Allelopathic potential of mutant rice varieties and its relation with grain quality.

The use of allelopathic rice varieties has recently been increasing due to their safety and sustainability in weed management. This study aims to investigate the allelopathic effects of rice varieties developed through N-methyl-N-nitrosourea (MNU) mutation on the growth of lettuce and barnyard grass, as well as to establish the relationship between grain quality and the allelopathy of rice plants. Rice straw, husk, and grain samples of rice varieties K1, K2, K3 and K4 were collected and extracted with methanol. The methanol extracts were investigated for antioxidants, total phenolic content (TPC), total flavonoid content (TFC) and the presence of momilactones A (MA) and B (MB). They were subjected to high-performed liquid chromatography (HPLC) coupled with a UV detector and tested for their allelopathic potential. MA and MB were quantified using Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LC-ESI-MS). The results revealed that mutant varieties exhibited higher antioxidants and TPC in both the grain and straw. Additionally, the mutant varieties increased the presence of MA and MB in the straw and husk. The straw exhibited stronger inhibitory effects compared to the husk. The straw samples from mutant rice varieties exhibited stronger inhibition towards lettuce (Lactuca sativa L.) and barnyard grass (Echinochloa crus-galli L.). Both the straw and husk strongly inhibited seed germination, shoot length and root length in barnyardgrass compared to lettuce. The inhibition was more pronounced in root growth than shoot growth. Rice varieties with higher allelochemical contents in their straw and husk exhibited stronger allelopathic effects. These findings suggest that rice varieties developed through the MNU mutation exhibited higher allelopathic activity compared to their wild-type cultivars. Therefore, the MNU mutation shows promise for breeding allelopathic rice varieties, which can help reduce the reliance on synthetic herbicides for weed control. [ABSTRACT FROM AUTHOR]