| China is very short of water resources,the total per capita water resources only account for 28%of the world average,water and fertilizer waste in the actual production of crops in the field is very serious,resulting in the low utilization efficiency of water and fertilizer in China’s agricultural production.This study sought to change the traditional pattern of apple irrigation and fertilization,using modern water fertilizer integration technology to study the effects of supply pattern of growth and development state,root zone moisture availability,the absorption of moisture,dry matter accumulation,especially the effect of water use efficiency and water productivity mechanism of young apple trees in northern semi-arid area.Finally,the optimal irrigation and fertilization system and corresponding technical parameters under the coupling effect of water and fertilizer on apple trees were proposed.The main research results are as follows:(1)Under different coupling treatments of water and fertilizer,the maximum growth amount of young apple trees at the growth stages(germination and flowering stage,new shoot growth stage,fruit setting expansion stage and maturity stage)appeared in F1W2 treatment,which were 10.9,15.4,13.1 and 7.6 cm respectively,increased by 6.9%,6.2%,11.0%and 2.7%compared with F1W1 treatment in 2019,and reached 13.6,18.1,16.1 and 9.6 cm respectively,which increased by 9.7%,5.8%,8.8%and 3.2%compared with F1W1 treatment in 2020,and the minimum values all appeared in F3W4 treatment in both years.In 2019,the maximum growth amount of basal stem of young apple trees at different growth stages all appeared in F1W2treatment,which were 1.82,2.10,2.46 and 2.52 mm at germination and flowering stage,new shoot growth stage,fruit setting expansion stage and maturity stage,respectively,only increased 3.4%,5.5%,5.6%and 1.6%,respectively,compared with F1W1treatment.The maximum value of basal stem growth in 2020 appeared in F1W1treatment at germination and flowering stage and fruit setting stage,and appeared in F1W2 treatment at new growth stage and maturity stage,and the minimum value all appeared in F3W4 treatment.Meanwhile,the maximum leaf area of each growth stage appeared in F1W2 treatment,which increased by 9.3%,5.8%,5.0%and 3.3%,respectively,compared with F1W1 treatment in 2019.The maximum leaf area of each growth stage was 1.44,2.05,2.38 and 2.58 m~2/plant,respectively,in 2020,which the germination and flowering stage appeared in F1W1 treatment,and the other growth stages appeared in F1W2 treatment,and the minimum values all appeared in F3W4treatment.The SPAD of young apple trees increased with the growth period,and increased sharply at the germination and flowering stage and new shoot growth stage,and then increased gradually at the fruit setting expansion stage and maturity stage.The maximum value of SPAD in the shoot growing stage appeared in F1W2 treatment,the maximum value of SPAD in F1W1 treatment and the minimum value in F3W4treatment.(2)Under different coupling conditions of water and fertilizer,the net photosynthetic rate,transpiration rate and stomatal conductance of young apple trees basically increased with the increase of irrigation amount and fertilizer amount,and the maximum values all appeared in F1W1 treatment with high water and high fertilizer amount,and the minimum values all appeared in F3W4 treatment.The maximum net photosynthetic rates in 2019 and 2020 were 26.65 and 32.17μmol/(m~2·s),respectively,which were reduced by 4.2%and 2.1%under F1W2 treatment.The maximum transpiration rates were 6.38 and 6.85 mmol/(m~2·s),respectively,and F1W2 treatment reduced 9.7%and 11.5%compared with F1W2 treatment,respectively.The maximum stomatal conductance was 412.71 and 428.51 mmol/(m~2·s),respectively,which were reduced by 4.2%and 3.0%under F1W2 treatment.The maximum water use efficiency(WUE)was 4.43μmol/mmol in 2019 and 5.20μmol/mmol in 2020 under F1W2treatment,which was increased by 5.9%and 10.6%compared with F1W1 treatment,respectively,and the minimum values were 3.50μmol/mmol and 4.24μmol/mmol in F3W4 treatment,respectively.Under the condition of different fertilizer,net photosynthetic rate,transpiration rate and stomatal conductance of daily variation trends are characterized by rosing sharply and then fell in the morning,rosing again and then slowly subsided in the afternoon.Basically all of them showed the characteristics of M bimodal,two peaks appear at 10 AM and 2 PM.There was a short"lunch break"phenomenon at 12 noon,and the minimum values of each treatment appeared at 6 PM.(3)At the same irrigation amount,the dry matter mass of young apple trees increased with the increase of fertilizer amount,and the mild water deficit treatment was more conducive to the accumulation of dry matter mass,but the dry matter mass still increased with the increase of irrigation amount under the condition of low fertilizer amount.The maximum dry matter weight(543.27 g/plant and 654.06 g/plant)during the whole growth period appeared in F1W2 treatment under different water and fertilizer treatments in 2019 and 2020,which only increased by 0.8%and 0.6%compared with F1W1 treatment.Under F1W2 water and fertilizer treatment,the dry matter quality and water productivity reached the maximum during the whole growth period.Compared with F1W1 treatment,the dry matter quality and water productivity increased by 0.8%and 14.6%in 2019,0.6%and 11.1%in 2020,respectively,while water consumption decreased by 12.2%and 9.4%in two years.Therefore,F1W2 water and fertilizer treatment was the best coupling system. |
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