Broadening Genetic Base of Rice and Identification of Pre-Breeding Lines for Resistance to Brown Plant Hopper, Nilaparvata lugens (Stål.)

Pre-breeding includes basic research to achieve wide crosses and facilitate the use of exotic materials or wild relatives for both qualitative and quantitative traits. The main objective is to provide breeders with more ‘attractive’ PGR that are easier to use, i.e. resistance sources in acceptable genetic background; or inbreeding tolerant forms of out crossing species for hybrid breeding. Forty seven pre-breeding lines were evaluated against Brown Plant Hopper under glasshouse condition over a period of two years (2018 and 2019). Out of these, two pre-breeding lines were moderately resistant to BPH having score 3. Two pre-breeding lines were moderately susceptible to BPH having score 5, five lines were susceptible having score 7 and rest thirty nine pre-breeding lines were highly susceptible to BPH with a score of 9.

Physiological and Biochemical Responses of Ageratum conyzoides, Oryza sativa f. spontanea (Weedy Rice) and Cyperus iria to Parthenium hysterophorus Methanol Extract

The current study was designed to investigate the effect of Parthenium hysterophorus L. methanol extract on Ageratum conyzoides L., Oryza sativa f. spontanea (weedy rice) and Cyperus iria L. in glasshouse condition. Here, Parthenium hysterophorus methanol extract at 20, 40, and 60 g L−1 concentrations was applied on the test species to examine their physiological and biochemical responses at 6, 24, 48 and 72 h after spraying (HAS). The phytotoxicity of P. hysterophorus was strong on A. conyzoides compared to weedy rice and Cyperus iria at different concentrations and exposure times. There was a reduction in photosynthesis rate, stomatal conductance, transpiration, chlorophyll content and carotenoid content when plants were treated with P. hysterophorus extract concentrations. Exposure to P. hysterophorus (60 g L−1) at 24 HAS increased malondialdehyde (MDA) and proline content by 152% and 130%, respectively, in A. conyzoides compared with control. The activities of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)) were also increased in the presence of P. hysterophorus extract. Present findings confirm that the methanol extract of P. hysterophorus can disrupt the physiological and biochemical mechanism of target weeds and could be used as an alternative to chemical herbicides.