CN115643984A

CN115643984A - Method for promoting enlargement of giant pumpkin fruits

Info

Publication number: CN115643984A
Application number: CN202211041973.0A
Authority: CN
Inventors: 陈晨; 潘刘; 杨雅婷; 缪旻珉; 张治平
Original assignee: Yangzhou University
Current assignee: Yangzhou University
Priority date: 2022-08-29
Filing date: 2022-08-29
Publication date: 2023-01-31

Abstract

The invention relates to the technical field of pumpkin cultivation, in particular to a method for promoting the enlargement of giant pumpkin fruits, which comprises the following steps: step one, performing conventional seedling raising on giant pumpkins, and planting the giant pumpkins when the seedlings grow to be three leaves and one heart; and step two, spraying a growth regulator in stages 20 days after the pumpkin is fixedly planted, on the day of flowering and 10-30 days after flowering, and determining the combined concentration of the sprayed growth regulator by researching the influence of photosynthetic characteristics, sugar metabolism related enzyme activity, gene expression and soluble sugar content in the pumpkin growth process so as to promote the pumpkin fruit to increase. The invention can accelerate the rapid expansion of the pumpkin by spraying the growth regulator to regulate and control the growth of the pumpkin at different periods. The cultivation success of the giant pumpkin not only shows advanced modern agricultural breeding technology and cultivation technology and becomes a bright point of agricultural science popularization education, but also enriches the agricultural sightseeing and tourism contents in scenic spots and has higher commercial value.

Description

Method for promoting enlargement of giant pumpkin fruits

Technical Field

The invention relates to the technical field of pumpkin cultivation, in particular to a method for promoting the enlargement of giant pumpkin fruits.

Background

The Giant pumpkin Atlantic Giant is a special type with oversized fruits in Cucurbitaceae Cucurbita, the weight of a single fruit can reach hundreds of kilograms, and the fruits are attractive in appearance and are highly spherical or elliptical; the peel is smooth and bright, and is mostly red, yellow and orange yellow; the pulp is yellow or orange, and can be eaten, and has high ornamental value. In recent years, due to the directional breeding of varieties and the improvement of cultivation technical conditions, the world record of the single fruit weight of the giant pumpkins is continuously updated. At present, 1226.0kg of giant pumpkin creates the most important record of south pumpkin in the world and is loaded into the Ginis world record.

With the adjustment of the industrial structure of China and the development of sightseeing agriculture and special agriculture, the heat tide for planting giant pumpkins is also raised in all places, and the heat tide becomes a key item for attracting visitors in a plurality of agricultural parks in all parts of the country. In addition, the huge pumpkin is a visiting hotspot of some fair every year and is deeply favored by vast visitors. The cultivation success of the giant pumpkin not only shows advanced modern agricultural breeding technology and cultivation technology to become a bright point of agricultural science popularization education, but also enriches the agricultural sightseeing and tourism contents in scenic spots and has higher commercial value. For giant pumpkins, the fruit size is the most important fruit quality attribute, and it is of great significance to make a feasible strategy to improve the fruit size. The cultivation of the giant pumpkin usually supplies nutrients by increasing the number of leaves and enlarges the nutrient absorption area by utilizing adventitious roots; or the fruits are planted in cold areas, and the weight of the fruits is increased by methods of prolonging the planting period beyond summer and the like. At present, no report related to the regulation of the weight of the pumpkin fruits by using a growth regulator is found.

Disclosure of Invention

The invention aims to solve the technical problems in the prior art. Therefore, the invention provides a method for promoting the fruit enlargement of giant pumpkins, and aims to accelerate the rapid expansion of the pumpkins and improve the ornamental value and the economic value of the pumpkins by spraying a growth regulator to regulate and control the growth of the pumpkins at different periods of growth and development.

Based on the above purpose, the invention provides a method for promoting the enlargement of giant pumpkin fruits, which comprises the following steps:

step one, conventionally culturing seedlings of giant pumpkins, planting the giant pumpkins when the seedlings grow to be three leaves and one heart, and digging a planting hole with the depth of 50cm and the diameter of 1-1.5 m for each plant;

and step two, spraying a growth regulator in stages 20 days after the pumpkin is fixedly planted, on the day of flowering and 10-30 days after flowering, and determining the combined concentration of the sprayed growth regulator by researching the influence of photosynthetic characteristics, sugar metabolism related enzyme activity, gene expression and soluble sugar content in the pumpkin growth process so as to promote the pumpkin fruit to increase.

