青海草地早熟禾生长和根系特征对刈割强度的响应研究

Study on response of the growth and root characteristics of Poa pratensis L.“Qinghai”to cutting intensity

为研究青海草地早熟禾生长和根系特征对刈割强度的响应,试验采用随机区组设计,选取长势均匀的青海草地早熟禾人工草地,划分为12个小区,设置4种处理,分别为对照(CK,不进行任何处理)、轻度刈割(LC,留茬10 cm)、中度刈割(MC,留茬5 cm)、重度刈割(HC,留茬2 cm),每种处理3次重复,于2019年6月底和7月底各刈割1次,并分别于刈割30 d后测定各处理青海草地早熟禾的株高、生长速度、分蘖数、地上总生物量、地下生物量、根系特征(表面积、体积、直径)和地下芽数量。结果表明:6月底和7月底刈割后各处理株高的大小顺序均为CK>LC>MC>HC。6月底刈割后,各处理生长速度的大小顺序为CK>LC>MC>HC;7月底刈割后,各处理生长速度的大小顺序为LC>CK>MC>HC。6月底刈割后,各处理分蘖数大小顺序为LC>CK>MC>HC;7月底刈割后,各处理分蘖数大小顺序为CK>LC>MC>HC。6月底和7月底刈割后,各处理地上总生物量的大小顺序均为LC>CK>MC>HC。6月底和7月底刈割后,各处理地下生物量、禾根系表面积、根系体积的大小顺序均为CK>LC>MC>HC。6月底刈割后,各处理根系直径的大小顺序为LC>MC>HC>CK,但各处理根系直径均差异不显著(P>0.05);7月底刈割后,各处理根系直径的大小顺序为LC>CK>MC>HC。6月底刈割后,各处理地下芽数量大小顺序为LC>CK>MC>HC;7月底刈割后,各处理的地下芽数量大小顺序为LC>MC>CK>HC。青海草地早熟禾的株高与分蘖数、地上生物量、地下生物量、根系表面积、根系体积和地下芽数量均呈极显著正相关(P<0.01);分蘖数与地上生物量、地下生物量、根系表面积、根系体积、地下芽数量之间呈极显著正相关(P<0.01),与根系直径呈显著正相关(P<0.05);青海草地早熟禾的地上生物量与地下生物量、根系表面积、根系体积、地下芽数量呈极显著正相关(P<0.01);青海草地早熟禾的地下生物量与根系表面积、根系体积之间呈极显著正相关(P<0.01),与地下芽数量呈显著正相关(P<0.05);青海草地早熟禾的根系表面积与根系体积呈极显著正相关(P<0.01);根系直径与地下芽数量呈极显著正相关(P<0.01),与株高、地上生物量、地下生物量、根系表面积、根系体积相关性不显著(P>0.05)。说明轻度刈割能够在一定程度上提高青海草地早熟禾的生长速度、分蘖数、地上生物量,促进地下芽的生长;而中度和重度刈割则会降低青海草地早熟禾的生长速度、分蘖数和地上生物量,抑制地下芽的生长。

In order to study the response of Poa pratensis L.“Qinghai”growth and root characteristics to cutting intensity,a randomized block design was used in the experiment.The Poa pratensis L.“Qinghai”artificial grassland with uniform growth in Qinghai was selected and divided into 12 plots.Four treatments were set up:control(CK,without any processing),mild cutting(LC,stubble 10 cm),moderate cutting(MC,stubble 5 cm),and heavy cutting(HC,stubble 2 cm).Each treatment was repeated three times.The aboveground biomass was performed once at the end of June and once at the end of July 2019.The plant height,growth rate,tillering number,aboveground biomass,underground biomass,root characteristics(surface area,volume,diameter)and underground bud number of bluegrass were measured 30 days after cutting.The results showed that the order of plant height in each treatment was CK>LC>MC>HC after cutting at the end of Jure and July.After cutting at the end of June,the order of growth rate in each treatment was CK>LC>MC>HC.After cutting at the end of July,the order of growth rate in each treatment was LC>CK>MC>HC.After cutting at the end of June,the order of tillering number in each treatment was LC>CK>MC>HC.After cutting at the end of July,the order of tillering number in each treatment was CK>LC>MC>HC.After cutting at the end of June and the end of July,the order of the total aboveground biomass in each treatment was LC>CK>MC>HC in each treatment.After cutting at the end of June and the end of July,the order of underground biomass,root surface area and root volume of bluegrass in each treatment was CK>LC>MC>HC in each treatment.After cutting at the end of June,the order of the root diameter in each treatment was LC>MC>HC>CK,but there was no significant difference among all treatments(P>0.05).After cutting at the end of July,the order of the root diameter in each treatment was LC>CK>MC>HC.After cutting at the end of June,the order of the number of underground buds in each treatment was LC>CK>MC>HC.After cutting at the end of July,the order of the number of underground buds in each treatment was LC>MC>CK>HC.The plant height of bluegrass was positively correlated with the number of tillers,aboveground biomass,underground biomass,root surface area,root volume and underground bud number(P<0.01),and the number of tillers was positively correlated with aboveground biomass,underground biomass,root surface area,root volume and underground bud number(P<0.01).It was positively correlated with root diameter(P<0.05).The aboveground biomass was positively correlated with underground biomass,root surface area,root volume and underground bud number of bluegrass(P<0.01).The underground biomass of Poa pratensis L.“Qinghai”was significantly positively correlated with root surface area and root volume(P<0.01),and significantly positively correlated with the number of underground buds(P<0.05).The root surface area was positively correlated with the root volume(P<0.01),and the root diameter was positively correlated with the number of underground buds(P<0.01),but had no correlation with plant height,aboveground biomass,underground biomass,root surface area and root volume(P>0.05).The results indicated that light cutting could improve the growth rate,tillering number and aboveground biomass of bluegrass and promote the growth of underground buds to a certain extent.However,moderate and severe mowing reduced the growth rate,tillering number and aboveground biomass of bluegrass,and inhibited the growth of underground buds.