Weed Seed Germination and Emergence in Response to Soil pH Modification in Paddy Rice Production

Abstract

Soil pH is a critical edaphic factor influencing weed seed germination, emergence patterns, and early seedling establishment in rice-based agroecosystems. The present study evaluates the response of major paddy weed species to soil pH modification under controlled and field-simulated conditions. Seeds of dominant weed flora associated with rice production systems were exposed to a range of soil pH levels to assess germination percentage, mean germination time, and seedling emergence dynamics. Results revealed significant variation in germination responses among species, indicating differential adaptability to altered soil pH conditions. Neutral to slightly acidic pH levels generally favored higher germination and faster emergence in most weed species, while strongly acidic or alkaline conditions suppressed germination and delayed seedling emergence. Soil pH modification also influenced seed viability and early seedling vigor, with marked reductions in root and shoot growth under extreme pH conditions. Emergence patterns under simulated field conditions showed that soil pH shifts altered the timing and density of weed emergence, thereby affecting crop–weed competition dynamics in rice fields. Certain weed species exhibited broad pH tolerance, indicating high ecological plasticity and persistence potential in variable soil environments. The study highlights that soil pH management can indirectly influence weed population dynamics and may serve as a supplementary component of integrated weed management strategies in paddy rice production. Overall, the findings demonstrate that soil pH significantly regulates weed seed germination and emergence behavior, and understanding these responses is essential for predicting weed infestations and improving sustainable weed management in rice-based cropping systems.