Higher costs associated with glyphosate tolerant (GT) compared to nonGT alfalfa (Medicago sativa L.) seed stimulates questions about reduced seeding rates in combination with the GT technology. Our objective was to determine if glyphosate herbicide in combination with GT alfalfa could improve the persistence, productivity, or forage quality when seeding alfalfa at a reduced rate. Glyphosate-tolerant alfalfa was seeded at seven locations into conventionally tilled seedbeds at rates of 6.7, 11.2, 15.7, and 20.2 kg ha -1 pure live seed (PLS) in the spring of 2006. Stand density, botanical composition, yield, and forage quality were determined for each seeding rate under three herbicide treatments: (i) glyphosate [N-(phosphonomethyl)glycine], (ii) a nonglyphosate herbicide, and (iii) no herbicide. Level of weed infestation was diff erent among locations, but there were no weed infestation × seeding rate or herbicide × seeding rate interaction. Lower seeding rates had lower plant mortality than higher seeding rates. Seeding rate had no aff ect on forage quality or weed content at any harvest. At only the fi rst harvest in the seeding year did the 6.7 kg ha -1 seeding rate produce less alfalfa forage (about 250 kg ha -1 ) than other seeding rates. In both the seeding year and year aft er seeding, using herbicides resulted in less weed and greater alfalfa yield than when no herbicide was used. Regardless of weed control treatment, seeding rates of GT alfalfa greater than 6.7 kg ha -1 did not improve weed control, alfalfa yield, total herbage (alfalfa + weeds) yield, or forage quality.Abbreviations: ADF, acid detergent fi ber; CP, crude protein; DM, dry matter; NDF, neutral detergent fi ber; PLS, pure live seed.

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Three varieties of Sorghum bicolor (L.) Moench, (i.e., 'Early Hegari,' '80-Day 2Vlilo,' and 'Wheatland') were grown in controlled environment chambers and subjected to all combinations of 10-, 12-, and 14-hour photoperiods, 27 and 32 C day temperatures, and 16 and 21 C night temperatures. Days to floral initiation were determined for each variety under each treatment combination. In addition, days to anthesis and days in the floral period (from initiation to anthesis) were determined for the treatment combinations involving 21 C night temperatures. Ten-hour days hastened floral initiation and anthesis of each variety at all temperature combinations. ~'ourteenhour days delayed development, but with some temperature regimes the delay was not significant, compared to the shorter days. The rate of development for the varieties under 12-hour days was highly dependent upon day and night temperatures, since floral initiation ranged from as early as that obtained with 10-hour days to later than that obtained with 14-hour days. The response to day temperature during the floral period was small, but statistically significant. The time to anthesis followed a pattern similar to that for the time to floral initiation.

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