Scarification studies on southern grass seeds

1. The large percentage of empty florets, delayed germination and ergot are some of the factors which reduce materially the chances of successfully establishing some of the southern grasses from seed. 2. Seed yields taken on 3,500 Bahia plants at Tifton indicate that strains capable of producing 300 to 600 pounds of seed per acre can be found. 3. Seed samples taken from 175 different Bahia grass plants were planted in steam-sterilized soil in the greenhouse and optimum growing conditions were maintained throughout the experiment. Three months after these samples were planted, 35 of them still showed no signs of life and an average viability of 3.2% was obtained in the remaining 140 seed lots. 4. All germination tests were made by planting 100 seeds in duplicate or triplicate in flats of steam-sterilized soil in the greenhouse. Seedling counts were usually made at weekly intervals thus giving the effect of the various treatments on the germination rate. 5. Seventy degrees C dry heat for 4 hours, soaking in water 24 hours with and without reduced pressure, and treatment with concentrated HCl for 5 minutes did not increase the germination of Bahia grass seed significantly. 6. Removing the palea, treating the seed in concentrated technical H(2)SO(4) for 5 minutes, and removing both lemma and palea by rubbing the seeds between sandpaper blocks (the dry 1936 seed had to be rubbed so hard that many of the flat caryopses were cracked and killed) hastened germination materially. 7. Higher germination rate obtained with 1-year-old untreated Bahia grass seed as compared with fresh seed suggests that a change favoring germination occurs in storage. 8. Immediate germination of the 1937 seed following removal of the glumes indicates that Bahia grass seed, unlike many other grasses, requires little if any rest period. 9. Scarification of the 1937 seed in concentrated technical H(2)SO(4) for 10 minutes and of the 1936 seed for 15 minutes induced a 52 and 48% germination 8 days after planting. Untreated seed germinated 0.3% 3 weeks after they were planted. The reduced germination obtained from treating the 1937 seed for 15 minutes indicates that some of the seeds were injured and that the optimum period of treatment for different lots of seed may not be the same. 10. Treating unhulled Bermuda grass seed with concentrated HCl for 5 minutes increased the germination rate. A 5-minute treatment in concentrated technical H(2)SO(4) apparently killed most of the seeds. 11. Seed of Vasey grass and carpet grass germinated readily without treatment. All scarification treatments reduced the viability of these seeds. 12. Scarifying Dallis grass seed with concentrated technical H(2)SO(4) for 5 minutes hastened germination materially. The value of 35% NaOH as a mild scarifying agent was demonstrated. 13. Five and 10-minute treatments with either 55% HCl or 35% NaOH increased the germination rate of centipede grass seed. The practicability of establishing centipede lawns from seed was demonstrated. 14. Scarification of Bahia grass seed with crude sulfuric acid (used in making superphosphate) for 45 to 60 minutes proved about as effective as a 10-minute scarification in concentrated technical H(2)SO(4). Since crude sulfuric acid is much cheaper than technical acid, and since there is less danger of killing the seed from over-treatment, its use is recommended. 15. A viability test on Bahia grass seed stored at room temperature for 8 months after its treatment with H(2)SO(4) indicates that acid scarification reduces the longevity of the seed. 16. Field tests made in 1938 demonstrated that acid-scarified Bahia grass seeds germinated quite readily. Prolonged drought subsequent to the emergence of the seedlings killed most of them, making the determination of the effect of seed treatment upon the establishment of the grass impossible. 17. A machine which will facilitate the acid scarification of rather large quantities of seed is described.