阅读说明：本技术 适用于设施西瓜网架栽培的提质增效施肥方法 (Quality-improving and efficiency-improving fertilizing method suitable for facility watermelon net rack cultivation ) 是由 胡仲远 张明方 杨景华 郝俊芳 于 2021-08-01 设计创作，主要内容包括：本发明公开了一种适用于设施西瓜网架栽培的提质增效施肥方法,在西瓜种苗前一次性施用商品有机肥,在西瓜的伸蔓期、开花期、膨瓜期施用化肥；化肥中的N在伸蔓期、开花期、膨瓜期的用量比为30:30:40；化肥中的P-(2)O-(5)在伸蔓期、开花期、膨瓜期的用量比为20:60:20；化肥中的K-(2)O在伸蔓期、开花期、膨瓜期的用量比为10:30:60。本发明在保证西瓜产量和品质不下降(品质略有提升)的前提下,减少化肥使用量,提高肥料利用率。(The invention discloses a quality-improving and efficiency-increasing fertilizing method suitable for facility watermelon net rack cultivation, which is characterized in that commodity organic fertilizer is applied at one time before watermelon seedlings, and chemical fertilizer is applied in the vine extending period, flowering period and melon expanding period of watermelons; the dosage ratio of N in the fertilizer in the vine stage, the flowering stage and the melon expanding stage is 30:30: 40; p in chemical fertilizers 2 O 5 The dosage ratio of the components in the vine stage, the flowering stage and the melon expanding stage is 20:60: 20; k in chemical fertilizers 2 The dosage ratio of O in the vine stage, the flowering stage and the melon expanding stage is 10:30: 60. The invention reduces the using amount of the fertilizer and improves the utilization rate of the fertilizer on the premise of ensuring that the yield and the quality of the watermelon are not reduced (the quality is slightly improved).)

1. The quality-improving and efficiency-increasing fertilization method suitable for the net rack cultivation of the facility watermelon is characterized in that the fertilizer is applied once before the watermelon seedlings, and each 667m²Applying commercial organic fertilizer (600 +/-50) kg, and is characterized in that:

applying fertilizer in the vine stage, flowering stage and melon expanding stage of the watermelon;

the dosage ratio of N in the fertilizer in the vine stage, the flowering stage and the melon expanding stage is 30:30: 40;

p in chemical fertilizers₂O₅The dosage ratio of the components in the vine stage, the flowering stage and the melon expanding stage is 20:60: 20;

k in chemical fertilizers₂The dosage ratio of O in the vine stage, the flowering stage and the melon expanding stage is 10:30: 60.

2. The quality-improving and efficiency-improving fertilizing method suitable for the net rack cultivation of the facility watermelon according to claim 1, which is characterized in that:

in the total dosage of the fertilizer, N is P₂O₅:K₂The weight ratio of (1.4 +/-0.1) to (1.5 +/-0.1) of O.

3. The quality-improving and efficiency-improving fertilizing method suitable for the net rack cultivation of the facility watermelon according to claim 1, which is characterized in that:

the total dosage of the fertilizer is 10.161-17.782 kg/mu.

4. The quality-improving and efficiency-improving fertilizing method suitable for the net rack cultivation of the facility watermelon as claimed in claim 3, which is characterized in that:

the total dosage of the fertilizer is (15.24 +/-0.5) kg/mu.

Technical Field

The invention belongs to the technical field of vegetable cultivation, and particularly relates to a quality-improving and efficiency-improving fertilizing method suitable for facility cultivation of watermelons.

