The genetic control of somatic embryogenesis in alfalfa (Medicago sativa L.) was studied using one nonembryogenic and three embryogenic genotypes: A70-34, a selection from 'Rangelander'; RA3, a selection from 'Regen-S'; and C2-4, a selection from a breeding population that had A70-34 in its pedigree. Crosses of embryogenic × embryogenic and embryogenic × nonembryogenic and S1 and BC1 testcrosses were evaluated for in vitro regeneration. Selfing reduced the expression of the trait. Somatic embryogenesis was dominant and explained by two loci. All three regenerating genotypes shared a common genetic system.Key words: alfalfa, Medicago sativa, somatic embryogenesis, tissue culture.

A market for timothy (Phleum pratense L.) hay exists in Asia and is adapted under irrigation in southern Saskatchewan, but variation among cultivars for the required quality characteristics was unknown. We evaluated forage yield and quality for export and traditional hay markets of timothy cultivars on two irrigated sites in southern Saskatchewan. Eleven cultivars were grown at two N fertilizer rates (100 and 150 kg N ha−1) at Swift Current and Outlook for 3 yr. Seed head length, stem length, leaf/stem ratio, forage dry matter yield, neutral detergent fiber, acid detergent fiber, and crude protein concentrations were determined. Seed head length and stem length, which are quality characteristics for export to Japan, were subject to site × cultivar × year interaction due to instability of some cultivars. ‘Drummond’ had the longest seed heads in five of six site‐years while ‘Toro’ had the shortest in four site‐years. ‘Timfor’ and Toro ranked first to fourth for stem length while Drummond and ‘Bottnia II’ had the shortest stems. Thus, the requirement for long heads and long stems was not met by one cultivar. Principal component analysis separated cultivars based on maturity compared with yield. Richmond, the earliest‐maturing cultivar, was distinct from Drummond, the latest cultivar. The second principal component separated Timfor, a high‐yield and low‐quality cultivar from Bottnia II, a low‐yield and high‐quality cultivar. Drummond is the best cultivar for export markets while Richmond is better suited for traditional markets.

. 1998. Reevaluation of row spacing/plant density of seeded pasture grasses for the semiarid prairie. Can. J. Plant Sci. 78: 257-264. Previous research in the semiarid prairie at Swift Current, Saskatchewan, indicated that optimum row spacing for forage production was 60 or 90 cm for crested wheatgrass (Agropyron cristatum [L.] Gaertner) and Russian wild ryegrass (Psathyrostachys juncea [Fisch.] Nevski). However, recent research suggested that harvest method affects forage yield estimates from row spacing experiments. An experiment with three row spacings of mixtures of alfalfa (Medicago sativa L.) with crested wheatgrass and Russian wild ryegrass was harvested mechanically and by hand. Yield differences between methods of harvesting were affected by row spacing; larger differences were observed at 15 cm than at 60 cm spacing, particularly for Russian wild ryegrass. The highest hand-harvested forage yield estimates were observed in the narrowest row spacing. In a second experiment, plant density was evaluated for the same grasses using square grid spacings of 30, 45, 60, 75 and 90 cm. Decreasing plant density was associated with decreased hand-harvested forage yield in both species. In a third experiment, 60-and 90-cm row spacing resulted in more seed heads and lower leaf content than 30-cm row spacing. Leaf digestibility increased slightly with increased row spacing. These results suggest that 30-cm row spacing should be recommended to producers for sustainable pastures in the semiarid prairie region. ] Nevski) pour la production fourragère. Des recherches plus récentes suggèrent cependant que la méthode de récolte influe sur les rendements fourragers calculés à partir des expériences sur la largeur des interlignes. Nous avons donc réalisé une expérience à trois largeurs d'interligne sur des associations de luzerne (Medicago sativa L.) et d'agropyre à crête ou d'élyme de Russie dans laquelle la récolte se faisait soit à la machine soit manuellement. Les différences de rendement attribuables aux méthodes de récolte variaient selon la largeur de l'interligne, elles étaient plus prononcées à l'écartement de 15 cm qu'à celui de 60 cm, en particulier pour l'élyme de Russie. Le plus fort rendement de fourrage récolté à la main allait à l'écartement le plus étroit. Dans une deuxième expérience, la densité de peuplement était évaluée sur ces mêmes graminées, utilisant pour chaque espèce des espacements équidistants de 30, 45, 60, 75 et 90 cm entre les plantes. Une diminution de la densité de peuplement était associée chez les 2 espèces à une baisse de rendement fourrager récolté à la main. Dans une troisième expérience, les écartements de 60 et de 90 cm entre les lignes donnaient lieu à une plus abondante production d'inflorescences et à une moindre proportion de feuilles dans le fourrage que l'écartement de 30 cm. La digestibilité des feuilles augmentait légèrement à mesure que l'interligne s'élargissait. Il ressort de ces observations que 30 cm est la largeur d'interligne qu'il faudrait recommander aux producteurs de...

