不同生育时期断根对花生光合特性及产量的影响

Effects of root cutting at different growth stages on photosynthetic characteristics and yield of peanut Arachis hypogaea L.

在田间试验条件下,以青花5号花生品种为材料,研究了不同生育时期断根对花生功能叶片光合特性及产量的影响。结果表明:适期断根(花后20d)可促进花生叶片生长,显著提高叶面积指数,且维持较高的叶面积指数和叶绿素含量的时间较长;植株功能叶片的净光合速率、气孔导度和蒸腾速率较高,胞间CO2浓度较低,光合效率显著提高;可增加花生结果数量和果重,提高单株生产力,显著提高荚果产量和经济系数。过早断根(花后5d至10d)叶面积增长慢、峰值低、后期下降快,叶绿素含量低;功能叶片净光合速率、气孔导度、蒸腾速率峰值低且峰值过后下降速度快,而胞间CO2浓度一直维持在较高水平;断根时间越早,产量越低。过晚(花后25d)断根不利于叶面积指数的发展和较高叶绿素含量的维持,基本不影响花生叶片各光合性能指标,对产量影响较少。研究认为,开花后20d断根可作为花生栽培中的一项技术措施。

The aim of the present paper is to investigate the effects of root cutting on leaf photosynthetic characteristics and yield of peanut,which can provide the theoretical basis for root cutting applied to peanut production as an agronomic technology. Under the field condtions with Arachis hypogaea L. cv. ‘Qinghua 5＇as the experimental materials in 2011 and 2012,the experiments was conducted to study the effects of root cutting at different growth stages on functional leaf photosynthetic characteristics and yield of peanut. The experiments were subjected to five treatments at different growth stage： root cutting on the fifth day after the first flowering date（ T1）,the tenth day after the first flowering date（ T2）,the fiftieth day after the first flowering date（ T3）,the twentieth day after the first flowering date（ T4）,and the twenty-fifth day after the first flowering date（ T5）,while the intact plants without root cutting were taken as the control treament（ CK）. The results showed that root cutting（ T4） at the suitable stage promoted the leaf growth,significantly improved the leaf area index（ LAI） and functional leaf chlorophyll content,moreover,maintained a longer time of higher LAI and chlorophyll content until later growth stage,compared with CK and other treatments,.Root cutting（ T1,T2） at the early stages caused low growth speed and LAI peak value. LAI decreased rapidly at the late growth stage. The chlorophyll content in the functional leaf of T1 and T2 treatment was higher than that of CK,but significantly lower than that of T4 treament. Root cutting（ T5） at the later stage was unfavorable to the development of LAI and maintaining high chlorophyll content. under By root cutting at the optimum stage,the net photosynthetic rate,stomatal conductance,and transpiration rate of functional leaves were higher,and the intercellular CO2 was lower compared to the other treatments,which significantly improved thephotosynthetic efficiency of functional leaves. Under root cutting too early, there were low peak values of the net photosynthetic rate, stomatal conductance, and transpiration rate of functional leaves. At the same time, these photosynthetic characteristics of functional leaves dropped fast after the peak value,and decreasd to lower level at the late stage,except the intercellular CO2 maintaining at a high level all the time. Root cutting too late did not affect the leaf photosynthetic characteristics of peanut. Root cutting at the optimum stage increased pod number and weight per plant,and improved the productivity per plant,with the high pod yield and economic coefficient of peanut. The pod yield under the T4 treatment reached 4148 kg / hm2,which improved by 9.1% compared to CK. Pod number and weight per plant improved by7.1% and 3.3% compared to CK,respectively. Root cutting at the early stages reduced the yield,moreover,the earlier root was cut the lower yield peanut reduced. Pod yield of peanut under T1 treatment reduced by 10.3%. Root cutting too late has the less influence on pod yield of peanut. It was concluded that root cutting on the twentieth day after the first flowering date can be used as a management practice of peanut cultivation.