The researchers wanted to see if baby rice plants could be transplanted by machines. They grew different types of rice plants in rock wool trays from 1986 to 1988. Baby rice plants raised for more than 4 days were the best for machine transplanting. They had more tillers per meter compared to young and semi-adult plants. Although the heading dates were similar, directly sown rice plants were later. Baby plants had more panicles per meter but lower ripened ratio due to lodging. Overall, there wasn't a big difference in yield between the different types of plants. The best option was baby rice plants with plumule lengths over 5cm, raised for 7 days in rock wool.