Study On The Continuous Production And Improving Quality And Efficiency Technology Of Apple Orchard In Weibei Dry Region

The Loess Plateau is a high-quality apple producing area in China,the apple industry has become the pillar industry in this area.With the planting scale extending and the planting age increasing,a series of problems like the soil desiccation and biennial bearing being exacerbated which caused by the capacity of soil moisture regulation reducing,nitrate nitrogen accumulating in deep subsoil had appeared.Therefore,it was necessary to controlling the apple orchard ecosystem to achieve the goal of the apple production with high quality,efficiency and sustainability.So,a measure of controlling the supply of water and fertilizer was proposed,which include appropriate productivity,surface mulching technology and accumulate and conserving soil water technology.At the same time,soil moisture,nutrients and yield of different experimental treatments had been analyzed in order to offer a scientific guidance for harmonious development of apple production technology,economic income of farmer,and the apple orchard ecosystem.The results prove that:1)In order to determine a suitable crop load for sustainable development of dryland apple orchards,5 different productivity crop loads were limited to 1.8×10⁵（I）,2.25×10⁵（II）,2.7×10⁵（III）,3.15×10⁵（IV）,and 3.6×10⁵（V）fruit per hectare,using flower and fruit thinning by hand.Volumetric soil water content and economic benefit were then analyzed under each treatment over a 7-year period.Soil water content was found to be closely related to rainfall,with three seasonal periods recognized annually.Average water content in 2009–2015ranked treatment II（21.54%）>III（20.99%）>I（20.16%）>IV（19.86%）>V（19.58%）,in which treatments II and III were significantly higher than other treatments.The soil water content has significant differently in different productive levels.And with the productivity increased,the soil water consumption was increased.From an economic perspective,when the productivity level crop load was lower（treatments II）,the percentage of high-quality fruit increased as did the economic benefits.In conclusion,controlling fruit productivity crop load effectively reduced fluctuations in production,enhance the tree potential,prolong the fruit period,increased the economic benefits,and maintained the health of the orchard ecosystem.The appropriate productivity crop load level for mature apple orchards in the gully region of the Loess Plateau was deemed to be 2.25×10⁵ fruit per hectare.2)In order to solve the effect of water shortage on the production and growth of fruit trees in Loess Plateau,the effects of different surface mulching techniques on orchard ecosystem were monitored from 2008–2015.Different mulching measures,including grass cover（GC）,film mulching（FM）,straw mulching（SM）and gravel mulching（GM）,can effectively enhance the regulatory capacity of soil reservoir,in which the soil water content of SM and FM were higher than other treatments.With the increase of planting age,the use of deep soil water content increasing,soil water content showed decreasing trend and the trend of soil desiccation has been partially alleviated because of the surface mulching.The different mulching treatments techniques can improve water use efficiency and apple yield,in which GM and SM had the best effect.The treatment GM had lower soil water content,but high yield,so the water use efficiency was high,and the effect was better during2008–2012.The benefits of GM decreased beginning 2012,due to the mixture of gravel and topsoil.The treatment SM had higher soil water content and yield,and the regulation effect of temperature was better than other treatments.Although the water content of FM was high,but the yield and water use efficiency of treatment FM were low.After the rainy season,soil moisture recovery rate was low and the root growth of fruit trees was affected by high summer heat in treatment FM.In conclusion,SM and GM were the appropriate technique to improve the water and heat status and fruit yield of apple orchard soil in the gully region of the Loess Plateau.3)Different rainfall harvesting and mulching technologies,including Ridging（Ridge of film over short straw mulching and furrow of vinegar residue and fly ash mixed backfill,L）,impermeable layer（artificial impermeable layers of red clay with a thickness of 5 cm,F）and“ridging+impermeable layer”（the combination of F and L,FL）were used to solve the problem of water shortage and nitrate deep leaching.Treatment FL（23.6%）and L（24.3%）can significantly improve soil water