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Acta Prataculturae Sinica ›› 2023, Vol. 32 ›› Issue (3): 163-178.DOI: 10.11686/cyxb2022129

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Aboveground and belowground phenotypic characteristics of Cynodon dactylon lines differing in drought resistance and endogenous hormone response to drought stress

Yi-long ZHANG1(), Qi-kun YU1, Wen LI1, Pei-ying LI1,2,3(), Zong-jiu SUN1,2,3   

  1. 1.College of Grassland Science,Xinjiang Agricultural University,Urumqi 830052,China
    2.Key Laboratory of Grassland Resources and Ecology of Xinjiang,Urumqi 830052,China
    3.Key Laboratory of Grassland Resources and Ecology of Western Arid Region,Urumqi 830052,China
  • Received:2022-03-25 Revised:2022-05-05 Online:2023-03-20 Published:2022-12-30
  • Contact: Pei-ying LI

Abstract:

This study investigated the effects of drought stress on Cynodon dactylon lines varying in drought resistance, in order to identify patterns in morphological and ecophysiological traits and endogenous hormone levels correlated with drought resistance. It was anticipated this research would enhance understanding of drought resistance in C. dactylon and thereby provide a theoretical basis for use of exogenous hormones to regulate drought resistance in industry practice. Plants were established in pots made from PVC pipes then subjected to predetermined levels of water deficit for 10 days. The relative water content, relative conductivity, endogenous hormones [indole acetic acid (IAA), abscisic acid (ABA), gibberellin A3 (GA3), zeatin riboside (ZR), brassinolide (Br)], leaf characteristics (leaf length, leaf width, leaf area), root characteristics (total root length, root surface area, root volume, root average diameter, root dry weight, longest root length and root activity) were measured. The changes in endogenous hormone levels in leaves and roots of C. dactylon with different drought resistance and the correlations between phenotypic characteristics and hormones were analyzed. The results showed that with increased intensity of drought stress, leaf length, leaf width, leaf area and root average diameter of both drought-tolerant and intolerant C. dactylon were reduced, while the growth and development of roots was promoted. The content of ABA in leaves and roots was increased, and the contents of IAA, GA3, ZR and Br were decreased, and IAA∶ABA and GA3∶IAA ratios were inversely correlated with leaf indexes and root indexes. This showed that the leaf and root systems of C. dactylon root adopted contrasting survival strategies under drought stress: promotion of underground growth and reduction in aboveground growth. Drought-resistant C. dactylon exhibited comparatively better adaption to a water deficit stress environment by maintaining some growth, larger leaf area, a more developed root system and higher ZR∶ABA, GA3∶ABA, IAA∶ABA and Br∶ABA ratios under the same level of water deficit stress.

Key words: drought stress, Cynodon dactylon, phenotypic characteristics, endogenous hormone, differentiated response strategy