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The cambial activity and periodicity of secondary xylem and phloem formation have been less studied in tropical tree species than in temperate ones. Cambium activity is the only source of timber production. Studies on its activity and xylem formation can provide helpful data for dendrochronology and possible factors that control tree growth, the yield and quality of wood. Cinnamomum camphora is an important fast-growing tree for furniture and sculpture wood in South China. Its dynamics of cambial activity was not reported. During the growth season in 2011, five trees of Cinnamomum camphora plantation were monitored on the campus of Huazhong Agricultural University in central china (located on 113°41’ to 115°05’ E and 29°58’ to 31°22’ N). Sampling time was from 13, February 2011 to 13, February 2012. Some small stems of 15–20 cm length were selected to sample in the middle of 2–3 years old health branches in the central crown of these trees. The observational study found that the cambium of camphor trees was active from March to October and dormant from November to February. Onset of cambial cell division was observed in early March, one week after sprouting of new buds. The morphology of the cells and number of cell layers in the cambium zone varied throughout the year. In early March, cambium reactivated with the rising of temperature, the cell wall was relative thick. The number of cell layers increased from 2–3 in middle Feb. to 3–5. In June, the number of cell layers in cambium reached the maximum of 5–7 in a radial direction. In mid March, phloem cells began to differentiate, followed by xylem three weeks later. The number of cell layers in immature phloem and xylem increased dramatically before mid June and the increment of cell layers in xylem was almost fifth times of phloem in the differentiating process. The phloem cells mainly stopped dividing new cells in end of October, but xylem cells were still in the activity a week later. The annual activities of cambium was in accordance with the air mean temperature change in 2011–2012. The results showed that the cambial activity and formation of xylem and phloem were related to the environmental factors, especially the temperature.
One of the most important problems in horticultural seed science and technology nowadays is looking for new methods to improve seed quality. Especially interesting are the ones, in which compounds of natural origin are used. One of such groups is ethereal oils from plants. The commercial seed samples of lettuce (Lactuca sativa L. ‘Dumka’) were soaked in 9 different treatments of 5% alcoholic solution of camphor tree (Cinnamomum camphora L.) ethereal oil and 9 different treatments of 5% alcoholic solution of patchouli plant (Pogostemon cablin Benth.) ethereal oil. Then the seeds were routinely tested for seed germination, the length of the received seedlings was also measured and the seeds health status was evaluated. The tested ethereal oils had no effect on the germination of lettuce seeds. However, soaking the seeds in the ethereal oils solutions did decrease the percentage of dead seeds in the tested samples. Soaking of the seeds in the ethereal oils solutions also increased the percentage of healthy ungerminated seeds. Treating the seeds with the concentrations of the ethereal oils solutions, although had no effect on their germination, still shortened the length of seedlings. Moreover, the used ethereal oils lowered the amount of identified Alternaria alternata and Cladosporium sphaerospermum fungi on the seeds.
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