施肥量对山地核桃光合与快速叶绿素荧光特性的影响

Effects of Fertilizer Dosage on Photosynthesis and Fast Chlorophyll Fluorescence Characteristics of Juglans regia in Mountainous Region

[目的]为探讨不同施肥量对山地核桃生长量、光合特性、快速叶绿素荧光特性的影响,筛选出适合山地核桃的最佳肥料用量,为西北山地核桃优质高产提供理论依据。[方法]以10年生核桃品种"鲁光"为试验材料,采用随机区组设计方法,通过测定山地核桃生长量、光合日变化、响应曲线及快速叶绿素荧光等指标分析不同施肥量处理下核桃的光合特性。[结果]表明:山地核桃净光合速率日变化呈双峰曲线;随着施肥量的增加,核桃树体生长量、叶绿素含量、光合参数升高,但超过一定范围,尤其在高光强下,高施肥量会造成叶绿素含量、光合速率下降;CO2饱和浓度下的最大净光合速率(Pnmax2)比饱和光强下的Pnmax1高,表明强光下核桃光合速率在很大程度上受CO2供应的限制;中午高强光下核桃的OJIP曲线变形为OKJIP曲线,高施肥量的荧光诱导曲线中K点和J点明显高于其它处理,说明高温对核桃叶片放氧复合体(OEC)和PSⅡ反应中心造成了伤害。[结论]适宜的施肥量能提高核桃光合能力,可以缓解高温及强光对核桃叶片的胁迫程度,而过高的施肥量不利于核桃光合速率的提高;在本试验条件下,建议山地核桃的株施肥量为尿素612.8 g、磷酸二铵187.5 g、硫酸钾230.77 g。

[ Objective] A field experiment was conducted to study the effects of fertilizer dosage on the biomass, photosynthetic characteristics as well as the fast chlorophyll fluorescence on walnut in mountainous region in order to select suitable fertilizer dosage and provide theoretical basis for high yield and good quality of walnut in Northwest mountainous region. [ Method ] Using ten-year-old walnut variety ＂Lu Guang＂ as materials, random sampling group design method was used in field experiments. The photosynthetic characteristics of walnut were analyzed by measur- ing the growth amount, photosynthetic diurnal variation, response curve and fast chlorophyll fluorescence. [ Result ] The daily variation of net photosynthetic rate of walnut in mountainous region presented a bimodal curve, within a certain range, the biomass, chlorophyll content, photosynthetic parameters increased with increasing fertilizer dos- age. But high fertilizer dosage treatment lead to the chlorophyll content and photosynthetic rate decreased and lower than that of CK, especially under high photosynthetic active radiation. The maximum net photosynthetic rate （P,maa） of the walnut leaves under saturated intercellular COEconcentration was higher than that under saturated irradiance, indicating that the photosynthetic efficiency was limited to the great extent by CO2supply. The chlorophyll fluorescence OJIP curve of walnut was deformation to OKJIP curve under high temperature and strong light at noon. The K and J points of the fast chlorophyll fluorescence induction dynamics curve under high fertilizer dosage treat- ments were higher than other treatments, indicating that high temperature damaged the leaf oxygen evolving complex （OEC） and PS 11 reaction centers. [ Conclusion] Appropriate fertilizer dosage can improve photosynthetic capacity and alleviate the stress come from high temperature and strong light on walnut, while excessive fertilizer dosage is unfavorable to raise photosynthetic rate of walnut. It is suggested that the fertilization dosage should be kept at 612. 8 g urea, 187.5 g P205, and 230.77g K20 per plant in the condition similar to the experiment site.