As an alternative embodiment, the growth regulator is a combined regulator of NAA and EBR, and the concentration of NAA is 20-30 mg.L ^-1 The EBR concentration is 0.5-1.5 mg.L ^-1 。

Preferably, the combination regulator of NAA and EBR is sprayed 20 days after planting, 10 days after flowering and 20 days after flowering of the pumpkins.

More preferably, the concentration of NAA is 20 mg.L ^-1 The EBR concentration was 1.0 mg.L ^-1 . The concentration is the optimal combination concentration, and the pumpkin fruit enlargement can be better promoted relatively.

Preferably, the sprayed parts are the front and back surfaces of the fruits and the leaves.

Preferably, the row spacing of the plants is set to be 5m multiplied by 2m, 40 sections of the main vines of the pumpkins are controlled to be reserved, 3 to 4 sections of the secondary vines are reserved, and only one fruit is reserved for each plant.

Preferably, one fruit retained per plant is the second fruit on the main stem.

Optionally, 8-12 kg of compound fertilizer and CaSO are applied to each plant ₄ 8-12 kg of fertilizer, 5-15 kg of rapeseed cakes and 15-25 kg of cattle manure; n in the compound fertilizer: p ₂ O ₅ ：K ₂ O＝15：15：15。

The method improves the activities and expression levels of pumpkin photosynthesis, inositol galactoside synthase (GolS), raffinose Synthase (RS), stachyose synthase (STS) and alkaline alpha-galactosidase (AGA).

In the method, a combined regulator of NAA and EBR is sprayed to improve the contents of sucrose, glucose and fructose in the fruits.

The concentration of the compound used in the invention is 20 mg.L ^-1 NAA +1.0 mg. L of ^-1 The EBR is respectively sprayed on leaves and fruits 20d after the giant pumpkin is fixedly planted, 10d after flowers and 20d after flowers, and the effect of increasing the weight of the pumpkin fruits is a result of the synergistic effect of all the parts in the source (leaves), transportation (phloem juice) and storage (fruits). The NAA + EBR is sprayed in the source (leaf), so that the photosynthetic rate, the stomatal conductance and the transpiration rate of the leaf can be obviously improved, and the synthesis of an assimilate substance and the supply of water are promoted; simultaneously promoting GolS, RS and STS gene expression and enzyme activity, and improving synthesis of stachyose in leaves of pumpkin; in the transportation (phloem juice), NAA + EBR is sprayed to improve the concentration of stachyose, sucrose and glucose and fructose in the juice from 0d of flowering to 20d of flowering, thereby improving the efficiency of transporting the assimilates to fruits through fruit stalks; in the storehouse (fruit), the NAA + EBR treatment improves the AGA activity and expression level, improves the contents of sucrose, glucose and fructose in the fruit, is beneficial to metabolism of an assimilate substance, provides substance energy for the growth of pumpkin and finally promotes the fruit enlargement.

The invention has the beneficial effects that: the invention accelerates the rapid expansion of the pumpkin by spraying the growth regulator to regulate and control the growth and development of the pumpkin at different periods. The cultivation success of the giant pumpkin not only shows advanced modern agricultural breeding technology and cultivation technology and becomes a bright point of agricultural science popularization education, but also enriches the agricultural sightseeing and tourism contents in scenic spots and has higher commercial value. The value of the giant pumpkin is not different from the weight of the giant pumpkin, the single fruit weight of the giant pumpkin is increased, the ornamental value and the price of the pumpkin can be improved, the number of tourists in an agricultural park is increased, the income of farmers is increased, certain economic value and social benefit are brought, and the giant pumpkin has good industrial application prospect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the description below are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic diagram showing the effect of NAA and EBR spraying at different concentrations on the weight of single fruit of giant pumpkin;

FIG. 2 is a schematic representation of the effect of the time period and number of NAA and EBR administration of the present invention on the weight of single fruit of giant squash;

FIG. 3 is a schematic diagram showing the effect of NAA and EBR spraying on the photosynthetic property of giant pumpkins in the present invention;

FIG. 4 is a schematic diagram showing the influence of NAA and EBR spraying on the sugar metabolism-related enzyme gene expression level and activity of giant pumpkins;

FIG. 5 is a schematic diagram showing the effect of NAA and EBR spraying on the soluble sugar content in giant pumpkin leaves;

FIG. 6 is a schematic diagram showing the effect of NAA and EBR spraying on the soluble sugar content in the phloem juice of the stalks of giant pumpkins;

FIG. 7 is a schematic diagram showing the effect of NAA and EBR spraying on the expression level and activity of the giant pumpkin alkaline alpha-galactosidase;

FIG. 8 is a schematic diagram of the effect of NAA and EBR spraying on the soluble sugar content of giant pumpkin fruits.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments and the accompanying drawings.

