7Allard H A. Complete or partial inhibition of flowering in con- tain plants when days are too short or too long[ J ]. J. Agric. Res, 1938,57 (10) :775 - 789.
8Cathey H M and H A Borthwick. Bot. Gaz,1964,125:232 - 236.
9Post K and Kamemoto H. Proc. Amer Soc. Hort. Sci,1950,55 : 477 - 482.