| As one of the main producing areas of Camellia oleifera Abel,Jiangxi ranks second in China.Reasonable cultivation management is the basis for the good growth and high yield of Camellia oleifera.As a common conservation measure in agroforestry,mulch affects the growth,death and turnover of fine roots by affecting the habitat of fine roots,thus affecting the transportation of effective resources to the above-ground parts,ultimately affecting tree growth and fruit yield.Mulch promotes the growth of Camellia oleifera,but the effect on underground fine roots is unknown.In order to understand the effects of different mulching treatments on the fine roots of Camellia oleifera and the action of above-ground and below parts,the four types of mulching materials commonly used in production practice(Peanut stalk + straw,black mulch,ecological film,Camellia oleifera shell)were selected based on’Changlin No.4’ Camellia oleifera planted in 2010,including control a total of 5 treatments,and the Camellia oleifera forest was mulched in the spring of 2015.The micro-root tube dynamic detection technology was used to monitor the fine roots of Camellia oleifera for one year,and the tree growth and fruit yield were followed up for 3 years.The main results and conclusions are as follows:(1)Different mulch treatments had different effects on the growth and death of fine roots of Camellia oleifera.Compared with non-mulching(CK),the treatments of peanut stalk + straw and black mulch significantly increased the total root length and total surface area of active fine roots of Camellia oleifera.The four kinds of mulching treatments significantly reduced the average diameter of dead fine roots,and the effect of peanut stalk+ straw treatment was the most significant.The existing amount of active fine roots of Camellia oleifera peaked from June to July,and the peak amount and the maximum value of live fine roots appeared in spring(March)after the black mulch treatment.while the existing amount of active fine roots was showed significant peaks in summer(July)after peanut stalk + straw treatment.The fine roots of Camellia oleifera died less in the spring and continued to increase in the summer,especially in the treatment of black mulch,and the death of fine roots peaked in June.In general,peanut stalk + straw and ecological membrane treatment promoted the growth and death of fine roots of Camellia oleifera,especially in small diameter fine roots.(2)Mulch changed the spatial distribution of the fine roots of Camellia oleifera,and the effects in different mulching treatments were different.The fine roots of Camellia oleifera have the least distribution in the outermost soil layer(0～10 cm)and the most in the deep soil layer(30～40 cm).The four kinds of mulching treatments all made the distribution ratio of the fine roots of Camellia oleifera in the 30～40 cm soil layer decreased compared with CK,while the proportion of the 20～30 cm soil layer increased.Compared with CK,peanut stalk + straw treatment increased the ratio of total root tip number,total root length and total root surface area in the 10～30 cm soil layer.However the proportion of fine roots of Camellia oleifera in the 20～30 cm soil layer was greatly increased after the black plastic film was mulched.Compared with CK,the effect of peanut stalk + straw treatment on increasing the existing amount of fine roots of Camellia oleifera was the most significant among the four soil layers.The effect of biofilm treatment on the fine roots of0～10 cm soil layer was larger than that of other soil layers,while the black plastic film treatment had a great effect on the fine roots of 10～40 cm soil layer.In general,mulch had a tendency to promote the distribution of fine roots of Camellia oleifera to the shallow layer.(3)Mulch had a certain impact on the turnover and annual net productivity of fine roots of Camellia oleifera.Turnover rate 1,turnover rate 2 and turnover rate 3 are annual growth/average stock,annual death/average stock,annual growth/maximum existing stock,respectively.The turnover rate 1 of fine roots of Camellia oleifera was significantly reduced with the deepening of the soil layer,and mulch reduced the turnover rate of fine roots of Camellia oleifera in whole.In the turnover rate 2 and the turnover rate 3,the Camellia oleifera shell treatment significantly accelerated the fine root turnover of 0～10cm soil layer,followed by the ecological membrane treatment.The net growth rate of fine roots of Camellia oleifera increased first and then decreased during the growing period,and peaked from May to June.Peanut stalk + straw treatment significantly increased the net growth rate and annual net production of fine roots of Camellia oleifera.Overall,peanut stalk + straw cover was the best treatment to improve the net productivity of Camellia oleifera.(4)Different mulching treatments had different effects on the abocve growth of Camellia oleifera.Although the growth index of each tree treated by black mulching film was lower than that of CK,its annual growth rate was always larger than that of CK,especially in the crown and ground diameter of the last two years.Compared with other treatments,the trend of plant height,ground diameter and north-south crown width of Camellia oleifera under ecological membrane treatment was the most obvious,and the difference between years was significant.The effect of ecological membrane treatment on the diameter of the ground was more obvious,and the effect of peanut stalk + straw treatment on plant height was more obvious.Compared with CK,the Camellia oleifera shell treatment had little effect on the tree growth.In general,in addition to the Camellia oleifera shell,the mulch promoted the growth of Camellia oleifera.(5)Different mulching treatments had different effects on the fruit yield and its economic traits of Camellia oleifera.The treatment of Camellia oleifera shells had the most obvious effect on the number of single fruit seeds,the number of fruits per plant,the yield per plant,and the oil yield per plant,followed by peanut stalk + straw treatment;peanut stalk + straw treatment on Camellia oleifera seeds and seeds.The kernel weight,the fruit morphology and the fresh fruit oil yield were better,and the black mulch was the second.In terms of improving the fruit oil yield,the Camellia oleifera shell treatment was the best;It had the best effect on improving the fresh weight of single fruit after peanut stalk + straw treatment;the order of the yield and economic traits of each mulching treatment was: peanut stalk + straw treatment > black mulch > Camellia oleifera shell >CK > ecological membrane.(6)The fine roots of Camellia oleifera were closely related to the growth of the aerial part.In terms of the above-ground part,promoting the height of the Camellia oleifera tree and increasing its crown width and ground diameter were the basis for increasing the yield of the current year.From the underground part,whether it was a live fine root or a dead fine root,fine roots increased their surface area by increased the root length.The small diameter of the active fine root promoted the growth of the tree on the Camellia oleifera in current year,and the root length density,root surface area density and fine root annual growth of the active fine root were positively correlated with the tree growth index of the year.The annual growth,annual death,root length density,surface area density and annual net growth of both active fine roots and dead fine roots were positively correlated with the fruit yield and oil production per plant in the current year,but the average diameter were negatively correlated with both. |
