Effects of Grape Balanced Nutrition Fertilizer on Yield and Quality of Wine Grapes

Jianhua LUO Haisen YU Lin SHI Xin KE Yu WANG Jixian DONG Zhigang GUO Donglian LI Pengzhao GAO

Abstract In this study， the wine grapes balanced nutrient fertilizer （BNF） was designed according to the wine grape nutritional requirements in different growth stages， and objected to reduce fertilizer application rate of wine grape cultivation， improve fertilizer utilization rate， achieve stable yield and improve the quality of wine grapes. The experiment was carried out at the Great Wall Sanggan Winery， and the Aristocratic Winery. The experiment was designed with two treatments： Namely BNF treatment， and the traditional fertilization （CK）. We investigated the effects of BNF on the quality of wine grapes by examining the plant traits of wine grapes in different experimental areas during the growing season， the fruit traits at maturity， and determined the contents of VC， organic acids， amino acids， flavonoids， soluble total sugars， soluble solids， tannins， total phenols and catechins. The results show that： ① The application of grape BNF greatly reduced the application amount of nitrogen， phosphorus and potassium， while the vine had no fertilizer deficiency phenomenon; ② It increased the single fruit weight， the ear weight and yield to varying degrees， and the yield increase range was between 12% and 41%; ③ The wine grapes with BNF had the following characteristics： tight infructescence， even color， small fruit less， no fruit dropped， strong fruit colloid feeling， better aroma and taste; ④ It greatly improved the quality of wine grapes， and increased the content of soluble solids， soluble total sugar， organic acids， VC， total phenols， flavonoids， amino acids and tannins in fruits; ⑤ It greatly increased the total catechin content of "Riesling" and "Syrah"， and had no significant effects on the catechin content of "Merlot" and "Cabernet Sauvignon". In summary， the application of grape BNF has certain practical significance for guiding the production of local wine grapes， ensuring the yield while improving the quality， increasing the income and reducing the environmental pollution caused by excessive fertilization.

Key words Wine grapes; Balanced nutrition fertilizer; Quality; Catechins; Nitrogen and phosphorus reduction

Huailai County is affiliated to Hebei Province and adjacent to Beijing in the east. It is located in the golden zone of grape cultivation at 40 degrees north latitude in the earth where the annual average temperature is 8.9 ℃， the average annual precipitation is 400 mm. It has the characteristics of distinct seasons， abundant sunshine， hot and rainy seasons， and large temperature difference between day and night. It is surrounded by mountains， Sanggan River， Yanghe River and Yongding River running through it. The unique regional microclimate and diverse topography and many types of sandy soil provide unique natural conditions for the growth of vine. Huailai has a history of grape cultivation for thousands of years. The production of "white milk"， "longan" grapes are well-known， and the "longan" grapes of Warm Spring are the tribute of the royal palace and the national banquet. At present， the countys grape planting area reaches 16 700 hm2， with 37 wine processing enterprises including the Great Wall， Sanggan， Sino-French， Rongchen， Amethyst and Noble. The annual output and sales of grape wine reaches 70 000 t， and the grape industry has become the pillar industry of Huailai County.

In agricultural production， chemical fertilizer plays an extremely important role in improving crop yield. However， long-term large-scale application of chemical fertilizer results in the decline of soil quality and environmental pollution[1]. Meanwhile， it also leads to the decrease of soil organic matter content and biological activity， which makes the soil more barren[2]. Studies have shown that in areas with excessive nitrogen application， increasing nitrogen input will not only not increase production， but also increase pollution[3]. In recent years， with the aging of some vineyards， as well as years of over-fertilization and spraying， the soil environment has been deteriorating. The organic matter of most plots are below 1%， the lowest soil is 0.25%， which indicates that the soil organic matter is seriously insufficient; and the pH has reached a minimum of 8.1， and individual plots are as high as 9.15. Soil alkalization is serious， which seriously affects the absorption and utilization of soil nutrients by vine， thus affecting the quality and yield of grapes.

