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胡杨(Populus euphratica)是塔里木河流域荒漠河岸林重要的抗逆种质资源,胡杨幼苗的存活及生长受水分和氮素的限制。为了研究干旱胁迫下氮素供应对胡杨幼苗早期形态建成的影响,本试验以1年生胡杨实生幼苗为研究对象,采用温室盆栽试验,设置4个水分处理(D_1、D_2、D_3、D_4,土壤含水量为20%~25%、40%~45%、60%~65%、80%~85%)和3种施氮水平(N_0、N_1、N_2:0、3、6 g·pot-1),测定胡杨幼苗的生长指标、叶绿素荧光和光合参数。结果表明:轻度干旱胁迫(D_3)下,施氮量为N_1时,胡杨幼苗的表观生长和光合能力显著提高;幼苗根冠比在D_1时最低,施氮使其显著增大;干旱胁迫(D_1、D_2、D_3)下,N对幼苗生长的促进作用大于N_2;严重干旱胁迫(D_1)时,施氮显著提高幼苗荧光参数和光合速率,增强其光合能力;因此,胡杨幼苗在土壤相对含水量60%~65%(D3)、氮素量为3g·pot~(-1)(N_1)时,其生长表现为最佳状态;干旱胁迫下,氮素能显著增强幼苗地下部分生长和光合能力,表明氮素对干旱胁迫具有补偿效应,可促进幼苗的早期形态建成,有效帮助幼苗渡过生长脆弱期。
Populus euphratica is an important anti-germplasm resource of desert riparian forests in the Tarim River Basin. The survival and growth of Populus euphratica are limited by water and nitrogen. In order to study the effect of nitrogen supply on the morphogenesis of Populus euphratica seedlings under drought stress, the seedlings of one-year-old Populus euphratica were studied in this experiment. Four greenhouse plants (D_1, D_2, D_3 and D_4, (N_0, N_1, N_2: 0, 3, 6 g · pot-1) under the conditions of 20% ~ 25%, 40% ~ 45%, 60% ~ 65%, 80% ~ 85% The growth index, chlorophyll fluorescence and photosynthetic parameters of Populus euphratica seedlings were determined. The results showed that under mild drought stress (D_3), the apparent growth and photosynthetic capacity of Populus euphratica seedlings significantly increased when the nitrogen application rate was N_1; the root and shoot ratio of seedlings was the lowest at D_1 and increased significantly under nitrogen application; (D_1, D_2, D_3), N promoted the growth of seedlings more than N_2. Under severe drought stress (D_1), nitrogen application significantly increased the fluorescence parameters and photosynthetic rate of seedlings and increased their photosynthetic capacity. Therefore, When the water content was 60% -65% (D3) and the amount of nitrogen was 3g · pot -1 (N_1), the growth performance was the best. Under the drought stress, nitrogen could significantly increase the growth of the underground part and Photosynthetic capacity, indicating that nitrogen has a compensatory effect on drought stress can promote the early morphological seedling formation, effectively help seedlings through the growth of vulnerable period.