It should be noted that technical terms or scientific terms used in the embodiments of the present invention should have the ordinary meanings as understood by those having ordinary skill in the art to which the present disclosure belongs, unless otherwise defined.

1. Materials and methods

1.1 materials

The material tested was Atlanticgiant giant pumpkin, of the variety Cucurbita maxima, the Seed of which was purchased from the Sustainable Seed Company, covelo, california, USA.

Conventionally raising seedlings, and planting the seedlings in a plastic greenhouse of an agricultural ecological garden of the Shatou Zhenluo active garden in Yangzhou city when the seedlings grow to 3 leaves and 1 core. Modified according to the giant pumpkin planting method Langevin et al (2003). Each plant is dug with a planting hole with the depth of 50cm and the diameter of 1 to 1.5 m. Applying 10kg of compound fertilizer (N: P) to each plant ₂ O ₅ ：K ₂ O＝15：15：15)、CaSO ₄ 10kg of fertilizer, 10kg of rapeseed leaves and 20kg of cow dung. The row spacing of the plants is 5m multiplied by 2m. The main vine is reserved for 40 sections, the secondary vine is reserved for 3-4 sections, and each plant is reserved with only one fruit (namely, the second fruit on the main stem).

1.2 methods

1.2.1 NAA and EBR different concentration combined test design

During the fruit rapid expansion period (20 d after flowering), the leaves (obverse and reverse sides) and the fruits were sprayed with different concentrations of NAA and EBR until water drops began to fall, and distilled water was used as a control (Tween-20 with a volume fraction of 0.1%), and each treatment was repeated 3 times with 20 plants each. The concentrations of NAA and EBR are specifically designed as shown in Table 1.

TABLE 1 different concentration combinations of NAA and EBR

1.2.2 Duration and number of NAA and EBR administration

The combination with the largest single fruit weight increase in the NAA and EBR random combination experiment is selected, different spraying times and spraying time are set, the effect of the NAA and EBR on the weight increase of the giant pumpkins is further researched, and the specific test design is shown in Table 2.

TABLE 2 period and frequency of hormone administration

Note: "-" indicates no hormone sprayed: s: spraying hormone.

1.2.4 determination of the fruit weight alone

When the pumpkin fruits stop growing, the pumpkin fruits are harvested, the weight of each fruit is measured by an electronic scale, and the final result is the average value of 60 fruits.

1.2.3 Collection of samples

Sampling every 10 days after treatment, and taking leaves and fruits at the node positions of the remained melons, wherein 1 time of repetition is carried out for every 5 leaves or fruits, and 3 times of repetition is total. Collection of bast juice from fruit stalks according to Mitchell et al (1992), the fruit stalks were cut into leaves, and the bast juice was collected from the plant side by means of capillaries. To reduce contamination of the cells of the cut sections and xylem sap, the sap collected during the first 2 seconds was discarded. All samples were frozen in liquid nitrogen immediately after being taken and stored in a refrigerator at-80 ℃ for later use.

1.2.4 leaf photosynthetic characteristic measuring method

And (4) selecting leaves at fruiting nodes at 0d and 20d after flowering for photosynthetic index determination. Photosynthetic Rate (Pn), intercellular CO were measured using a portable LI-6400XT photosynthetic System and a Standard transparent leaf Chamber (LI-COR, USA) ₂ Concentration (Ci), stomatal conductance (Gs), and transpiration rate (Tr). The measurement time was 8 am to 4 pm, and 5 strains were measured for each variety, 5 times every 2 h.