There are more than 30 varieties of wine grapes planted in Huailai County. The main varieties of red wine are "Cabernet Sauvignon"， "Snake Dragon Ball"， "Merlot （Meilu）"， etc. The main varieties of white wine are "Riesling"， "Semillon"， "Baiyu Ni"， "Chardonnay" and so on. Wine grape berries contain flavonoids and other substances which can scavenge free radicals and various vitamins for anti-aging. They have positive preventive and therapeutic effects on senile dementia[4]. Resveratrol in pulp has been widely used in organ transplantation for its ability to inhibit the proliferation of healthy cells and cancer cells， and to reduce rejection[5]. In order to screen suitable fertilizer for wine grape cultivation， reduce the amount of fertilization， scientific and precise fertilization， improve the physical and chemical properties of soil， improve the nutrient absorption and utilization of wine grapes， and improve the quality and yield of wine grapes， a comparative fertilizer experiment was carried out on wine grape.

Materials and Methods

Test material

The Wine grape varieties tested were "Riesling" （aged 30 years， old roots and new strips）， "Syrah" （aged 5 years）， "Merlot" （aged 18 years， old roots and new strips） and "Cabernet Sauvignon" （aged 18 years， old roots and new strips）.

The balanced nutrients fertilizer （BNF） of grapes were designed by Zhejiang Tsinghua Triangle Research Institute and provided by Beijing Shuimu Fertile Earth Biotechnology Co.， Ltd. The BNF of grape is a special nutrient for grape， which is synthetically designed according to the requirement of nitrogen， phosphorus， potassium， calcium， magnesium， sulfur， iron and other nutrients during the growth and development of grape in one year， as well as the physical and chemical properties of different soils and climatic environment. The nutrient is used in a small amount， the vine has high absorption and utilization rate， and the nutrition is comprehensive and balanced， which can well maintain the vegetative growth and reproductive growth balance of the vine.

Experiment design

The "Riesling" fertilization test was carried out at Huailai Great Wall Sanggan Winery， and the "Cabernet Sauvignon"， "Sila" and "Merlot" fertilization tests were carried out in Huailai County Noble Winery. The fertilization treatments in the above experimental areas were the same， with BNF treatment area and control area （CK）， covering half of the total area respectively. The BNF treatment plot was applied with grape BNF 600 kg/hm2 contained N 52.8 kg/hm2， P2O5 17.4 kg/hm2， K2O 113.4 kg/hm2， and the total amount of NPK was 183.6 kg/hm2. The control area was applied with cow and sheep dung （contained 1.3% nitrogen， 0.6% phosphorus， 0.4% potassium） about 75 t/hm2， therefore， the amount of nitrogen， phosphorus and potassium applied in the control area was about 450， 300 and 225 kg/hm2， respectively. If the release rate is about 30%， the actual amount of nitrogen is 135 kg/hm2， the phosphorus is 90 kg/hm2， the potassium is about 67.5 kg/hm2 and the total amount of nitrogen， phosphorus and potassium is 292.5 kg/hm2. The experimental treatments and control areas of "Riesling"， "Cabernet Sauvignon"， "Syrah" and "Merlot" were 1.67 hm2， respectively.

Sample collection and pretreatment

Soil sample collection

Soil samples from 30 to 50 cm deep of the experimental plot were collected before fertilization （April） and after grape harvesting （October） for soil nutrient detection and analysis， which provided scientific basis for fertilization effect. Sampling avoided fertilization ditches and roots， so as not to have an impact on the experiment. Three soil samples were taken from each treatment. Soil samples were collected and placed in natural air-drying， and impurities such as roots and stones were picked out， and then the samples were grinded and sifted， marked and stored separately.

The soil nutrient test was measured by JN-QYF type full-scale soil fertilizer and nutrient detector， and the method for determining each index used the rapid detection method package provided by the instrument.

Fruit sample collection

The grape fruit sample used for quality determination analysis was sampled in early September; and one ear was taken from each vine in the test area， 10 vines were randomly selected for sampling， and the bag with sample was labeled and brought back to the laboratory to determine the basic quality indicators.

