Growth, Development, and Alkaloid Content of Doubled Haploids vs. Inbreds of Burley Tobacco

Plants with improved morphological and chemical characteristics can be developed more rapidly through haploid and doubled haploid methods than through conventional inbreeding, but plants derived by the two methods need to be compared. Growth and developmental characteristics of first and second cycle doubled haploids were compared with those of highly inbred plants of five burley tobacco (Nicotiana tabacum L.) cultivars. When averaged across cultivars, doubled haploids flowered later and developed smaller plants that produced less cured leaf with lower alkaloid content than did the inbreds. Within cultivars, there were some developmental differences among first cycle doubled haploid lines derived from different microspores from a given inbred plant. Differences observed among first cycle doubled haploid lines were evident in the second generation families, indicating genetic rather than environmental cause. Some additional differences were noted among second cycle doubled haploid lines derived from anthers cultered from a given first cycle doubled haploid plant. The amount of variability among second cycle doubled haploid lines from a first cycle doubled haploid plant differed among the five cultivars, and in most cases was less than that observed among the first cycle doubled haploids of the same inbred plant. Although there were some variations among doubled haploid lines, variances among plants within plots for time of flowering and number of leaves per plant indicated that there was more uniformity among selfed progeny within doubled haploid lines than among selfed progeny within inbred lines. Haploids and doubled haploids offer an excellent meant so obtain tobacco lines with modified chemical and morphological features. However, some mutations may occur in the process, and utilization of doubled haploids should involve confirmation of the characteristics of each line before using it in physiological investigations or in plant breeding.