Effect of plant spacing on incidence of rice planthoppers in transplanted rice crop

The rice planthoppers (RPHs) are considered as important rice pests in Asia including Pakistan. As phloem-feeders, they can cause severe losses to rice. Besides climate their population abundance is also affected by plant spacing. The optimum plant spacing is among the key agronomic parameters that influence crop growth, performance and yield. The present study to examine the effect of rice plant spacing on incidence of RPHs was conducted during Kharif season of 2018 and 2019 at farmer’s field in the Kallar tract. The study composed of four treatments of rice plant spacing viz. 18 × 18 cm, 23 × 23 cm, 28 × 28 cm and 33 × 33 cm. The experiment was set in a Randomized Complete Block Design (RCBD) with three repeats. The nursery of rice cultivar Super Basmati was transplanted with uniform age of 35 days in all treatments. The data regarding RPHs was recorded 60 DAT till harvesting of crop. Results revealed that plant spacing had significant effect on number of tillers per plant, panicle length, sterility %age, plant height, straw and grain yield. The highest grain yield 6.75 tonns per ha was obtained from 23 × 23 cm plant spacing followed by 6.59, 5.83 and 5.46 tonns per ha from 28 × 28 cm, 33 × 33 cm and 18 × 18 cm plant spacing, respectively. Whereas, on an average RPHs population per plant was maximum (48.81) at minimum plant spacing (18 × 18 cm) and was minimum (3.57) at maximum (33 × 33 cm) plant spacing. The incidence of RPHs started 70 DAT and was very low in the beginning of the cropping season. It increased with the age of the crop and reached to a maximum level of 60 per plant at 110 DAT. On the basis of results 28 × 28 cm rice plant spacing could be recommended in RPHs vulnerable areas having good yield, low resource intensive and compatible with green plant protection measures. In turn this little yield reduction will highly pay in lieu of sustainable rice production and environment protection by reducing excessive and irrational use of pesticides and their cost of application and thus enhancing the biodiversity conservation potential of rice crop agroecosystem.