Effect of heat stress on seed germination of lettuce (Lactuca sativa L.): genotypic variability and assessment of thermotolerance

Posted on 23.06.2026 by admin
UDC 635.52: 581.142
https://doi.org/10.25630/PAV.2026.21.14.008

Ilin I.E., Tsiunel M.M., Mironov A.A.

The aim of this work was to assess the effect of different temperature regimes (10, 15, 20, 25, and 30 °C) on the seed quality of six lettuce cultivars from «NIISOK» LLC (Frezer, Tsezar, Kaskad, Kassiopeya, Seladon, Patritsii) and to identify the most resistant to temperature stress among them. Germination was carried out under laboratory conditions in Petri dishes according to GOST 12038-84 in triplicate with 50 seeds per replicate, with daily counting of germinated seeds for 10 days. Based on the results, laboratory germination (LG), mean germination time (MGT), and thermal inhibition coefficient (TC) were calculated as the ratio of germination at 30 °C to germination at 25 °C. Statistical processing was performed using two-way ANOVA with Tukey's HSD post-hoc test and hierarchical cluster analysis by Ward's method. It was found that in the range of 10–25 °C, all cultivars were characterized by high germination (82–100 %) and differed mainly in germination time (MGT from 1.00 to 4.34 days). At 30 °C, a sharp genotypic differentiation was observed: cultivars Frezer and Kaskad maintained high germination (78 and 72 %, TC 0.78 and 0.77, respectively) and minimal germination time (MGT 1.68 and 2.04 days), whereas cultivars Kassiopeya and Patritsii showed a sharp drop in germination (30.7 and 0.7 %, TC 0.31 and 0.01). Cultivars Tsezar and Seladon occupied an intermediate position. Also, based on TC, the cultivars were divided into three thermotolerance groups: thermotolerant (Frezer, Kaskad), moderately tolerant (Tsezar, Seladon), and thermosensitive (Kassiopeya, Patritsii). From the data obtained, it can be concluded that the temperature threshold for triggering the thermoinhibition process in the studied cultivars lies between 25 and 30 °C.

Key words: lettuce, Lactuca sativa, thermal inhibition, thermotolerance, germination, mean germination time (MGT), heat stress, thermoinhibition rate.

Ilin I.E., postgraduate student, Department of Molecular Breeding, Cell Technologies and Seed Production, Russian State Agrarian University – Moscow Timiryazev Agricultural Academy. E-mail: ivan13ilin@gmail.com

Tsiunel M.M., Cand. Sci. (Agr.), Head of the Department of Green Crops and Root Vegetables Breeding, «NIISOK» LLC. E-mail: mciunel@yandex.ru

Mironov A.A., Candidate of Agricultural Sciences, Associate Professor, Department of Molecular Breeding, Cell Technologies and Seed Production, Russian State Agrarian University – Moscow Timiryazev Agricultural Academy. E-mail: a.mironov@rgau-msha.ru

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For citing: Ilin I.E., Tsiunel M.M., Mironov A.A. Effect of heat stress on seed germination of lettuce (Lactuca sativa L.): genotypic variability and assessment of thermotolerance. Potato and vegetables. 2026. No4. Pp.  57–60. https://doi.org/10.25630/PAV.2026.21.14.008 (In Russ.).

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