Jdnb 3, 1920. 



The Florists' Review 



17 



GERMINATION OF SWEET PEAS 



^<i w''?< i v?Vt i ,^t l »^A-« i t^« i .^» l »^A-tlrA-» l r^^ ^ 



EOWEES have experienced 

 difficulty in securing a 

 satisfactory germination 

 of sweet pea seed, par- 

 ticularly with the white- 

 seeded sorts and some of 

 the newer introductions of 

 the dark-seeded varieties. 

 The experimental commit- 

 tee of the State Florists' 

 Association of Indiana, at a meeting in 

 September, 1919, requested the experi- 

 ment station at Purdue University to 

 investigate causes of low germination 

 and possible remedies. Preliminary ex- 

 periments were therefore started at the 

 university greenhouse. One of the 

 senior students assisted in securing the 

 data reported in this article. 



The investigation as undertaken can 

 properly be divided into two phases; 

 first, a study of different methods of 

 germination, and second, a germination 

 test of some of the principal varieties. 

 The first phase was divided into five 

 parts, as follows: 



Methods of Oermination. 



1. Effect of soaking the seed in water 

 for different lengths of time. 



2. Effect of chipping the coat of all 

 seeds not swollen after soaking in water. 



.■?. Treating the seeds with sulphuric 

 acid. 



4. Comparison of the germination in a 

 warm and a cool house. 



5. Comparison of the germinations of 

 seeds planted in sand and in soil. 



Three varieties were selected for this 

 phase of the work; namely, Mrs. M. 

 Spanolin, Lavender Orchid and Bridal 

 Veil. Mrs. M. Spanolin was chosen be- 

 cause it was thought this variety would 

 act as a check on the results obtained 

 from the germination of the other two 

 varieties, which commonly give low 

 germination. Fifty seeds were used for 

 each test. 



As had been expected, the variety Mrs. 

 M. Spanolin gave a rather uniform 

 germination throughout the experiment, 

 regardless of the treatment, while the 

 other two varieties varied from no 

 germination at all to 100 per cent 

 germination with the different treat- 

 ments. 



Soaking Seed in Water. 



Sufficient lots of each variety were 

 counted and soaked for six, twelve, 

 eighteen and twenty-four hours in warm 

 water. The seeds were immersed in 

 water heated to 140 degrees and placed 

 in the rose house, where the tempera- 

 ture of the water doubtless fell to ap- 

 proximately the temperature of the air. 

 After the soaking, some of the seeds 

 were planted directly in the soil in the 

 sweet pea house, while other lots were 

 planted in 2%-inch pots and sprouted 

 in the rose house and in the sweet pea 

 house, i^xcept in a few unexplainable 

 cases, the soaked seed gave better germi- 

 nation than the checks not soaked. The 

 germination was somewhat better in the 

 soil of the ground bed than in the pots, 

 ])robably because the pots were occa- 

 sionally allowed to become too dry. 



By H. D. BROWN, 



Of Purdue University Kxperimcnt Station, 

 La Fayette. Intl. 



Better germination was secured in the 

 cool house than in the warm house. 

 Seeds of the varieties Bridal Veil and 

 Lavender Orchid, when soaked for 

 twelve, eighteen and twenty-four hours 

 and planted in soil, gave fully as good 

 results as unsoaked seed in sand, prov- 

 ing that sand is not always necessary 

 for best results. 



Table 1 — Seed treated with warm water and 

 planted In ground beds of cool house. 



Per cent germinated 



Hours Mrs. M. Lavender Bridal 



treated Spanolin Orchid Veil 



6 82 10 82 



12 CO 78 , 64 



18 88 66 96 



24 76 78 88 



Check 82 36 38 



Chipping the Seed. 



A considerable number of seeds failed 

 to swell after the six hours' soaking, 

 but after the twelve hours' treatment 

 most of the seeds had swollen. The 

 seeds of the variety Mrs. M. Spanolin 

 absorbed water more slowly than those 

 of the other two varieties. The seed 

 coats of one lot of seed were chipped 

 in the cases where the seeds had not 

 swollen after the period of soaking. 

