| In order to explore the effects of different segments of stem and vine on the yield and node position of the sweet potato,the suitable segments of stem and node for high-yeild cultivation was obtained,it provides theoretical basis and practical production guidance for the high-yield cultivation of the sweet potato and rational utilization of resources.Three starch-type varieties Yushu 198,Yushu 50 and Xushu 22 were used as materials,and the 12-section long vines were divided into 1-4,1-8,1-12,5-8,and 9-12segments,samples were taken at 28 d,38d,60 d,90 d,and 120 d,and harvested at 150 d.The randomized blocks experiment was conducted to studied the effect of root development,organogenesis,yield difference and tuber formation among different nodes(1-4 nodes,1-8 nodes,1-12 nodes,5-8 nodes,and 9-12 nodes)of the sweet potato.The main results are as following:1)Effect of different treatments on the yield and the number of the sweet potato per plant:the results showed that properly increasing the number of planting nodes increase the yield and the number of tubers per plant.The yield production of Yushu 198,Yushu50 and Xushu 22 were the highest in apical cuttings with 8 nodes,which were 4304.95kg/667m~2,3380.61 kg/667m~2,2710.60 kg/667m~2,respectively.The weight of average potato is higher,The number of the tubers in apical cuttings with 12 nodes are the highest,and the average number of tubers per plant was 3.87,2.32 and 3.83,respectively.Among the 4 nodescuttings,Yushu 198,Yushu 50 and Xushu 22 have the highest yield withapical cuttings,which were 3471.59 kg/667m~2,2522.51 kg/667m~2,1690.63 kg/667m~2,respectively.And the average number of tubers per plant was 3.33,1.77 and 2.71,respectively.The yield of base cuttings with 4 nodes were lowest,only 1303.23 kg/667m~2,2177.06 kg/667m~2,1399.99 kg/667m~2,respectively.And the average number of tubers per plant was only 1.33,1.50,and 1.43,respectively.2)Effect of different treatments on the development of sweet potatao root system:along with the increase of the number of transplanting nodes,the number of nodes in soil increased,the root system developed more in the early stage of root expansion,the root tip number,root surface area,volume,root length,and number of developed rough roots were all at a high levels in the apical cuttings with 8 nodes(1-8 nodes)and 12 nodes(1-12 nodes).As the decrease of segments,the root development of sweet potato was delayed and the number of roots were less.After transplanting in 4 segments with tip,the root system was vigorous,and developed rapidly.3)Effects of different treatments on stem and leaf growth of the sweet potato:the number of planting segments increased appropriately,such as apical cuttings with 8 nodes and 12 nodes,in the early stage of tuber expansionincrease the branching,the growth rate of the aboveground,the root-shoot ratio and the leaves area index,provides sufficient nutrients for the rapid expansion of the underground part in the later period.In the later period of tuber expansion,the growth rate of the upper part of the sweet potato tends to be consistent.There is no significant difference in the number of branches and leaf area index between different segments,but for the tuber enlargement in the underground has obvious promotion effect,and the root-shoot ratio of apical cuttings with 8 nodes is still larger.Between the sections of different parts,the apical cuttings with 4 nodes and the middle cuttings with 4 nodes have an increasing growth rate than the base cuttings with4 nodes in the early and middle stages of tuber expansion,and the plant stems and leaves grow faster,the expansion of tubers promots.4)Performance of sweet potato node tuberization:in the 4 nodes cuttings,the number of sweet potatoes in the downward node is larger,and the weight of sweet potato is higher.In the apical cuttings with 8 nodes,the sweet patato weight of Yushu 198,Yushu50 and Xushu 22 are mainly concentrated in nodes 3-6,whose potato weights account for89.42%～100%,90.37%～97.13%and 83.66%～92.13%of the total potato weight,respectively.The number of sweet potato is 88.90%～100%,77.50%～93.30%and81.80%-88.60%,respectively.Among the apical cuttings with 12 nodes,the sweet potato weight of Yushu 198 was mainly concentrated at nodes 3-6.The sweet potato of the four nodes accounted for 84.30%～89.40%of the total potato weight,and the number of sweet potato accounted for 79.20%～85.90%.The sweet potato weights of Yushu 50 and Xushu22 are mainly concentrated in nodes 3-7.The weight of sweet potato is 84.80%～100%and 83.10%～94.00%of the total weight,and the number of sweet potato is 82.00%～100%and 73.90%～81.00%.Nodes 3,4,5,and 6 have relatively strong potato forming ability.Apical cuttings with 4 nodes,middle cuttings with 4 nodes,and base cuttings with 4nodes are all 2 node buried in the soil,and the nodes in the deeper soil had a stronger root formation ability.Node 5 of Yushu 198,Yushu 50 and Xushu 22 had a stronger ability to form potatoes in 8-node cuttings,and node 6 had no significant difference in root formation between 8-node cuttings and 12-node cuttings.In short vines,nodes exert a greater potential for roots. |
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