Atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine] effectively controls many annual weeds in established warm‐season range grasses but can damage some of these grasses in the early seedling stage. This study determined the relative atrazine tolerance of seedlings of selected warm‐season grasses and evaluated the effectiveness of a greenhouse bioassay for seedling atrazine tolerance in range grasses. Seed of ‘Pathfinder’ switchgrass [Panicum virgatum L.], ‘Nebraska 54’ indiangrass [Sorghastrum nutans (L.) Nash], ‘Butte’ side‐oats grama [Bouteloua curtipedula (Michx.) Torr.], an experimental blue grama ‘PMK 1483’ [ B. gracilis (H.B.K.) Lag ex Steud], ‘Plains’ bluestem (Bothriochloa ischaemum var ischaemum (L.) Keng), ‘Caucasian’ bluestem [B. caucasica (Trin.) C.E. Hubbard] ‘Blaze’ little bluestem [Schizachyrium scoparium (Michx.) Nash], and a Nebraska experimental prairie sandreed [Calamovilfa longifolia (Hook) Scribn.] were planted in the greenhouse in a 1:1 soilsand mixture that contained 0,1,2, or 3 mg kg−1 atrazine. Seed lots from one cycle of field selection for atrazine tolerance of indiangrass and side‐oats grama were included. A field study was also conducted on a silty clay loam (Typic Argiudoll) and on a loamy sand (Udic Haplustoll) site using little bluestem, blue grama, prairie sandreed, Caucasian bluestem, and Plains bluestem. Survival ranking at 3 mg kg−1 atrazine, in the greenhouse, was: Caucasian bluestem = switchgrass > Plains bluestem > prairie sandreed > indiangrass (check) = indiangrass (cycle 1) > side‐oats grama (cycle 1) = side‐oats grama (check) = blue grama. Atrazine also reduced height in the surviving seedlings. Height reduction in did not appear to be related to seedling survival. Greenhouse data correlated closely with the loamy sand site. because the bioassay used a soil‐sand mixture. Excellent stands of Plains and Caucasian bluestem were obtained on the silty clay loam site at all atrazine rates. The bioassay was an effective screen to separate grasses with differing atrazine tolerances.
Substrate formulations of sawdust, wheat bran, and millet were inoculated with spawns from one hybrid and two parental genotypes of Lentinula edodes. Biological efficiency (BE) and size data on mushrooms harvested from two substrate formulations with spawn run times of 60, 90, and 120 days were analyzed. A significant genotype-spawn run time-substrate formulation interaction was observed for BE. The longer spawn runs resulted in greater BE than the shorter spawn runs. This study points to the need for more work to determine the underlying variability within genotypes.
The logistic and Weibull functions are mathematical equations that have been used to describe the characteristic curve of cumulative germination of plant seeds. The three objectives of this study were to determine (i) if either the logistic or Weibull function described the efffect of temperature on cumulative germination of alfalfa (Medicago sativa L.) seed; (ii) if the parameters of the equations could distinguish differences in germination among seed sources; (iii) and if either equation was predictive. ‘Saranac AR’ alfalfa seed was germinated at 5, 15, 25, or 35 °C over a period of 14 d in petri dishes containing filter paper saturated with distilled water. The logistic and Weibull functions both fit the curves generated by the four temperatures. Validation was accomplished by repeating the germination procedure described above at 10 and 20 °C with a germination period of 10 d and seed lots of six alfalfa cultivars. Parameters were estimated for the validation data set and prediction of the validation data set occurred using parameters estimated from the original data set. Both the Weibull and logistic functions gave satisfactory fits to the validation data set, but more accurate predictions of the validation data set were obtained with the Weibull than with the logistic equation derived from the original data set. The shape and scale Weibull parameters indicated that temperature and cultivar affected the rate of germination or vigor of the cultivars. However, the rate parameter of the logistic equation did not indicate any difference between the varieties. Therefore, use of the Weibull parameters increased the amount of information available for selecting for vigorous germination.
Three experiments were performed to determine the effect of selected saccharides on mushroom yield and basidiome size of shiitake (Lentinula edodes) when grown on a synthetic substrate. Substrate formulations of sawdust, wheat bran, and millet were nonamended or amended with sucrose, fructose, or glucose. Addition of sucrose (0.6 to 1.2% [dry weight]) to the substrate stimulated mushroom yield by 11 to 20% or more. Addition of fructose at 1.2% and glucose at 0.6% resulted in similar yield increases. Most of the yield increase occurred on the first break. The substrate amended with 1.2% sucrose tended to have a more synchronous maturation for the second break resulting in fewer days when mushrooms were harvested.
Crop residues in conservation tillage can provide excellent habitats for invertebrates that feed on alfalfa seedlings. The impact of invertebrate feeding on seedlings has been assessed for alfalfa no‐till seeded into wheat (Triticum aestivum L.) stubble and grass sods, but not oat stubble. Thus, our objective was to determine the influence of weed and invertebrate control on alfalfa (Medicago sativa L.) establishment in oat (Avena sauva L.) stubble. Alfalfa was drilled into a plowed seedbed or into oat stubble. Postplant weed control (none or sethoxydim) and slug and insect control (plowing, methiocarb bait [3,5‐dimethyl‐4‐(methylthio)phenol methylcarbamate], carbofuran [2,3‐dihy‐dro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate], methiocarb plus carbofuran, and none) treatments were evaluated during the establishment of alfalfa at the Rock Springs Agricultural Research Center in Centre County, PA, on a silt loam (Typic Hapludalf; fine, mixed, mesic) soil. Slug numbers were measured 1,3, and 6 wk after planting. Seedling frequency and invertebrate feeding were measured 3 and 6 wk after planting. Morphological development was measured 6 wk after planting. Yields were taken the spring following planting. Reducing weed populations increased seedling shoot weight, trifoliolate leaves per plant, and production year first‐cut yields. Invertebrate management decreased gray field slug (Derocerus reticulatum) populations and increased seedling frequency during initial seedling growth. Controlling volunteer oat was the major factor affecting establishment and yield of alfalfa no‐till seeded into oat stubble.
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