Inbred Planting Technique for Nakhon Sawan 3 Hybrid Maize Seed Production

Abstract

In Nakhon Sawan 3 hybrid seed production, conventional planting uses a 4:1 ratio of female to male rows. After pollination has finished, the male rows are eliminated, causing an empty space in the production field. To increase the yield and utilization of the area by female plants, in 2008, an experiment was conducted to study a compact planting technique involving planting male inbreds between female rows at the Nakhon Sawan Field Crops Research Center. The experiment used a split-plot design with three replications, with the main plot consisting of two plantings of parent material: 1) planting female and male inbreds on the same day; and 2) planting female inbreds two days later. Sub-plots consisted of four male planting methods: 1) compact planting between 65 cm female rows; 2) compact planting between 75 cm female rows; 3) compact planting between 85 cm female rows; and 4) planting female to male rows in the ratio of 4:1. The results showed that all compact plantings tended to increase yield by 12-28% compared with that of a female to male row planting ratio of 4:1. Compact planting between 75 cm female rows produced the highest yield of 2,381 kg ha^-1. Compact planting between female rows at 85 cm, 65 cm and planting female to male rows at a ratio of 4:1 produced a yield of 2,288, 2,081 and 1,856 kg ha^-1, respectively. Increased yield was due to the number of ears harvested per hectare increasing by up to 10-25%. All compact planting options delayed the time to 50% pollen shedding from 63 d (in planting female to male rows at a ratio of 4:1) to 64, 65 and 66 d in compact planting between rows of 85 cm, 75 cm and 65 cm, respectively. There was no effect of compact planting on the number of days to 50% silking of female inbreds and on male and female height. The results showed that planting inbreds on the same day tended to increase yield by 20% compared with that of planting female two days later.