A Comparative Analysis of the Efficacy of Three Plant Growth Regulators and Dose Optimization for Improving Agronomic Traits and Seed Yield of Purple-Flowered Alfalfa (<i>Medicago sativa</i> L.)
2025
Xianwei Peng | Qunce Sun | Shuzhen Zhang | Youping An | Fengjun Peng | Jie Xiong | Ayixiwake Molidaxing | Shuming Chen | Yuxiang Wang | Bo Zhang
This study evaluated the effects of different plant growth regulators and their concentration gradients on the agronomic traits, seed yield, and yield components of <i>Medicago sativa</i> L. cv. “Xinmu No. 5” alfalfa. This experiment comprised 10 treatments, including 98% mepiquat chloride (200, 250, and 300 mg/L), 5% prohexadione-calcium (150, 250, and 350 mg/L), and 5% uniconazole (50, 100, and 150 mg/L), each at three concentration levels, along with a distilled water control (CK). The results show that the 98% mepiquat chloride treatment (MCT3) significantly reduced plant height (by 22%) and internode length (by 28.3%), while increasing stem diameter, branch number, and seed yield. Plant height and internode length exhibited a significant positive correlation, and both were highly significantly negatively correlated (<i>p</i> < 0.01) with seed yield components, indicating that controlling vegetative growth can enhance seed yield. Principal component analysis (extracting four principal components with a cumulative contribution rate of 80.8%) further confirmed that the 98% mepiquat chloride treatment MCT3 (300 mg/L) was the most effective treatment for improving seed yield of alfalfa in arid regions.
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