Full Length Research Paper
Abstract
Seedlings of thirteen genotypes of rice were photoautotrophically grown on MS medium and subsequently exposed to 0 (control) or 200 mM NaCl (salt stress) for 14 days. Chlorophyll a (Chla), chlorophyll b (Chlb) and total carotenoids (Cx+c), in the salt stressed leaves of all genotypes decreased significantly, but the extent of the decrease varied among different genotypes. Maximum quantum yield of photosystem II (PSII) (Fv/Fm), photon yield of PSII (FPSII) and net photosynthetic rate (Pn) in salt stressed seedlings of all genotypes dropped significantly, whereasFPSII in cv. Homjan (HJ), Dokpayom (DPY), Chewmaejan 2 (CMJ2) and upland rice 1 (UR1) were alleviated. Moreover, growth parameters including shoot height, root length, fresh weight, dry weight and leaf area in salt stressed plantlets of all genotypes were significantly inhibited. The pigment degradation, photosynthetic abilities and growth inhibition in saline regimes were subjected to hierarchical cluster analysis, which lead to the classification of Kumuangluang (KML), Khao Dawk Mali (KDML), Pokkali (POK), HJ, DPY, Chewmaejan 1 (CMJ1), CMJ2, UR1 and Chowho (CH) as salt tolerant and R258, Pathumthani 1 (PT1), IR29 and upland rice 2 (UR2) as salt sensitive.
Key words: Chlorophyll a fluorescence, growth reduction, net-photosynthetic rate, pigment degradation, salt-tolerant classification.
Abbreviation
SES, Standard evaluation score; LAI, leaf area index; UR1, upland rice 1, UR2, upland rice 2; DPY, Dokpayom; CMJ1, Chewmaejan 1; CMJ2,Chewmaejan 2; CH, Chowho; KML, Kumuangluang, KDML105, Khao Dawk Mali 105; POK, Pokkali; HJ, Homjan; PT1, Pathumthani 1; RH, relative humidity; Chla,chlorophyll a , Chlb, chlorophyll b TC, total chlorophyll; Fv, variable fluorescence;PSII, photosystem II; FPSII, photon yield of photosystem II; Pn, net-photosynthetic rate; SH, shoot height; RL, root length; FW, fresh weight; DW, dry weight; LA, leaf area; NPQ, non-photochemical quenching.
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