Increasing commercial use of controlled release fertilizer (CRF) has prompted the need to predict N release simply and viably in the greenhouse environment. Two CRFs were tested, i.e., P40d and P100d by incubating them for 40 or 100 days either in static water at 10, 15, 20, 25, and 35 °C or in the soil of vegetable plots in a greenhouse lacking temperature controls. Cumulative nitrogen release (CNR) from a CRF was represented by a parabola curve and significantly affected by the incubation temperature. A method to calculate N m (the maximum N release percentage from CRF) was established using a first-order kinetic equation and the method of least squares. N m was 90.9% to 99.9% for P40d and 72.1% to 87.1% for P100d at 10–35 °C, respectively. A relationship function between the N release rate and naturally fluctuating greenhouse soil temperatures was established using the activation energy of the N release reaction. Then a model was constructed with field temperature as the variable to predict N release throughout the entire greenhouse crop production season. The value of ψ representing a property of the coating material of a CRF is ≈ 1.0 for the release period of the CRF of 35–55 days and ≈ 1.2 of 80–120 days. We validated the model using two seasons of greenhouse tomato, Solanum lycopersicum L., and cucumber, Cucumis sativus L., production data, and found that the error was less than 12% points. This indicated that the constructed model was sufficiently simple, practical, and accurate for use by growers, and fertilizer industry and regulatory personnel.
Qiang Xiao, XiaoHui Fan, XiaoHui Ni, LiXia Li, GuoYuan Zou and Bing Cao
Qianqian Shi, Xiaoxiao Zhang, Xiang Li, Lijuan Zhai, Xiaoning Luo, Jianrang Luo, Lixia He, Yanlong Zhang and Long Li
Tree peony (Paeonia sp.) is a popular traditional ornamental plant in China. Among the nine wild species, Paeonia rockii displays wide-ranging, deep purple variegation at the base of the petals, whereas Paeonia ostii exhibits purely white petals. Overall, the posttranscriptional regulation involved in tree peony flower opening and pigmentation remains unclear. To identify potential microRNAs (miRNAs) involved in flower variegation, six small RNA libraries of P. ostii and P. rockii petals at three different opening stages were constructed and sequenced. Using Illumina-based sequencing, 22 conserved miRNAs and 27 novel miRNAs were identified in P. rockii and P. ostii petals. Seventeen miRNAs were differentially expressed during flower development, and several putative target genes of these miRNAs belonged to transcription factor families, such as Myb domain (MYB), and basic helix-loop-helix (bHLH) transcription factors. Furthermore, an integrative analysis of the expression profiles of miRNAs and their corresponding target genes revealed that variegation formation might be regulated by miR159c, miR168, miR396a, and novel_miR_05, which target the MYB transcription factors, chalcone synthase (CHS), and ABC transporter. Our preliminary study is the first report of miRNAs involved in Paeonia flower pigmentation. It provides insight regarding the molecular mechanisms underlying the regulation of flower pigmentation in tree peony.