Response of Six Alfalfa Populations to Selection under Laboratory Conditions for Germination and Seedling Vigor at Low Temperatures

Abstract

Alfalfa (Medicago sativa L.) seeded in early spring often germinates and emerges under cold temperatures. We conducted this study to determine if phenotypic recurrent selection improved germination time and seedling growth under cool temperatures in the laboratory. Four selection methods were conducted in the laboratory for two cycles within six commercial alfalfa cultivars: 5454, Alfagraze, Amerigraze 401+Z, Innovator +Z, Magnum IV, and WL252HQ ranging in fall dormancy class from two to four. Cycles 0, 1, and 2 were evaluated in controlled environmental chambers. Two cycles of selection for rapid germination at 5°C decreased germination time (GT) by 29%. Response to selection was greatest in the first cycle. Two cycles of selection for high seedling vigor increased seedling height (SH) after 45 d at 10°C by 15%. In some cultivars, selection for high seedling vigor was effective at increasing SH in the laboratory and further increases may be expected. Selection for high seedling vigor increased GT, indicating an association between these traits under laboratory conditions. The mean realized heritability estimates were 0.49 for GT and 0.18 for SH. Selection for both early germination and high seedling vigor resulted in an average decrease in GT of 29% with no effect on SH after two cycles, but combined selection against both traits increased GT by 162% and decreased SH by 18%. Laboratory selection for decreased GT and increased SH under low temperatures can be successful, but the amount of improvement is population dependant.

A butenolide, isolated from smoke, can overcome the detrimental effects of extreme temperatures during tomato seed germination

“…Sub-optimal temperatures proved less detrimental for the progress of seed germination compared to the supra-optimal temperatures for tomato seeds. Similar differential effects of temperature have previously been documented for other crop plants such as alfalfa (Klos and Brummer 2000), sesame (De Carvalho et al 2001) and pea (Sincki et al 2004). The exposure of seeds to low temperature often results in slow growth of seedlings due to metabolic arrest.…”

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

“…Two cycles of phenotypic recurrent selection were conducted within each cultivar using the following four methods (Klos and Brummer, 2000):…”

“…Selection under laboratory conditions for GT and seedling vigor under low temperatures was conducted in six alfalfa cultivars (Klos and Brummer, 2000). Two cycles of selection for early germination at 5°C decreased the average GT in the laboratory by 29%.…”

“…The objectives of this study were to assess changes in emergence and seedling height in the field after two cycles of phenotypic recurrent selection for GT and seedling vigor at suboptimal temperatures under laboratory conditions and to compare these results with those observed in laboratory evaluations (Klos and Brummer, 2000).…”

Germination response of Hylocereus setaceus (Salm-Dyck ex DC: ) Ralf Bauer (Cactaceae) seeds to temperature and reduced water potentials

“…In Medicago sativa L. (alfafa), for example, rapid germination and primary root growth at infra-optimal temperatures in the laboratory was positively correlated with high emergence at field conditions (Klos and Brummer, 2000). Thus, germination cueing determines a particular set of environmental conditions that a germinant will encounter (Donohue, 2005) and seeds often respond to combinations of environmental factors that are most favourable to the seedling growth and survival (Simao et al, 2007;De La Barrera and Nobel, 2003) Temperature is a very important factor controlling seed germination, affecting both the rate and final percentage of germination.…”