The Effect of Dry Heat on Alfalfa Seed and its Adulterants¹

Abstract

Many experiments dealing with the result, as measured by germinative power, of the application to seeds of different amounts of heat for varying periods of time have been carried out. Seeds ot a large number of plants have been subjected to tests and the results recorded. The investigations include the effect of heating seeds in soil, in water, in atmospheres of different relative humidities, in carbon dioxid, in ether, in carbon disulphid, and in dry air. Each specific experiment has been associated with various temperatures and with various periods of time. The actual methods used in determining results are about as diversified as the tirri.e and temperature.This study presents data dealing only with the effects of dry heating seed at high temperatures. In the discussion of the literature, therefore, only that material will be considered which has a direct bearing upon this phase of the heating problem.

Effect of Heat on Impermeable Seeds of Alfalfa, Sweet Clover, and Red Clover1

“…Unlike the findings of Staker (15), this study showed that the percentage of germination regularly increased . as either the temperature or the length of treatment was mcreased, within limits.…”

“…Lute (8), Hopkins (3), Leggart (5), and Whitcomb (18,19,20), among others, proved that all, or nearly all, hard seed~ in legumes are live seeds. Many investigators have searched for methods to make hard seeds permeable so that germination would occur along with naturally permeable seeds (1,2,3,4,7,8,9,11,12,14,15,16,20). Of this group of investigators, a few experimented with the effect of dry heat on hard seeds of legumes with varying degrees of success (2,7,15,16).…”

“…It was also found that the treated seed showed no loss of vitality after 5 months. Staker (15) in 1925 concluded that a temperature of 60°C. was as effective in increasing germination as one of 90°C.…”

Ecological Significance of Seed Coat Impermeability to Moisture in Crimson, Subterreanean and Rose Clovers in a Mediterranean‐Type Climate

“…l\Iartin ( 1945) reported that impermeable seeds of sweet clover, in natural field seedlings and when stored over-winter in unheated buildings in Iowa, became 80-lOOo/a permeable by the middle of the following April. Hutton and Porter ( 1937), Lute (1928), Rincker (1954), Staker (1925) and Stewart ( 1926) found that subjecting seeds of impermeable species to dry heat temperature of 60°-85 oC for periods of 2-6 hr effectively decreased the percentage of impermeable seeds. Stone and Juhren (1951) found that the fire induced germination of Rhus ovata.…”

Effect of dry heat treatment on seed-borneFusarium graminearumand other cereal pathogens

“…(Kuhle 1908), and Fusarium graminearum Schwabe (Shapovalov 1917). Atanasoff and Johnson (1920) Besides pathogen control, dry heat can also kill weed seeds (Staker 1925) and insects in grain (Eman 1992;Czerniakowski 1993). Studies have shown that both seeds and pathogens vary in their ability to tolerate heating (Takano et al 1985;Gao 1990;Temiesagdie and Takano 1990).…”