The external surfaces and internal structures of particles of milled pine bark (Pinus taeda L. and P. elliottii Engelm.) were examined with scanning electron microscopy. Numerous external openings, cracked cell walls and internal cellular connections, that might allow water penetration were observed. Periderm surfaces were without pores, and contained rough surfaces and apparently waxy substances that might resist water penetration or absorption.
Attempts at the reciprocal cross between Petunia parodii and P. inflata using standard emasculation and pollination techniques failed. Limited pollen tube growth down the style in reciprocal crosses led to reproductive isolation between the self-compatible P. parodii and self-incompatible P. inflata. The interspecific hybrid was successfully produced by bud-pollination of P. parodii with P. inflata as the male parent in 22 percent of attempts, but not in the opposite direction. In vitro pollination of P. parodii ovaries with P. inflata pollen also produced hybrids. The small size of the ovary made it technically impossible to use P. inflata as the female parent for in vitro pollination. The interspecific hybrids were intermediate, as compared to the two parents, for six of the seven plant and flower characters measured. Furthermore, the hybrids had high pollen fertility, set abundant seed upon self-pollination, and readily inter-crossed with the parental species. The results are consistent with a high degree of chromosomal homology in the parental species and with minor genetic divergency leading to reproductive isolation that is pre-zygotic in nature. Overcoming the barriers to cross-incompatibility by practical techniques resulted in fertile interspecific hybrids that segregated for parental characters. The potential value of employing the parental species in somatic hybridization experiments is discussed.
Environmental effects on several CAM plants which bring than IN CAM (when plants show diurnal fluctuations in the concn of titratable acid) and OUT OF CAM (when acid concn remain low with no diurnal fluctuation) were studied. Change in photoperiod alone caused the greatest amplitude of the acid fluctuation from 23.8 to 1.8 meq acid/100 g FW in Kalanchoe daigremontiana as compared to either Kalanchoe tubiflora or Sedum telephoides. The K/Ca ratio varied from a high when IN CAM to a low when OUT OF CAM in the 3 species. The plasma emission spectrograph analysis of the leaf tissue grown in the specific environment showed the presence of high levels of Mn, B, Cu, Zn, Na, Al and Si in some CAM plants.The elemental analyses of CAM plants showed 1.8 to 14.7% K.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.