Grasses were clipped at threeleaf, heading and seed set. Yield, leaf-to-stem ratio (LSR), botanical composition (BC), crude protein (CP), phosphorus, fibre and in vitro dry matter digestibility (IVDMD) were determined. There were differences (P < 0.05) between the grasses in yield at each growth stage with smooth bromegrass and creeping foxtail having high yields and meadow bromegrass low yields at all growth stages. The BC of most target grasses was greater than 60%. Exceptions were Dahurian wild ryegrass, crested wheatgrass, tall wheatgrass and meadow bromegrass. There were few significant differences between the grasses for LSR, except that Russian and Altai wild ryegrasses and meadow bromegrass had higher LSR (P < 0.05) than the other grasses. Differences in CP, P, neutral (NDF) and acid (ADF) detergent fibres were inconsistent and small at each growth stage but CP and P declined (P < 0.05) while NDF and ADF increased (P < 0.05) with plant maturation. There were differences (P < 0.05) between years and cuts for all traits except between years for yield, BC and LSR at seed set (P > 0.05). Dry matter intake (DMI) NDF and in vivo dry matter digestibility (DMD) were determined for hay cut from each plot using sheep. The relationship between forage NDF and DMI: was used to calculate predicted DMI (PDMI) for all clipped samples. Hay IVDMD differed from DMD (P < 0.05) and the regression DMD = 1.27 IVDMD -5.75 (r 2 = 0.89; RSD = 3.21; P < 0.001) was used to adjust IVDMD to predicted in vivo digestibility estimates (PDMD). PDMD differed (P < 0.05) between the grasses only at heading and seed set. Yield of PDDM (YPDDM), yield of CP (YCP) and the sum of these and PDMI were used to rank the grasses for usefulness as hay or pasture for early or late grazing.

Seedling tiller number is a possible selection criterion to improve seedling establishment of Altai wildrye, Leymus angustus (Trin.) Pilger, an important grass for autumn grazing of beef cattle in semiarid environments. Forty‐two half‐sib families selected for high seedling tiller number (HTN) and eighteen half‐sib families selected for low seedling tiller number (LTN) by four cycles of divergent recurrent selection were compared with four controls, Altai wildrye cultivars Prairieland, Eejay and Pearl, and crested wheatgrass (Agropyron desertorum (Fisch. Ex Link) Schultes), cultivar Nordan, on dryland and irrigated sites at Swift Current, Saskatchewan, Canada. Seedling tiller count, seedling height, tiller weight and seedling dry‐matter yield (DMY) were determined on two plants per plot and DMY was determined for each plot for 2 years post‐establishment. HTN half‐sib families had more, lighter and shorter tillers than LTN half‐sib families. There was a negative correlation (r=–0·42, P < 0·01, n=60) between seedling DMY and tiller number. HTN half‐sib families had higher DMY in post‐establishment years at the dryland site only. Seedling tiller number in Altai wildrye may be related to DMY at sites at which resource availability delays seedling establishment, but selection for HTN will not increase seedling DMY owing to concomitant changes in carbon allocation.