Background

With the continuous increase of population in China, the food safety is always in tight balance. In order to ensure the safety of Chinese bowls, the high-quality development of agriculture is imperative. Meanwhile, the bearing capacity of resources and environment in China is increasingly fragile, and improper application of chemical fertilizers and pesticides in agricultural production brings serious threat to ecological safety. The fertilizer is the grain of plants and is very important for the development of modern agriculture. Data of the national statistical bureau show that the applied purity of agricultural chemical fertilizer in 2016 is 5984 ten thousand tons, the production and usage of the chemical fertilizer all account for 1/3 (Zhou Fang et al, 2016) in the world, and the contribution rate of the input of the chemical fertilizer to the grain yield increase in 2016 reaches 20.79% (Limna domestica et al, 2013). At present, the application amount of fertilizer per unit area in China is 3 times of the average level in the world, but the fertilizer utilization rate is only 1/3 of developed countries such as the United states. In order to solve a series of negative effects such as soil quality degradation, water eutrophication and the like caused by improper fertilizer application, China starts large-scale soil measuring and formula fertilization (Koelreuteria paniculata and the like, 2013) in 2005, adopts an accurate drip irrigation technology to improve the utilization rate of the fertilizer (Huanglihua and the like, 2008) and the like, and expects that the use of the fertilizer is reduced and the utilization rate of the fertilizer is improved by various methods while ensuring that the yield and the quality of crops are not reduced.

The effect of reducing and increasing the amount of chemical fertilizer can be achieved through scientific fertilization, and the key technologies of the scientific fertilization at present mainly comprise a soil testing and formula fertilization technology, a slow and controlled release fertilizer application technology, an accurate variable fertilization technology, an irrigation fertilization technology (water and fertilizer integration) and a typical fertilization technology of a large number of crops (Tang and Han, etc., 2019). The soil testing formula fertilization technology mainly solves the contradiction between crop fertilizer demand and soil fertilizer supply, realizes scientific quantification, and supplies fertilizer according to the lack of nutrients by mastering the difference between the crop fertilizer demand and the soil fertility, thereby improving the utilization rate of the fertilizer and reducing the waste of resources (Zhang, 2018). The slow-controlled release fertilizer is a fertilizer which can slowly release the fertilizer into soil according to a certain speed, can effectively reduce the fertilizing times and the application amount, reduces the fertilizer loss caused by the leaching effect, and improves the utilization rate of the fertilizer. The precise variable fertilization technology is a fertilization technology which is suitable for local conditions and is comprehensively balanced, and is an optimized combination of multiple technologies such as information technology, biotechnology and the like. The irrigation and fertilization technology is also called as water and fertilizer integration, and is a modern fertilization technology, which combines moisture and nutrients required by crop growth, realizes comprehensive regulation and integrated management of the moisture and the nutrients, and improves the overall utilization rate of the water and fertilizer. Typical fertilization techniques for bulk crops vary from crop to crop (Tang Han et al, 2019).

Watermelon is an important horticultural (vegetable) crop in China, the planting area of the watermelon in China in 2013 is 183 ten thousand hectares, the watermelon planting area accounts for 53 percent of the total planting area of the watermelon in the world, the total yield is 7319 ten thousand tons, and the watermelon planting area accounts for 67 percent of the total yield of the watermelon in the world. Statistics data of a watermelon and melon industrial technical system 2015 in China show that 55% of watermelons in China are cultivated on land and 45% of watermelons in China are cultivated in facilities. The high-quality and high-yield watermelon does not need to use chemical fertilizers, the watermelon production in China has great blindness in fertilization, resource waste and soil degradation are caused, and particularly in facility cultivation, the problem that the secondary salinization of soil is easily caused by the large-amount use of the fertilizers due to the lack of the leaching effect of rainwater (Wang is reluctant, etc., 2012).

Nitrogen, phosphorus and potassium are the most important major elements, are key objects for reducing the weight and increasing the efficiency of chemical fertilizers, and are also the key points for researching the nutrient requirement of watermelons. In the early growth stage of watermelons, sufficient nitrogen fertilizer, proper phosphorus fertilizer and proper potassium fertilizer are required to be ensured, and in the later growth stage, a large amount of nitrogen fertilizer and potassium fertilizer are ensured, which is favorable for improving the yield and quality of watermelons (Zyufeng, etc., 2006). The labor-saving net rack cultivation mode of the facility watermelon is researched and developed by Zhang Ming dynasty professor team of Zhejiang university for many years. The cultivation mode can reduce labor for field management such as vine hanging, pruning and the like, improve ventilation and light transmission conditions, reduce the occurrence of plant diseases and insect pests, has the effects of saving labor, improving quality and the like, and has higher influence on facility cultivation of watermelons in the east, south and coastal areas.

