The effects of paclobutrazol (PBZ) on the ex vitro transfer efficiency of in vitro grown Dendrobium nobile seedlings were investigated. The survival percentage was increased by 41.6 % with 0.8 mg dm -3 PBZ treatment compared to controls. The PBZ-treated D. nobile plants were shorter than the control plants. Morphological and anatomical analyses show that root diameter, especially at the root apex, became larger after treatment with PBZ which is consistent with the increases in cortical cell sizes and row numbers. In addition, the first observations of thickened velamen of the PBZ-treated seedling were made in the present study. The activities of cellulase and indole acetic acid oxidase increased in the PBZ-treated plantlets, whereas that of cell wall-associated peroxidase declined compared to the controls. The content of endogenous gibberellic acid and iso-pentenyladenosine of root tips changed little by PBZ but that of indole-3-acetic acid decreased by 53 %. These results indicate that PBZ could improve the transfer efficiency of D. nobile from in vitro culture to pots due to its effects on root development.

To investigate the genotypic differences associated with the growth potential and leaf traits of Cornus wilsoniana W., we planted twenty C. wilsoniana families in southeastern China and analyzed nineteen leaf morphological and physiological traits that have potential relationships with growth. Seedling growth and leaf traits exhibited high variability among the C. wilsoniana families. The phenotypic coefficients of variation (CVs) of these traits varied from 5.33% (leaf length/leaf width, LL/LW) to 23.17% (stomatal conductance, gs), and their heritabilities (H 2 ) ranged from 0.17 (chlorophyll a/chlorophyll b, Chla/Chlb) to 0.75 (stem height, H and Chla). There was greater genetic variation in the physiological traits than in the morphological traits. H was significantly positively correlated with instantaneous water use efficiency (WUE), Chla, Chlb and total Chl, and diameter (D) was significantly positively correlated with net photosynthetic rate (Pn), gs, WUE, Chla, Chlb and total Chl and was negatively correlated with leaf phosphorus (LP). Based on cluster analysis, three families were selected as superior families for the study area due to their seedling growth and leaf traits. These results indicate that Pn, Chla, Chlb and total Chl are good indicators to use for selecting superior families of C. wilsoniana with better growth performance; additionally, high WUE and low LP are also critical leaf traits for cultivar selection because plant adaptation to environmental conditions is important for growth performance.

The impact of persisting herbicide residues on succeeding crops is of great concern to farmers because even the presence of very low concentrations can inhibit growth of crop and cause crop reduction. Furthermore, wastewater irrigation can lead to cadmium accumulation in soils. Thus, the co-occurrence of low amounts of herbicide residues and cadmium within agricultural fields are difficult to avoid. How the combination of these two pollutants affect plant metabolites remains to be elucidated and thus warrants investigation. Maize seeds were planted in soil that had been sprayed with chlorsulfuron and Cd, then we studied the effects of exposure to the herbicide chlorsulfuron (0.001, 0.003, 0.005, 0.008, and 0.010 mg kg -1 ) and cadmium (as 5.0 mg kg -1 CdCl2) on maize seedlings by utilizing nuclear magnetic resonance (NMR) after 21 d. Principle component analysis of 1 H NMR spectra clearly discriminated between control and treatment groups. Compared with chlorsulfuron-only treatments, treatments using both contaminants showed higher content of phenolic acids, aspartic acid, choline, β-galactose, and α-glucose in the seedlings. Contrary to previous reports, we found larger pools of branched-chain amino acids in seedlings exposed to chlorsulfuron and CdCl2. These findings indicate that CdCl2 did not aggravate the effects of chlorsulfuron on maize seedlings metabolites. CdCl2 elicited significant changes in plant metabolism at a concentration that did not impair plant growth. Moreover, chlorsulfuron did not inhibit branched chain amino acid synthesis.