Nowadays, there are more varieties of fruits and the quality is also good. Even pears are delicate, crispy and sweet, without the sourness in memory, "said Wang Xin, a resident of Wuxi, Jiangsu, when she mentioned the" Su Cui No.1 "pear she had eaten. Compared to twenty or thirty years ago, the sweetness of fruits has indeed generally increased. ”Professor Li Bingbing from the College of Horticulture, China Agricultural University, introduced that for example, watermelons on the market generally have a sugar content of 12 or above, while 20 years ago it was usually around 9. How do fruits become sweet? Carrying out breeding of excellent varieties is an important reason for the sweetness of fruits. Li Xiaogang, director of the Pear Innovation Team at the Fruit Tree Research Institute of Jiangsu Academy of Agricultural Sciences, introduced that through hybrid breeding and evaluation of botanical and economic traits, individuals with excellent comprehensive traits are selected, thus laying a "sweet" foundation at the genetic level. With the development of agricultural technology, the efficiency of conventional hybrid breeding has significantly improved, coupled with the application of modern breeding techniques such as molecular marker assisted breeding, breeding has become more precise. ”Li Xiaogang said. Researchers have elucidated the molecular mechanism of sugar accumulation in tomatoes and strawberries, and combined with molecular breeding methods, can regulate the sugar content in fruits such as tomatoes and strawberries. ”Li Bingbing introduced that understanding the mechanism of fruit sugar accumulation at the molecular level can regulate the process of sugar production and achieve the right amount of sugar. The selection and breeding have been completed, and there are also considerations for planting. Li Dang Village, Xinjie Town, Taixing, Jiangsu Province, is one of the planting areas of "Su Cui 1". Yan Wei, the person in charge of the thousand acre pear orchard, said that in order to maintain the stability of its high sugar characteristics, "Su Cui 1" is grafted onto Du Li rootstock for asexual reproduction. At the same time, planting varieties of pear trees such as "Fengshui", "Qingxiang", and "Huangguan" around them as pollination trees can help increase the glucose and fructose content in the fruit during flowering and complete pollination. Harvesting too early or too late can lead to a deterioration in the flavor and texture of fruits. ”Li Xiaogang introduced that in order to determine the optimal harvesting time, researchers observe the color of the fruit skin, determine the soluble solids content of the fruit, and taste the fruit flesh flavor every day when the fruit is close to maturity. After a systematic evaluation, the optimal harvesting period is determined to be 105 to 110 days after flowering. Some consumers are worried that the sweet fruit varieties on the market may have unknown "fierce competition"? Li Bingbing said that the sweetness of fruits mainly comes from soluble solids such as sucrose, fructose, and glucose. Different combinations and metabolic transformations can produce different flavors, and fruit sweetness cannot be artificially enhanced. So, is the sweeter the fruit, the better? Simple sweetness can make the taste greasy, while excellent varieties emphasize a balance between sugar and acidity. ”Li Xiaogang said that moderate acidity can enhance the layering of flavor, making sweetness fresher and more three-dimensional. For example, good apples and citrus fruits are always sweet with a hint of acidity, and pears are no exception. In addition to taste, smell is also a part of the flavor experience. Making fruits more fragrant is much harder than simply adding sweetness, "said Li Bingbing. The aroma of fruits is mainly composed of volatile compounds such as esters, aldehydes, and alcohols. Breeding experts attach great importance to the types and concentrations of aromatic substances in fruits, "said Li Xiaogang." The value of fruits with rich aroma is much higher than that of fruits with only sweet taste. Some pear varieties have special aroma and are important resources for breeding. "We continuously rediscover the 'fruit flavor' of fruits to provide consumers with more diverse choices." In addition, the texture of fruits, such as crispness, slagging ability, juice content, as well as disease resistance, storage and transportation resistance, high yield and stability, are all part of fruit quality. Nowadays, more and more breeding workers are paying attention to the content of nutrients such as vitamins, antioxidants, and dietary fiber, in order to cultivate sweeter and healthier fruits, "said Li Xiaogang. (New Society)