Spring wheat (Triticum aestivum L. vat. ‘Lee’) was grown in pots in the greenhouse in water baths controlled at 12.8 ± 0.3 and 18.3 ± 0.3 C. Wheat straw was applied on an area basis at rates equivalent to 0 and 5,040 kg/ha. Selected groups of pots were shifted between temperature baths at specific growth stages. Soil temperatures measured continuously with thermocouples were lower with surface residue than without surface residue during the earlier stages of growth, with the greater difference occurring in the 12.8 C bath. There was a significant correlation between temperature at the 0–3 growth stage and the number of tillers, number of heads, and total grain yield. The percentage of heads to tillers ranged from 34 to 50 with no clearcut correlation with temperature or mulch treatment. There was no correlation between yield and mulch treatment. Significant correlation coefficients were also obtained for soil temperature during the 10–10.5 stage of growth and weight per kernel, number of kernels per head and weight of grain.

Non-Peer Reviewed

Non-Peer Reviewed

Atrazine [2-chloro-4(ethylamino)-6-(isopropylamino)-s-triazine] and propazine [2-chloro-4,6-bis(isopropylamino)-s-triazine] were applied to sorghum [Sorghum bicolor (L.) Moench] at 1.12 to 8,96 kg/ha on separate plots in 1960–63, 1965, and 1966 at 11 experimental locations across Nebraska. Winter wheat was seeded 15 months later. Atrazine, when applied to sorghum at recommended rates, did not affect subsequent winter wheat yields at North Platte on Holdrege loam and Holdrege silt loam. Occasionally, there was winter wheat stand reduction following atrazine and propazine at 4.48 and 8.96 kg/ha. At Alliance on Keith very fine sandy loam, winter wheat fall top growth was reduced by atrazine at 4.48 kg/ha in 1962 and 1963. Thinning of stand did not always reduce grain yields because of subsequent tillering. There was an increase in winter wheat grain yields in 1964 on plots treated with atrazine at 2.24 kg/ha in the sorghum in 1962. At Lincoln, on Sharpsburg silty clay loam, winter wheat yields were reduced from atrazine carryover in 1963 but not in 1964. Under most Nebraska conditions, atrazine applied to sorghum at recommended rates will not persist long enough to cause yield losses of winter wheat in a winter wheat-sorghum-fallow rotation.

Non-Peer Reviewed