Physiological Rupture of Soybean Hypocotyls in Germination and Vigor Tests1
Kar-Ling J. Tao2
In rolled towel germination and seedling growth rate tests, some soybean (Glycine max. (L.) Merr.) hypocotyls became swollen and frequently were found to develop transverse and longitudinal cracks. The occurrence of ruptured seedlings was as high as 46% for a seed lot of the 'Williams' cultivar at the seventh day of germination, while only 1% rupture was observed at the third day. The number of ruptured seedlings increased from 2 to 17% with increased moisture of the paper towels. The presence of light during germination markedly reduced the percentage of ruptured seedlings.
Additional index words: Glycine max. ( L. ) Merr., cultivar, abnormal seedlings.
Effect of Storage Conditions on Viability, After-Ripening adn Induction of Secondary Dormancy of Kentucky Bluegrass Seed1
Bangalore R. Phaneendranath and C. R. Funk 2
One of the most important factors that affects germination of Kentucky bluegrass (Poa pratensis L.) seeds is the conditions under which they are stored. The objective of this study was to store seeds at various temperature/relative humidity (RH) combinations and then germinate at sub-optimal (10-20 C ), optimal (15-25 C ), and supra-optimal (20-35 C) temperature conditions and determine their effects on viability, after-ripen ing and possible induction of secondary dormancy.
Storage at high temperature (37.8 C ) and high humidity had a very detrimental effect on the viability of seeds. Seeds stored at 37.8 C/25% RH showed less after-ripening dormancy during the first few weeks of storage than seeds at lower temperature and relative humidity combinations. Touchdown Kentucky bluegrass seeds stored at most of the conditions exhibited fluctuations in germination which were possibly due to induced secondary dormancy and not endogenous germination rhythms. Endogenous germination rhythms, if present would have been expressed by similar fluctuations or oscillations in germination being unaffected by storage conditions and/ or germination temperatures.
Storage at -16.7 C, 5.6 C/25% RH, room temperature, and 21 C/ 25% RH maintained seed viability at a higher level for a longer period of time. After-ripening, however, was generally faster when the total degrees in Centigrade plus relative humidity in percentage was between 40 to 70.
Freshly harvested seeds germinated well at 10-20 and 15-25 C, and not at 20-35 C showing that they had possibly not completed their after ripening processes. They developed this faculty only after a period of storage at favorable conditions.
Seeds stored at -16.7 C and 5.6 C/25% RH failed to germinate at 20-35 C, even after 56 weeks of storage. The reason for Kentucky bluegrass seeds not germinating at 20-35 C, was not that they were either dead or pushed into thermodormancy, but, is a case of high-temperature induced inhibition of germination or "imposed inactivity." This was evident by almost complete recovery of germination of these seeds when transferred to 15-25 C.
Additional index words: Poa pratensis L., endogenous germination rhythms, seed germination, imposed inactivity.
Effects of Inoculation Time and Cultivar on Internal Infection of Bean Seed by Pseudomonas phaseolicola
A.W. Saettler, S. ]. Stadt, and L. T. Pontius1
We studied internal infection of bean seed by the halo bacterial blight pathogen Pseudomonas phaseolicola. Plants of halo blight susceptible Charlevoix and tolerant Montcalm, Seafarer, and Tuscola cultivars were inoculated with aqueous suspensions of cells of P. phaseolicola R13 (a mutant resistant to 50 ppm rifampin). Pods were collected at normal maturity and internally-borne blight bacteria were isolated in liquid rifampin-containing media.
Effect of Relative Humidity and Temperature on Germination of Seeds of Two F1 Sorghum Hybrids and their Parents During Storage
P. K. Agrawal, R. B. Patil, M . Dadlani, and Daljit Singh
Seeds of two Sorghum bicolor (L.) Moench F1 hybrids and their parents were stored at 20, 45 and 80% relative humidity (RH) and 20 and 33 C for 432 days. Loss of viability increased with either increased RH (from 20 to 80%) or increased temperature (from 20 to 33 C).
Additional index words: Viability, inheritance.
Fluid Sowing of Tomato Seed-Influence of Phosphorous Additions to Five Gels1
Wallace G. Pill2
The effect of 0, 5, 50, and 500 ppm P addition to five gels on percentage emergence (PE) , emergence rate index (ERI), and on shoot growth and P composition after fluid-sowing pregerminated 'Marglobe' tomato seed was investigated in the greenhouse. Pregerminated seed in gels without P addition generally showed significantly greater PE, ERI, and shoot dry weights than dry-sown seed.
Additional index words: Lycopersicon esculentum Mill., chitted seed, pregerminated seed, fluid drilling, gel additive.
A Comparative Study Between Field Soil and Perlite Infested with Pythium as Media for the Corn (Zea mays L.) Cold Test1
D.M. Garzonio and A. L. Larsen2
A modified corn (Zea mays L.) cold test was developed utilizing perlite infested with a pathogenic isolate of Pythium sp. as a substitute for unsterilized field soil. The procedure was evaluated by correlating soil and perlite cold test results for nine hybrid seed corn lots, both treated (captan) and untreated, with field emergence results for two planting times at each of two locations.
Additional index words: vigor test, fungicide effects, Pythium ultimum Throw. var sporangiferum.