The technical key points of the cultivation of the watermelon net rack with the facility are as follows:

1.1. seeding and planting

Time of sowingStarting from the bottom of 11 months to 2 months before the next year. The net rack cultivation generally adopts thin planting. Making furrows close to two sides of the greenhouse, wherein each 667m of furrows are formed²Applying 600kg of commercial organic fertilizer and 40kg of sulfur-containing ternary compound fertilizer, and performing centralized furrow application, wherein in addition, 10kg of ternary compound fertilizer and 25kg of calcium superphosphate are applied on the surface of a furrow; after fertilization, two ridges are formed near the edges of the shed, and transparent or silvery mulching films are adopted to cover the ridges for temperature increase and soil moisture preservation. The plant spacing is 40-60cm, and each 667m²About 300 strains.

1.2. Management of field

Before the watermelon climbs the vine, an arch-shaped frame cover net can be built in the greenhouse at proper time. An arch frame with the width of 5.2m and the height of 1.8m can be built in a common 6m greenhouse, a space of at least 80cm is required to be reserved between a vine climbing frame and a greenhouse film before watermelons climb vines, a net piece is covered on the arch frame, the thickness of the net piece is preferably 9 strands, and the size of the net piece is about 10 cm. The net rack cultivation can simplify pruning or not pruning, and 3-5 strong lateral vines can be reserved according to the growth vigor of plants except for the main vines. When the watermelon seedlings extend to about 50cm, the vines are guided to the vine upper rack, and the watermelon vines are respectively bound on the bamboo chips or the net sheets.

1.3. Fruit supporting, marking and thinning

When the young watermelon is large in egg size, thinning fruits and selecting melons, generally keeping 1 melon per vine, and removing deformed melons to improve the commodity of the watermelons. When the young watermelon is about 250g, the watermelon is supported by a fruit support, and the part of the watermelon stem close to the fruit can be firmly tied by a plastic wire. The plastic wires can be selected from various colors, and one color is changed every 3d (days) to achieve the marking effect, so that the maturity can be conveniently judged during picking.

1.4. Harvesting at the right time

According to the characteristics of the variety, the fruit is generally ripe about 30 days after pollination, the surface patterns of the fruit are clear and glossy, the base part of a fruit stem is slightly contracted, the fuzz is sparse and falls off, the fruit navel is inwards sunken, and the marked days after pollination and fruit setting can be used as a picking standard. The net rack watermelon grows below the watermelon vine, has the blades to block direct sunlight, and the ripe fruit is 3-5 days later than climbing watermelon, but the sugar degree is higher than climbing cultivation, the taste is good, and the appearance is beautiful, and is very suitable for sightseeing picking or packing and selling with gift melons.

Under the existing cultivation mode, the greenhouse watermelon cultivation is not only applied with commercial organic fertilizerAlso, N: p₂O₅：K₂The compound fertilizer with the O ratio of 1:1:1 and the calcium superphosphate fertilizer are used, and the disposable basal fertilizer (pure quantity) is N: p₂O₅：K₂O＝10.422:14.591:10.422。

The commercial organic fertilizer can be, for example, Deqing local commercial 'ground-rise' organic fertilizer, the content of NPK fertilizer is 7-8%, and the content of organic matter is 55-60%.

Disclosure of Invention

The invention aims to provide an upgrading and efficiency-increasing fertilizing method suitable for greenhouse watermelon net rack cultivation. The invention can solve the problems of low utilization rate of the fertilizer and fertilizer waste caused by one-time uniform fertilization due to different types and quantities of the required fertilizers in different growth periods of watermelons in the prior art.

In order to solve the technical problems, the invention provides an upgrading and efficiency-increasing fertilizing method suitable for greenhouse watermelon net rack cultivation, wherein the watermelon seedlings are fertilized once before each 667m²Applying 600 +/-50 kg of commercial organic fertilizer, and applying chemical fertilizer (applied by adopting a fertilizer-water integrated method) in the vine extending period, the flowering period and the melon expanding period of the watermelon;

the dosage ratio (the pure amount of the fertilizer and the application amount distribution ratio) of N in the fertilizer in the stretching period, the flowering period and the melon expanding period is 30:30: 40;

p in chemical fertilizers₂O₅The dosage ratio of the components in the vine stage, the flowering stage and the melon expanding stage is 20:60: 20;

k in chemical fertilizers₂The dosage ratio of O in the vine stage, the flowering stage and the melon expanding stage is 10:30: 60.

