The objective of this field study was to determine the effect of Austrian winter peas [Pisum sativum spp. arvense (L.) Poir] used as either a green manure (GMP) or seed pea (SP) crop on soil N levels, and yields of subsequent crops of winter wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.). The Austrian winter pea-winter wheat-spring barley (GMP-WW-SB) rotation was compared with seed pea-winter wheat-spring barley (SP-WW-SB), spring barley-winter wheat-spring barley (SB-WW-SP), and summer fallow-winter wheat-spring barley (SF-WW-SB) cropping sequences at two sites similar in annual precipitation. After harvest of the initial rotational crop, plots were divided into four subplots and four rates of N were applied as a topdress application following planting of ‘Stephens’ winter wheat. Spring barley was planted the third year. Winter wheat yields, spring barley yields, and inorganic soil N were not significantly affected by rotation ✕ N fertilizer interactions. Winter wheat yield averages following GMP, SP, SF, and SB were 6.6, 6.4, 6.3, and 4.7 Mg ha⁻¹, respectively. Average N feitilizer equivalent values of 94, 75, and 68 kg ha⁻¹ were provided by GMP, SP, and SF, respectively, to the following winter wheat crop. Yield differences resulting from crop rotation or N fertilization rate were not observed in the third year of the cropping sequence. Austrian winter peas used as either a GMP or SP crop provided more inorganic N for the following winter wheat crop than SF or SB. From a 3-yr total yield the SP-WW-SB was the most efficient cropping sequence, as cereal yields were comparable to the GMP-WW-SB and SF-WW-SB rotations; however, since SP was harvested three crops instead of two (other rotations) were produced. Contribution from the College of Agric., Univ. of Idaho. Approved for publication by the Director of the Idaho Agric. Exp. Stn. as res. paper 88-7-25.

Cold hardening of winter wheat (Triticum aestivum L.) crowns results in decreased water content, and in increases and changes in solutes. These facts led us to hypothesize that osmotic potential (ΨII) of hardened wheat crowns might be used as a screening technique for winterhardiness. Winter wheat with different levels of winterhardiness, ranked from long-term trials, were grown in the field. Periodically, during two winters, plants were removed and the ΨII of the crowns determined. Contrast comparisons between two hardy, and two or three less hardy cultivars showed significant differences, at every sampling date with the hardy lines having lower ΨII. During one winter the ΨII of 24 cultivars whose winter-hardiness had been evaluated over several years in the field was determined on three dates. Linear correlations (r²) between field scores (5 = most winterhardy, 1 = least hardy) and ΨII were highly significant, and varied from 0.75 to 0.83. Based on these data, we suggest that measurement of ΨII of winter wheat crowns following cold acclimation may be a valuable tool in the selection of winterhardy wheat cultivars (formerly graduate research assistant, Montana State Univ., Bozeman). Contribution of the Montana Agric. Exp. Stn. Journal No. J-2075.

Enhanced quality is essential to improve marketability of northwestern USA soft white winter (SWW) wheat (Triticum aestivum L.). The objectives were to compare four major SWW cultivars for six quality criteria and their relative environmental stabilities. Cultivars Daws, Lewjain, Nugaines, and Stephens were grown in 63 site years and evaluated for flour yield, cookie diameter, percent flour protein, alkaline water retention capacity (AWRC), hardness, and sedimentation. Cultivar and environmental effects were significant (P<0.0l) for all traits. Genotype ✕ environment interactions were small, but significant. Among the variance components, years contributed most to total variance for percent protein, sedimentation, and AWRC. The year ✕ site component was greatest for flour yield, cookie diameter, and hardness. Relatively large cultivar ✕ environment components for cookie diameter, hardness, and AWRC required their evaluation across multiple site years. All cultivars had satisfactory overall SWW wheat quality, yet Lewjain and Stephens had the best cookie diameter and flour yield, respectively. Daws was marginal for cookie diameter and hardness, and Nugaines was usually low for flour yield. Stephens and Lewjain were generally the least and most sensitive to environmental variation for quality parameters. Most quality traits were correlated (P < 0.05) with each other within cultivars. The AWRC gave low and usually nonsignificant correlations with all quality parameters except cookie diameter. Intragenotypic differences in grain yield and grain volume weight were correlated (P < 0.05) with all quality traits except AWRC. Grain volume weight differences accounted for 26 to 40% and 36 to 67% of the variation in cookie diameter and flour yield, respectively. Contribution from USDA-ARS and College of Agric. and Home Econ. Res. Ctr., Washington State Univ.

This paper gives the results of wheat stomatal resistance influenced by environmental factors. The analysis method is multiple regression. The results show that soil water potential in the root zone is the major factor that influences stomatal resistance. The effect of environmental factors to abaxial stomata and adaxial stomata are different: the abaxial stomatal resistance is mainly influenced by soil water potential, but the adaxial stomatal resistance is mainly influenced by air temperature and air humidity