Physiol. 1940 January; 15(1): 137–141.
RESPONSES OF VARIOUS SPRING WHEATS TO VERNALIZATION
P. J. WORT
(WITH TWO FIGURES)
There is little information in the literature regarding North American varieties of spring wheat which are responsive to vernalization treatment. The same variety has been reported by different investigators to react positively or negatively to treatment. For example, VAN HOEK (3) obtained acceleration of maturity when spring wheat was vernalized, but treatment of the same variety by GMELIN (1) gave no acceleration of flowering. WORT (4), using the same treatment with two different samples of Marquis wheat, found that the acceleration of flowering was 21 days in one case, and 2.6 days in the other, although growing conditions were similar. KOSTJUCENKO and ZARUBAILO (2) and others suggest from experiments with cereals grown in northern latitudes that at least part of the stage of vernalization (thermostage) may be completed during ripening and that this partial completion may reduce subsequent reaction to treatment. The environment, acting on a developing seed, affects the behavior of the plant produced by the seed.
|1The writer is indebted to Dr. O. H. DUNGAN of the University of Illinois; Dr. S. P. SWENSON of the University of South Dakota; and Dr. L. B. WALDRON of the University of North Dakota for the supplies of seeds used.|
Samples of various spring wheats (table I) obtained from the Departments of Agronomy at the State Universities of Illinois, North Dakota, and South Dakota,1 were vernalized in an attempt to determine which varieties respond to vernalization and if varieties grown in different areas respond differently.
The procedure used for vernalization was as follows: (1) the amount of water, given in the formula used, was added to 20 gm. of seed in Petri dishes; (2) the seeds were allowed to germinate for 24 hours at 20°C.; (3) the Petri dishes were then stored for the required lengths of time in mechanical ref rigerators at the temperatures given in the formulas. The lids of the Petri dishes were removed daily and the seeds aerated for a few seconds.
The factors in a formula in order are length of chilling in days, temperature during chilling in degrees C., and amount of water added in percentage of the original air-dry weight of the seed. Three formulas were used: (1) for early varieties, 6: 10: 50; (2) for medium varieties, 9 : 6: 50; and (3) for late varieties, 12: 4: 50. These formulas are referred to by number in table I. Control seed was germinated 24 hours at 20°C., the water added being 50 per cent.
Five plants of treated or control grain were grown in 6-inch pots filled with well-mixed loam soil. Three replicates were used. All plantings were made on Sept. 9, 1939. Daylight was supplemented by 200-watt mazda lamps suspended 3 feet above the pots to give a 16-hr. day for the first 10 days, and an 18-hr. day thereafter. The plants were watered once a day. Flowering was assumed to have occurred when the anthers were first extruded.
Results and discussion
The results are recorded in table I. The source of the grain is stated in the second column and the rating of the wheat by local authorities is on the basis of very early (VE), early (E), medium early (ME), medium (M), medium late (ML), and late (L).
VERNALIZATION TREATMENTS, AND ACCELERATION OF FLOWERING OF SPRING WHEATS
|General San Martin||Ill.||2||38.9||39.3||0.4|
|Illinois 1 (Station)||Ill.||2||43.0||44.0||1.0|
|Illinois 1 (Mann)||Ill.||2||44.5||44.0||-0.5|
|Reliance x Prelude||S.D.||M||2||52.5||53.5||1.0|
* Minus sign indicates n retardation in flowering.
An examination of the table shows that a total of 27 samples responded to vernalization by acceleration of flowering and 9 were retarded by treatment. This ratio of 3:1 holds for the three main groups, early, medium, and late. Accelerations or retardations of less than one day, however, are probably insignificant. In some eases all samples of the same variety obtained from two or more sources (Marquis, Pilot, Premier, Renown, Rival, and Thatcher) responded similarly, and in other cases differently to treatment. Thus the accelerations of flowering of samples of Premier, obtained from North Dakota and South Dakota, were practically the same, being 0.7 and 0.9 days respectively. Marquis from South Dakota was accelerated in its flowering by 3.4 days; from North Dakota, retarded by 1.5 days; and a sample obtained in Chicago responded to treatment with an acceleration of 1.8 days. In a number of cases the relative flowering time of the samples grown in the greenhouse, did not correspond to the earliness rating given by the institutions supplying the grain.
|FIG. 1. Representative plants, South Dakota Marquis wheat, age 46 days. V = vernalized, C = control.|
The average height of the vernalized plants was slightly greater than control in most cases; for example, Marquis (South Dakota) was 10.5 per cent, taller, and Thatcher (North Dakota) was 7.6 per cent. taller than their controls when measured on Oct. 31. The increased height was due to longer internodes. The appearance of these plants on Oct. 25 is shown in figures 1 and 2.
|FIG. 2. Representative plants, North Dakota Thatcher wheat, age 46 days. V = vernalized, C = control.|
The varied responses of the cereals make it very difficult to correlate the available weather data covering the period of flowering of the parent plant, and ripening of the seed later treated, with the seed's reaction to vernalization. It can be said, however, that the five varieties whose flowering was accelerated most by treatment—Comet (3.7 days), Marquis (3.4 days), Purdue (3.1 days), Rival (3.0 days), and Komar (2.3 days)—had been grown in South Dakota or Illinois where the temperature during flowering and ripening was higher than that in North Dakota. Of six varieties that had been grown in North Dakota and some other state only two of those produced in the more northerly area gave a greater response when tested.
While the vernalization formulas used may not have been optimum for all varieties, the results indicate those which are most responsive to treatment and hence most favorable for vernalization studies.
Thirty-six samples of various spring wheats from different regions in the United States were vernalized; of these, 27 responded with an acceleration, and 9 with a retardation of flowering. Some varieties responded differently to treatment depending on the location where the seed had been produced, others responded similarly irrespective of their origin. The samples that responded most to vernalization were those that had been produced in areas with relatively high temperatures during the flowering and ripening of the parent plant.
DEPARTMENT OF BOTANY
THE UNIVERSITY OF CHICAGO