Adventitious shoot formation from leaf explants of Rhododendron
A protocol for high frequency adventitious shoot regeneration adventitious shoot regeneration from leaf explants of Rhododendron spp. has been developed. The highest percentage of regeneration and the greatest number of shoots were obtained when leaf explants were cultured on Anderson's medium containing 4.9 μM IBA and 73.8 μM 2iP. Genotypic variation was observed for adventitious shoot regeneration potential among the seven cultivars tested. Regeneration frequencies ranged from 0 to 96%. ‘Lodestar’ had the highest rate of regeneration after 3 months of culture with 96% shoot regeneration and an average of 14 shoots per explant. Regenerated shoots were rooted in soil in about 2 months. This protocol should be useful in applying gene transfer techniques to Rhododendron improvement.
In vitro micropropagation of three rare, endangered, and endemic rhododendron species of Northeast India
In vitro propagation of three rare, endangered and endemic rhododendron species—Rhododendron dalhousiae var. rhabdotum, R. elliottii, and R. johnstoneanum—was attained. Nodal explants were used for multiple shoot induction studies. Three cytokinins (isopentenyladenine, benzyladenine, and kinetin) were evaluated in all three species. Isopentenyladenine performed better in all three species, especially at the concentration of 39.36 µM. Testing of combinations of growth regulators revealed that explants grown on Anderson medium supplemented with 39.36 µM isopentenyladenine and 4.90 µM indole butyric acid gave optimum results with 100% multiple shoot induction, 18 shoots per explant, and shoot length of 2.07 cm with R. johnstoneanum. Indole butyric acid was found to be the best auxin for root formation. Around 60% of the in vitro-raised plants of R. elliottii, R. johnstoneanum, and R. dalhousiae var. rhabdotum were able to establish ex vitro.
Physiological Factors Affecting Composition of Soybeans. I. Correlation of Temperatures During Certain Portions of the Pod Filling Stage with Oil Percentage in Mature Beans1
THE rapid increase in the importance of the soybean as an agricultural product in recent years has been due in considerable measure to its high oil content and to the usefulness of this oil as a constituent of food and industrial products. While there have been extensive research programs to develop new varieties that will produce more oil, and to develop new uses for the oil, there has been relatively little study of the physiological factors that affect oil formation, i.e., the response of the oil forming mechanism to environment. That elements of the climate might affect the composition of soybeans was suggested many years ago by Garner, et al. (2), who concluded that under usual conditions climate is a more potent factor than soil in controlling size and oil content of soybean seeds. Viljoen (9) studied the relation of temperature during the growing season to oil content at maturity. He found no correlation between maximum temperatures and oil percentage. He did, however, find a highly significant correlation between mean minimum temperature and oil percentage, and between mean temperature and oil percentage. These correlations existed for two varieties and two growing seasons at from 9 to 12 field locations in South Africa. The temperatures of the different locations ranged from a monthly mean maximum of 91.3° to a monthly mean minimum of 46.0°. The extreme temperatures for single days were 102.2° and 34.5°. There was also a wide variation in rainfall at the different locations, the total for the growing season ranging from 1.88 in. to 25.67 in. Dillman and Hopper (1) determined correlations between oil percentages of four varieties of flax and July temperatures at a group of nonirrigated and irrigated stations. For the nonirrigated stations, the correlation coefficients of oil percentage with average maximum, average minimum, and average mean were negative and were significant at the .01 probability level for all four varieties. For the irrigated stations, the only significant correlation coefficients were negative coefficients for two varieties with average minimum (P = .01) and the same two varieties with average mean (P = .05). It thus appeared that the