Planting time and seedling age: Deciphering yield and economic output under mechanized transplanting of rice in Tamil Nadu

Tamil Nadu Rice Research Institute, Aduthurai, conducted a study to establish a package of techniques for mechanised rice transplantation in 2021-22 and 2022-23. Six treatments were tested in a randomised block design, including two ages of seedlings (15 and 21 days old), two planting periods (normal and 15 days delayed) and conventional transplanting with 25 days old seedlings under normal and 15 days delayed conditions. The mat nursery was constructed for the 8-row "Yanmar" transplanting machine. Mechanised transplanting with 15-day-old seedlings under regular June planting resulted in a higher number of tillers (355 m-2), grains per panicle (162) and grain yield (5511 kg ha-1). Delaying transplanting by 15 days resulted in a drop in grain output. Rice transplanting delayed beyond June 30th resulted in a yield drop ranging from 361 to 1001 kg ha-1. Mechanised transplanting of 15-day-old seedlings resulted in higher net revenue (54506 ₹ ha-1) and B-C ratio (2.2) during the regular June planting season. Regardless of the age of the transplanted seedling, a 15-day delay in transplantation resulted in a drop in grain output.