Root Morphology and Vigor Effects on Winter Heaving of Established Alfalfa¹

Abstract

There has been considerable speculation regarding the influence of root system morphology on the susceptibility of alfalfa (Medicago sativa L.) to frost heaving injury. This field study represents a first attempt at quantification of that relationship. A tagging technique was developed for monitoring heave of established alfalfa plants during winter. Measurements were made on a Collamer silt loam (Glossoboric Hapludalf) intergrading to a Niagara silt loam (Aeric Ochraqualf) near Ithaca, NY. Final (net) crown displacement above the soil surface was positively correlated with plant upheaval in midwinter, although maximal uplift was partially reversed as the soil thawed. Plants were retrieved after the winter and evaluated for differences in vigor and taproot architecture. Under comparable soil heaving conditions, 2‐yr‐old plants with the creeping root trait experienced a mean net uplift of 5.5±1.1 mm compared to 8.5±1.2 mm for plants with a pronounced taproot; this difference was significant at P < 0.06. In contrast, spatial variation in maximum soil heave was more important than root morphological parameters in determining uplift of 3‐yr‐old plants from a single taprooted cultivar. Only 45% of the total variance in maximal crown displacement could be explained by multiple regression analysis, suggesting that undefined variables, such as root anchorage and tissue elasticity, may be involved. Approximately 60% of the taproots appeared to have heave related lesions. The vigor of these mature plants was generally unrelated to frost heaving; net upheaval was correlated with the degree of crown rot, but not with root rot, number of crown buds, or curculio (Sitona hispidula F.) scarring.

Frost heaving of forest tree seedlings: a review

“…Shimada et al (1982) showed that heaving resistance is weak in alfalfa plants having a straight deep tap root with few branch roots. Perfect et al (1987) found that alfalfa plants with a broken taproot experienced greater soil heaving in midwinter. Gill (1977) studied the susceptibility of 16 onion varieties to frost heaving and found that root number and length played an important role.…”

“…x Biswell et al 1953MacGillivray and Hartley 1973Soderstriim 1973 x Low 1969, 1975Shaw et al 1987Zalasky 1980I Graber 197 1 Sutton 1968, 1991, 1992Haasis 1923Shimada et al 1982cox 1979Gill 1977Kinbacher 1956Cox and Mason 1955Biswell et al 1953Lamb 1936 Factors Factors affecting forest heaving of forest tree species and agricultural crops Haasis 1923Brink et al 1967Russell et al 1978Sutton 1969, 1992Cooper 1940Perfect et al 1987Shimada et al 1982;Portz 1967Gill 1977 Hook. and Am.)…”

“…and Am.) and wedgeleaf ceanothus ( Woods et al 1978Woods et al , 1979 x Ledgard 1976Haasis 1923Holmes and Robertson 1960Gradwell 1960 ladino clover (Trifolium Decker and Ronningen 1957 Noble andAlexander 1977 Schubert 1970;Larson 1960Biswell et al 1953Wright 1944 alfalfa (Medicago sariru L.) Perfect et al 1987;Shimada et al 1982;Russell et al 1978 hardinggrass ( Kinbacher 1956Lamb 1936 placed between the plots consisting of three seed rows sown across the width of the seedbed. The following spring a slight frost heaving of seedlings in the center rows of the plots was observed.…”

“…Root systems of many 4-and 5-year-old white spruce on soils subject to frost heaving were highly asymmetric in plan view (Sutton 1969). Perfect et al (1987) believed that the differential frost upheaval of healthy plants may depend on endogeneous factors such as root strength and branching. Deeper roots probably provide greater anchorage within the subsoil, thereby lessening the amount of heaving damage.…”

Responses to divergent selection for adventitious root growth in red clover (Trifolium pratense L.)

“…Specific root traits have been correlated with better persistence in these crops. In alfalfa, root branching (Perfect et al, 1987) or creeping roots (Heinrichs & Morley, 1960) and number of secondary roots (Hansen & Viands, 1989) have been positively associated with better persistence. Adventitious roots originating from the crown are thought to promote better persistence in red clover.…”