1.2.5 measurement of expression amount of sugar metabolism-related enzyme Gene

Using RNAlso ^TM Plus (TaKaRa, japan) kit, carrying out total RNA extraction on leaves and fruits of pumpkins according to the instruction. Use of reverse transcription

One-Step gDNA Removal and cDNA Synthesis Super Mix kit (Beijing Quanji Biotechnology, china) was used for cDNA Synthesis according to the kit instructions. qRT-PCR utilization

Ex

Kits (Bio-Rad, USA) and procedures according to the product instructions. The reaction system is

Ex Taq ^TM II 12.5. Mu.L, cDNA 1.0. Mu.L, primers 0.5. Mu.L each, ddH ₂ O to 20. Mu.L. Using CFX96 ^TM Real-time quantitative PCR instrument (Bio-Rad, USA), the reaction program is: 94 ℃ for 2min;94 ℃ for 10s,60 ℃ for 5s, and 35 cycles; then at 0.5 ℃ min ^-1 The rate of (2) was slowly increased from 65 ℃ to 95 ℃. Adopts pumpkin reference gene standardized data, and uses 2 ^-ΔΔCt The method calculates the relative expression level of the gene. The primers used are shown in Table 3.

TABLE 3 qRT-PCR primers

1.2.6 sugar metabolism related enzyme extraction and enzyme activity determination method

0.5g of the freeze-ground sample, 2mL of an extract (50 mmol. Multidot.L) ^-1 HEPES-NaOH buffer (pH 7.0), 2 mmol. L ^-1 DTT、10mg·mL ^-1 PVP), homogenizing; standing for 15min, and centrifuging at 18000 Xg for 30min; the supernatant was retained and washed with a solution containing 25 mmol. Multidot.L ^-1 HEPES-NaOH and 1 mmol. L ^-1 The DTT buffer was dialyzed overnight and the enzyme solution was collected for further use.

The measurement methods refer to the methods of Li et al (2011) and Wang et al (2012). GolS, RS and STS activity assay: each of the 200. Mu.L reaction systems contained 100 mmol. Multidot.L ^-1 HEPES-NaOH buffer (pH 7.0), 20 mmol. L ^-1 Beta-mercaptoethanol, 5 mmol. L ^-1 MgCl ₂ ，4mmol·L ^-1 DTT, but different enzymes require the addition of different reaction substrates; the reaction system for determining the GolS activity also contains 40 mmol.L ^-1 Sucrose, 20 mmol. L ^-1 Inositol and 5 mmol. Multidot.L ^-1 UDP-galactose; the reaction system for measuring RS activity contains 20 mmol.L ^-1 An inositolgalactoside; the reaction system for determining STS activity contained 40 mmol. Multidot.L ^-1 Raffinose, 20 mmol. L ^-1 An inositolgalactoside. Then 50 μ L of enzyme solution is added, water bath is carried out for 3h at 30 ℃, boiling is carried out for 5min in boiling water, after cooling, HPLC sample injection determination is carried out, and the activities of GolS, RS and STS are respectively expressed by the generated galactoside inositol, raffinose and stachyose.

Measurement of AGA Activity: the extraction of the enzyme solution was performed by the method of Miao et al (2007). Specifically, 0.25g of a frozen and ground tissue sample was weighed, and 1mL of an extract (50 mmol. L.) was added ^-1 HEPES-NaOH buffer (pH 7.4), 2 mmol. L ^- ¹ MgCl ₂ 、1mmol·L ^-1 EDTA、1mmol·L ^-1 DDT) homogenate, stood for 15min, 18000g.min ^-1 Centrifuging for 30min; collecting supernatant, adding 5% (W/V) PEG6000, and dissolving completely, wherein the concentration is 18000g min ^-1 Centrifuging for 30min; adding 50% (W/V) PEG6000 into the supernatant, and centrifuging again; the supernatant was discarded, and the buffer solution (25 mmol. Multidot.L) was added ^-1 HEPES-NaOH， 1mmol·L ^-1 DTT) re-dissolved the precipitate and dialyzed overnight. Reference Wang et al (2016) assay method, in which stachyose is used as a substrate and 100. Mu.L of the reaction system contained 100 mmol.L ^-1 HEPES-NaOH buffer (pH 7.4) and 16 mmol. Multidot.L ^-1 Stachyose is prepared from stachyose and stachyose. Adding 30 μ L of enzyme extract into the reaction system, reacting for 15min, adding 100 μ L of 5% (W/W) NaCO ₃ The reaction was stopped by boiling for 5 min. The amount of stachyose consumed was determined by HPLC and is indicative for the activity of the enzyme.