Measuring items and methods

Plant traits during growth period

One month after fertilization， the growth of vines was observed comparatively. Three points were randomly selected from each BNF treatment area and control area， and selected Several vines with similar size to measure the leaf color， leaf size， leaf thickness， the number and length of ears.

Fruit traits during maturity

Three points were selected randomly in each BNF treatment area and control area： cutting 1 ear， testing the length and width of ear， ear weight， tightness， grain diameter and transverse diameter， single fruit grain weight， sugar content and the yield; and testing the sugar content and acidity of juice， etc.

Fruit quality index

VC： 2，6-dichlorophenol indophenol titration; Organic acid： Acid-base neutralization titration; Amino acid： Ninhydrin method; Flavone： Aluminium trichloride method; Total soluble sugar： Anthrone colorimetry; Soluble solid ： LB32T handheld sugar meter; Tannin： Spectrophotometer method; Phenol content： Folin-phenol method; Catechin： High pressure liquid chromatography.

Statistical analysis

Data processing was performed using Excel 2007 and SPSS 17.0 statistical analysis software for differential significance analysis.

Results and Analysis

Effects of grape BNF on the growth and development of wine grapes

Field observation showed that different varieties of vines with BNF have the following characteristics： dark green and thick leaves， not easy to be damaged by wind， strong vines， moderate ear size， full grains， compact ears， thick powder and uniform fruit size. Compared with the BNF， the control leaves were thinner， brittle， easily damaged by wind， the ears were smaller and looser， the grains were smaller， the powder was thinner， and the fruit size was uneven.

Effects of grape BNF on the growth and development of "Riesling"

The following table showed the results of the investigation on September 10， 2018. The "Riesling" applied grape BNF had fewer rotten fruits， firmer and heavier ears， lower acidity. There was no significant difference in soluble solids content and sugar content， and the acid content was lower. The actual yield was 5 632.5 kg/hm2， and the control yield was 5 016 kg/hm2， with an increase of 12.3% （Table 1）.

Effects of grape BNF on the growth and development of "Syrah"

The following table showed the results of the "Syrah" investigation on September 10， 2018. Compared with the control， the treatment of balanced nutrients fertilizer of grapes had compact and heavier ears， sweet and sour tasty， and slightly increased sugar content， acid content and grain weight， but there was no significant difference compared with the control. There was no significant difference in fruit size， seed number and soluble solids content between the two treatments. According to the average weight of the ear， the yield of the control was about 7 200 kg/hm2， and the yield of "Syrah" with balanced nutrients fertilizer of grape was 8 190 kg/hm2， which increased by 13.7% （Table 2）.

Effects of grape BNF on the growth and development of "Merlot"

The following table showed the results of the "Merlot" investigation on September 12， 2018. The results showed that "Merlot" with BNF of grapes had aroma and was not easy to produce juice， and its ears were loose. Compared with the control， there was no significant difference in sugar content， acid content and grain weight; the ears were larger and heavier， and there was no significant difference in grain size; the seeds of the control treatment were more; and the content of soluble solids was significantly increased. According to the average panicle weight， the yield of the control treatment was about 4 080 kg/hm2， and that of the grape BNF was about 5 790 kg/hm2， with an increase of 41.9% （Table 3）.

Effects of grape BNF on the growth and development of "Cabernet Sauvignon"

The following table showed the results of the "Cabernet Sauvignon" investigation on September 12， 2018. The results showed that the "Cabernet Sauvignon" with BNF of grape was thicker， more uniform， thicker pericarp， sweeter and sour. The indexes of sugar content， acid content， grain weight， seed number， ear weight and soluble solids content were higher than those of the control， but there were no significant differences. According to the average ear weight， the yield was about 3 909 kg/hm2， and that of the control was 3 900 kg/hm2. There were no differences between the two yields （Table 4）.

