| In order to solve the problems of cold and drought in the south of Ningxia.The field experiment of different tillage depth(ploughing 15 cm(P15),subsoiling 30 cm(S30),subsoiling 40 cm(S40)and subsoiling 50 cm(S50))with mulching measures(straw mulching(JM),ordinary plastic film mulching(DM),Degradable water permeable plastic mulching(FM)and no mulching(BM))was set in the south of Ningxia from October 2020 to October 2021.The study was conducted to investigate effects of soil water,heat and fertilizer environment,root characteristics and plant growth on tubers yield under different tillage depth with mulching modes,and to provide theoretical reference for building high-yield cultivation of dry potato.The main research results are as follows:(1)Tillage,mulching and their interaction could improve soil nutrient status and regulate soil C/N during potato harvest.S30 cm treatment had the best effect on increasing soil total nitrogen,available phosphorus and alkali-hydrolyzable nitrogen contents,and combined S30×JM treatment had the best effect,which significantly increased by 45.14%,55.39%and 19.09%compared with P15×BM treatment,respectively.S40 cm treatment had the best effect on increasing soil organic matter,available potassium and C/N contents,respectively.Significantly increased by 39.29%,38.99%and 15.18%,respectively.Under the same tillage depth,the effect of JM treatment was higher than that of DM and FM.(2)Tillage,mulching and their interaction could significantly affect root morphological characteristics and physiological activity of potato at key growth stages(budding,tuber formation and tuber enlargement).Under the same mulching material,S40 and S30 treatments had the best effect on root length,root volume and root activity.Compared with P15×BM,S40×JM treatment had the best effect on root length,root volume and root activity,which were significantly increased by 28.06%,45.87%and 65.85%on average,respectively.Compared with P15×BM,S30×JM significantly increased the root surface area and active absorption area by 14.93%and 76.61%,respectively.JM treatment was better under the same tillage depth.(3)Tillage,mulching and their interaction could increase potato emergence rate,compared with P15×BM,S40×DM treatment significantly increased by 17.35%,S30 was the best treatment for plant height,stem diameter and leaf area index at all growth stages,FM and DM were the best treatments for mulch material at early growth stage,and JM was the best treatment at late growth stage Plant height,stem diameter and leaf area index were the highest in S30 × DM,S30 × FM and P15 × DM treatments,respectively,which were significantly increased by 78.69%,79.97%and 10.16%on average compared with P15 ×BM treatment,respectively,compared with those of P15xBM,Compared with P15×BM,S30×JM treatment significantly increased plant height and stem diameter by 59.46%and 35.33%,respectively.Leaf area index(LAI)of S50×FM treatment was the highest,which was significantly increased by 31.68%compared with P15×BM treatment on average.S40×JM treatment can significantly increase the number of potato stolons.S30 and S40 were the best treatments for dry matter accumulation in potato shoot and lower part,FM was the best treatment in the early growth stage,JM was the best treatment in the middle and late growth stage.The interaction of shoot dry matter accumulation between S40×FM treatment and P15×BM treatment was the highest at seedling stage,which significantly increased by 69.75%compared with P15×BM treatment.Compared with P15×BM treatment,S30×JM treatment was the highest from bud to harvest,which increased significantly by 60.29%on average.The underground dry matter accumulation was the highest in S40×FM treatment at the early growth stage,which was significantly increased by 81.00%compared with P15×BM treatment.In the later stage,S40×JM treatment was the highest,which was significantly increased by 60.78%compared with P15×BM treatment.The Logistic equation was used to fit the dry matter accumulation of potato above ground and underground parts.It was found that S30×JM and S30×FM treatments had higher theoretical biomass and growth rate during the fast growth period.(4)Tillage,mulching and their interaction had certain effects on the activities of protective enzymes and photosynthetic characteristics of potato leaves during the critical growth period(budding to harvest).Compared with P15×BM,S30×JM treatment significantly increased net photosynthetic rate,transpiration rate and potential activity of PSII by 102.06%,84.28%and 35.00%,respectively.Compared with P15 × BM,S40 X JM treatment significantly increased SPAD value and maximum photo chemical efficiency of PS ii by 21.02%and 24.77%,respectively.(5)Tillage and mulching can increase potato yield,commercial potato rate and economic benefit.Compared with P15×BM treatment,S40×JM treatment was the best for the interaction of the two treatments,which increased significantly by 106.24%,13.91%and 275.25%,respectively.(6)According to the correlation analysis of various indexes,potato root morphological and physiological characteristics had extremely significant or significant positive correlation with soil available p,available K,leaf enzyme activity,net photosynthetic rate and yield.Root length,root volume,root activity and root absorption area were positively correlated with dry matter accumulation in aboveground,total nitrogen and organic matter,Root activity and root active absorption area had significant positive correlation with potato growth and commercial potato rate.Principal component analysis and comprehensive score showed that Root length,POD,net photosynthetic rate and CAT were most closely related to yield,which were important factors limiting high yield of potato Soil fertility and potato plant growth indexes were most affected by 40 cm deep soiling combined with straw mulching.In conclusion,tillage depth combined with mulching can effectively improve soil fertility in ningnan arid region,promote the growth of potato roots and aboveground plants,and then significantly increase potato tuber yield,commercial potato rate and economic benefit,among which,the treatment of subsoiling 40 cm combined with straw mulching has the best effect. |
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