1.2.7 soluble sugar extraction and determination

Extraction and measurement of soluble sugar in pumpkin tissue referring to Miao et al (2007), 0.3g of sample was weighed and sufficiently ground, and 10mL of 80% ethanol was added to extract 10min,6000 g.min ^-1 Centrifuging for 15min, and collecting supernatant. Evaporating at 40 deg.C under reduced pressure in a rotary evaporator, and evaporating with ddH ₂ O dissolved, 2.5mL chloroform added, shaken and centrifuged to remove the organic phase. With 0.1 mol. L ^-1 The aqueous phase is adjusted to pH7.0 with NaOH, evaporated to dryness again under reduced pressure and finally treated with 1mL of ddH ₂ O dissolved and filtered through a 0.45 μm pin filter. And (3) carrying out HPLC sample injection measurement under the same chromatographic conditions as the standard substance, and calculating the content of soluble sugars such as stachyose, raffinose, sucrose, glucose, fructose and the like by using an external standard method. The chromatographic column is Agilent Hi-PlexCa (Duo) column (300 mm. Times.6.5 mm), mobile phase is ultrapure water, column temperature 80 deg.C, flow rate 0.5mL min ^-1 The injection volume is 5 μ L, qualitative by retention time, and quantitative by peak area.

1.2.8 data processing

The test data were collated using Microsoft Excel software and analyzed for differential significance using SPSS statistical software and presented graphically using graphpad prism 9.0.

2. Results and analysis

2.1 influence of NAA and EBR spraying on weight of single fruit of giant pumpkin

NAA and EBR with different concentrations are sprayed 20 days after giant pumpkin flowers, and clear water is sprayed to serve as a Control (Con), so that the weight average of single fruits of pumpkins sprayed with NAA and EBR is higher than that of the Control group (87.6 kg), except for spraying T1 (0.5 mg. L) ^-1 ETR) and T4 (10 mg. L) ^-1 NAA) had no significant difference in individual fruit weight from the control, and significant differences were achieved in the individual fruit weights of the other 13 treatments. The maximum fruit weight of the fruit in each treatment room is T10 (20 mg. L) after spraying ^-1 NAA+1.0mg·L ^-1 ETR) of about 112.4 ± 3.8kg, about 1.28 times the weight of the control fruit; secondly, spraying T14 (30 mg. L) ^-1 NAA+1.0mg·L ^-1 ETR) and T11 (20 mg. L) ^-1 NAA+1.5mg·L ^-1 ETR), the weight of each single fruit is about 107.1kg and 106.3kg respectively, which shows that the NAA + EBR spraying of the pumpkin leaves and fruits has obvious effect on promoting the weight of the fruits, and the effect of treating T10 is most obvious (figure 1).

Further research on the effect of the application time and frequency of NAA and EBR on increasing the single fruit weight of giant pumpkin discovers that 20 mg.L is adopted ^-1 NAA+1.0mg·L ^-1 EBR sprays leaves and fruits, and the post-planting 20d + day of flowering + post-flowering 10d + post-flowering 20d spray (T18) has a significant effect on promoting the weight of fruits, the treated fruit weight alone is about 127.2 ± 3.6kg, increased by 44.1% compared to the control, and increased by 15.3% compared to the post-flowering 20d spray 1 time (T10). Meanwhile, the effect of increasing the single fruit weight of the pumpkin fruits by spraying NAA and EBR is also found, the spraying frequency is not in direct proportion to the spraying frequency, and the single spraying is carried out for 5 times (20 d after planting, the day of flowering, 10d after flowering, 20d after flowering and 30d after flowering are respectively sprayed for 1 time, T19)The fruit weight was lower than treatment T18, and no significant difference was achieved between the two (fig. 2). However, the high temperature in summer in Jiangsu province is too high, the growth period of the pumpkins is short, and the growth of giant pumpkins is severely restricted, which is probably a reason that the weight of the pumpkins in the invention is more different from that reported in world records.

