Allelopathic potential of purple nutsedge (Cyperus rotundus L.) on germination and initial seedling vigour of Bt cotton hybrid

Abstract

Allelopathic effects of Cyperus spp. have been generally reported and are considered the major factor limiting the initial establishment of agricultural crops. A laboratory study was conducted to examine the allelopathic effects of Cyperus rotundus L. on Bt cotton. Since it was hypothesised that C. rotundus exudates enters in the rhizosphere environment in the form of aqueous extract at the time of germination of tubers. The allelopathic effect was assessed in series of laboratory environments at Department of Agronomy, Annamalai University, Annamalai Nagar, Tamil Nadu during start of two seasons viz., October 2023 (Rainfed) and January 2024 (Irrigated). At the time of cropping the germinated C. rotundus rhizomes were collected from the cotton field and the aqueous stock solution of 1:1 (w/v) was prepared and dilutions were made in 0, 10, 20, 30, 40 and 50% concentrations. Bt cotton seeds (RCH 659 BG II) were incubated for 10 days under respective concentrations and biometrics were recorded. The pooled data of the present experiment indicated that aqueous extract of germinated rhizomes C. rotundus significantly reduced the frequency of percent germination, seed germination potential; increased the percent mortality rate, abnormal germination rate, germinal length inhibition index and seedling vigour index.