| Located in the northern part of Hebei Province,the cold and arid area of North China has a cold climate and sufficient sunshine.It is a semi-arid ecological area and is the main production base of short-season fresh potatoes in my country.However,its water resources are extremely scarce,and the uneven distribution of precipitation from year to year has become an important factor restricting potato production.In order to clarify the effect of seasonal drought on potato production,this field test was conducted.This study uses shelters to block natural precipitation,and uses local annual precipitation as the background of water supply to create drought stress and post-drought rehydration environment in different periods,revealing the decisive characteristics and compensatory growth effects of water environment on potato production at different periods of time,and The yield and quality characteristics of potato water stress and rehydration.The potential of potato production under the natural rainfall resources in the cold and arid areas of North China is clarified,providing a basis for stable potato production and efficient use of water resources.Below are key research findings.1.Clarified the effects of water stress on potato growth characteristicsWater stress at any time during the potato growth period will inhibit the growth of potato plant height,leaf number and leaf area.In 2019,the average plant height during the growth period of each stress treatment was reduced by 5.39%～37.23%compared with CK;in 2020,it was reduced by 7.14%～37.32%compared with CK.The number of potato leaves was weakened after water stress.In 2019,the average number of leaves during the whole growth period of each stress treatment decreased by 7.28%～20.19%compared with CK,and the leaf area of the corresponding population decreased by 6.95%～74.20%compared with CK.The average number of leaves during the growth period of each stress treatment in 2020 decreased by 2.63%～19.40%compared with CK,and the leaf area of the corresponding population decreased by 15.76%～69.24%compared with CK.After rehydration,the plant height of each treatment increased.In 2019,the plant height of rehydration treatment was reduced by 0.32%～23.17%compared with CK,and in 2020,it was reduced by 4.58%～22.23%compared with CK.W1 R and W2R have a better compensation effect for the number of leaves and leaf area in the later period due to the earlier rehydration period.The average number of leaves during W1 R growth period exceeded CK 2.90%-6.10%in two years.The average leaf area during the growth period of each rehydration treatment in 2019 was reduced by 9.75%～52.16%compared with CK,and in 2020,it was reduced by 9.93%～31.35%compared with CK.2.Clarified the effects of water stress on the physiological characteristics,yield and quality of potatoesWater stress at each time period increased the relative chlorophyll content(SPAD)and nitrogen balance index(NBI)of leaves,and the longer the stress time,the more obvious the increase effect.In 2019,the average SPAD value of the growth period of each stress treatment was 0.99～1.14 times of CK,and in 2020 it was 1.02～1.22 times of CK.The average NBI during the 2020 growth period is 1.04～1.26 times that of CK.Water stress will weaken the activity of the PS II reaction center,inhibit the original light energy efficiency(Fv/Fm),reduce the net photosynthetic rate(Pn),and the water stress effect is the heaviest at noon.Water stress will reduce the spectral reflectance in the 750～1150nm band,and increase the reflectance in the 1950～2450 nm band.Water stress treatment significantly reduced the weight of each potato plant,the rate of commercial potatoes and the yield.In 2019,the weight per plant of the stress treatment decreased by 2.04%～75.51%compared with CK,the economic yield decreased by 13.76%～74.50%compared with CK,and the biological yield decreased by 12.98%～68.38%compared with CK,In 2020,the weight of a single potato plant was reduced by 21.05%-71.93%compared with CK;the economic output was reduced by 0.06%～61.82%compared with CK,and the biological yield was reduced by 6.73%～58.19%compared with CK.After rehydration,the economic output in 2019 was reduced by 6.15%～33.23%compared with CK,and the biological output was reduced by 13.29%～31.04%.The economic output in 2020 will be reduced by 4.26%～31.79%,and the biological output will be reduced by 5.25%～28.30%.Therefore,effective farmland water supply is an important measure to ensure potato production.3.Clarified the positive correlation between potato yield,water consumption and cumulative leaf areaThere is a very significant quadratic positive correlation between potato economic output(y)and field water consumption(x),that is,with the increase of field water consumption,potato economic output shows an upward trend.In 2019,the correlation equation between the two is y=-8E-06x2+0.1059x-63.938,R2=0.9814;in 2020,the correlation equation is y=-2E-05x2+0.1666x-198.59,R2=0.9406.There is also a very significant quadratic positive correlation between potato economic output(y)and cumulative leaf area(x)during growth period.In 2019,the relationship between the two is y=0.0029x 2+0.5417x+27840,R2=0.8882,in 2020,the relationship is y=-0.0102x 2+102.84x-87632,R2=0.7492.In summary,the water stress at each period of the growth period will have an impact on the agronomic,physiological,yield and quality of the potato,and as the stress time prolongs,the impact will become more severe.With the aggravation of drought stress,the spectral reflectance of potato canopy decreased in the 750～1150 nm band,but increased in the 1950～2450 nm band.Rehydration after water stress has a certain compensation effect on potato growth,but it cannot achieve equal compensation.The yield of potato tubers showed a quadratic growth with the increase of field water consumption and cumulative leaf area during the growth period.Stable water supply in the field and increasing the water consumption capacity of potatoes are the technological innovation directions for increasing potato production in the cold and arid regions of North China. |
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