Influence of Growth Stage and Stubble Height on Herbage Yields and Persistence of Smooth Bromegrass and Timothy1
- Daniel P. Knievel,
- Aino V. A. Jacques and
- Dale Smith2
Although it is generally accepted that time of cutting and height of cutting are important in yield and persistance of forage grasses, studies of their interaction have produced variable results. Differences in environmental conditions (e.g., temperature and moisture) among field investigations could be responsible for this variability. Smooth bromegrass and timothy were harvested at three growth stages and two cutting heights in the field. Timothy was grown at warm and cool temperatures in the growth chamber and harvested at five growth stages and two cutting heights.
Highest seasonal herbage yields and stand persistence of smooth bromegrass (Bromus inermis Leyss.) and timothy (Phleum pratense L.) in the field were obtained when the first crop was cut at early anthesis. Stand persistence was not affected by stubble height when both grasses were cut at early anthesis. Seasonal herbage yields were higher with a 4-cm than with a 10-cm stubble height. Bromegrass was more productive and persistent than timothy over the entire experimental period. Very few weeds occurred in the bromegrass during 1967 and 1968, and in the timothy during 1967. In 1968, timothy stands cut at early anthesis contained only 1 to 2% of weeds, but there were 6 to 15% in treatments cut at the tillering or inflorescence emergence stages.
Highest herbage growth rate (HGR) and tillering rate of timothy in the growth chamber occurred with cutting at an early leafy stage or at early anthesis at both cool (18 C day/10 C night) and warm (32 C day/24 C night) temperatures. Lowest HGR occurred with cutting at midstem elongation and inflorescence emergence. Warm temperatures significantly reduced HGR and tillering rates at all growth stages and stubble heights. Cutting at a 4-cm compared with a 12-cm stubble height significantly lowered HGR at almost all growth stages at warm temperatures, but only at the tillering stage at cool temperatures. These results indicate that the yield and stand persistance response of cool-season grasses to growth stage at cutting and height of cutting is partially dependent on temperature before and after cutting.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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