Effects of low temperature stress on the physiology and growth of Caragana korshinskii seedlings from seed source of different stand ages
qian qiangou Guohua Wang GUO Wenting ZHANG Yu ZHANG Yan
Chin J Plant Ecol. 2024, 48 (2):
201-214.
doi:10.17521/cjpe.2022.0210
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Abstract
Aims This study investigated the effects of stand age, low temperature stress and their interaction on the growth and leaf physiological characteristics of Caragana korshinskii seedlings.
Methods In this study, the seeds of C. korshinskii in an artificial forest were selected from five stand ages (7, 13, 19, 41 and 51 a) in the hilly and sandy area of northwest Shanxi Province for germination, and the seedlings (about 2 months) were taken as test material. The low temperature stress of (-8 ± 1) °C was set, and the different stress levels were W1 (6 h), W2 (12 h), W3 (24 h), W4 (48 h) and W5 (72 h), and 25 °C (normal temperature) was taken as a control (CK). The growth physiological indexes related to frost resistance were determined, and the membership function method was used for comprehensive evaluation.
Important findings The results showed that: (1) There were significant differences in the effects of low temperature stress on photosynthetic pigments and osmotic adjustment substances in C. korshinskii seedlings of different stand ages. Among them, stand age and low temperature stress had significant effects on chlorophyll a content, and the standage, low temperature stress and their interaction had significant effects on the contents of chlorophyll b, total chlorophyll, carotenoid and chlorophyll a/b in C. korshinskii seedlings. The interaction between low temperature stress and stand ages and low temperature stress had a significant effect on soluble sugar content, and the stand ages, low temperature stress and their interaction had a significant effect on free proline content. With the increase of low temperature stress time, the contents of chlorophyll a, chlorophyll b and total chlorophyll in the leaves of C. korshinskii seedlings decreased first and then increased, while the chlorophyll a/b and carotenoid content increased first and then decreased, and the content of free proline increased. (2) The effects of low temperature stress on the growth of C. korshinskii seedlings at different stand ages were significantly different. On one hand, there were significant differences in plant height, leaf number, dry mass, main root length and root/shoot ratio of seedlings germinated from seeds from different ages plants, which increased first and then decreased with the increase of stand age. On the other hand, low temperature stress significantly inhibited the plant height of seedlings, while the interaction between stand age and low temperature stress had no significant effect on the above growth parameters of seedlings. (3) The seedlings germinated from the seeds of young mother (7, 13 a) have stronger frost resistance than those of older (19, 41, 51 a) ones. In summary, physiological indicators chlorophyll b content, total chlorophyll content, chlorophyll a/b, carotenoid content and growth indicators plant height, leaf number, dry mass, main root length and root/shoot ratio can be used as indicators of frost resistance identification of C. korshinskii seedlings. At the same time, when the natural regeneration of C. korshinskii forest is promoted artificially, the seeds of young and middle-aged C. korshinskii can be selected for seedling cultivation, thereby improving the success of regeneration.
Keywords windy and sandy hilly area in northwest Shanxi; stand age; Caragana korshinskii seedlings; low temperature stress; osmoregulation; photosynthetic pigment; root/shoot ratio