C. PHAIKAEW¹, S. INTARIT², S. TUDSRI³, E. TSUZUKI⁴, H. NUMAGUCHI⁴ and Y. ISHII⁴

¹Division of Animal Nutrition, Department of Livestock Development, Bangkok
²Lampang Animal Nutrition Research Center, Lampang
³Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
⁴Faculty of Agriculture, Miyazaki University, Miyazaki, Japan

Abstract

The effects of time of final closing cut on seed production of Paspalum atratum were examined in 1999–2000 from 2 experiments conducted in Lampang province, northern Thailand. The results showed that the time of final closing cut had a significant effect on seed yields of P. atratum in both years.
In Experiment 1, where plots were cut at 30-day intervals, plots closed in mid-June produced the highest seed yield of 1333 kg/ha, followed by plots closed in mid-May and mid-April. Plots closed in mid-July produced about one-third the seed yield of plots closed in mid-June, and plots closed in mid-August produced no seed. Severe lodging at seed harvest occurred in plots closed in mid-April, mid-May and mid-June, resulting in a decrease in seed yield.
Experiment 2 was conducted to determine more accurately the most suitable date of final closing cut by comparing cutting at 15-d intervals during the critical period from June 1 to August 1. Seed yields were consistently high at over 1489 kg/ha from plots closed between June 1 and July 1, and yields then dropped in plots cut on July 15 to one-fifth the seed from plots cut on July 1. Plots closed on August 1 produced no seed.
There were small differences in seed quality attributes among plots from both experiments, which produced good seed quality, averaging 88% seed germination, 3.01 g thousand-seed weight and 81% seed purity. From the results in both experiments, it was confirmed that final closing cut date of P. atratum should not be delayed later than July 1.