Assessment of rice yield losses and nutrition status in response to varied Nilaparvata lugens nymph densities and exposure durations
摘要
Studies on the assessment of rice yield losses and nutrition status in response to varied brown planthopper (BPH), Nilaparvata lugens (Stal) nymph densities and exposure durations were carried out on the 45 days old plants of PR 121variety in the screen houses at Punjab Agricultural University, Ludhiana during 2022 and 2023 wet crop seasons. Results indicated a consistent decrease in yield-related factors like tiller number, plant height, SPAD meter (soil and plant analysis development) values, panicle traits, grain weight and overall yield with increasing BPH nymph density. Concurrently, flowering advanced with escalating population. Major plant nutrients, like total sugars and total soluble proteins, exhibited a decreasing trend with an increase in exposure period and BPH nymph density hill−1, while total free amino acids showed an increasing trend. A substantial 48.78% yield loss was recorded at a nymph density of 50 hill−1, and a complete 100% yield loss occurred at pest densities of 75 and 100 nymphs hill−1. Additionally, as the exposure period of rice plants to BPH nymphs extended from 0 to 16 days, most yield-contributing parameters progressively decreased. The group with a 16-day exposure period recorded the highest yield loss, reaching 36.34% compared to the control group. Similar to nymph density, plant nutrients such as total sugars and total soluble proteins showed a declining trend with an increase in exposure period, while total free amino acids demonstrated an increasing trend compared to unexposed plants.