2.2 Effect of NAA and EBR spraying on photosynthetic characteristics of giant pumpkin

Further, 20 mg.L was analyzed 4 times for spraying ^-1 NAA+1.0mg·L ^-1 Effect of EBR (T18) on photosynthetic properties of giant pumpkins on the day of flowering and 20 days after flowering (fig. 3). The photosynthetic rate, air pore conductance and transpiration rate of 20 days after flowering are higher than those of the day of flowering, which indicates that more assimilates need to be produced and more water needs to be supplied in the fruit rapid expansion period; spraying 4 times 20 mg. L ^-1 NAA+1.0mg·L ^-1 EBR significantly improves the photosynthetic rate, stomatal conductance and transpiration rate of leaves, but for intercellular CO ₂ The concentration has no obvious influence, promotes the synthesis of the assimilate substance and the large supply of water, and is beneficial to the expansion of the pumpkin.

2.3 the influence of NAA and EBR spraying on the expression quantity and activity of sugar metabolism related enzyme genes of the giant pumpkin

The expression of CmGolS1, cmRS and CmSTS genes in the leaf of the node where the giant pumpkin fruit is located is basically consistent with the change trend of enzyme activity in the growth and development process of the pumpkin fruit (figure 4). The expression of CmGolS1 is higher in the early development stage of the fruit and is reduced after 50 days; the expression level of CmRS is maintained at a relatively stable level during fruit development, the expression of CmSTS is increased after the fruit enters a rapid growth period and is gradually reduced after 50 days. Spraying 20 mg.L for 4 times ^-1 NAA+1.0mg·L ^-1 The EBR can obviously improve the expression of CmGolS1, cmRS and CmSTS genes and the activity of enzyme, and shows that the hormone spraying can promote the synthesis of stachyose on leaves of pumpkin and be used for outputting and supplying the fruit for quick growth.

2.4 influence of NAA and EBR spraying on soluble sugar content in giant pumpkin leaves

With the growth and development of fruits, the contents of stachyose, raffinose, sucrose, glucose and fructose in the fruit part of the pumpkin and the fruitsThe development of the parenchyma decreased gradually, but the time points for the initial decline of the various sugars differed (FIG. 5). The content of stachyose and raffinose is kept at a higher level in the early stage of fruit development, the content of stachyose and raffinose is obviously reduced after the fruit development lasts for 50 days, but the reduction degree is different, the raffinose is reduced by about 42.3 percent on average and the stachyose is reduced by 19.6 percent on average when the fruit develops for 60 days. The sucrose gradually decreases after the pumpkin fruit develops for 30 days, and slightly increases in the later period, but is not obvious. From the day of flowering, the content of glucose and fructose is obviously reduced, the content of glucose is reduced to the minimum value 30d after flowering, the content of fructose is reduced to the minimum value 20d after flowering, and the glucose and the fructose are basically not changed in the later development process of the pumpkin. Spraying 20 mg.L for 4 times ^-1 NAA+1.0mg·L ^-1 EBR can increase stachyose content in leaves, and in the later stage of fruit development, although stachyose is reduced obviously, the content is reduced by 15.1% after treatment, and the content is reduced by 24.2% in comparison. However, spraying NAA and EBR had no significant effect on the concentration of other soluble sugars.

2.5 influence of NAA and EBR spraying on soluble sugar content of phloem juice of giant pumpkin stalks

The control group and the treatment group of the content of stachyose and sucrose in the phloem juice of the pumpkin stalks tend to be consistent, the general trend of the change is ascending along with the growth and development of the pumpkin fruits, and the content of the stachyose and the sucrose in the NAA and EBR spraying group is obviously higher than that in the control group, and is respectively increased by about 1.3 to 3.1 mg.g ^-1 And 0.8 to 2.5mg g ^-1 . The raffinose is in a trend of ascending first and then descending in the pumpkin development process, reaches the maximum value 20 days after the flowers and reaches the minimum value 60 days after the flowers, but the spraying of NAA and EBR has no influence on the raffinose. The change of the glucose content in the pumpkin development process is consistent with the change trend of the raffinose, but the NAA and the EBR are sprayed 30 days before the fruit development to increase the glucose content. The fructose content decreased overall and reached a value of 0 at 30d after flowering, and the NAA and EBR phloem sap content was higher than the control at the initial stage of overgrowth (10 d after flowering) (FIG. 6). The results show that the NAA + EBR treatment can improve the stachyose and the sucrose in the phloem juice of the carpopodium and the juice from 0d to 2 d after floweringThe concentration of glucose and fructose at 0d indicates that the treatment improves the transport efficiency of the assimilates.

