Study On The Effect Of Hemp-chilli Rotation Cropping System On Chilli Anthracnose

Chilli is an important vegetable and condiment.Its acreage is one of the largest among vegetables in China.The chilli industry has become one of the pillar industries in Yunnan with clear regional characteristics.The continuous cultivation of chilli has caused a large number of soil-borne diseases,which has significantly reduced the quantity and quality of chilli fruits and the ecological environment of the soil.Anthracnose infection is one of the main reasons for the yield reduction on a continuous chilli cropping field.In our preliminary investigation,it was found that hemp-chilli rotation significantly reduced the occurrence of chilli anthracnose infection.In this experiment,industrial hemp（Yunma NO.1）were rotated with two varieties of chilli（‘YangJiaoLa’and‘TaiYangHong’）in the field and greenhouse,the changes of pepper yield and growth and physiological indexes after hemp rotation and the changes of anthracnose incidence were analyzed,by which explores the mechanism of hemp rotation to reduce chilli anthracnose.The main findings are presented as follows:1.The effect of hemp-chilli rotation cropping system on chilli anthracnoseRotation and continuous cropping patterns had no significant effect on stem thickness,crown width,plant height,shoot fresh weight,and yield of total fruit of chilli.However,the rotation and continuous cropping patterns had significant effect on the health fruit and disease infected fruit yield of chilli,and.The yield of chilli health fruit was highest in hemp rotated field.The index of anthracnose infection of two varieties of chilli in hemp rotated field were 21.58%²4.29%lower than that of continuous chilli cropping;The index of anthracnose infection of chilli varieties of"YangJiaoLa"in corn rotated field were significant lower than that of continuous chilli cropping（22.38%）,but the disease index of’TaiYangHong’chilli after maize rotation was not significantly lower than that of continuous cropping.2.The effect of hemp-chilli rotation on the physiological indexes of potted chilliThe results of several physiological indicators of the two varieties of chilli potted in the greenhouse showed that,in comparison with continuous chilli cropping,hemp rotation increased the chlorophyll content of the chilli leaves,enhanced antioxidant enzyme activities（SOD and POD）,and an increase in the vigor of root of chilli,of which the difference is particularly significant during the harvest period.The intercellular CO₂ concentration,stomatal conductance and transpiration rate of chilli leaves after rotated with hemp significantly higher than the leaves of continuous cropping,which promoted the growth and development of chilli.3.The inhibitory effect of hemp extract on chilli anthracnoseexperiment was conducted to study the effect of the extracts from the root,stem and leaf of hemp seedlings on the growth of anthracnose spores and mycelium.The results showed that The growth of anthracnose spores and mycelium were inhibited by hemp extracts and the inhibitory effect increased with increasing concentration.The average inhibition rate of 5%concentration root,stem and leaf extracts on spore germination was 31.34%,and the average inhibition rate on mycelial growth was53.72%.4.Screening of antagonistic bacterium in hemp rhizosphere soil for chilli anthracnoseAntagonistic bacteria with significant inhibitory effects on chilli anthracnose were isolated from the rhizosphere soil of hemp.They are mainly belonging to Enterobacteriaceae.In summary,chilli rotated with hemp had a significant inhibitory effect on chilli anthracnose,which resulted in an increase in the yield of health chilli fruit.This effect may be attributed to the synergy of hemp allelochemicals and antagonistic bacteria against chilli anthracnose,better maintain the growth and development of chilli.