| Petunia (Petunia hybrida Vilm.) belongs to the Solanaceae family and is a popular annual bedding ornamental plant using in the home gardens and commercial landscaping trade. The petunia plant has a short lifecycle and can be easily propagated asexually from cuttings, callus or protoplasts, it has been used as a model plant for studying genome sequencing and flavonoid synthesis. Currently, petunia is widely cultivation in highways, parks and residential quarters around the world, which means that petunia offers the potential value for high economic income on flower industry. However, recent progress in nutrient management of petunia is less reports. In intensive horticulture, the management of mineral nutritients are a key factor on ornamental value and environment quality. In this study, we compared growth characteristics, biomass accumulation and NPK translocation among three cultivars of petunia at different developmental stages, analyzed the reactive oxygen and secondary metabolites under different nutrient deficiency stress, studied the optimal amount of Petunia by pot experiment and hydroponic experiment. The main results are summarized as following:(1) Three cultivars of potted petunia (the double florabunda, single milliflora and single florabunda) were compared accumulation and distribution characteristics for mineral nutrition. The resultes showed N, P, Ca, Mg, Fe, Mn, Cu and Zn accumulation were gradually decreased with developmetal stage; the dynamic changes of K and Mn accumulation showed undulate curve. In different cultivars, the maximum absorption amount were370.09-442.63mg N,46.13-65.73mg P,198.46-220.05mg K,282.21-307.12mg Ca,49.58-62.88mg Mg,5.98-7.21mg Fe,2.88-2.95mg Mn,0.35-0.52mg Cu and1.08-1.34mg Zn with the order N> Ca> K> P> Mg> Fe> Mn> Zn> Cu in these reserch. The mineral nutrients were main distribution in the leaves and stems during the seedling stage and early flowering stage, when the growth central changed from vegetative growth to reproductive growth, these mineral nutrients translated into bud, flower and capsules. The maximum uptake stage generally occurred at bud and full-bloom stage, K, Mg and Mn accumulation rate were42.74%,53.91%and30.80%at bud stage, respectively; N, P, Cu, and Zn accumulation rate were29.49%,54.36%,37.79%and36.57%at full-bloom stage, respectively; Ca and Fe maximum accumulation rate were26.95%and43.41%at senescence stage. The above study suggested that bud and full-bloom stage were important stage for nutrients management. (2) Urban Soils pH were weakly alkaline compared with nature soil, soil organic matter was at deficient or middle level, soil N was at deficiency level, available P and K were at optimum or abundance level, available Ca, Mg, S, Fe, Mn, Cu, Zn and B were at optimum level. In addition, based on the "3414" fertilizer experiment design, pot experiments in greenhouse were conducted to study the effects of NPK fertilizers and fertilizer recommendation amount on four tested soil, the results showed the range of N recommendation amount was0.28-0.54g/kg; P2O5was0.17-0.20g/kg; K2O was0.19-0.23g/kg.(3) Nitrogen fertilization increased chlorophyll content, branches number, dry weight as well as flower number. Active oxygen metabolism and lipid peroxidation were variation under the different nitrogen concentration. With decreasing of N concentrations, O2·-production rate, H2O2and MDA content increased significantly in leaves, however flowers showed non-significantly increased of MDA content. Nitrogen content and protein content reduced in the flowers under N deficiency, which increased enzyme activity and anthocyanins accumulation through competing on nitrogen source between primary metabolism and secondary metabolism, anthocyanins as phenolic compounds may effectively scavenge free radical effective in plants.(4) Phosphorus fertilization increased branches number, dry weight as well as flower number. Antioxidant enzyme activity increased significantly in leaves and flowers under P deficiency stress, however MDA content increased significantly on leaves that had opposite effect on flowers. Soluble sugar and flavonoids content increased with decreasing P concentration, thus, anthocyanins accumulation would relate to flavonoids secretion and sugar transport.(5) Branches number, dry weight and flower number were decreased with reducing the potassium concentration. MDA content both in leaves and flower were increased under K deficiency stress, which caused lipid peroxidation of petunia. Phenylalanine and flavonoids content were increased under K deficiency stress. phenylalanine and flavonoids as synthesis precursor of anthocyanins metabolism, which may lead to anthocyanins accumulation on petals. In addition, potassium had positive correlationand on water content of cell, anthocyanins accumulation also may incease by concentration effect.(6) Iron deficiency significantly influenced growth and blooming of petunia. The chlorophyll content of young leaves significantly increased with increasing Fe concentration. Activity of antioxidant enzyme significantly decreased in leaves and flowers under Fe deficiency stress, which increased MDA content and peroxidation damage. Flowers were the majoy ornamental organ of Petunia, Fe application changed corolla anatomy, corolla diameter and length of cross-sections of Fe-deficiency treatment were much lesser than that of Fe-sufficient treatment. In addition, Fe as co-factor of anthocyanins synthase directly participated in anthocyanins synthesis, so anthocyanins content had positive correlation on Fe concentration.(7) The extract of the petal of Petunia was analyzed by HPLC-ESI-MS, identification and peak assignment of anthocyanins was based on comparison of their retention times and mass spectral data with those of standards and published data. Three peaks identified as cyanidin3-sophoroside, cyanindin-3-glucoside (galactose) and Peonidin-3-glucoside (galactose) both in nutrient deficiency and nutrient supply treatment. Ratio of anthocyanins content showed non-transformation on N, P, K deficiency treantment and changed from Cy to Pn under Fe-deficiency. |
PDF Full Text Request