Effects of grape BNF on the quality of wine grapes

The quality of wine grape is determined by many factors， including sugar， tannin， acid， phenols， content and composition of aroma components， etc. The results showed that fertilization could increase the contents of total phenols， flavonoids and tannins in the peel of Cabernet Sauvignon[6]. Phenols are important secondary metabolites in grapes. They are widely distributed in grape skin， grape seeds and pulp. They are mainly composed of phenolic acids， flavonols， flavanols， anthocyanins and polycondensated tannins[7]. These substances play an important role in grape fruit color， flavor， wine color， taste， nutritional value and so on. In addition， these substances also have biological activities such as antioxidant， free radical scavenging， anti-virus， anti-cancer and so on[8]. The results showed that the contents of total phenols， flavonoids and tannins in the pericarp of Cabernet Sauvignon grape treated with nitrogen were higher than those of CK. This is similar to the results of Delgado et al. Delgado believed that the application of appropriate nitrogen fertilizer could increase the contents of total phenols， total anthocyanins and flavonoids in peel. Studies including that of Cavaliere[9] suggested that increasing nitrogen application could increase the production of flavonoids in fruits.

Effect of grape BNF on the quality of "Riesling"

The following table showed the effects of BNF on the quality of "Riesling". The results indicated that the contents of soluble solids， dry matter， soluble sugar， flavonoids and amino acids in grape fruits treated with BNF were significantly higher than those in the control group; the contents of tannins were also higher than those in the control group， but there were no significant differences. Simultaneously， there were no significant differences in single fruit weight， VC， organic acid and total phenol between BNF treatment and control （Table 5）.

The following table analyzed the content of catechins， a polyphenolic substance in the fruit of "Riesling". Seven kinds of catechins were detected， namely gall catechin （GC）， epigallocatechin （EGC）， catechin （C）， epigall catechin gallate （EGCG）， gall catechin gallate （GCG）， epicatechin gallate （ECG） and catechin gallate （CG）. Catechins and epicatechins are the main components of grapes and wines， and their content not only affects the taste of grapes， but also play an important role in the color， taste and astringency of grapes. The results showed that the contents of total catechins， GC， EGC and C of "riesling" applying grape BNF were significantly reduced. Therefore， the astringency of grapes was reduced to a certain extent， and the flavor and taste of grapes were improved significantly （Table 6）.

Effect of grape BNF on the quality of "Syrah"

The following table showed the effects of BNF on the quality of "Syrah". The results showed that the single fruit weight， soluble solids， dry matter， total soluble sugar， flavonoids and amino acid contents of grape fruits treated with BNF were significantly higher than those of the control group， while the contents of VC， organic acid， total phenols and tannins were also higher than those of the control group， but the differences were not significant （Table 7）.

The following table analyzed the detection data of catechins， a polyphenolic substance in the fruit of "Syrah". The results showed that the total catechin content in the fruit treated with BNF was significantly lower than that in the control treatment. Although there were eight kinds of catechins in the fruit treated with BNF， their accumulation was very low. Only GC and C catechins were detected in the control treatment， the astringency was more obvious because of the high content of C. The "Syrah" with BNF had weaker astringency， and the flavor and taste were greatly improved （Table 8）.

Effect of grape BNF on the quality of "Merlot"

The following table showed the effects of BNF on the quality of "Merlot". The results showed that the single fruit weight， flavonoids and total phenols content of wine grapes treated with BNF were significantly higher than those of the control group， and the contents of soluble solids， VC， organic acids， total soluble sugar， amino acids and tannins treated with BNF were also higher than those of the control group， but there were no significant differences between the two treatments. Meanwhile， there was no significant difference in dry matter content between the two treatments （Table 9）.

The following table analyzed the detection data of polyphenols-catechins of "Merlot" by applying BNF. The results showed that the total catechins accumulation of the two fertilization treatments were basically the same. From the content of different catechins， the GCG content of BNF was higher than that of control， while the CG content of the control was higher than that of BNF. In terms of nutrient accumulation， there was no significant difference in bitterness between the two fertilization treatments. The contents of soluble solids， total soluble sugar， flavonoids and amino acids in the fruit treated with BNF were significantly higher than those in the control， and therefore， the taste of "Merlot" was still greatly improved （Table 10）.