2.6 influence of NAA and EBR spraying on alkalescence alpha-galactosidase expression level and activity in giant pumpkin fruit

Under normal conditions, the expression of alkaline α -galactosidase 1 (CmAGA 1) and alkaline α -galactosidase 2 (CmAGA 2) in pumpkin fruits hardly changed significantly during fruit development, but AGA activity increased first and then decreased (fig. 7). The expression levels of CmAGA1 and CmAGA2 in the pumpkin fruits which are exogenously applied with NAA + EBR tend to increase, the increase of CmAGA2 is more obvious, and simultaneously, the activity of AGA is also obviously increased, which indicates that the NAA + EBR can enhance the unloading capacity of the pumpkin assimilates and increase the bank strength.

2.7 influence of NAA and EBR spraying on soluble sugar content of giant pumpkin fruits

Stachyose in the pumpkin fruit tends to decrease after rising, reaches a maximum value after the pumpkin grows for 20d, then rapidly decreases, decreases to a minimum value after flowering for 60d, and decreases and rises after raffinose, reaches a maximum value after flowering for 20d, and then increases to a certain extent; however, spraying NAA and EBR had no effect on the content of both RFOs. During the development process of the pumpkin fruit, the content of sucrose and fructose in the fruit is consistent with the change trend of stachyose; the glucose content reached a maximum value 10d after flowering and then gradually decreased, although there was a local increase, but the overall trend was downward. The sucrose, glucose and fructose contents in the fruits were all significantly higher in the treated group than in the control group (fig. 8). The results show that the NAA and EBR spraying obviously improves the contents of sucrose, glucose and fructose in the fruits, but has no obvious influence on stachyose and raffinose. The NAA + EBR spraying leaf and fruit treatment is beneficial to the metabolism of the assimilate, provides substance energy for the fruit growth, promotes the fruit to expand rapidly, and increases the weight of the fruit.

Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the invention, also features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

The present embodiments are intended to embrace all such alterations, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalents, improvements, and the like that may be made without departing from the spirit or scope of the present invention are intended to be included within the scope of the present invention.

Claims

1. A method for promoting the enlargement of giant pumpkin fruits is characterized by comprising the following steps:

step one, conventionally culturing giant pumpkin seedlings, planting the giant pumpkin seedlings when the giant pumpkin seedlings grow to three leaves and one heart, and digging a planting hole with the depth of 50cm and the diameter of 1-1.5 m for each plant;

2. The method of claim 1, wherein the growth regulator is a combination of NAA and EBR, and the concentration of NAA is 20-30 mg-L ^-1 The EBR concentration is 0.5-1.5 mg.L ^-1 。

3. The method for promoting the fruit enlargement of giant pumpkins according to claim 2, wherein a combined regulator of NAA and EBR is sprayed 20 days after the planting, the day of flowering, 10 days after flowering and 20 days after flowering of pumpkins.

4. The method of claim 2 or 3, wherein the NAA is present in a concentration of 20 mg-L ^-1 The EBR concentration was 1.0 mg.L ^-1 。

5. The method for promoting the fruit enlargement of giant pumpkins according to claim 2, wherein the spraying parts are the front and back surfaces of the fruits and the leaves.

6. The method for promoting the enlargement of the giant pumpkin fruits according to claim 1, wherein the row spacing of the plants is set to be 5m x 2m, 40 nodes of the main vine of the pumpkin are controlled to be reserved, 3-4 nodes of the secondary vine of the pumpkin are controlled to be reserved, and only one fruit is reserved for each plant.

7. The method of claim 6, wherein one fruit of each plant is the second fruit of the main stem.

8. The method for promoting the fruit enlargement of the giant pumpkin according to claim 1, wherein 8-12 kg of compound fertilizer and CaSO are applied to each plant ₄ 8-12 kg of fertilizer, 5-15 kg of rapeseed cakes and 15-25 kg of cow dung; n in the compound fertilizer: p ₂ O ₅ ：K ₂ O＝15：15：15。

9. The method of claim 1, wherein the method increases the activities and expression levels of pumpkin photosynthesis, galactinol synthase, raffinose synthase, stachyose synthase, and alkaline alpha-galactosidase.

10. The method for promoting the fruit enlargement of giant pumpkins according to claim 2, wherein a combined regulator of NAA and EBR is sprayed in the method for increasing the contents of sucrose, glucose and fructose in the fruits.