Study On Photosynthetic Physiological Characteristics And Ecological Effects Of Fuji Apple In Yan’an Mountain

This article takes the Fuji apple Changfu in the Yan’an mountain area as the research object.In June,July,August,September and October 2019,the GFS-3000 portable photosynthesis instrument was used to measure the net photosynthetic rate（Pn）of the Fuji apple Changfu in the mountain area.,Transpiration rate（Tr）,water use efficiency（WUE）and other related data,researched and analyzed the photosynthetic physiological characteristics,water physiological characteristics,and light response of the mountain Fuji apples of different tree ages,different slope directions and different slope positions in Yan’an.The curve and the relationship with ecological factors have evaluated the ecological effects of Fuji apple growth in different tree ages,slope orientations,and slope positions.The main findings are as follows:（1）The photosynthetic characteristics of Fuji apples at different ages are quite different:6-year-old and 15-year-old Fuji apples have a net photosynthetic rate in the five months of June,July,August,September,and October（The Pn）diurnal variation curve has two peaks,which is a typical photosynthetic"noon break"phenomenon.The lunch break is weaker in June and October;the light saturation point（LSP）of 6-year growth is830μmol·m^-2·s^-1 and above,the light compensation point（LCP）is between 40～90μmol·m^-2·s^-1,the value of chlorophyll a/b is between 0.773 and 1.942;the light saturation point（LSP）of 15 years of growth is 840 Aboveμmol·m^-2·s^-1,the light compensation point（LCP）is between 30 and 80μmol·m^-2·s^-1,and the value of chlorophyll a/b is between 0.697 and 1.718.The 15-year-old growth has a low light compensation point,a high light saturation point,a low chlorophyll a/b,and a strong adaptability to strong light.For 6-year growth,the ratio of bound water/free water is large in August,physiological life metabolism is slow,and drought resistance is stronger.In September,bound water/free water is lower,metabolism is faster,and growth is faster.In the 15-year growth period,the ratio of bound water/free water is large in August,the physiological life metabolism is slow,and the drought resistance is stronger.In July,the bound water/free water is lower,the metabolism is faster,and the growth is faster.（2）There are big differences in the photosynthetic characteristics of Fuji apple Changfu in different slope directions:the net photosynthetic rate of Fuji apple Changfu in June,July,August,September,and October in the five months of June,July,August,September,and October The daily variation of（Pn）shows a"double peak"curve,and the lunch break phenomenon is more obvious on the sunny slope than the shaded slope.The light saturation point（LSP）of Yangpo Fuji apple Changfu is above 860μmol·m^-2·s^-1,the light compensation point（LCP）is between 40～80μmol·m^-2·s^-1,and the value of chlorophyll a/b Between 0.664 and 1.346;the light saturation point（LSP）of the shade Fuji apple Changfu is above 800μmol·m^-2·s^-1,and the light compensation point（LCP）is between 30～90μmol·m^-2·s^-1,The value of chlorophyll a/b is between 0.829 and 2.102.The Yangpo Fuji apple has a lower light compensation point,higher light saturation point,lower chlorophyll a/b,and stronger adaptability to strong light.Yangpo Fuji apple grows rich in August with a large ratio of bound water/free water,slow physiological life metabolism,strong drought resistance,lower bound water/free water in July,faster metabolism,and faster growth.Fuji apples grown on shady slopes have a large ratio of bound water/free water in August,slow physiological life metabolism,and strong drought resistance.In September,the bound water/free water is lower,the metabolism is faster,and the growth is faster.（3）The photosynthetic characteristics of Fuji apples at different slope positions are quite different:the net photosynthetic rate（Pn）days of Fuji apples on the slope and at the bottom of the slope in June,July,August,September,and October The change curve has two peaks,among which the morning break of the slope is more obvious than the bottom of the slope;the light saturation point（LSP）of the Fuji apple at the bottom of the slope is above 850μmol·m^-2·s^-1,and the light compensation point（LCP）is between 50 and 100μmol·m^-2·s^-1,and the value of chlorophyll a/b is between 0.639 and 1.620;the light saturation point（LSP）of the Fuji apple on the slope is 890μmol·m^-2·s^-1 or more,the light compensation point（LCP）is between 50～90μmol·m^-2·s^-1,and the value of chlorophyll a/b is between 0.549 and 1.400.The Fuji apple on the slope has a lower light compensation point,a higher light saturation point,lower chlorophyll a/b,and a stronger adaptability to strong light.The slope bottom Fuji apple grows rich in August with a large ratio of bound water/free water,slow physiological life metabolism,strong drought resistance,lower bound water/free water in June,faster metabolism,and faster growth.The Fuji apple on the slope has a large ratio of bound water/free water in August,slow physiological life metabolism,and strong drought resistance.In June,the bound water/free water is lower,the metabolism is faster,and the growth is faster.（4）Comparison of the ecological effects of Fuji apples with different tree ages,different slope directions and different slope positions:From the perspective of different months,whether it is tree age,slope direction,and slope position,the daily carbon fixation and oxygen release of mountain Fuji apples They are the largest in July,September,August,and October in descending order,and the smallest in June.The daily transpiration rate is the highest in August,and the ability to cool and increase humidity is the strongest;Fuji apples of different ages grow rich in carbon sequestration.The variation range of the amount is 1138.54 g～1329.04 g,of which the 15-year-old is the highest,which is 1329.04 g;the annual transpiration water volume of the 15-year-old Fuji apples varies from 251.49 kg to 331.86 kg in different slope positions and directions,of which the annual transpiration on the sunny slopes The highest amount of water is331.86 kg.Mountain Fuji apples are 15 years old,with high net photosynthetic rate（Pn）,high water use efficiency（WUE）,high drought resistance and strong adaptability to the environment on sunny slopes and slopes;at the same time,mountain Fuji apples have long rich slopes The upper and sunny slopes have relatively strong carbon fixation and oxygen release,cooling and humidification capabilities,and good ecological effects.