Tillage systems in the spring wheat (Triticum aestivum L.) production areas of the North Central Great Plains are changing to control soil erosion and increase soil water conservation. Therefore, a field study was conducted under three environmental conditions to determine if there was a cultivar X tillage interaction for grain yield, plant establishment, tiller number at boot and maturity, grain volume weight, and plant height. Eighteen adapted hard red spring wheat cultivars were evaluated using two tillage systems, till and no-till, during 1985 and 1986 on a Beotia silt loam (fine-silty, mixed, Pachic Udic Haploboroll) and during 1986 on an Aberdeen silt clay loam (fine, montmorillontic, glossic Udic Natriboroll). There was a significant cultivar X tillage interaction for grain yield, with a range from a 9.8% increase to a 11.6% decrease depending on cultivar when examined over all environments. There was a cultivar X tillage interaction for seed weight (P = 0.07) and grain yield (P < 0.05).Stand establishment was superior at all locations in no-till. Tillering at various growth stages did not explain grain yield differences. This study indicated that selection under no-till should be considered to more efficiently develop spring wheat cultivars for no-till production systems.

Previous field studies have indicated yield responses of small grain crops to KCl on very high K-testing soils, which were likely due to Cl fertilization. Suggested mechanisms for the involvement of Cl range from plant disease effects to effects on plant water relations. The possibility that climatic and biological environment may interact with the Cl response could make plant and soil diagnostic relationships difficult to interpret. The objectives of this study were to determine the relationships of plant tissue and soil Cl concentrations to hard red spring wheat (Triticum aestivum L.) yield, and to examine possible interactions with plant diseases and water relationships. Field experiments at 14 locations over 3 yr were conducted on Typic Argiustolls, Pachic and Udic Haplustolls, and Pachic Udic and Udic Haploborolls. A critical plant Cl concentration of 1.5 g kg-• for whole plants at head emergence assured 96% of maximum grain yield. Soil Cllevels > 43.5 kg ha-• (60 em) or 75 kg ha-• (120 em)

Spring wheat (Triticum aestivum L.) can be either daylength sensitive or insensitive. Sensitive wheat require long days for timely flowering, whereas insensitive wheat mature normally even in short days. The objective of this study was to compare near‐isogenic daylength insensitive and sensitive hard red spring wheat lines to determine whether insensitivity had adverse effects on agronomic traits and grain protein. Eleven pairs of phenotypically diverse hard red spring wheat lines near isogenic for daylength response were evaluated in 25 environments in the upper Midwest. The grain yield for insensitive lines of all pairs was the same as or higher than for the sensitive lines, averaged over all environments. Yield differences between paired insensitive and sensitive lines varied for specific environments, but a general yield disadvantage for insensitive lines was not observed in any environment. Insensitive lines tended to outyield their sensitive counterparts in environments with lower mean yields or shorter grain fill periods. The insensitive lines were earlier in heading than the sensitive lines for most but not all pairs. Grain protein content for insensitive lines was the same as or lower than for sensitive lines, but selection of insensitive lines with adequate protein should not be difficult. The incorporation of insensitivity appears to result in genotypes generally well adapted to the upper Midwest, and may have beneficial effects on some agronomic traits.

Cereal grain yield response to KCI fertilization has been reported on high K-testing soils in the Northern Plains. Other field studies have demonstrated that wheat (Triticum aestivum L.) yield increases to CI fertilization occurred where disease incidence was high. Therefore, field experiments on high K-testing soils were conducted over a 3-yr period to determine the responsiveness of spring wheat, barley (Hordeum vulgare L.), and oats (Avena sativa L.) to KCI fertilization and to determine whether responses were due to K or to CI. Experiments were conducted on soils representing Typic Argiustolls, Pachic Udic and Udic Haploborolls, and Pachic and Udic Haplustolls in eastern South Dakota. Spring wheat, barley, and oats showed grain yield increases (0.10 probability level) at four out of six, three out of six, and zero out of five sites, respectively, on soils that tested very high in ammonium acetate-extractable K. Wheat grain yield increases varied form 0.2 to 0.5 Mg ha-•. Comparison of KCI, KN0 3 , and CaCh treatments, soil analysis, and plant analysis all indicated that the yield increases on very high K-testing soils were due to the CI in the KCI and not due to the K. Six additional wheat experiments were conducted to determine the influence of starter K and CI (applied with seed) on grain yield; however, no yield increases to CI were detected in these studies. Both KCI and KN0 3 at a 20 kg K ha _, rate significantly decreased yield at one of six sites. Other experiments showed that if sufficient CI was present in the soil or broadcast applied, no additional benefit to seed placed CI occurred. Generally, broadcast and seed placed KCI appeared equally effective. However, rates required for maximum yield at several sites were too high to be placed in direct seed contact with drill application due to potentially adverse salt effects. Grain yield increases were large enough to make KCI fertilization of these soils very economical, provided responsive sites could be predicted.

The rooting patterns of two tall and three semi‐dwarf winter wheat (Triticum aestivum L. em Thell.) cultivars were evaluated under dryland field conditions in eastern Colorado. Radioactive phosphorus (32P) was foliar applied at the soft dough stage of plant development and allowed to distribute through the root system for a 5‐ day period. Root systems were then evaluated by measuring the relative distribution of radioactivity in soil‐root cores at 30‐cm increments through the soil profile to a 300‐cm depth. Soil moisture contents, determined at harvest, were used to compare the five cultivars for associated soil profile moisture contents. We found no significant relationships between cultivar height and rooting depth or moisture extraction patterns. All cultivars rooted to a minimum depth of 300 cm both years of this experiment.