水分和养分添加对羊草功能性状和地上生物量的影响

Effects of water and nutrient additions on functional traits and aboveground biomass of Leymus chinensis

研究水分和养分添加对植物功能性状的影响,对于揭示植物对环境变化的响应和适应规律至关重要。该文采用盆栽试验的方法,进行不同水平水分处理(增水50%,减水50%,以498mm降水量作为对照)和养分添加(无养分添加,单施氮肥,单施磷肥,氮磷共施),研究羊草(Leymuschinensis)的10种功能性状和地上生物量对水分和养分添加的响应。得出以下结论:(1)双因素方差分析结果表明,水分主效应对羊草株高、分蘖数、茎生物量、叶生物量、叶面积、叶质量、净光合速率、蒸腾速率、水分利用效率存在显著影响;养分主效应对羊草分蘖数、茎生物量、净光合速率、蒸腾速率、水分利用效率存在显著影响;水分和养分的交互作用对羊草分蘖数、茎生物量、蒸腾速率、水分利用效率存在显著影响。(2)各功能性状对降水量的响应在不同养分添加水平是不同的,分蘖数和叶面积在单施氮肥和氮磷共施条件下随降水量增加而增加,而在无养分添加和单施磷肥条件下无显著变化;茎生物量在无养分添加、单施氮肥和单施磷肥条件下随降水量增加而增加,而在氮磷共施条件下无增加趋势;比叶面积在单施氮肥条件下增水处理显著低于对照组,而在其他养分添加条件下无明显变化。(3)短期氮磷处理显著影响羊草叶片光合生理性状,而对叶形态性状影响不显著。(4)羊草地上生物量随降水量的增加呈现上升趋势,并且在单施氮肥条件下,增水处理使地上生物量达到最高,为522.55 g·m^-2。总之,羊草的功能性状对降水量增加表现出明显的响应,响应格局在不同养分条件下不同,反映了其对水肥环境变化的适应。

Aims The research on the response of plant functional traits to environmental change, such as precipitation change and nutrient additions is very important to understand how plant species adapt to variable environments. Methods We conducted a pot experiment with a gradient of water treatments(increase precipitation by 50%, HW;decrease precipitation by 50%, LW;take 498 mm precipitation as control, MW) and nutrient additions(without nutrient addition, CK;nitrogen(N) addition, NA;phosphorus(P) addition, PA;nitrogen and phosphorus additions, N+P). We investigated 11 plant functional traits and aboveground biomass of Leymus chinensis. Important findings The effects of moisture on plant height, tillers, stem biomass, leaf biomass, leaf area, leaf mass, net photosynthetic rate, transpiration rate, water use efficiency were significant. The effects of fertilizers on tillers, stem biomass, net photosynthetic rate, transpiration rate, water use efficiency were significant. And the combination of fertilizers and moisture had a significant influence on tillers, stem biomass, transpiration rate and water use efficiency(two-way ANOVA). The pattern of functional traits in response to precipitation differed between plants with varied fertilizer additions. Tillers and leaf area were increased in treatments with HW under N and N+P additions, but not changed under CK and P addition. Stem biomass increased along the precipitation gradients under CK, N addition and P addition, but did not change under N+P additions. Specific leaf area with HW was significantly higher than that of MW under N addition, but not changed under other nutrient addition. Short-term nutrient additions significantly affected photosynthetic physiological traits of L. chinensis, but it had no significant effect on morphological traits under the same precipitation. The aboveground biomass of L. chinensis increased with the increase of precipitation, and reached the highest level of 522.55 g·m^-2 with HW treatment under N addition. In conclusion, our results indicate that the functional traits in L. chinensis respond to precipitation addition and the patterns of responses differ under different nutrient additions, reflecting the adaptation to changes in water and nutrient availability.