International Journal of Horticulture, 2025, Vol.15, No.5, 218-233 http://hortherbpublisher.com/index.php/ijh 228 This shows that high temperature inhibits the supply of photosynthetic products at the source and directly inhibits the activity of enzymes in the sink. The dual effects lead to poor sugar accumulation. In relatively heat-resistant varieties, some sucrose synthase and antioxidant enzyme genes maintain high expression, thus showing better sugar production stability. The impact of low temperature on sugarcane cannot be ignored. Most sugarcane varieties grow slowly when the average daily temperature is below 20 °C. If the temperature drops further to below 10 °C, the photosynthetic efficiency is significantly reduced and the sucrose transport rate slows down. Sometimes metabolic byproducts such as starch accumulate in the stems and leaves, affecting sugar conversion. Studies have found that the activity of neutral invertase in the stems of sugarcane increases after being cold, which may be an attempt by the plant to increase the concentration of cell sap by increasing sucrose decomposition to prevent frost damage, but this also reduces the net accumulation of sucrose. Therefore, it is one of the traditional experiences to harvest in time before the arrival of winter to avoid the sugar content of sugarcane being reduced by low temperature. In addition to light and temperature, water conditions also significantly affect the sweetness and texture of sugarcane. Adequate water is conducive to photosynthesis and the dissolution and transportation of sugar, but excessive water supply or drought will have negative effects. Especially under dry farming conditions, if there is a lack of effective irrigation, the stomata of the plants will close, resulting in reduced photosynthesis and reduced sucrose accumulation in the stems; at the same time, drought will accelerate the lignification process to enhance drought resistance, and the stems will become harder and more fibrous, which is not conducive to fresh eating. An experiment in Guangdong compared the quality of sugarcane grown in dryland sprinkler irrigation and traditional dryland. The results showed that sprinkler irrigation significantly increased the sugar content of sugarcane stems by 1.42 Bx and reduced the fiber content by about 0.47 percentage points. It can be seen that improving water conditions can not only help to increase sweetness, but also help to make the texture tender. This suggests that in the cultivation and management of fresh sugarcane, we should provide crops with a suitable water and nutrient environment through irrigation and other measures, so that they can maintain good metabolic functions even in high-light and high-temperature seasons, thereby achieving efficient accumulation of sugars and moderate reinforcement of cell walls. Environmental factors such as light, temperature and moisture profoundly regulate the network of stalk sweetness and texture formation by affecting the supply of photosynthetic products and the expression of metabolic enzyme genes in sugarcane. In production practice and breeding strategies, it is necessary to fully consider the impact of the environment on quality traits, and select and promote high-quality sugarcane varieties with higher resistance to adverse environments (Mehdi et al., 2024a). 6 Case Studies in High-Quality Fresh-Eating Cultivars 6.1 Sweetness accumulation in purple vs. green rind varieties Fresh sugarcane can be roughly divided into two categories according to the color of the stem skin: purple-skinned (black-skinned) and green-skinned (yellow-green-skinned) varieties. For example, typical purple-skinned sugarcane varieties include Black Skin No. 3 in Guangxi and Puzhe Black Skin in Yunnan, while green-skinned varieties include Baiyuzhe (Bamboo Sugarcane) in Guangdong and Green-skinned Sugarcane in Taiwan (Figure 2) (Ni et al., 2021). It is generally believed that the skin color is determined by the deposition of anthocyanins in the epidermis and does not directly affect the sucrose synthesis pathway. Therefore, there is no obvious difference in the potential sugar content between purple-skinned and green-skinned sugarcanes. However, in actual planting, different color varieties are often accompanied by other genetic background differences, resulting in different sweetness performance. Common varieties of purple-skinned sugarcane have thick stems and strong growth potential. At the same maturity, the sucrose content of their stem juice is often slightly higher than that of some green-skinned varieties (Chen et al., 2022). This may be because many purple-skinned sugarcanes are selected from the offspring of traditional inferior sugarcane varieties (tropical sugarcane S. officinarum), retaining the high-sugar gene; while some green-skinned bamboo sugarcane varieties have medicinal or processing purposes and are not specifically enhanced for high-sugar traits.
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