Abstract
For maximizing annual dry matter (DM) yields of Rhodes grass (Chloris gayana cv, Pioneer), Guinea grass (Panicum maximum, OK-73-1040) and Napier grass (Pennisetum pureum), the effects of clipping intervals on the DM production of each grass were compared in relation to the climatic data. The plant length was stopped to grow within 60 days of regrowth periods in Rhodes grass and in Guinea grass, however it continued to grow in Napier grass throughout 90 days of regrowth periods. Annual DM yields appeared to be highest in Napier grass followed by Guinea grass and by Rhodes grass. The highest yield was obtained with two-month clipping in Rhodes grass and in Guinea grass and with three-month clipping interval in Napier grass. Monthly DM yields appeared to be lower from Sep. to Mar. and higher from Apr. to Jun. in Rhodes grass, lower in Jan. and Feb. and higher in Aug. and Sep. in Guinea grass and lower in Nov. and Dec. and higher from Apr. to Aug. in Napier grass. Water concentration in plant was higher in Napier grass than in Guinea grass and Rhodes grass and showed a seasonal variation pattern being higher from Jul. to Oct. and lower from Nov. to May. With the results above, both Rhodes grass and Guinea grass should be clipped in between 30 and 60 days of regrowth and Napier grass after 60 days of regrowth periods for maximizing annual DM yields. Judging from the relations of monthly DM yield with mean monthly temperature or with rain fall, the growth of Rhodes grass will be limited with temperature above 25℃ and very susceptible to water shortage and either Guinea grass or Napier grass grow better with higher temperatures but Napier grass is susceptible to water shortage.
