Influence of Cutting Management and Environmental Variation on the Yield, Bud Activity, and Autumn Carbohydrate Reserve Levels of Crownvetch1

Abstract

Abstract‘Chaining’ crownvetch (Coronilla varia L.) was grown at four West Virginia locations: Morgantown, Wardensville, Reedsville, and Point Pleasant. These locations vary in amount and distribution of rainfall, temperature, snow cover, and length of growing season and show how combinations of environmental factors affect yield, morphology, and carbohydrate reserves. Yield and bud activity as affected by cutting at different growth stages and heights are presented. The effect of two and three harvests per season on yield and fall carbohydrate levels was also studied.Yields varied greatly among locations and years. Greater than 10,000 kg/ha were produced at Morgantown in 1969 and Reedsville in 1970 compared with total yields at Point Pleasant of 2,000 to 4,000 kg/ha from a thin stand. Greater yields generally were produced by two rather than three harvests per season. Clipping to stubble heights of 7.5 or 15.0 cm resulted in similar yields. First cutting yields generally increased as the first harvest was delayed to full bloom (mid‐June); however, delaying harvest past this period seldom increased yield. Cutting treatments did not detrimentally affect any of the stands, except possibly at Morgantown, where general vigor of the stand was lower the second season.The proportion of axillary buds producing growth increased with delay of spring harvest until full bloom and then declined. Delay of the first cutting and adequate moisture increased the proportion of axillary buds that produced regrowth. Cutting at different stubble heights generally had no effect on activation of axillary buds.Initiation of growth from crown buds was determined 2 weeks after cutting. Active buds at the crown and up to 2.5 cm from the base of 100 randomly selected stems were counted. Growth initiation from crown buds was greater when plots were cut at 7.5 cm than when cut at 15.0 cm for most cutting dates and locations. Crown bud activity was generally less during early spring and periods of moisture stress.Total non‐structural carbohydrates (TNC) in autumn were similar among locations. Slightly higher TNC values were associated with the 15.0 cm cutting heights, due mainly to changes in starch levels.