| 其他摘要 | Soil moisture status is a major factor influencing crop production, and the irrigation is
an important measure for the field crops soil moisture supply. Meanwhile for facility
agriculture, irrigation is the only way for crops to get water. In this paper, morphological
indexes, physiological indexes, yield, fruit quality and water use efficiency of cucumber
were studied under the different soil moisture treatments during different growth stages in
pot experiment by simulation of drip irrigation. Proper water moisture irrigation maximum
and minimum during different growth stages were determined through the analysis of
water consumption and the water production function of cucumber, which provided
scientific and reliable irrigation parameters for the intelligent irrigation control system of
cucumber in greenhouse. The conclusions are as follows:
1) The effect of different water treatments on morphological indexes of cucumber
during different growth stages showed that: The irrigation minimum during initial bloom
stage could be appropriately lower, 55% field water capacity was the suitable soil moisture.
Moderate water stress in initial bloom stage, which could promote root development and
expand the untilization range of soil moisture of cucumber roots, was of benefit to improve
soil water use efficiency and promote the plant height growth later to some extent. Plant
height compensation benefit was obvious after irrigation recovery. Moderate water deficit
during every growth stage was conducive to the growth of stem diameter, and the higher
soil moisture during early-fruit stage was favored for the growth of leaf area. while the
lower irrigation limits during mid-fruit stage could reduce the growth of leaf area.
2) The effect of different water treatments on physiological indexes of cucumber
during different growth stages showed that: during the whole growth stage, the transpiration rate and stomatal conductance increased with the increase of the
photosynthetic rate, which showed the same variation with photosynthetic rate. The diurnal
course of physiological indexes of cucumber displayed single peak in initial bloom stage
and mid-fruit stage, and got the maximum at 12:00, while the diurnal course of
physiological indexes of cucumber displayed in a double-peak pattern curve in early-fruit
stage, and showed obvious "midday depression " in 12:00. The double peaks of
physiological indexes appeared at 10:00 and 14:00 respectively, the peak value of
photosynthetic rate at 14:00 was slightly larger than that at 10:00, while the peak of
stomatal conductance and transpiration rate at 14:00 were much larger than the peak at
10:00. The lower irrigation minimum during initial bloom stage and early-fruit
stage favored the promotion of photosynthetic parameters of cucumber, while the higher or
the lower soil moisture during mid-fruit stage could reduce photosynthetic parameters,
75~90% field water capacity was the suitable soil moisture, which reached the maximum
of photosynthetic parameters.
3) The cucumber fruit quality under different irrigation limits treatments during
different growth stages showed the same variation. All the indexes increased with the
decreasing of the irrigation minimum during different growth stages. This meant that
moderate water deficit by controlling the water supply could improve the fruit quality. The
shoot biomass, root biomass and root biomass and shoot biomass ratio under different
treatments during different growth stages increased with the decreasing of the irrigation
minimum. From the relationship between plant height and root biomass, root
biomass/shoot biomass, the root biomass, root biomass/shoot biomass under different
treatments during initial bloom stage and early-fruit stage increased with the increasing of
plant height, indicating that the growth of aboveground and underground parts had the
same variation.
4) The treatment maintaining the soil moisture 55~90%, 75~90% and 75~90% field
water capacity at initial bloom stage, early-fruit stage and mid-fruit stage respectively
(Treatment A3) could not only meet the needs of water consumption in the whole growth
period of cucumber but also get the best yield and water use efficiency, and then achieve
the dual objectives of high yield and high efficiency at the same time. The cucumber water
consumption throughout the whole growth period increased flatly at first then steeply, The amounts of water consumption at initial bloom stage was lower than that at early-fruit
stage, and the highest water consumption amount was at mid-fruit stage. And the difference
among the daily water consumption under the different water treatments were more and
more apparent with the extending of the growth period.
5) Water sensitivity indices calculated by the Jensen model using Genetic Algorithm
went down successively from mid-fruit stage, early-fruit stage to initial bloom stage, and
the water sensitivity indices were 0.635, 0.290, 0.275, respectively. The water sensitivity
indices at mid-fruit stage was the highest, which meant that if soil moisture during this
growth stage was lower or soil water was deficit, it would have a great impact on the final
yield. The water sensitivity indices at initial bloom stage was the smallest, indicating that
the moderate water deficit during this growth stage had little effect on the later yield, and
appropriate water deficit was allowed in a short time at initial bloom stage. The early-fruit
stage was the crucial period from the vegetative growth to reproductive growth of
cucumber, water requirement was increasing, the appropriate water stress had no great
impact on the final yield of cucumber.
6) The morphological indexes, physiological indexes, fruit quality, water use
efficiency, shoot biomass, the dry root weight and root-top ratio under treating 90% field
water capacity as soil water irrigation maximum were all better than that under 100% field
water capacity treatment. Although the yield of per-plant under treating 90% field water
capacity as soil water irrigation maximum decreased by 0.9% compared with that under
100%, the water use efficiency increased by 16.84%. So the treatment of 90% field water
capacity as soil water irrigation maximum was more reasonable than other treatments.
7) For the (spring and summer) cucumber in greenhouse, the irrigation minimum
during initial bloom stage, early-fruit stage and mid-fruit stage were 55%, 75% and 75%
field water capacity respectively. The appropriate soil water irrigation maximum in the
whole growth should be 90% field water capacity.
Key words: Cucumber; growth stages; irrigation minimum; soil water irrigation
maximum; yield; fruit quality; root-top ratio; water production function;
water use efficiency |
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