指数施肥对美国山核桃幼苗生物量及氮积累的影响

Effects of exponential fertilization on biomass and nitrogen accumulation of Carya illinoensis seedlings

为探究施肥对美国山核桃(Carya illinoensis)幼苗生长和氮素积累的影响,以一年生美国山核桃实生苗为试验材料,共设置0(CK)、100、200、400、600和800 mg·株^(-1)6个供氮水平,运用指数施肥法研究了6个供氮水平处理下美国山核桃生物量和氮积累的变化。结果表明:美国山核桃幼苗茎生物量、叶生物量和总生物量均随施氮量的增加而呈现先增后减的趋势,均在600 mg·株^(-1)达到最大值,分别为2.30、4.39和9.33 g,是CK组的2.30、4.99和2.17倍,而根生物量随着施氮量的增加呈现递减的趋势;与CK组相比,各指数施肥处理的美国山核桃幼苗根、茎、叶氮质量分数分别提高了0.79~6.40、1.01~3.52和0.43~1.03倍,而根、茎、叶氮积累量分别提高了1.84~6.66、2.40~9.35和4.02~8.23倍;当施氮量为≤600 mg·株^(-1)时,美国山核桃幼苗的总生物量和总氮累积量均随施氮量的增加而增加,而当施氮量达到800 mg·株^(-1)时,其幼苗的总生物量和总氮累积量出现明显下降,总氮质量分数始终保持上升趋势。因此,施氮量600 mg·株^(-1)左右为美国山核桃幼苗温室培育的最适施氮量。

An exponential fertilization experiment was conducted with six N application levels（ 0（ CK）,100,200,400,600,800 mg·seedling^-1） to examine the effects of N application levels on the growth and N accumulation of pecan（ Carya illinoensis） seedlings. The objective of this study was to reveal the N demand and determine the optimal N application amount for pecan seedlings. Results showed that the stem biomass,leaf biomass,and total biomass of pecan seedlings increased as fertilization levels increased from 0 to 600 mg·seedling^-1 and then decreased with the levels increased from 600 to 800 mg ·seedling^-1. The maximum values of these three variables were 2.30,4.39 and 9.33 g·seedling^-1,being 2.30,4.99 and 2.17 times as high as that of the CK respectively. Root biomass decreased with the increases of N supply. For exponential fertilization treatments,the N concentration increased by 79%-640% in roots,101%-352%in stems,and 43%^-103% in leaves with N content increasing 184%-666% in roots,240%-935% in stems,and 402%-823% in leaves. The N content and total biomass of pecan seedlings increased as the N fertilization increased from 0 to 600 mg·seedling^-1 and then decreased with the fertilization levels from 600 to 800 mg·seedling^-1. The N concentration of pecan seedlings increased with the increases of N supply. We concluded that 600 mg·seedling^-1 would be the optimal N application level for pecan seedlings in greenhouse.