| 其他摘要 | Anthesis and fruit setting periods are critical time of water requirement for jujube.
It can provide physiological technology for reasonable irrigation to analyze water
requirement information of jujube. Based on analysis of the present status and
existing problems of relative research in home and abroad, this text took the three
years old pear jujube under four water levels, namely T0 (-33～-25kPa), T1
(irrigating once at beginning), T2(-60～-100kPa) and T3(-100～-200kPa) in jujube
water-saving demonstration located in Loess Plateau as the object of study to measure
stem diameter micro-change, leaf water potential and gas conductance. Taken
meteorological factors in account, the suitable indicator diagnosing water information
of jujube in anthesis and fruit setting periods was analyzed, based on the relationship
between the indicator and soil matrix potential, reasonable soil matrix potential
threshold was defined. Further, the practical significance of the threshold was verified
by the production under different soil matrix potentials. The preliminary conclusions
are as follows:
(1) Under different soil matrix potentials, the daily change of soil matrix potential
were similar in 30cm soil depth in three years old pear jujube woodland, and
increased the daily reduced extension of soil matrix potential with the decrease of soil
matrix potential. The daily change of soil matrix potential were similar in 60cm soil
depth showed similar regular as that of 30cm, but daily change curve of soil matrix
potential in 60cm was platter than that in 30cm, with higher soil matrix potential and
lower daily reduced extension, on one hand, which can attribute to evaporation
condition, on the other hand, jujube root mainly distributed in 30cm, where jujube
consumed more water than that in 60cm.
(2) During the experiment, four, two and two times irrigation were conducted in
T0(-33～-25kPa), T2(-100～-60kPa) and T3 (-200～-100kPa) treatments, with
average soil matrix potential of -28, -80, and -150 kPa respectively. There were
significant differences of soil matrix potential between treatments. Compared with T0 treatment(-33～-25kPa), the soil matrix potential in T1 (-10～) could be divided into
three stages, which were significantly higher than that T0(-33～-25kPa) lasting 15
days, similar with T0 (-33～-25kPa)lasting 16 days and significantly lower than
T0(-33～-25kPa) lasting 19 days.
(3) The diurnal changes of jujube stem diameter have periodicity. The diurnal
variation curve was similar to "U" type, with maximum around 8am and minimum
around 6pm. If without water stress, maximum of stem diameter can be restored with
growth trends; while, the maximum of stem diameter can not be restored to that of the
day before with water stress.
When the soil matrix potential changed, trunk maximum diameter shrinkage,
maximum trunk diameter, gas conductance and midday leaf water potential all could
showed reflection accordingly, but by comprehensive comparison, it can conclude that
maximum diameter shrinkage was the most suitable indicator conducting irrigation of
jujube in anthesis and fruit setting periods, mainly because it could respond to water
stress quickly and noticeably with smaller variability compared to other three
indicators.
Reference crop evapotranspiration and midday vapor press deficit could behave of
the drought degree of climate. The relationships of maximum diameter shrinkage and
reference crop evapotranspiration, midday vapor press deficit indicated that maximum
diameter shrinkage could also show the effect of meteorological factors on plant
status.
In all accounts, maximum diameter shrinkage was the suitable indictor diagnosing
the water requirement information of jujube in anthesis and fruit setting periods in the
experiment.
(4) In the curve of maximum diameter shrinkage signal intensity and soil matrix
potential, by measuring whether the maximum diameter shrinkage signal intensity
was one or not, the suitable soil matrix potential values of pear-jujube in anthesis and
setting periods was identified between -40 kPa and -25kPa. And the values higher
than -25kPa was named jujube luxurious soil matrix potentials.
There were significant differences of jujube productions under different soil matrix
potential conditions. In T0 treatment(-33～-25kPa), where soil matrix potential were
between -25 and -40 kPa, with average value of -28kPa, jujube production was
highest, production in T2 treatment (-100～-60kPa) was a few smaller than that in T0
treatment(-33～-25kPa), while production in T3 treatment (-200～-100kPa) was
smallest, which make clear that the suitable soil matrix potential defined in the
experiment has practical importance and can indicate jujube irrigation |
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