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  • Author or Editor: Xiaojing Wang x
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Paeonia ostii T. Hong & J. X. Zhang is a perennial oil and medicinal plant with great importance as well as landscaping. P. ostii is being extensively planted in China, but the soil fertility limits the yield and quality. There is little information available on the effects of phosphorus fertilization on productivity, physiological characteristics, and seed yield and quality. This study investigated the influence of different phosphorus levels, 0 kg·hm−2 (CK), 90 c−2 (P1), 135 kg·hm−2 (P2), 180 kg·hm−2 (P3), 225 kg·hm−2 (P4), and 270 kg·hm−2 (P5), on the photosynthesis, morphology, physiological parameters, and yield of P. ostii. The results indicated that the net photosynthetic rate, stomatal conductance (g S), and transpiration rate of P. ostii increased significantly with the application of P4, which increased by 34.77%, 65.72%, and 21.00% compared with CK, respectively. Simultaneously, the contents of soluble sugar, soluble protein, and photosynthetic pigment in P4 were the highest compared with other treatments. In addition, thousand-grain weight (326.4 g) and seed yield per plant (37.33 g) of P4 were significantly higher than the control. However, the total amount of unsaturated fatty acids in P4 was lower compared with other treatments. The indexes of high correlation coefficients with Dim 1 and Dim 2 were g S and superoxide dismutase (SOD), respectively. The results showed that phosphorus levels improved plant photosynthetic capacity and increased antioxidant capacity as well as seed yield. Furthermore, phosphate fertilizer had significant effects on the oil composition. Moreover, the effect of phosphorus application rate on the growth index of P. ostii was greater than that of the physiological index.

Open Access

Golden camellia flowers are treasured for their unique yellow color and bioactive chemical compounds. Because of its high market demand, there is strong interest in inducing early flowering in golden camellias for earlier harvest. Previously, we have successfully induced flowering in Camelia chrysantha (Hu) Tuyama juvenile grafted plants and seedlings with paclobutrazol (PBZ). During this study, we investigated the efficacy of PBZ on C. tamdaoensis juvenile rooted cuttings. C. tamdaoensis is a yellow-flowering camellia species that is native to Vietnam and valued by the local population. It was found that applications of 100 and 200 ppm PBZ generated an average of 13 and 30 flowers per 5-year-old plant, respectively. None of the control plants flowered. The average flower diameter was 17.2 cm for 100-ppm-induced flowers and 26.0 cm for 200-ppm-induced flowers. The dynamics of various phytohormones (indoleacetic acid, abscisic acid, salicylic acid, and jasmonic acid) were altered by PBZ treatment. It is suggested that low indoleacetic acid, high abscisic acid, and jasmonic acid and a gradual increase in salicylic acid benefit floral initiation of golden camellias. The study provided the first insight regarding the action mechanism of PBZ for the initiation of camellia flowering.

Open Access

Camellia chrysantha flowers are in great market demand as a result of their high ornamental and medicinal values. To induce early flowering in 4-year-old juvenile C. chrysantha seedlings, three levels of paclobutrazol (PBZ) concentration (100, 200, and 300 ppm) were applied to the roots. PBZ is a triazole-type cytochrome P450 inhibitor that was found successful in inducing flowering in juvenile C. chrysantha grafted plants in a prior report. The current study shows that all three PBZ concentrations were equally effective in induction of floral buds, resulting in an average of 20 floral buds per treated plant. In comparison, none of the untreated plants flowered. Although the induced flowers were smaller than the ones from mature trees, PBZ treatment did not affect C. chrysantha flowers’ medical values, because there was no significant change in the content of pharmacologically active compounds (polysaccharide, polyphenols, flavonoids, and saponins). None of the PBZ treatments had a negative effect on the current year’s growth in height and basal diameter, photosynthesis, and levels of water-soluble sugars and nutrients [phosphorus (P), nitrogen (N), potassium (K), and carbon (C)]. It is concluded that PBZ is an effective flowering inducer for juvenile C. chrysantha plants. It was also found that PBZ-treated plants experienced defoliation, and there existed a strong correlation between severity of defoliation and PBZ concentration. This might be attributed by the stress induced by PBZ, as demonstrated by the increased activities of some of the stress-related enzymes [ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD)], and the level of malondialdehyde (MAD). Considering that severe defoliation can cause stunted or malformed plants and reduce aesthetic value, 100 ppm is the optimal PBZ concentration for flowering induction in C. chrysantha seedlings.

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