 4 h • -0.8 MPa PEG-6000, during 12 h After application of priming treatments seeds were germinated in seed germination paper (Anchor paper company, USA), in drought treatment (-0.3 MPa) created using PEG 6000 concentration or in control treatment (0.0 MPa). Number of germinated seeds was counted at the 9th day [6], and on the 15th day of growth different morphological and physiological measurements were performed: • root morphological traits (root length (RL), depth (RD), width (RW), surface area (RSA), volume (RV), average diameter (RAD), number of tips (RNT), number of forks (RNF)) • leaf chlorophyll content index (CCI), • gas exchange parameters (net photosynthesis rate (A), stomatal conductance (gs), transpiration rate (E), mesophyll CO2 concentration (ci), water use efficiency (WUE)) • chlorophyll fluorescence (Fv/Fm and Fv/Fo) • root fresh weight (RFW), shoot fresh (SFW), root dry weight (RDW) and shoot dry weight (SDW). Data were analysed using mixed model ANOVA. By combining drought treatments and priming treatments different groups were created and discriminant analysis (PROC DISCRIM) was performed to evaluate how valid the groups are, and which variables distinguish the best among them. Reduced chlorophyll fluorescence (both Fv/Fm and Fv/Fo) indicate stress among plants grown in drought treatment. Drought treatment significantly decreased all measured root traits except average root diameter which increased. In addition, drought treatment increased average CCI, probably due to reduced SFW and SDW, but decreased average A, and gs values. Irespectivly to drought treatments, priming treatments affected CCI (highest found in KNO3 primed plants), and root traits (the smallest values, except RAD, were found in PEG primed plants and the highest in CaCl2 primed plants). The first axis of canonical correspondence analysis explains more than 50% of the total variation and differentiates among drought treatment and control tretament groups. First axis is positively correlated to root traits (except the RAD which is negatively correlated) and negatively to CCI. Second canonical component explains more than 20% of the total variation and differentiate among: drought_H2O, drought_CaCl2 and control_H2O from other groups and is more correlated to gas exchange parameters.

root morphology, gas exchange, chlorophyll fluorescence

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