Physiological Effect of Cutting Height and High Temperature on Regrowth Vigor in Orchardgrass.
Physiological Effect of Cutting Height and High Temperature on Regrowth Vigor in Orchardgrass.
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DOI：
10.3389/fpls.2017.00805
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发表时间：
2017
影响因子：
5.6
通讯作者：
Fukao T
中科院分区：
文献类型：
--
作者：
Jones GB;Alpuerto JB;Tracy BF;Fukao T
鸭茅（Dactylis glomerata L.）美国大西洋中部的干草经历了再生活力的降低和草地持久性的下降。该地区的常见管理做法是在5月或6月通过在2.5-7.5厘米高度切割来收获第一次生长的干草。我们推测，高温和低切割高度相互作用，以限制再生率。为了测试这一点，将鸭茅植物切成2.5或7.5厘米，然后放入恒温为20或35°C的环境控制室中。在切割后第0、1、3和11天收获残茬并进行代谢物分析。在第3天和第11天测量再生叶的光合参数，并在第11天记录再生生物量。在最适生长温度（20°C）下，留茬组织越多，去叶后的营养生长越强。然而，在热应力下没有观察到这种优势。落叶通常会减少残茬中碳水化合物储备的丰度。有趣的是，高温刺激的淀粉和乙醇可溶性碳水化合物的积累，植物削减到7.5厘米。在蛋白质、氨基酸、硝酸盐和铵态氮中也观察到类似的趋势。这些反应并不明显，在植物削减到2.5厘米，大概是由于抑制光合作用和光系统II光化学。总的来说，我们预计热激活代谢物的积累是对压力的适应性反应的一部分。然而，修改分配的碳水化合物和氮储备导致减少营养再生后落叶。这些数据表明，在凉爽的季节或干草收获后凉爽的天气下，对鸭茅进行切割高度管理可能对其再生活力和生产力更有效。
Producers of orchardgrass (Dactylis glomerata L.) hay in the Mid-Atlantic US have experienced a reduction in regrowth vigor and a decline in the persistence of their swards. The common management practice for the region is to harvest the first growth of hay by cutting at 2.5–7.5 cm height in May or June. We hypothesize that high temperature and low cutting height interact to limit the regrowth rate. To test this, orchardgrass plants were cut to either 2.5 or 7.5 cm and then placed into environmentally controlled chambers with a constant temperature of 20 or 35°C. Stubble was harvested on days 0, 1, 3, and 11 following cutting and subjected to metabolite analysis. Photosynthetic parameters were measured in the regrown leaves on days 3 and 11, and regrowth biomass was recorded on day 11. Under optimal growth temperature (20°C), vegetative regrowth upon defoliation was significantly enhanced when more stubble tissue remained. However, this advantage was not observed under heat stress. Defoliation generally decreases the abundance of carbohydrate reserves in stubble. Interestingly, high temperature stimulated the accumulation of starch and ethanol-soluble carbohydrates in plants cut to 7.5 cm. The similar trends were also observed in protein, amino acids, nitrate, and ammonium. These responses were not pronounced in plants cut to 2.5 cm, presumably due to inhibited photosynthesis and photosystem II photochemistry. Overall, we anticipated that heat-activated metabolite accumulation is part of adaptive response to the stress. However, modified allocation of carbohydrate and nitrogen reserves leads to reduced vegetative regrowth upon defoliation. These data suggest that cutting height management for orchardgrass may be more effective for its regrowth vigor and productivity in cool seasons or when cool weather follows hay harvest.