The Pathway And Technology Of Controlling Appropriate Productivity On An Apple Orchard Ecosystem

Loess Plateau is one of the seven suitable apple growing regions in the world, and it is also the only one eugenic apple growing region in China. Since 1980's, with the planting scale extended, the economic income of farmer was increased and the economic development of this region was promoted. But at the same time, the soil desiccation was exacerbated, nitrite-nitrogen was accumulated, and the control capability of apple orchard ecosystem was declined. Producers want to maximum productivity, however extremely high levels of production can influence the orchard ecosystem and affect apple tree growth, yield quality and stability, and economic return. Therefore, it is necessary to controlling the apple orchard ecosystem to achieve the goal of the apple production with high quality, efficiency and sustainability.So, we took apple orchards in the Gully Region of the Loess Plateau as test object from Oct., 2007 to Oct., 2009, to study the appropriate productivity for mature orchards under clean tillage using controlling productivity from the environment, apple trees, and economic benefit on the apple orchard ecosystem. And to find out the most suitable surface mulching from controlling the soil environment in order to adjust the appropriate productivity, for further. The final purpose of this research is expected to offer scientific guidance for harmonious development of apple production technology, economic income of farmer, and the apple orchard ecosystem.The main results of this research showed as follows:(1) The spatial patterns of soil moisture in different productive levels were comparatively studied by means of classical statistics and geo-statistics on the Loess Plateau. The results showed that the soil water content is increased with the distance extend from the root layer in the vertical direction, and increased with the distance extend from the tree trunk in the horizontal direction. The soil water stability is strengthened with the distance extended from the surface and from the tree trunk. The soil water content has significant differently in different productive levels. And with the productivity decreased, the soil water consumption is reduced, the soil water stability is raised, and the spatial variability is augmented by the spatial autocorrelation, and decreased by the random part. In conclusion, the excess consumption of resources and the impact on environment can be reduced by controlling the productive levels.(2) With the productivity was reduced, the phenomenon of photosynthesis midday depression was abated; the net photosynthetic rate (Pn) was increased, and the highest Pn could increased by 25.71% compared with the control treatment (â… ). The transpiration rate (Tr) was decreased rapidly in the afternoon; and the optimum water use efficiency (WUE) could improved by 34.12% compared with theâ… . Through the controlling productivity, the soil moisture and photosynthetic characteristics could be improved; furthermore, the WUE could be increased, too.(3) According to quality analyzing, there is no significant differences in the soluble solid content, soluble sugar content and other internal qualities between the treatments of adjusted productivity levels and the treatment of unadjusted. The use of control methods to reduce productivity resulted in improvements in individual apple weight, firmness, and color. Based on external quality, the percentage of excellent fruit was 13%～24% higher in treatments with adjusted productivity levels compared to the unadjusted control treatment. And the leaf fresh weight has significant difference among different treatments. These results also indicated that controlling productivity increased sustainability, economic return, and ecological benefit and reduced fluctuations in production. The regression analysis showed the productivity of 2.25×105 Ind·hm^-2 has the highest net income, besides input-output ratio, the productivity of 2.25×105 Ind·hm^-2 has the best economic benefit.(4) An annual period can be divided into three periods according to the soil water storage: water decreased in spring & summer, water increased in summer & autumn, and water stabilized in winter & spring. Within the 600 cm profile, the highest average soil water content was the plastic film mulch, and the lowest one was the gravel mulch in all the three periods. And the soil water was recovered after the rainfall, the significant one was the gravel mulch (10.52%), the straw mulch was the secondary one (9.47%), and the clean tillage was the least one (6.53%). The depth of the water infiltration can be reached 260 cm. According to the yield, the water use efficiency of every treatment was that, clean tillage: 35.75 kg·mm^-1·hm^-2, grass cover crop: 0.31 kg·mm^-1·hm^-2, plastic film mulch: 47.81 kg·mm^-1·hm^-2, straw mulch: 58.99 kg·mm^-1·hm^-2, and gravel mulch: 80.25 kg·mm^-1·hm^-2. In conclusion, among the test surface mulching patterns, gravel mulch was most suitable for the apple orchards in the gully region of Loess Plateau, China.(5) The diurnal changes of the photosynthetic rate (Pn) were all double-peak curve in leaves of the clean tillage treatment and growing grass treatment, and the diurnal changes of the photosynthetic rate (Pn) in film mulching, straw mulching and gravel mulching were all one-peak curve; the diurnal changes of the transpiration rate (Tr) were all one-peak curve. The relationship between photosynthetic rate (Pn) and photosynthetically active radiation (PAR), air temperature (Ta), leaf temperature (Tl) were all quadratic curve; the photosynthetic rate (Pn) was significantly positively correlated with atmospheric relative humidity (RH), stomatal conductance (Gs), respectively; the photosynthetic rate (Pn) was significantly negatively correlated with intercellular CO₂ concentration (Ci). The relationship between transpiration rate (Tr) and photosynthetically active radiation (PAR) was power exponent; and with atmospheric relative humidity (RH) was quadratic curve, respectively. The transpiration rate (Tr) was significantly positively correlated with air temperature (Ta), leaf temperature (Tl) and stomatal conductance (Gs), respectively; the transpiration rate (Tr) was significantly negatively correlated with intercellular CO₂ concentration (Ci). The photosynthetic rate (Pn) of gravel mulching and straw mulching were highest; and there were little different in the average diurnal changes of transpiration rate (Tr) with different soil management models. The photosynthetic characteristics showed significant correlation with environmental factors and physiological factors, respectively.(6) Soil management practices had a significant effect on soil temperature and generally resulted in a decrease in the maximum soil temperature. The exception was the plastic film mulch treatment in which summer soil temperatures exceeded the maximum allowable temperature for continued root growth. With the exception of plastic film mulch, the soil management practices increased the rate of soil CO2 flux. Soil CO₂ flux was highest in the grass cover crop treatment. Apple tree growth and yield were affected by the soil management practices. Apple yield and the proportion of medium-sized tree branches were highest in the gravel mulch treatment. Apple yield was lowest in the grass cover crop treatment.The appropriate productivity for mature orchards under clean tillage in the Gully Region of the Loess Plateau was 2.25×10⁵ Ind·hm^-2, based on the environmental, biological responses, and economic benefit to controlling ecosystem in an apple orchard. Factor analysis indicated that among the management practices considered in controlling the soil environment, gravel mulching had the best effect on mature apple orchards in the Gully Region of the Loess Plateau, China.