Effect of Row Spacing on Brown Planthopper Incidence in Basmati Rice under Punjab Conditions

The field experiment was conducted at the Research Farm, Department of Climate Change and Agricultural Meteorology, Punjab Agricultural University, Ludhiana during Kharif 2018. Pusa Basmati variety was transplanted on 5th July (D1) and 15th July (D2) under three spacing (25 cm x12 cm, 20 cm x 15 cm and 30 cm x 10 cm). The brown planthopper incidence data from 2014 to 2016 and 2018 indicated that the highest incidence at Ludhiana was observed in 2016 and the lowest in 2018. Regression analysis was carried out between different meteorological parameters and brown planthopper incidence. According to present study, the favourable temperature for brown planthopper incidence was 30.2-33.4 oC (maximum temperature) and 20.6-22.5 oC (minimum temperature) while relative humidity was 86-90 per cent in the morning and 48-60 per cent in the evening. Hot, cloudy and humid conditions are conducive for brown planthopper multiplication. The micrometeorological data on relative humidity was recorded at different phenological stages. The higher relative humidity was recorded in closer spacing (25 cm x 12 cm) than wider spacing (20 cm x 15 cm and 30 cm x 10 cm). The peak incidence of brown planthopper was also observed in 25 cm x 12 cm spacing (3.1 brown planthopper population/hill) as compared to 20 cm x 15 cm spacing (2.9 brown planthopper population/hill) and 30 cm x 10 cm (2.4 brown planthopper population/hill) during 2018. Hence, microclimate modification through spacing is cost effective measure for brown planthopper management in basmati rice.