Description of the drawings: the elongation period, the flowering period and the melon expanding period are corresponding stages for conventionally distinguishing the watermelon growth, after the stages are reached, the corresponding fertilizers are melted into water, and the fertilizer is applied when plants are watered by drip irrigation. The commercial organic fertilizer can adopt a conventional furrow application mode.

The improvement of the quality-improving and efficiency-increasing fertilizing method suitable for the net rack cultivation of the facility watermelon is as follows:

in the total dosage of the fertilizer, N is P₂O₅:K₂O1 (1.4 + -0.1): 1.5 + -0.1)And (4) the ratio.

The quality-improving and efficiency-increasing fertilizing method suitable for the net rack cultivation of the facility watermelon is further improved as follows:

the total dosage of the fertilizer is 10.161-17.782 kg/mu (pure quantity);

the total dosage of the fertilizer is preferably (15.24 +/-0.5) kg/mu (reduced pure amount).

The invention provides a fertilizer application method for implementing watermelon net rack cultivation in different growth periods, aiming at solving the problems of low fertilizer utilization rate and waste caused by one-time base fertilizer application;

the invention relates to a method for screening the fertilizer decrement limit by applying a gradient decrement method, which comprises the following steps: firstly, according to the proportion of N: p₂O₅：K₂The equal proportion of O is decreased by 25 percent; 50 percent; the approximately fertilizer application reduction interval of 75 percent of watermelon net rack screening cultivation by the gradient test is 50 to 75 percent; and then finely adjusting the optimal application reduction scheme of each element according to the demand characteristics of the single element, namely, the invention finally obtains the fertilization scheme by gradually reducing the application in equal proportion and adjusting the proportion of different fertilizer components according to the current field situation.

In the preferred fertilization scheme set by the invention:

and (3) seedling stage: each 667m²Applying 600kg of commercial organic fertilizer, and not applying chemical fertilizer;

in the vine extending period: n: p₂O₅：K₂O is approximately equal to 2:1.87:1, and the fertilizer dosage is 2.852 kg/mu (pure quantity);

and (3) flowering period: n: p₂O₅：K₂O is approximately equal to 1:2.8:1.5, and the fertilizer dosage is 6.214 kg/mu (pure quantity);

during the melon expanding period: n: p₂O₅：K₂O is approximately equal to 1.43:1:3.2, and the fertilizer dosage is 6.174 kg/mu (pure quantity).

That is, the total amount of N (nitrogen fertilizer) used is 1.171+1.172+ 1.568-3.911 kg/mu (reduced basis weight), and P (nitrogen fertilizer) is used as a fertilizer₂O₅The total dosage of (1.095 +3.283+ 1.097) is 5.475 kg/mu (pure weight), K₂The total dosage of O is 0.586+1.759+3.509 which is 5.854 kg/mu (pure folding amount), therefore, the maximum application reduction degree in the facility watermelon net rack cultivation mode is that the N dosage is reduced by 62.5%,P₂O₅reduction by 62.5%, K₂The O content is reduced by 43.8%.

According to the quality-improving and efficiency-increasing fertilization method, by deeply analyzing the nutrient requirement characteristics of the watermelon in the whole growth period, the quality-improving and efficiency-increasing fertilization method suitable for facility watermelon net rack cultivation is developed, the fertilizer usage amount is reduced and the fertilizer utilization rate is improved on the premise that the watermelon yield and the watermelon quality are not reduced (the quality is slightly improved).

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

FIG. 1 shows the variation of the number of female flowers opened per day in the reduced application treatment of different fertilizers.

FIG. 2 is a longitudinal sectional view of a watermelon processed by different methods; the picking periods of the first and second batches were separated by 7 days.

FIG. 3 the effect of different fertilization treatments on the sugar degree of watermelon fruits.

Detailed Description

The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto.

