Screening Of Shade-tolerant Peanut Varieties And Their Photosynthetic Physiological Characteristics

Peanut planting is used to adopting the method of intercropping to prevent wind erosion,but the upper crops will block away the light the lower peanut crops need so that the photosynthesis of peanuts will be influenced and lead up to low yield.This experiment selected45 categories of peanut as experiment materials,and deal with shading process in their flowering and pegging period to study the feature characteristics,yield traits,photosynthetic characteristics and the chlorophyll fluorescence index among different categories of peanuts and to further screen the shade tolerance of peanuts.And in the next year,select the two varieties with strong shade tolerance and two with weak shade tolerance in accordance with the appraisal screening results to study the physiological mechanism of peanut photosynthetic characteristics’responses towards light shading,aiming to provide theological references of the breeding of shade-tolerant peanut varieties and their large scale production,and the research results are as follows:1.Morphology.In shading condition,the tallness of the plant has an obvious increase while their branches length,node numbers of main stem and other indexes are all decreased.Huaihua 6 and Nonghua 5 had a higher growth rate of plant height under shading,and a higher decline of side branch length,the number of main stem nodes,and the number of branches;Yueyou 85 and Huaihua 9819 planted under shade High growth rate is low,and the decline rate of indicators such as side branch length,main stem node number and branch number is low2.SPAD value and yield trait.Shading has a greater impact on the number of pods per plant,productivity per plant,hundred fruit weight and pod yield of peanuts,but has a small effect on the weight per hundred kernels and SPAD value.In this experiment,the lack of light due to shading affects the growth of crop morphology and structure,reduces crop light and ability,affects dry matter accumulation,and ultimately affects yield.In shading treatment,the number of pods per plant,productivity per plant,hundred fruit weight,pod yield,hundred kernel weight and other indexes all decreased.In this experiment,the effect of shading on pod yield was that Huayu 62 had the largest decrease of 47.43%,and Yueyou 85 had the smallest decrease of 9.54%.3.Evaluation of peanuts shade tolerance.Calculate the integrating valuation of different peanut varieties’shade tolerance with membership function,and divide these 45 varieties of peanut germplasms into 4 shade tolerant categories as strong shade tolerant type,relatively strong shade tolerant type,relatively weak shade tolerant type and not shade tolerant type.The first type concludes 8 varieties,which are Yueyou 85,Huaihua 9819,Qinglan 2,Shanhua 8,Huayu 32,Fuhua 12 Jiyou 98 and Jihua 5,belong to the strong shade tolerant type;the second type concludes 21 varieties,which are Huaxiaobao 103,Huayu 46,Xuhua 9,etc.,belongs to the type medium shade tolerant type;the third type concludes 11 varieties,which are Japanese Xiangxiang,Yubao 4,Fuhua 20,etc.,belongs to relatively weak shade tolerant type;and the fourth type concludes 5 varieties,which are Yueyou 7,Puhua 23,Huayu 62,Huaihua 6,Nonghua 5,belongs to weak shade tolerant type.Further through the stepwise regression equation,it is concluded that 10 of the inspected indicators have a significant impact on the shade tolerance of peanuts,namely plant height,lateral branch length,number of branches,number of main stem nodes,SPAD value,number of pods per plant,productivity per plant,hundred pod weight,hundred kernel weight and pod yield.4.Photosynthetic characteristics.In shading condition,the net photosynthesis rate（P_n）,stomatal conductance（G_s）and the transpiration rate（T_r）are all in decrease,in addition,the inter cellular CO₂concentration（C_i）increases as well.The decrease ranges of net photosynthesis rate（P_n）,stomatal conductance（G_s）and transpiration rate（T_r）of shade tolerant type Yueyou 85,Huaihua 9819 and Qinglan 2 is relatively lower and so as their increase ranges of the inter cellular CO₂ concentration（C_i）;but for the not shade tolerant types,the decrease ranges of net photosynthesis rate（P_n）,stomatal conductance（G_s）and transpiration rate（T_r）of Huayu 62,Huaihua 6,Nonghua 5 are relatively larger,so as the increase ranges of their inter cellular CO₂concentration（C_i）.5.Chlorophyll fluorescence index.In shading condition,the Y（II）、q P、ETR and NPQ of Yueyou 85 and Huaihua 9819 are all higher than Huaihua 6 and Nonghua 6.It s-uggests that,in shading condition,the photosynthesis ability and excess light energy dissipation capability of Yueyou 85 and Huaihua 9819 are better than it is of Huaihua 6 and Nonghua 5.6.Yield components and yield of different shade-tolerant peanut varieties.Under shading conditions,the varieties Yueyou 85 and Huaihua 9819 showed smaller declines in the number of pods per plant,productivity per plant,hundred fruit weight,pod yield,and hundred kernel weight,while the varieties Huaihua 6,Nonghua 5 dropped significantly.In the pod yield,the decline of Yueyou 85 and Huaihua 9819 was significantly lower than that of Huaihua 6 and Nonghua 5.Through this test,it was found that peanut varieties Yuyou 85 and Huai Hua 9819 had strong shade tolerance,and their shade tolerance performance was the strongest.Huai Hua 6and Nonghua 5 have weak shade tolerance,and their shade tolerance performance is the weakest.