Tripsacum dactyloides (L.) L., commonly known as eastern gamagrass, is useful for grazing, stored forage, soil amelioration and conservation, and as a biofuel feedstock. Our goal was to calculate accumulated growing d...Tripsacum dactyloides (L.) L., commonly known as eastern gamagrass, is useful for grazing, stored forage, soil amelioration and conservation, and as a biofuel feedstock. Our goal was to calculate accumulated growing degree days (GDD) from existing datasets collected for eastern gamagrass forage production experiments in northwestern Oklahoma, and discuss the use of GDD, instead of calendar harvest dates, in the production of eastern gamagrass forage. Growing degree days were calculated from 1 January each year using the “optimum day method”. For 10 harvest years, the first eastern gamagrass harvest required 690 ± 26 cumulative GDD. Based on long-term weather data from Woodward, Oklahoma, this would place the first harvest on or near 1 June. The second harvest required 635 ± 27 cumulative GDD which would place the second harvest on or near 15 July and the third harvest required 690 ± 23 cumulative GDD placing it on or near 30 August. Each of the 30 harvest required an average of 670 ± 15 cumulative GDD. Using GDD to predict harvest events is a useful tool that forage producer can use in the production of eastern gamagrass forage in the USA and possibly elsewhere.展开更多
Under field conditions water is often inadequate for satisfactory seed germination. An experiment was conducted to determine the effects of simulated dry conditions on germination and seedling growth of five bluegrass...Under field conditions water is often inadequate for satisfactory seed germination. An experiment was conducted to determine the effects of simulated dry conditions on germination and seedling growth of five bluegrass (Poa) species, including: Texas, P. arachnifera Torr.;annual, P. annua L.;mutton, P. fendleriana Vasey;Kentucky, P. pratensis L., and Sandberg, P. secunda J. Presl. bluegrasses. Fifty-seed samples of each species were germinated at water potentials of -1.6, -0.8, -0.4, -0.2, and 0 MPa for a 42-d period. Annual and Sandberg bluegrass tolerated moisture stress at germination better than the other species, requiring 14 d to reach 40% germination in water of -0.8 MPa potential. Kentucky bluegrass required 21 d to reach 40% germination under similar conditions. Mutton and Texas bluegrass were the least tolerant of low water potentials, requiring 42 d to reach 20% germination. Selection for increased seed germination at low water potentials should be possible in Poa species assuming the trait has moderate heritability.展开更多
文摘Tripsacum dactyloides (L.) L., commonly known as eastern gamagrass, is useful for grazing, stored forage, soil amelioration and conservation, and as a biofuel feedstock. Our goal was to calculate accumulated growing degree days (GDD) from existing datasets collected for eastern gamagrass forage production experiments in northwestern Oklahoma, and discuss the use of GDD, instead of calendar harvest dates, in the production of eastern gamagrass forage. Growing degree days were calculated from 1 January each year using the “optimum day method”. For 10 harvest years, the first eastern gamagrass harvest required 690 ± 26 cumulative GDD. Based on long-term weather data from Woodward, Oklahoma, this would place the first harvest on or near 1 June. The second harvest required 635 ± 27 cumulative GDD which would place the second harvest on or near 15 July and the third harvest required 690 ± 23 cumulative GDD placing it on or near 30 August. Each of the 30 harvest required an average of 670 ± 15 cumulative GDD. Using GDD to predict harvest events is a useful tool that forage producer can use in the production of eastern gamagrass forage in the USA and possibly elsewhere.
文摘Under field conditions water is often inadequate for satisfactory seed germination. An experiment was conducted to determine the effects of simulated dry conditions on germination and seedling growth of five bluegrass (Poa) species, including: Texas, P. arachnifera Torr.;annual, P. annua L.;mutton, P. fendleriana Vasey;Kentucky, P. pratensis L., and Sandberg, P. secunda J. Presl. bluegrasses. Fifty-seed samples of each species were germinated at water potentials of -1.6, -0.8, -0.4, -0.2, and 0 MPa for a 42-d period. Annual and Sandberg bluegrass tolerated moisture stress at germination better than the other species, requiring 14 d to reach 40% germination in water of -0.8 MPa potential. Kentucky bluegrass required 21 d to reach 40% germination under similar conditions. Mutton and Texas bluegrass were the least tolerant of low water potentials, requiring 42 d to reach 20% germination. Selection for increased seed germination at low water potentials should be possible in Poa species assuming the trait has moderate heritability.