1. The original cultivation technical key points of the facility watermelon net rack cultivation are as follows:

1.1. seeding and planting

The sowing time can be from the bottom of 11 months to 2 months before the next year. The net rack cultivation generally adopts thin planting. Ridging is carried out near two sides of the greenhouse, and contrast treatment (namely the original fertilization mode, CK1) is one-time fertilization before seedlings: each 667m²Applying 600kg of commercial organic fertilizer and 40kg of sulfur-containing ternary compound fertilizer, and performing centralized furrow application; in addition, 10kg of ternary compound fertilizer and 25kg of calcium superphosphate are spread on the surface of the furrow;

fertilizing 25% of the total amount in 2018 in the original cultivation mode; 50 percent; after 75% of the total amount is reduced, the watermelon yield is not greatly influenced when 25% -50% of the total amount is reduced in an equal proportion, but the plants show potassium deficiency symptoms; in 2019, the proportion of the potassium fertilizer is adjusted, and the nitrogen fertilizer accounts for 25-43.75% of the nitrogen fertilizer in the original fertilizing mode; the phosphate fertilizer accounts for 25 to 43.75 percent of the phosphate fertilizer in the original fertilizing mode; 37.5 to 65.63 percent of the potash fertilizer in the original fertilizing mode of the potash fertilizer is distributed and applied in different growth periods by a fertilizer and water integration technology (the specific fertilizer application amount is shown in tables 1-1 and 1-2).

After fertilization, two ridges are formed near the edges of the shed, and transparent or silvery mulching films are adopted to cover the ridges for temperature increase and soil moisture preservation. The plant spacing is 40-60cm, and each 667m²About 300 strains.

TABLE 1-1 fertilizer usage for different treatments and ratio to original fertilizer usage

Table 1-2, total proportion of fertilizers used in different treatments and proportion of fertilizers used in each period

Then according to the existing labor-saving net rack cultivation mode of the watermelon facility, the following operations are carried out:

1.2. management of field

Before the watermelon climbs the vine, an arch-shaped frame cover net can be built in the greenhouse at proper time. In general, 6m greenhouse can be built with arch frames with width of 5.2m and height of 1.8m, and at least 80cm of space is required to be reserved between the vine climbing frame and the greenhouse film. Before the watermelon climbs the vines, the arch frames are covered with the net sheets to form a net frame structure, the length of the arch frames is equal to that of the whole greenhouse, the thickness of the net sheets is preferably 9 strands, and the size of the net holes is about 10 cm. The net rack cultivation can simplify pruning or not pruning, and 3-5 strong lateral vines can be reserved according to the growth vigor of plants except for the main vines. When the watermelon seedlings extend to about 50cm, the vines are guided to the vine upper rack, and the watermelon vines are respectively bound on the bamboo chips or the net sheets.

1.3. Fruit supporting, marking and thinning

When the young watermelon is egg-sized, thinning and selecting the watermelon, generally keeping 1 watermelon per vine, and removing the deformed watermelon to improve the commodity of the watermelon. When the weight of the young watermelon is about 250g, the watermelon is supported by the fruit, and the part of the watermelon stem close to the fruit and the net piece can be firmly bound by using a plastic wire (the watermelon is prevented from falling off when the fruit is too heavy). The plastic wires can be selected from various colors, and one color is changed every 3d (days) to achieve the marking effect, so that the maturity can be conveniently judged during picking.

1.4. Harvesting at the right time

According to the characteristics of the variety, the fruit is generally ripe about 30 days after pollination, the surface patterns of the fruit are clear and glossy, the base part of a fruit stem is slightly contracted, the fuzz is sparse and falls off, the fruit navel is inwards sunken, and the marked days after pollination and fruit setting can be used as a picking standard. The net rack watermelon grows below the watermelon vine, has the blades to block direct sunlight, and the ripe fruit is 3-5 days later than climbing watermelon, but the sugar degree is higher than climbing cultivation, the taste is good, and the appearance is beautiful, and is very suitable for sightseeing picking or packing and selling with gift melons.

