The sweetness of citrus is the most important factor in the quality of citrus, but many people know that citrus should be sweetened, but they don't know that reducing acidity is more important, because only by reducing acidity can the sweetness of citrus stand out.
Sweet components of citrus
Sugar in citrus is mainly sucrose, glucose and fructose, among which fructose has the highest sweetness and glucose has a good taste. Only by increasing these sugar contents in a balanced way can we have citrus fruits with good taste.
Generally, citrus fruits grow earlier, and the sugar mainly precipitates in pulp cells, and then gradually rises after the middle period, reaching the peak at maturity. Therefore, the late stage of citrus fruit expansion is the key point to increase sugar.
Where does the sour taste of citrus come from?
Except sugar, citrus is sour because it contains two amino acids, citric acid and malic acid.
Among them, citric acid produces acid quickly and lasts for a short time; Malic acid is refreshing, slightly bitter, slow in taste and long in acidity.
During the growth of citrus fruit, the median calculation will continue to accumulate, and the level of organic acids will gradually decrease until it reaches the peak.
As we all know, delicious citrus must be sour and sweet, so we should grasp the sugar-acid ratio of citrus.
When the acid content of citrus is 1%, the sugar content will exceed 10% to have a good taste, that is, the sugar-acid ratio will be greater than 8.2, and when the sugar-acid ratio is greater than 12, the taste of citrus will be sweet.
What are the factors that affect the sweetness of citrus?
① Environmental factors
The growth of citrus needs suitable temperature and light. With the increase of temperature, the contents of sugar and soluble solids increase and the acidity decreases.
However, insufficient light will hinder photosynthesis, affect sugar accumulation, reduce sugar content, increase acid content and reduce quality.
② Water factor
Water is a necessary factor for the growth of citrus. On the premise of meeting the basic water supply, the watering amount of citrus can be reduced in a certain period of time, and the soluble solids and sugar content in fruit juice can be increased.
③ Fertilizer factors
Minerals can further reduce acid and sweeten, such as magnesium, zinc, calcium and potassium. This will reduce the assimilation products of fruit trees by affecting their photosynthesis.
The lack of iron and calcium will affect the degradation of organic acids; Lack of phosphorus will make the fruit smaller, hollow, rough skin, pale color, less juice and strong sour taste.
In the late growth stage of citrus, the supply of phosphorus and potassium fertilizer should be ensured so that citrus can have a good taste.
What fertilizer is used to sweeten citrus?
① Apply base fertilizer in winter.
If the basal fertilizer mainly composed of organic fertilizer is applied in autumn after picking, the basal fertilizer in the early stage is easy to ferment and decompose and be absorbed by trees, which is beneficial to the decomposition and transformation of organic fertilizer in winter and spring and the sustained release of nutrients.
In this way, citrus can send out new roots in time, so as to quickly restore growth and vitality in the coming year. Because it provides the nutrition needed for flower bud differentiation and early flowering and fruiting of citrus trees, it promotes flower bud differentiation, prevents flower drop and fruit drop, and can significantly improve the yield and quality of citrus fruits.
② Adding calcium fertilizer.
According to research, the acidity of citrus is related to the calcium content in soil. Citrus with high calcium content has relatively low acidity, and vice versa. Calcium deficiency is common in soil.
Therefore, the application of calcium fertilizers such as lime in citrus orchard soil can effectively supplement the calcium content in the soil and make up for the calcium content needed for citrus growth.
Generally, 50-60 kilograms of quicklime is sprinkled in the soil of orange orchard per mu to reduce the acidity of the soil of orange orchard, improve the accumulation of sugar and increase the sweetness.
③ Spraying foliar fertilizer.
Under normal circumstances, if mineral nutrition is sufficient, many fruit farmers also have a good effect by spraying potassium dihydrogen phosphate, such as phosphorus and potassium source pool, for 2-3 times in succession.
In general, it is not recommended to use foliar fertilizer containing growth regulators such as ethephon to promote early maturity. You can use it if you can. This foliar fertilizer is registered with phosphorus, potassium, boron, molybdenum and other elements, which is specially used to promote the discoloration and sweetness of oranges.