Seedling Growth Comparison of Arrowleaf, Crimson, Rose, and Subterranean Clovers

Abstract

Cool‐season annual clovers are a critical component of profitable pasture systems in the southeastern USA; however, there are little data comparing seedling development of major species. Arrowleaf (Trifolium vesiculosum Savi.), crimson (T. incarnatum L.), rose (T. hirtum All.), and subterranean (subclover) (T. subterraneum L.) clovers were planted in September for 3 yr in northeast Texas. Clovers were sampled biweekly during October and November, and plant density, leaves per seedling, leaf area index (LA1), shoot weight, nodules per seedling, root weight, root length, and root/shoot ratio were determined. Rainfall amounts and distribution caused differences among years (P < 0.05) for plant density, leaves and nodules per seedling, LAI, and root/shoot ratio. Averaged across years, crimson clover had the greatest number of leaves and nodules per seedling, and the greatest shoot weight, root weight, root length, and LAL. Subterranean clover was intermediate, and arrowleaf and rose clovers had the lowest values. Sampling date did not affect plant density and root/shoot ratio, but the other seedling parameters increased with succeeding sampling dates. The greater seedling vigor of crimson clover is due in part to its larger and faster‐expanding LAI and tolerance of cooler temperatures. Subterranean clover was the largest seeded species but is not as well adapted to cooler winter temperatures as the other species. The slower seedling vigor of arrowleaf clover was due to its smaller seed size. Poor nodulation may be responsible for the slow seedling growth of rose clover. Good seedling vigor of cool‐season annual clovers was primarily dependent on large seed size, rapid leaf area expansion, and early nodulation