| 其他摘要 | Based on the analysis for the present status and existing problems of relative research
in home and abroad, the soil properties, stem diameter micro-change, canopy structure, leaf
physiological, photosynthetic production and other growth and physiological indexes of
four years old pear jujube trees were invesstigated in this paper under four soil moisture
treatments, namely T1(-41～-51kPa), T2(-68～-84kPa), T3(-96～-135kPa) and T4(-311～
fruit wilting～-311kPa) in jujube water-saving demonstration base located on Loess
Plateau. Meanwhile meteorological environment for cultivation and principal
meteorological factors influencing stem diameter were studied. At last, water optimal
control theory of jujube cultivation were summarized by analyzing the quantitative
relations and inner link of indexes for each interface of soil-plant-atmosphere continuum.
The preliminary conclusions are were as followed:
(1) The meteorological environment had advantages and disadvantages for Jujube
cultivation in Northern shaan xi, where solar radiation value was high and radiated time
was long and daily average Rs was 226.80wat/m2 during the experimental period. Long
time and high value of solar radiation played an important role on the fruit coloring and
maturity in the later period. Daily temperature difference(DTD) value is high during
experiment period and the daily average value was 13.88℃, which was helpful for
improving fruit quality. In study area, the average daily rainfall was 1.71mm, average daily
reference crop evapotranspiration was 6.77mm, cultivation environment was relatively dry,
rainfall time was continuous, and vapour pressure deficit value and temperature were high
from 160 days to 220 days. Fruit expanding period, leaf expansion and flowering period
were the main water deficit period, and reasonable irrigation was needed to ensure healthy
growth of jujube trees in this time. (2)Daily stem diameter change could be divided into recovery type, deficit type and
special type. Daily diameter increase (DI) of recovery type was positive, and deficit type
was negative, while the special type has no clear DI. Dynamic change of stem diameter has
a negative similar trend with air temperature and a positive similar trend with air relative
humidity. MXTD usually appearred about 8 o'clock in the morning, and MNTD usually
appearred about 3 o'clock in the afternoon.
(3) Rs and Tmd were considered as the main decision variables influencing MDS, and
ET0 was the main limiting variables by analyzing the path between MDS and
meteorological factors. Transpiration intensity and radiation were thought as the main
factors influencing MDS. There were some other factors influencing MDS for the error
term value of direct path coefficients and decision-making coefficient were high.
(4) daily dynamic of jujube stem diameter and growth rate during the growing season
were closely related to soil moisture. The dynamic change of pear jujube stem
microvariation was stable in high water treatment plot, while the value was lower than the
that under low water treatment. The time of stem from the rapid growth to slow growth
was later and the turning point was also lagged behind compared with that under low water
treatment. So irrigation could extended the growth time. The stem was thick under low
water treatment. Growth Changes of stem diameter could be well fitted by Slogistic1 curve
equation.
(5) LAI was positively correlated with the soil moisture content, while light
transmittance of canopy and tree height were negative correlated with the soil moisture
content. Light transmittance of canopy under medium water treatment was in suitable
scope of 25% to 35% for a long time, which could make full use of the light energy and not
cause orchard canopy closure. Water treatment had an important influence on the
Chlorophyll relative content, stomatal limitation, and Ci. Chlorophyll relative content.
Stomatal limitation value of pear Jujube leaf was low, while the value of cond and Ci was
high in high water treatment plot. Chlorophyll relative content was down when rehydration,
but the decreased degree was different to different water stress degree. Net photosynthetic
rate and transpiration rate increased with the soil moisture content, but water use efficiency
dropped. Irrigation can raised The value of fruit setting rate, fruit retention rate, fruit
setting branches and fruit number could be increased significantly by irrigation, meanwhile
the total branches number, average fruit number of fruit setting branches and rate of fruit
setting branches were also enhanced, but the effect were not remarkable. Proper irrigation
could significantly improve fruit weight and total production, but if the water was too much, jujube tree’s growth would be affected by flooding stress, and fruit weight and total
production would be reduced.
(6)Appropriate soil water potential irrigation range of Jujube was from - 68 to -
84kpa, relative to the field capacity from 60% to 65%; Suitable periods for irrigation were
flowering and fruit bearing periods and fruit expanding period; Preferred water deficit
sensitivity indexes were stem diameter micro-changes (MDS, MXTD, MNTD), and
stomatal conductance, and net photosynthesis rate, and transpiration rate.
Key words: pear jujube tree; soil moisture; meteorological factor; Physical growth;
production; water deficit; stem diameter; water optimization |
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