Effect of grape BNF on the quality of "Cabernet Sauvignon"

The following table showed the effects of BNF on the quality of "Cabernet Sauvignon". The results showed that the contents of VC， total phenols， flavonoids， amino acids and tannins in grape fruits treated with BNF were significantly higher than those in the control. There were no significant differences in the contents of soluble solids， organic acids and total soluble sugar between the two treatments （Table 11）.

The following table showed the effect of BNF on the content of catechins in the fruit of "Cabernet Sauvignon". The results showed that there was no significant difference in total catechin content between the BNF and the control. Only five kinds of catechins were detected in the two treatments， but there were no significant differences in the contents of different catechins between the two treatments. Therefore， the sensation of the fruit is almost the same. However， the contents of VC， total phenol， flavonoids and amino acids in the "Cabernet Sauvignon" with BNF were significantly higher than that of the control， so the antioxidant level and mouthfeel of the fruit were greatly improved （Table 12）.

Effects of grape BNF on soil nutrients in vineyards

The following table showed the results of soil nutrient test before and after the application of grape BNF in Sanggan Winery experimental area. It could be seen that the soil pH value did not change significantly before and after fertilization. The EC value decreased， it indicated that the nutrients in the fertilizer were fully utilized， the nitrogen content did not change before and after fertilization; the P2O5 content decreased; the K2O content had no significant difference; the soluble calcium and magnesium content decreased significantly; and the sulfur ion content increased significantly， and the organic matter content decreased significantly. The results showed that the proportions of P2O5， Ca2+ and Mg2+ could be added appropriately in grape BNF， and some organic matters could be applied at the same time （Table 13）.

The following table showed the soil nutrient analysis data before and after the application of BNF in aristocratic winery test area. The results showed that there was no significant change in soil pH value before and after fertilization; the EC value decreased in autumn， indicating that nutrients were fully utilized; the total nitrogen and P2O5 content were decreased; and the K2O， sulfur ion， organic matter， soluble calcium and magnesium content were decreased significantly. The vineyard of noble winery is located in the river beach， and there are many small and medium-sized gravels in the soil and leaks water and fertilizer. Although the BNF of grapes can meet the needs of grape growth and development， some nutrients are lost because of leaking fertilizer. The problem of fertilizer loss could be solved by increasing the amount of fertilizer application or adding one topdressing （Table 14）.

The above test results showed that the nitrogen， potassium and sulfur contents in the soil with BNF are just enough， and the contents of available phosphorus， calcium and magnesium are somewhat deficient. It indicated that the demand of phosphorus， calcium and magnesium for wine grapes is large. Meanwhile， it provided a scientific basis for formula adjustment of BNF in grapes.

Conclusions and Discussion

Applying grapes BNF greatly reduced the application amount of Nitrogen， phosphorus and potassium. Compared with the application of organic fertilizer， the total amount of Nitrogen， phosphorus and potassium was saved by about 59%. Meanwhile， the vine was strong， the leaves were thick and dark green， and there was no phenomenon of lacking fertilizer;

Applying BNF of grapes increased the yield of single fruit weight and ear weight in varying degrees， and the yield increased ranged from 12% to 41%;

The grapes applied with BNF had compact ears， uniform color change， few small fruits， no fruit dropped， strong gum sense， and better aroma and taste;

The application of grapes BNF greatly improved the quality of wine grapes， and increased the contents of soluble solids， soluble total sugar， organic acids， VC， total phenols， flavonoids， amino acids and tannins of grapes in varying degrees;

The application of grape BNF greatly increased the total catechin content of "Riesling" and "Syrah"， and had no significant effect on the catechin content of "Merlot" and "Cabernet Sauvignon".

In summary， the application of grape balanced nutrient fertilizer has certain practical significance to guide the production of local wine grape， ensure the yield， improve the quality， increase the income， and reduce the environmental pollution caused by fertilization.

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