2. Test results and analysis

2018-2019, and research, development and demonstration of the fertilizer decrement and efficiency increase technology of early-spring mini watermelons are carried out by agriculture science and technology limited in Drift field, Zhejiang province.

The results in 2018 show that when the fertilizer is applied to each mu, N and P are contained in the fertilizer₂O₅，K₂The effective nutrient content of O is reduced by 62.5 percent, namely N, P₂O₅，K₂The amount of O is 3.91kg, 5.47kg and 3.908kg respectively, and the yield and quality of watermelon are basically unchanged. The 2019 test fertilization scheme further refines the nutrient difference application reduction amount on the 2018 test result so as to realize maximum fertilizer application reduction and efficiency improvement. Wherein N, P are processed differently₂O₅And K₂Total amount of O administered and K₂Adjusting the application proportion of O in the vine stage, the flowering and fruit setting stage and the melon expanding stage, N and P₂O₅The application rate was unchanged. The concrete conditions of the fertilizer application reducing and efficiency improving technology in 2019 are as follows:

the specific parameters are as follows:

quality-improving and efficiency-increasing fertilizing method suitable for facility watermelon net rack cultivation, wherein a furrow application mode is adopted every 667m before watermelon seedlings²600kg of commercial organic fertilizer is applied to the fertilizer,

applying the fertilizer by a fertilizer-water integrated technology after the watermelon enters a vine extending period, a flowering period and a watermelon swelling period;

respectively setting 4 schemes of T1, T2, T3 and T4, total fertilizer dosage (kg/mu, net weight) and N, P in the fertilizer₂O₅、K₂The amounts of O in the vine stage, flowering stage and cucumber expansion stage are shown in Table 2 below.

The watermelon variety is Na Bie.

TABLE 2 fertilizing amount of each treatment at different periods and the proportion of each treatment to the control

2.1 treating the growth and development conditions of watermelon plants at different periods

The influence of different treatments on the whole growth period of the watermelon is grasped by measuring indexes (table 3) of stem length, stem thickness, stem node length, single leaf area and the like of the main stem of each treated watermelon plant in the seedling stage, the vine stage, the flowering and fruit setting stage and the melon expanding stage in detail. After the seedling stage, the CK2 plants were spread later than the control CK1 and other treatment groups, and the dry matter content of the CK1 leaves per unit area was higher than that of the other treatment groups, but the growth vigor of each treatment group was basically the same, indicating that the nutrients in the soil are sufficient for the growth of seedlings.

The phenomenon that the growth vigor of each treatment begins to be different and the stem thickness is greatly different from the growth vigor of each treatment at the beginning of the elongation period, wherein the stem of the CK1 group is the thinnest and the stem of the T2 group is the thickest is probably related to the short-term insufficient fertilizer absorbing capacity after seedlings are applied to a base and applied with a large amount of fertilizer and enter a quick growth period. The accumulated amount of dry matter in the unit area of the CK2 leaves is lower than that in other treatments, which indicates that the watermelon growth is influenced by no fertilizer.

After the flowering period, the three treated plants, namely CK1, T1 and T2, have vigorous growth, the two treated groups, namely CK2 and T3, have common growth, and the T4 plant has the weakest growth. This indicates that the fertilizer reduction of the flowering and fruit setting period T1 and T2 has minimal influence on the growth of watermelon.

After the melon expanding period, the growth vigor of each treated plant is greatly changed, and the T2 and T3 treated plants have equivalent growth vigor and are obviously superior to other treated groups; the CK1, CK2 and T1 treated groups have the same growth vigor but are slightly worse than T2 and T3; the plants of the T4-treated group grew the worst. The fertilization mode of treating the swelling melon stage by the T2 and the T3 in the period is more beneficial to the growth of plants, and the effect is better than that of the control CK 1.

TABLE 3 treatment of watermelon growth at different times

2.2 chlorophyll content of watermelon plant leaves

During the whole growth period, the chlorophyll content of the leaves of the T2-treated group is generally high and is always in an ascending state. The total content of T1 and T3-treated chlorophyll immediately followed T2 and was consistently higher than CK 1. The total content of the chlorophyll of the early stage CK2 and the chlorophyll of the T4 is not obviously different from that of CK1, but the difference of the later stage is obvious, and the whole change range of the chlorophyll content of the two is large (Table 4). The fertilization modes of the three treatment groups of T1, T2 and T3 are favorable for synthesizing chlorophyll of plants and promoting photosynthesis. Provides sufficient nutrition for the growth and development and fruit setting of plants.

