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
Li-Xiao Yao, Yong-Rui He, Hai-Fang Fan, Lan-Zhen Xu, Tian-Gang Lei, Xiu-Ping Zou, Ai-Hong Peng, Qiang Li and Shan-Chun Chen
Ferric chelate reductase (FRO) is a critical enzyme for iron absorption in strategy I plants, reducing Fe3+ to Fe2+. To identify FRO family genes in the local Citrus junos cultivar Ziyang Xiangcheng and to reveal their expression model, the citrus (Citrus sp.) genome was searched for homologies of the published sequence CjFRO1. Five FROs were found, including CjFRO1; these were named CjFRO2, CjFRO3, CjFRO4, and CjFRO5, respectively, and cloned via reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) PCR. The deduced amino acid sequences of five CjFROs contained flavin adenine dinucleotide (FAD)-binding motifs, nicotinamide adenine dinucleotide (NAD)-binding motifs, and 6–10 transmembrane domains, with isoelectric points between 6.73 and 9.46, and molecular weights between 67.2 and 79.9 kD. CjFRO1 and CjFRO2 were predominantly found in the aboveground parts of C. junos, with CjFRO1 highly expressed in leaves, and CjFRO2 largely expressed in stems and leaves. CjFRO3 was less expressed in roots, stems, and leaves. CjFRO4 and CjFRO5 were predominately found in roots. Under iron-deficient conditions, CjFRO4 was significantly and specifically increased in the roots of C. junos, whereas CjFRO1 was upregulated in the roots and leaves.
Wei Hu, Ju-Hua Liu, Xiao-Ying Yang, Jian-Bin Zhang, Cai-Hong Jia, Mei-Ying Li, Bi-Yu Xu and Zhi-Qiang Jin
The banana, a typical climacteric fruit, undergoes a postharvest ripening process followed by a burst in ethylene production that signals the beginning of the climacteric period. Postharvest ripening plays an important role in improving the quality of the fruit as well as limiting its shelf life. To investigate the role of glutamate decarboxylase (GAD) in climacteric ethylene biosynthesis and fruit ripening in postharvest banana, a GAD gene was isolated from banana, designated MuGAD. Coincidently with climacteric ethylene production, MuGAD expression as well as the expression of the genes encoding the Musa 1-aminocyclopropane-1-carboxylate synthase (MaACS1) and Musa 1-aminocyclopropane-1-carboxylate oxidase (MaACO1) greatly increased during natural ripening and in ethylene-treated banana. Moreover, ethylene biosynthesis, ripening progress, and MuGAD, MaACS1, and MaACO1 expression were enhanced by exogenous ethylene application and inhibited by 1-methylcyclopropene (1-MCP). Taken together, our results suggested that MuGAD is involved in the fruit ripening process in postharvest banana.