 Although this practice resulted in a 

 slightly higher i)ercentage of germina- 

 tion in some instances, the difference 

 was not great enough to warrant its use 

 with any of these varieties. 



house, than in the warm or rose house, 

 although germination was hastened in 

 the warmer house. This holds true for 

 all varieties, regardless of the previous 

 treatment. The greatest differences 

 were shown by the varieties Lavender 

 Orchid and Bridal Veil. 



Table 4 — Seed with and without water treat- 

 ment, planted in 2!/.-inch pots and germinated 

 in warm and cool houses. 



Per cent Rorminated 



Hours Mrs. SI. Lavender Bridal 



treated Spanolin Orcliid Veil 



Warm house — 



6 66 2 6 



12 48 84 .')2 



18 88 44 68 



24 86 50 44 



Cool house — 



6 80 2 22 



12 SO 80 48 



18 82 ns 88 



24 84 52 86 



None 86 56 15 



Warm house — - 



None 56 28 



In Sand or Soil? 



Bridal Veil gave no germination in 

 soil in the rose house and ninety per 

 cent germination in sand, and a germi- 

 nation of fifteen per cent and eighty- 

 eight per cent for soil and sand in the 

 cool house, clearly indicating that this 

 variety germinates much better in 

 sand. Lavender Orchid gave a germina- 

 tion of twenty-eight per cent in soil and 

 seventy per cent in sand when grown in 

 the rose house, and fifty-six per cent and 

 seventy-eight per cent when germinated 

 in the cool house, also clearly indicating 

 that sand was a better medium for its 

 germination. The variety Mrs. M. 



Table 2. 



Hours 

 treated 



6 



12 



18 



24 



Check 



-Seed coats chipped if not swollen after water treatment. Planted in cool house. 

 (Compare results in Table 2 with those in Table 1.) 



Mrs. M. Spanolin 



Per cent Number 



germinated chipped 



74 44 



42 42 



85 2!» 



86 33 

 82 



Lavender Orchid 

 I'er cent Number 



germinated 



4 



100 



61 



fi(> 



30 



chipped 











1 



1 



Bridal \' 



Per cent 

 germinated 



r,c, 



80 

 !»6 

 06 

 38 



eil 



Number 



chipped 



22 



'o 



12 

 6 



Sulphuric Acid Injurious. 



The three varieties were each treated 

 for two, five, ten, thirty and forty 

 minutes in commercial sulphuric acid 

 (spg. 1.8.T) and rinsed in running water 

 immediately after treatment. The two 

 minutes' treatment had no injurious 

 effect on any of the varieties. Longer 

 treatments, however, reduced the germi- 

 nation of Bridal Veil and Lavender 

 Orchid to almost nothing, while the Mrs. 

 M. Sj)anolin was not affected by even 

 the forty minutes' treatment. Sulphuric 

 acid is not recommended. 



Table 3 — Seed treated witli sulphuric acid and 

 planted in ground l)od of cool liouse. 



— Per cent germinated 



In Warm or Cool Houses? 



In general, better germination was 

 secured in the cool house, or sweet pea 



Spanolin shows no better germination 



when startefl in sand. 



Table 5 — Seed planted in sand and soil in 2i4!- 

 ineh pots and genninated in the warm and cool 

 house. 



Per cent germinated 



Where Mrs. M. Ijiveiuler Bridal 



planted Spanolin Orchid Veil 



Sand in warm house... 70 70 90 



Soil in warm house... 56 28 



Siind in cool lioiise 78 7S 88 



■Soil in cool house 86 56 15 



Tests of Sixteen Varieties. 



The second phase of the work was 

 mainly a germination test of some of 

 the commercial varieties. The seeds 

 were all germinated in sand in 2i^- 

 inch pots in the rose house. Three lots 

 of each variety were selected, as fol- 

 lows: One lot of large seed, one of 

 average-sized seed and one of small 

 seed. In general, the large seed gave 

 by far the l)cst germination, the medium- 

 sized seed next best and the smallest- 

 sized seed the poorest germination. The 

 varieties germinated as indicated in 

 Table G, on the following page. 



From the foregoing experiments, it is 

 evident that there are a number of 

 factors which must be considered in tho 

 most effective sweet pea germination, 



