LIFE CYCLE DYNAMICS AND INVASIVE RISK OF Parthenium hysterophorus L. IN RICE ECOSYSTEM OF TEMPERATE KASHMIR

Abstract

Parthenium hysterophorous, globally recognised as one of the most problematic invasive weed species, demonstrates remarkable adaptability across tropical, subtropical, and warm temperate environments. This study, the first of its kind from Kashmir valley, investigated the life cycle dynamics of P. hysterophorus within rice agroecosystem under temperate conditions. The population was characterized in relation to geographic distribution, prevailing weather conditions, soil properties, taxonomic features, and biometric parameters. Parthenium plants were observed at varied phenological stages, including seedling/rosette, branching and flowering phases. Morphological measurements revealed considerable variation in plant height (7 to 76 cm), leaf count (3 to 26 plant⁻¹), flower and bud production (0-230 plant⁻¹), and shoot fresh weight (6-58 g plant⁻¹). Several plants cut 15-45 cm aboveground regenerated successfully through lateral shoots and new leaves. The high variability in plant height, branching, flower production, and biomass was presumably due to the differences in phenological stages. The field observations indicated that seeds over-wintered under sub-zero temperatures and high soil moisture, germinated during late spring, and reached reproductive maturity by the end of October. Mature seeds exhibited 65% germination under laboratory conditions, confirming the successful completion of life cycle under temperate Kashmir conditions. The study highlights the invasive potential of parthenium to establish and proliferate within rice ecosystems of Kashmir, posing a serious threat to local cropping systems under changing climatic scenarios. Comprehensive surveillance, early detection, targeted eradication, and long-term monitoring are, therefore, essential to mitigate its spread in Kashmir.