## 1 Introduction  
Millet (_Setaria italica_) is one of the world's most important and oldest domesticated crops. Noted for its low water requirement among all cereal crops and its adaptability to grow well in poor soils [1], it is also a short-season crop. Millet is rich in crude protein and fiber, making it an excellent feedstock [2]. However, its high moisture content can make storage challenging, and silage is a preferred method for preserving such feedstock. Silage involves chopping fresh plants, compacting them to reduce oxygen, and allowing anaerobic fermentation to convert soluble carbohydrates into organic acids, reducing pH and inhibiting the growth of spoilage organisms, thereby preserving nutrients [3]. Due to its soft texture, good nutritional value, and palatability, whole-plant millet has high potential for animal feed. Research by [PERSON] and others has shown that intercroppingmillet with _Paiaquas palisadegrass_ in different pasture systems enhances the dry matter content of the silage [4]. [PERSON] and others suggest that, compared to corn silage, millet silage contains higher CP and ADF levels. Replacing 67% of diet silage with millet silage in dairy cows' feed did not affect dry matter and crude protein intake, milk production, or lactose concentrations, but did increase milk fat concentration, thereby providing more energy-corrected milk [5]. Achieving high-quality whole-plant millet silage is complex due to the influence of multiple factors. [PERSON] et al. [6] explored the effect of the growth period on the nutritional quality of _Pennisetum glaucum_ (L.). R. silage and found that the growth period of pearl millet had a significant effect on the nutritional quality of silage, among which the DM content increased with the extension of growth period, while CP and ADF showed a decreasing trend. [PERSON] et al. [7] demonstrated that adding silage inoculants can improve the fermentation characteristics and dry matter (DM) content of millet silage, also providing additional energy when fed to cattle. Previous studies have shown that the nutritional composition of whole-plant millet, such as cellulose, carbohydrates, protein, moisture content, and the number of naturally adhering lactic acid bacteria, varies at different growth stages [6]. These factors are crucial in influencing the fermentation quality of silage. However, whole-plant millet has low water-soluble carbohydrate (WSC) content before ensiling, which may not meet the substrate requirements for high-quality silage fermentation without any treatments [8]. Research indicates that _Lactiplantiobacillus plantarum_ has excellent fermentation capabilities, promoting rapid fermentation of silage, lowering pH levels, inhibiting the growth of harmful microorganisms, and helping to improve silage quality [9]. [PERSON] et al. [10] noted that silage microbial inoculants can significantly alter various aspects of silage fermentation, such as pH, lactic acid (LA) content, acetic acid (AA) content, DM loss, and the digestibility of DM and fiber. Similarly, [PERSON], [PERSON] et al. [11] suggest that the addition of LAB to silage accelerates LA fermentation compared to untreated material. [PERSON], [PERSON] et al. [12] emphasized that LAB is a key factor in improving the fermentation quality and nutritional value of silage. Therefore, we hypothesize that the nutritional composition and the quantity and types of adhering microorganisms vary across the important growth stages of millet. The addition of the widely recognized _Lactiplantiobacillus plantarum_ and soluble sugars can regulate the microbial diversity of millet silage, thereby controlling the fermentation quality. Based on this, our experiment focuses on whole-plant millet, studying the effects of different growth stages and the addition of _Lactiplantiobacillus plantarum_ and soluble sugars on the fermentation quality, aerobic stability, and bacterial communities of millet.