TABLE 4 chlorophyll content of each treated watermelon leaf in different periods

2.3 watermelon leaf element content under reduced application of different fertilizers

After the nutrient application proportion is distributed according to the fertilizer requirement rule of the watermelon, the element absorption and accumulation of different stages of the whole growth period of the watermelon are not greatly influenced by the reduced application treatment of different fertilizers. The absorption characteristics of other treatment elements are not obviously different from those of the control CK1 except that the T2 treatment promotes the absorption of potassium element and iron element in the seedling stage and the vine stage, the T3 treatment promotes the absorption of magnesium element in the flowering and fruit setting stage, and the T1 treatment increases the accumulation effect of iron element in the melon expanding stage. The fertilizer application reduction based on nutrient demand characteristics of the watermelon vegetables can not cause nutrient deficiency in each stage of the watermelon growth period. In particular, in the CK1 (basic application of fertilizer in large quantity), the individual element content is lower than that in the reduced application treatment (T1-T4) and CK2 (Table 5) without fertilizer appears in each growth period, which shows that the one-time large-quantity application of fertilizer can affect the absorption of watermelon on individual nutrient elements in a specific period.

TABLE 5 treatment of elemental content of watermelon leaves at different time periods

2.4 flowering and fruiting conditions of watermelon plants

The days from the time when each female flower is opened to the field planting of the watermelon is used for representing the time when the female flower is opened, the female flower of each treatment group starts to be opened after 28 days of field planting, and the number of the opened female flowers of each treatment group is counted every day from 28 days of field planting to 46 days of field planting. Under the local net rack cultivation mode, the change trend of the total open number of the female flowers in each treatment day is basically the same. 4 open peaks, T3(278 flowers/mu), T2(434 flowers/mu), T1(272 flowers/mu) and CK2(506 flowers/mu), appear on the 31 st to 32 th days, 37 th days, 41 th days and 45 th to 46 th days after planting. In the early stage of female flower opening, the female flowers are treated to have larger opening amount per day by T1, T2 and T3; the CK2 control group has the least fertilizing amount and the latest flowering, and the single-day opening amount of female flowers is gradually increased until the opening amount of CK2 female flowers reaches the maximum in the 4 th peak. The single-day flowering amounts of the female flowers of the CK 1-treated group were at a medium level at the early stage and at a low level at the later stage, while the single-day flowering amounts of the female flowers of the T4-treated group were at a low level all the time (FIG. 1). It is shown that excessive fertilizer application reduction can affect the flowering and fruit setting of the watermelon.

The T1 first female flower opened for 29.60 days at the shortest time, the number of female flowers opened in 25 knots was 4.00, which was significantly larger than that of the control (3.27), T1 significantly shortened the opening time of the first female flower and increased the number of early female flowers compared to the control group. In the remaining fertilizer reduction treatment, the date of the first female flower opened, the node of the opening, the ability of female flowers to continuously open and the node of first melon were not significantly different from the control CK1 (table 6). The fertilizer application reducing and efficiency improving fertilizing mode does not influence or enhance the flowering and fruit setting capability of the watermelons.

TABLE 6 Effect of reduced application of Fertilizer on the patency and setting of the treated female flowers

2.5 watermelon fruit yield and quality

2.5.1 watermelon fruit quality

In the former two batches of melons, the weight of each of the T1 and T2 treated groups is larger, and no obvious reduction trend exists; the weight of the second batch of the CK1 treated melon was significantly less than that of the first batch, the weight of the T3 treated melon was the smallest, and the control CK1 and T3 treated melons showed a gradual decrease in quality in different batches (table 7), with no significant difference in pulp and flesh color in each treatment (fig. 2). The processing quality of CK1, CK2 and T2 in the first batch of fruits is equivalent, and the content of central soluble solids is higher than that of T1, T3 and T4 processing groups; the difference in the soluble solids content at the T1, CK1, and T2 edges was not significant and higher than the remaining groups. In the second fruit batch, there was no significant difference in sugar content between the treated groups (fig. 3). The results show that proper fertilizer reduction combined with on-demand fertilization can maintain the stability of fruit quality among different batches, thereby improving the uniformity of commodity quality.

