修剪高度对季节性温度变化下早熟禾生理生态特性的影响

修剪高度的差异会影响冷季型草坪草的生长，探究合理的修剪高度可为草坪草可持续利用提供理论基础。本研究通过测定两年生长季（2012年和2013年）草地早熟禾（8年生）草坪的外观质量（TQ）、地上部分生物量（AB）、光合作用（Pn）、总呼吸作用（R_total）和碳水化合物（TNC）等指标，探讨了修剪高度对冷季型草坪草生理生态特性的影响。试验结果表明，当大气温度高于23~24℃时，不同修剪高度7.6 cm （高修剪高度，HM）和3.8 cm （低修剪高度，LM）下的早熟禾TQ、AB和Pn均降低，与HM相比，在LM下下降更显著。在7—9月的高温条件下，早熟禾地上部分、根系和土壤R高于Pn；但在美国新泽西州较冷的季节（5—6月） Pn高于R。研究表明，较低的修剪高度尤其是在高温条件下降低了草坪草Pn，季节性温度变化下可以通过改变修剪高度影响成熟草坪草的生长，从而缓解高温对草坪生长带来的不利影响。

Effects of Different Mowing Heights on Physiological and Ecological Characteristics of Kentucky Bluegrass in Response to Seasonal Temperature Changes

The growth of cold season turf grass is affected by different mowing heights,and study on reasonable mowing heights can provide theoretical basis for the sustainable use of turf grass. The experiment was conducted to estimate effects of mowing height on physiological and ecological characteristics of kentucky bluegrass (Poa pratensis ‘Baron’) under different temperatures which is a kind of cool-season turfgrass. Different physiological and ecological indices including turf quality,shoot biomass,shoot photosynthesis,total respiration,and total non-structure carbon were measured during 2012 and 2013 seasons by field-experiment. Mature (8 year old) turf was mowed at 7.6 cm (high mowing height,HM) or 3.8 cm (low mowing height,LM). The results showed that both LM and HM plots displayed significant decline in turf quality,shoot biomass,and canopy photosynthetic rate (Pn) with increasing air temperature above 23~24℃ in both years,and the decline was more pronounced at LM. Turf plots exhibited greater total respiration rate of shoots,roots,and soil (R_total) than canopy Pn under high temperatures during July and September,but maintained greater Pn than R_total during cooler seasons (May and June) in New Jersey,America. Lowering mowing height accelerated the decrease of canopy Pn,particularly under high temperatures. Our results suggested that seasonal temperatures and increasing mowing height could help offset the deleterious effects of high temperature.