Bioscience Methods 2026, Vol.17, No.1, 23-31 http://bioscipublisher.com/index.php/bm 26 3.3 Physiological and physical mechanisms for regulating the whole-grain rice yield rate When discussing the whole-grain rice yield rate, the harvest period is often an unavoidable factor, but the way it affects the result is not simple. For example, if the harvest is too early, the grains may appear to be fully formed on the surface, but their interiors are not yet fully filled. The endosperm structure is loose, and the mottling is obvious. During the milling process, they are prone to breakage; while if the harvest is delayed, the moisture content of the grains decreases too much, and combined with the repeated dry-wet changes in the field, cracks are more likely to form inside (Zhou et al., 2025). In contrast, rice harvested at an appropriate time point has a more balanced maturity and moisture condition, which avoids the problem of under-ripeness and reduces the risk of dry cracking (Teng et al., 2024). Naturally, the broken grains are fewer, and the whole-grain rice yield rate is more likely to remain at a high level. 4 Impact of Harvesting Period on Rice Flavor Quality 4.1 Effects of different harvesting periods on rice sensory quality When rice is harvested at different times, both its taste and appearance will change, which is more obvious in practice. For example, if the harvest is too early, the rice grains have not fully developed and the aroma is not strong when cooked. There is often a hint of grassiness. When the harvest is at the appropriate time, the rice grains are plump and transparent, and the aroma and taste after cooking are more harmonious, and they are easier to be accepted (Sultana et al., 2023). However, if the harvest is too late, the rice grains have been dried for a long time, and the flavor will gradually fade, even giving a sense similar to aged rice. The rice will also be harder. Due to such significant differences, controlling the harvesting period within an appropriate range can better ensure the appearance and flavor quality of rice, meeting consumers' expectations (Khan et al., 2021). 4.2 Impact of harvesting period on amylose content and gel cohesiveness When evaluating the quality of rice, the content of amylose and gelatinization degree are often mentioned. However, these two indicators are more influenced by the variety itself rather than the timing of harvest. Even if the harvest time is slightly earlier or later, the changes will not be too significant as long as it is within the normal range (Figure 3) (Zhang et al., 2025). Some studies have already pointed out that for most varieties, the content of amylose remains relatively stable under different harvest periods. In this experiment, a similar situation was observed. Regardless of whether it is amylose or gelatinization degree, the differences between different treatments were not prominent (Lu et al., 2025). Overall, compared to processing performance or flavor changes, the impact of harvest time on the starch-related qualities within the rice is not significant. Figure 3 The 1000-grain weight of mature and immature rice (A), the difference in 1000-grain weight between mature (M) and immature (I) rice (M-I) (B). <5, 5-10, 10-15, and ≥15 mean the 50.20% 24.50% 13.70% 11.60% 25.30% <5% 5%-10% 10%-15% ≥15% Figure 3. The 1000-grain weight of mature and immature rice (A), the difference in 1000-grain weight between mature (M) and immature (I) rice (M-I) (B). <5, 5-10, 10-15, and ≥15 mean the green rice rate was lower than 5%, from 5% to 10%, 10 to 15%, and beyond 15%, respectively. ** represents the 1000-grain weight significant difference between mature and immature at the level of p < 0.01. Ya are the average differences in 1000-grain weight between mature and immature rice in each green rice rate threshold (Adopted from Zhang et al., 2025)
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