TABLE 7 Effect of different fertilization treatments on the growth and development of watermelon fruit

2.5.2 watermelon yield and yield increasing effect

5 batches of watermelons are harvested in each treatment group, and the number of the watermelons harvested in the T3 treatment group is the highest, and the yield per mu is the highest. T1 and T2 treatment groups were not widely separated. The T4 treated group was comparable to controls CK2 and CK 1. Compared with CK1 (original fertilization mode on farm) watermelon total yield of 2404.97 kg/mu, CK2 (without fertilizer) yield is reduced by 3.83%, T1-T4 in 4 fertilizer reduction treatment, T3 yield is 2786.56 kg/mu at most, 15.87% of yield is increased, T2 time is less, yield is 2725.08 kg/mu, and yield is increased by 13.31%. The average single melon weight of the T2-treated group was at most 1.251kg, which is 10.36% greater than that of CK1, and the average single melon weight of the T3-treated group was at least 1.105kg, which is 2.55% less than that of CK1 (table 8).

The market habits of local watermelons in the current year are divided into 3 grades, wherein the selling price of watermelons below 0.8kg per kilogram is 4 yuan, the selling price of watermelons between 0.8kg and 1.5kg per kilogram is 6 yuan, and the selling price of watermelons more than 1.5kg per kilogram is 10 yuan. Finally, compared with CK1, the selling price per mu is 14591 yuan, CK2 is 13765 yuan minimum, and the income is 5.66% less than that of CK 1; the selling price of the T2 treatment group is the highest, is 18596 yuan/mu, and the income is increased by 27.45 percent compared with that of CK 1; t1, T3 increased yields by 17.15%, 16.88%, respectively, compared to CK1 (table 9).

TABLE 8 watermelon yield and yield increasing effect of different treatment groups

TABLE 9 Total yield and income increasing effect of watermelons in different treatment groups

2.6 conclusion of the test

T1-T3 treatment groups for reducing fertilizer application of 3 fertilizers, N, P₂O₅The dosage is reduced by 56.25 to 68.75 percent, and K₂The O consumption is reduced by 34.37 to 53.12 percent, the yield per mu is increased by 10.24 to 15.87 percent, and the selling price per mu is increased by 16.88 to 27.45 percent. However, the quality of the watermelon in the T2-treated group is not obviously different from that of the control CK1, the quality of T1 and the quality of T3 are reduced, and the economic benefit of T2 is the highest. The T4 treatment reduced the fertilizer application amount the most, but the quality of the single melon was significantly lower than that of the other control groups. Thus, the T2 treatment group fertilization program was optimal, i.e., N, P₂O₅，K₂The total O consumption per mu (converted pure amount) is 3.908kg, 5.471kg and 5.862kg (N, P)₂O₅The using amount is reduced by 62.5 percent, K₂The O is reduced by 43.75 percent) and is applied according to the fertilizer requirement rule of the watermelon by combining the water and fertilizer integrated technology. In the vine stage: application of N: p₂O₅：K₂O (per mu pure weight) is 1.172kg and 1.094 respectivelykg. 0.586 kg; application of N: p₂O₅：K₂O (per mu pure weight) is respectively 1.172kg, 3.283kg and 1.759 kg; during the melon expansion period, N: p₂O₅：K₂O (per mu pure folding amount) is respectively 1.563kg, 1.094kg and 3.517 kg. The fruit yield can be improved by 13.31 percent, the yield can reach 2725.08 kg/mu, the selling price per mu is improved by 27.45 percent, and the yield value is 18596 yuan/mu.

Description of the drawings: the above-mentioned protocols T1-T4 were also conducted on a small scale in different varieties of watermelon, and the trends of the results were almost the same, so T2 was the preferred protocol.

Finally, it is also noted that the above-mentioned lists merely illustrate a few specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.