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Wang Y.,China Agricultural University | Li B.,China Agricultural University | Li B.,Shandong Kingenta Ecological Engineering Co. | Du M.,China Agricultural University | And 5 more authors.
Journal of Experimental Botany | Year: 2012

To elucidate the phytohormonal basis of the feedback regulation of leaf senescence induced by potassium (K) deficiency in cotton (Gossypium hirsutum L.), two cultivars contrasting in sensitivity to K deficiency were self- and reciprocally grafted hypocotyl-to-hypocotyl, using standard grafting (one scion grafted onto one rootstock), Y grafting (two scions grafted onto one rootstock), and inverted Y grafting (one scion grafted onto two rootstocks) at the seedling stage. K deficiency (0.03mM for standard and Y grafting, and 0.01mM for inverted Y grafting) increased the root abscisic acid (ABA) concentration by 1.6- to 3.1-fold and xylem ABA delivery rates by 1.8- to 4.6-fold. The K deficiency also decreased the delivery rates of xylem cytokinins [CKs; including the zeatin riboside (ZR) and isopentenyl adenosine (iPA) type] by 29-65% and leaf CK concentration by 16-57%. The leaf ABA concentration and xylem ABA deliveries were consistently greater in CCRI41 (more sensitive to K deficiency) than in SCRC22 (less sensitive to K deficiency) scions under K deficiency, and ZR- and iPA-type levels were consistently lower in the former than in the latter, irrespective of rootstock cultivar or grafting type, indicating that cotton shoot influences the levels of ABA and CKs in leaves and xylem sap. Because the scions had little influence on phytohormone levels in the roots (rootstocks) of all three types of grafts and rootstock xylem sap (collected below the graft union) of Y and inverted Y grafts, it appears that the site for basipetal feedback signal(s) involved in the regulation of xylem phytohormones is the hypocotyl of cotton seedlings. Also, the target of this feedback signal(s) is more likely to be the changes in xylem phytohormones within tissues of the hypocotyl rather than the export of phytohormones from the roots. © 2012 The Author(s). Source


Yang Y.-C.,Shandong Agricultural University | Zhang M.,Shandong Agricultural University | Zheng L.,Shandong Kingenta Ecological Engineering Co. | Cheng D.-D.,Shandong Agricultural University | And 2 more authors.
Agronomy Journal | Year: 2011

The effects of newly developed controlled release urea (CRU) and its placement method on the N use efficiency and nutritional quality of winter wheat (Triticum aestivum L.) grown on a loam soil were investigated during 2 yr.the winter wheat was grown on a loam soil.the CRU was applied at 0, 75, 150, and 225 kg N ha-1 and the urea was applied at 225 kg N ha-1.the CRU was applied with wheat seeds during sowing while the urea treatment was split into two applications:two-thirds applied during sowing and one-third at the 5-tiller stage (Z25). Results showed that N release rates of CRU fit N requirements of wheat and the placement of wheat seeds with CRU improved wheat's apparent N uptake efficiency by 28.5% compared to urea treatment. Although the CRU treatment at 150 kg N ha-1 had one-third less supplied N than that of conventional urea treatment (225 kg N ha-1),the wheat with CRU at 150 kg N ha-1 produced 6.5% more grain. In addition, at the same or one-third reduced amount of N compared withthe conventional urea treatment, CRU significantly increased the contents of Fe and Mn, providing additional nutrition and quality to the wheat grain. © 2011 by the American Society of Agronomy. Source


Wang S.,CAS Nanjing Institute of Soil Science | Zhao X.,CAS Nanjing Institute of Soil Science | Xing G.,CAS Nanjing Institute of Soil Science | Yang Y.,Shandong Agricultural University | And 2 more authors.
Agronomy for Sustainable Development | Year: 2015

The efficiency of classical mineral NPK fertilizers is usually low because a major part of these fertilizers does not reach plant roots and ends up polluting groundwaters with nitrates and phosphates. Recently, a novel polymer-coated urea made from recycled plastics was proposed to enhance N availability in cereal production. To evaluate the efficiency of this polymer for rice production, we set up field plots, microplots, and pot experiments with 15N tracing. We compared rice yield, N uptake, and N loss between conventional three split applications of urea and a single basal application of four derivatives from the polymer-coated urea. The four derivatives included a blend with 70 % of N from 6 % (w/w) coated urea and 30 % from urea and three coated urea fertilizers with 6, 8, and 12 % coating at an identical N application rate during two rice-growing seasons. Results show that 6 % coated urea improved 15N recovery, reduced 15N loss, and increased grain yield slightly due to an initial 15N burst occurring at high field temperatures after basal fertilization; 8 or 12 % coated urea better met plant N demand from transplanting to heading, greatly enhanced 15N recovery, and decreased 15N loss and NH3 volatilization. Nevertheless, unlike a significant increase of yield for 12 % coated urea, 8 % coated urea did not increase yield due to 15N release and excessive 15N uptake by plants at ripening. Overall, our findings show that a single basal polymer-coated urea application improves N use efficiency and reduces N loss in rice agroecosystem. © 2015, INRA and Springer-Verlag France. Source


Yang Y.,Shandong Agricultural University | Zhang M.,Shandong Agricultural University | Zheng L.,Shandong Kingenta Ecological Engineering Co. | Cheng D.,Shandong Agricultural University | And 3 more authors.
Journal of Plant Nutrition | Year: 2013

Controlled-release urea (CRU) and its placement method in rice production were investigated during 2007 and 2008 seasons. Controlled-release urea was applied at 62.5, 125, and 187.5 kg nitrogen (N) ha-1, and the urea was 187.5 kg N ha-1. All the CRU treatments were applied to the nursery beds once, and they were brought into the paddy field during transplanting, while the urea treatment was split into three applications from the plowing to the harvest. The results showed that rice seedlings with CRUs germinated and grow well and there was no salt damage at the nursery stage. The CRU treatment with 125 kg N ha-1 had 33% less N than urea treatment (187.50 kg N ha-1), but it produced significantly higher grain and straw yields, higher total N uptake and total apparent N uptake efficiency. In addition, all the CRU treatments effectively decreased floodwater ammonium (NH4 +)-N and nitrate (NO3 -)-N concentrations, pH, and N runoff. © 2013 Copyright Taylor and Francis Group, LLC. Source

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