content.The soil water content of treatment F（22.7%）was slightly higher than that of the control（22.3%）,and there was no significant difference between them.The soil water content of treatment L and FL can be significantly increased in0-40 cm（24.5%and 23.8%respectively）and 40–300 cm（24.3%and 23.5%respectively）.The soil water content of treatment F can be significantly increased in the 0–40 cm soil layer（22.7%）,but the water content in the 40–300 cm soil layer（22.6%）was slightly higher than the control（22.4%）,and there was no significant difference between them.Both FL and L can significantly improve soil temperature,and it was beneficial to increase soil microbial activity and activate soil nutrient.The average content of nitrate nitrogen in the soil layer of0–300cm was that:FL(74.0 mg·kg^-1)<L(90.9 mg·kg^-1)<F(98.5 mg·kg^-1)<CK(101.4mg·kg^-1).The nitrogen content of FL was significantly lower than that of control,and the spatial distribution of nitrate was changed by F and L,but there was no significant difference among them.The nitrogen content of FL(78.3 mg·kg^-1)and F(79.9 mg·kg^-1)in the 0–40 cm soil layer were significantly higher than that in the control group(51.9 mg·kg^-1),and the maximum value was appeared at the 40 cm soil layer.It indicating that the impermeable layer can effectively block the leaching of nitrate nitrogen by blocking the water transport and increase the surface nitrate nitrogen content.The nitrogen concentration of L in deep soil layer was higher than that of the control,the peak value appeared in the 300 cm soil layer(139 mg·kg^-1),while the control treatment appeared at 240 cm(140.1 mg·kg^-1),indicating that the ridging measures increase the deep leaching of nitrate nitrogen through the accumulation of water and the cumulative peak was moved down.The treatment of FL can promote the absorption of nitrogen fertilizer and increase the utilization rate of nitrogen fertilizer,thus reducing the nitrate nitrogen content in the soil.4)The treatment of F,FL and L can significantly improve the growth of the fruit trees,whether the size of the crown or the number of fruit-bearing branches is significantly improved,and the treatment of FL was the best among all the treatments.Treatment of F and L can significantly improve the growth of tree branches and leaves.Treatment FL in the highest proportion of short branches,is conducive to fruit quality,high yield and stable yield.Treatment FL has lower mean tilt angle and higher canopy openness,so the ventilation is good and the interception of solar radiation is strong.The mean tilt angle and canopy openness of L are smaller and the extinction coefficient is higher,so the interception capacity of solar radiation is strong,but the ventilation is poor.Treatment FL and L have higher chlorophyll content,significantly higher than the control treatment.The fresh weight,dry weight and leaf weight of FL were the highest,significantly higher than the other three treatments.In contrast,the control treatment has lowest fresh weight of leaf,treatment F has lowest dry weight of leaf,and treatment L has lowest specific leaf weight,but there was no significant difference among these three treatments.5)Treatment FL,F and L can significantly improve the apple fruit weight,yield,soluble sugar content and transverse and vertical diameter of fruit,in which treatment FL has the highest value,followed by treatment F,the control treatment was the lowest.The fruit of apple grows rapidly during the young fruit period and developing fruit period.The growth rate of the whole growth period presents the growth trend of"S"curve.The vertical diameter of apple is greater than the transverse diameter before 60 d.The transverse diameter begins to be larger than the vertical diameter after 60 d.Logistic and Richards equations have a good effect on the simulation of apple’s transverse and vertical diameters,and Richards equation has a high fitting accuracy,but its parameters are quite different from the actual measurement values.In conclusion,“accumulate-store water technology”nicely combines the advantages of“artificial impermeable layer”and“plastic film-mulch,ridge and furrow rainwater harvesting system”.It can gather the limited rainfall in the ditch,and acid-sludge and flyash effectively to prevent water evaporation,to create a high water and fertilizer,porous,slightly acidic environment.It can effectively improve the soil water use efficiency,weaken the trend of nitrate nitrogen leaching into deep soil layer and increase the quality and quantity of apple.It is a water and fertilization regulation technology and worthy of promotion.