BACKGROUND & AIMS:
:Plants have different physiological characteristics as the season changes, grazing management in compliance with plant growth and development characteristics may provide new ideas for sustainable livestock development. However, there has been little research on seasonal grazing and plants physiological responses under it. Here, we studied a typical steppe ecosystem of Inner Mongolia, with Leymus chinensis as the dominant species, in five grazing treatments: continuous grazing, seasonal grazing (which started in spring or in early and late summer), and no grazing (the control). We analyzed growth and resistance of L. chinensis in the five treatments by measuring annual primary productivity, morphological traits and various physiological processes. Compared with continuous grazing, seasonal grazing significantly alleviated grassland degradation. The plants were less affected by stress under spring grazing, with net photosynthesis and non-photochemical quenching closer to the control values and with a lower malondialdehyde content. The annual primary production of plants under grazing started in the early and late summer were 3-4 times the value under continuous grazing. Regrowth under early-summer grazing was greatly improved, and stress resistance was stronger with a higher proline content and high antioxidant enzyme activity. And nutrient accumulation at the end of the growing season such as abundant soluble sugars were transferred from aboveground tissue to the roots in September under late-summer grazing, which benefited regrowth the next year. All these physiological processes were regulated by hormonal changes. Our results highlight how plants response grazing stress in different growing seasons and suggest that seasonal grazing can improve the stress resistance and regrowth capacity of forage vegetation, and applying this knowledge can promote more sustainable grazing practices.
背景与目标:
: 随着季节的变化,植物具有不同的生理特征,放牧管理符合植物生长发育特征,可能为畜牧业的可持续发展提供新思路。然而,关于季节性放牧和植物在其下的生理反应的研究很少。在这里,我们研究了内蒙古典型的草原生态系统,以羊草为优势种,在五种放牧处理中: 连续放牧,季节性放牧 (从春季开始或夏初和夏末开始) 和不放牧 (对照)。我们通过测量年度初级生产力,形态特征和各种生理过程,分析了五种处理中中华L的生长和抗性。与连续放牧相比,季节性放牧明显缓解了草地退化。春季放牧下植物受胁迫的影响较小,净光合作用和非光化学猝灭更接近对照值,丙二醛含量较低。夏初和夏末开始放牧的植物年初级产量是连续放牧的3-4倍。初夏放牧条件下的再生长大大提高,抗逆能力强,脯氨酸含量高,抗氧化酶活性高。在夏末放牧的情况下,生长季节结束时的养分积累 (例如丰富的可溶性糖) 从地上组织转移到9月的根部,这有利于第二年的再生。所有这些生理过程都受到激素变化的调节。我们的结果强调了植物在不同生长季节如何应对放牧胁迫,并表明季节性放牧可以提高牧草植被的抗逆性和再生能力,应用这些知识可以促进更可持续的放牧实践。