| 其他摘要 | Based on analysis of research status and existent problems of relative studies in home
and abroad, this text took four years old pear-jujube (Ziziphus jujuba Mill.) in jujube
water-saving demonstration located in Mizhi Yulin. It is to study the responses of trunk
daily fluctuations, canopy structure, physiological indexes and fruit quality to different soil
water potential in sprout and flowering period, fruit growth period and fruit ripening period
of pear-jujube trees. There are four treatments, namely T1 (-41~-84 kPa), T2 (-41~-84kPa),
T3 (-61~-135 kPa) and T4 (non-irrigation in sprout and flowering period and covering to
sufficient irrigation). The preliminary conclusions are as follows:
(1) Under different soil water potential, maximum daily trunk diameter (MXTD)
and maximum daily shrinkage (MDS) are significantly different. The values of MXTD and
MDS fluctuated by pear-jujube growth and development period in different soil water
potential. The curve of trunk daily fluctuation is similar to “U” type, with maximum in the
morning and minimum in the evening. In different pear-jujube growth and development
periods, the curves are different caused by different factors.
(2) Leaf area indexes, Cap fraction, extinction coefficient and diaphanous rate are
significant different in different soil water potential. The mild water stress influenced these
indexes, but they recovered sharply after covering water, which is called compensation.
(3) In shoot period the suitable soil water potential was in the range of -41~-72 kPa,
However, the suitable soil water potential for pear-jujube flower bud was in the range of
-41~-132 kPa. In shoot period, mild water stress did not affect flower bud, made vegetative
growth less and optimized the relationship of vegetative growth and reproductive growth.
And, in flowering period, the suitable soil water potential is in the range of -54~-78 kPa for
pear-jujube in flowering period. While the suitable soil water potential for setting fruit was
in the range of -79~-114 kPa, in which the fruit set percent was greatest. Therefore, in flowering period, mild water stress could increase setting percentage.
(4) Firstly, in fruit low-growing stage maximum daily trunk diameter grew slowly.
And the high soil water potential may decrease the percentage of fruit abscission. Secondly,
MXTD and leaf relative water content can reflect the pear jujube water content in fruit
fast-growing stage. What’s more, in fruit fast-growing stage, high water content reduced
the percentage of fruit abscission and allowed to set fruit. The treatment after full irrigated
which soil water potential was -461 kPa in early experiment, the leaf photosynthetic
function and chlorophyll content was influenced. Finally, we discovered suitable
controlling soil water content could increase single fruit weight, with no effect of
production. We suggested the suitable soil water potential in fruit development period was
-41~-84 kPa.
(5) In fruit ripening period, the trunk daily fluctuation is insensitive to soil water
potential. Relative water content, taste and quality of pear-jujube fruit are different in
different soil water potential. Solid content, total sugar content and vitamin C content rise
by control irrigation properly. Solid content and total sugar content are the highest in T3
treatment, which soil water potential is in the range of -60~-112 kPa in fruit ripening
period. While in T2 treatment, which in the range of -68~-83 kPa, vitamin C content is the
highest.
In conclusion, responses of pear-jujube to different soil water potential are different in
different development periods. And the values of suitable soil water potential for different
periods are different, too. Flowering period and fruit development period are the critical
time of water requirement for pear-jujube. If the soil water potential is below -461 kPa, the
content of chlorophyll would be affected. Thus, soil water potential should be control by
need of pear-jujube in different growth and development period.
Key words: soil water potential, trunk diameter, growth and development period, water
stress, pear-jujube, physical growth |
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