施氮与水分胁迫对雪菊幼苗生长及生理的影响

【目的】研究雪菊幼苗期施氮对水分胁迫的生长、生理响应变化,为新疆干旱地区雪菊的科学种植提供理论依据。【方法】雪菊种子采自和田地区皮山县克里阳乡,采用盆栽控水处理方法,研究雪菊幼苗期(8叶1心)在不施氮(N0:0 g/kg土)、低氮(N1:0.1 g/kg土)、高氮(N2:0.3 g/kg土)条件及严重缺水(D1:25%±5%)、轻度缺水(D2:50%±5%)、正常灌水(D3:75%±5%)条件下的生长、生理响应。【结果】随着水分含量的不断降低,雪菊株高增长量、总生物量、根长、根冠比、地上、地下部鲜重均呈下降趋势;叶绿素含量、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO₂浓度(Ci)、水分利用效率(WUE)、光系统II量子产量(ΦPS II)、PSII的最大光化学效率(Fv/Fm)、电子传递效率(ETR)、光化学猝灭系数(q_p)持续走低,而叶绿素初始荧光(Fo)、非光化学猝灭系数(NPQ)、丙二醛(MDA)含量、脯氨酸含量、可溶性糖含量和抗氧化酶活性呈增长态势;低氮只对正常灌水条件下的幼苗生长有促进作用,但在土壤缺水条件下,低氮对幼苗生长未发挥作用;而高氮可增加雪菊幼苗在不同水分条件下的株高增长量、总生物量、根长、地上部、地下部鲜重、根冠比、叶绿素含量、Pn、Tr、Gs、Ci、WUE、ΦPS II、Fv/Fm、q_p、ETR,降低Fo、NPQ、MDA、脯氨酸含量、可溶性糖含量,尤其在严重缺水条件下,高氮处理对降低幼苗抗氧化酶活性与MDA含量的作用最大。【结论】适宜的供氮水平可一定程度上减轻水分胁迫对雪菊幼苗的负效应,有利于雪菊度过脆弱的幼苗生长期。

Effects of Water Stress and Nitrogen Application on Growth and Physiology of Coreopsis tinctoria Seedlings

【Objective】 The main planting area of Coreopsis tinctoria(Coreopsis tinctoria nutt.) is located in the arid and semi-arid climate area of Xinjiang. The physiological response of Coreopsis tinctoria seedlings to drought stress under nitrogen application was studied in order to provide theoretical basis for scientific cultivation of Coreopsis tinctoria in arid areas of Xinjiang.【Method】 Coreopsis tinctoria seeds were collected from Keliyang Township, Pishan County, Hotan area. The growth and physiological response under conditions of no nitrogen application (N0∶0 g/kg soil), low nitrogen (N1:0.1 g/kg soil), high nitrogen (N2:0.3 g/kg soil) and severe water shortage (D1:25%±5%) , mild water shortage (D2: 50%±5%) and normal irrigation (D3:75%±5%) at seedling stage (8 leaves and 1 heart) were studied.【Result】 With the decrease of water content, the plant height, total biomass, root length, root-shoot ratio and fresh weight of above-ground and underground parts of Coreopsis tinctoria decreased. Chlorophyll content, net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductivity (Gs), intercellular CO₂ concentration II quantum yield (φPSII), PS II maximum photochemical efficiency (Fv/Fm), electron transfer efficiency (ETR), photochemical quenching coefficient (qp) continued to decrease, while chlorophyll initial fluorescence(Fo), non-photochemical quenching coefficient (NPQ), malondialdehyde (MDA) content, proline content, The content of soluble sugar and the activity of antioxidant enzyme increased. Low nitrogen only promoted seedling growth under normal irrigation conditions, but low nitrogen did not play an important role in seedling growth under soil water shortage. High nitrogen could increase plant height growth, total biomass, root length, shoot fresh weight, root-shoot ratio, chlorophyll content and Pn, Tr, Gs, Ci,φPSII, Fv/Fm, qp, ETR, under different water conditions to decrease Fo, NPQ, MDA, proline content and soluble sugar content. Especially under severe water shortage, high nitrogen treatment had the greatest effect on reducing antioxidant enzyme activity and MDA content. 【Conclusion】 Mastering the appropriate nitrogen supply level can reduce the negative effect of water stress on Coreopsis tinctoria seedlings to a certain extent, which might be helpful for Coreopsis tinctoria to survive the frail seedling growth period.