Field Response to Selection in Alfalfa for Germination Rate and Seedling Vigor at Low Temperatures

Abstract

Successful establishment of alfalfa (Medicago sativa L.) stands in early spring may require emergence and seedling growth at soil temperatures below 10°C. The objectives of this experiment were to evaluate changes in emergence and seedling height after laboratory selection in six cultivars at suboptimal temperature for (i) early germination (EG), (ii) high seedling vigor (HSV), (iii) EG + HSV, or (iv) late germination and low seedling vigor (LG + LSV). Cycles (C) 0 to 2 were evaluated for emergence 8 d after planting, seedling height (SH) 27 d after planting, forage dry matter yield, and other agronomic traits in field trials at Ames and Nashua, IA, in early spring 1998. Emergence was improved in all selected populations at Ames but not at Nashua; HSV and EG + HSV selection were most effective at improving emergence. After two cycles, seedling height was increased 21% by HSV selection and 9% by EG selection; however, the response among cultivars was highly variable. Combined EG + HSV selection was less effective than HSV alone at increasing height. Selection for LG + LSV did not reduce seedling height in the field even though large decreases were previously observed in the laboratory. Most gain from selection was realized with C1, possibly because the variable seed production environment in the greenhouse may have limited more consistent responses in C2. Seedling height selection at suboptimal temperatures in the laboratory successfully improved seedling height in the field in some alfalfa populations without changing other agronomic characteristics.

Recurrent selection for wider seedling leaves increases early biomass and leaf area in wheat (Triticum aestivum L.)

“…Attempts to increase early vigour through either improved establishment or development of larger seedlings have been restricted to allogamous species where controlled intermating and seed production is simpler. Here genetic gains for vigour of up to 10% per cycle have been demonstrated across a range of species including pasture legumes ( Klos and Brummer, 2000 ; DeHaan et al , 2001 ) and various pasture grasses (e.g. Faulkner et al , 1982 ; Jefferson et al , 2001 ).…”

Study of the Effect of Low Temperatures and Calcium Chloride Treatment on the Germination of Iranian and European Barley Cultivars

“…Reducing the temperature reduced seedling growth, but seed germination was more tolerant to cold stress than seedling growth. Klos and Brummer (2000) stated that the temperature of the environment determines the success of germination and seedling growth, and affects the capacity and velocity of germination. Particularly temperatures below the optimum can cause poor seed germination.…”

Selection for Establishment Capacity in Reed Canarygrass

“…Similarly, selection for increased germination rate increased field emergence and seedling height in alfalfa, Medicago sativa L. (Klos and Brummer, 2000b). Similarly, selection for increased germination rate increased field emergence and seedling height in alfalfa, Medicago sativa L. (Klos and Brummer, 2000b).…”

“…Thus, it appears that an increased rate of seedling emergence may be a factor in the increased establishment rate of the selected populations. Similarly, selection for increased germination rate increased field emergence and seedling height in alfalfa, Medicago sativa L. (Klos and Brummer, 2000b). Variation among the 13 population means was not significant for the number of days to 50% emergence (D50).…”

“…increased seedling height by 8% cycle 21 and stand density by 13% cycle 21 (Voigt and Brown, 1969). Two cycles of selection for seedling height in alfalfa increased field emergence by 4% cycle 21 at one of two locations (Klos and Brummer, 2000b). Thus, seedling vigor appears to be a key component to seedling establishment across a wide array of perennial species.…”