| Arachis hypogaea is an important oil crop and cash crop in China.The supply-demand balance of China’s edible oil market is closely related to it.Arachis hypogaea has the function of root nodule nitrogen fixation and is suitable for understory intercropping.Cocos nucifera is an important cash crop and oil crop in the tropics.The economic benefit of young coconut garden is low and the planting density is small.It is suitable for agricultural and forestry intercropping,which is of great significance to improve the utilization efficiency and economic benefit of environmental resources such as land in young coconut garden.The test was first conducted at 4 m×4 m strains of Arachis hypogaea in Hainan were used as experimental materials:common pink peel（NK）,Benhong 1（YN1）,Benhong 2（GHH）and Benhong 3（WCH）under 4 m square coconut forests.The strains of Arachis hypogaea suitable for intercropping with young coconut forests were selected by comparing the agronomic characters,nutritional quality and photosynthetic characteristics of different strains of Arachis hypogaea.Four artificial shading treatment groups were set:0%（control）,25%,45%and 65%shading.The photosynthetic characteristics and agronomic characters of strains of Arachis hypogaea screened under different shade degrees were determined.Then YN1 was intercropped in the 3-year-old young coconut forests,and its photosynthetic and agronomic characteristics were measured.Five treatment groups with different shading degrees were set up in coconut forests shading test:0%（control）,5%～15%（4 m×8 m triangular coconut planting mode）,15%～25%（4 m×6 m triangular coconut planting mode）,25%～35%（4 m×4 m square coconut pattern）and 35%～45%shading intensity（4 m×4 m triangular coconut planting pattern）.The results showed that the yield and market economic benefits of Hainan peanut YN1 intercropping under young coconut forests were significantly higher than those of other Hainan local peanut strains,which was suitable for intercropping with young coconut forests.Under the intercropping treatment of young coconut forests,the number of fruit per plant,the number of effective pods per plant and the yield(6987.6 kg·ha-1)of YN1 were significantly higher than those of other peanut lines.There was no significant difference between the number of fruit per plant,the number of effective pods per plant and the yield of the other three peanut strains under the intercropping of young coconut forests;The light and shading indensity（L*value）of fresh pod of YN1was significantly higher than that of Hainan native peanut NK and WCH.Therefore,from the perspective of peanut yield and market economic benefits,YN1 was used as the test material under subsequent shading treatment.Artificial shading treatment showed that 25%shading treatment group could significantly improve the photosynthetic characteristics of peanut leaves（chlorophyll content,net photosynthetic rate,stomatal conductance,transpiration rate,intercellular CO2concentration,initial fluorescence value,maximum fluorescence value,variable fluorescence value and apparent electron transfer rate）.The 25%shading treatment group also had a certain effect on the agronomic characters of peanut,and could significantly promote the growth of leaf width,leaf area and yield of Arachis hypogaea.Combined with the comparative analysis of photosynthetic and agronomic characteristics of peanut in different artificial shading treatments,the optimum shading range of peanut was determined to be 25%～45%.The shading treatment of coconut forests with different densities showed that it was YN1 had better agronomic and photosynthetic characteristics in the 4 m×6 m triangular coconut planting mode（15%～25%shading indensity）.Compared with other intercropping shading treatment groups,15%～25%shading treatment is 4 m×6 m triangular coconut planting modecan significantly improve leaf stomatal conductance,transpiration rate and leaf area,and its net photosynthetic rate is as high as 18.27（μmol·m（-2）·s（-1））,Compared with the control group,it increased by 22.78%and the yield increased by 17.32%.The main factor affecting the photosynthetic and agronomic characteristics of peanut is the shade degree in the forests.Appropriate shade degree can improve the photosynthetic and agronomic characteristics of peanut.Based on the photosynthetic and agronomic characteristics of peanut under different artificial shading treatments and coconut forests shading treatments,it is preliminarily determined that the optimal shading range of peanut in coconut forests intercropping is about 25%.In field production,the young coconut peanut intercropping model with 4 m×6 m triangular coconut forests planting density has great economic benefits,and is expected to be applied and popularized in the local area. |
