Impacts Of Nitrogen Fertilization On Yield, Quality And Nitrogen Use Efficiency Of Wheat Varieties Released In Different Eras In Jianghuai Area

To understand the response of grain yield, quality, mineral element concentrations in grain and nitrogen (N) use efficiency (NUE) to N application rate for winter wheat from different eras can benefit new variety breeding and cultivation technique innovation for higher-yield, higher-quality and higher-efficiency of resource use in Jianghuai area.Therefore, we conducted an experiment (Yanling town, Danyang city, Jiangsu province,2010-2011) to study the actual change characteristics of productivity, quality, mineral element concentrations in grain and N use efficiency of winter wheat in Jianghuai area. Our experiment seted up three N application levels with winter wheat cultivars approved from1960s to the present in this area. The main results were as follows:(1) The winter wheat average yield showed rising trend along with cultivar improvement. Under low N level (N1), the average yield of1970s and1980s varieties were significant lower than which of1990s and2000s varieties. With the succession of winter wheat cultivars, the plant height reduced significantly, while the kernel number per ear and1000kernel weight showed increasing trends. The spike number and spikelet number increased firstly and then decreased. No significant change trend was found in the ears and spike length, while the above-ground biomass decreased significantly under the high N level (N2). With the application of N fertilizer, the grain yield increased significantly. Comparing with the non-fertilization control(No), the grain yield of1960s,1970s,1980s,1990s and2000s varieties under the low N level (N1) increased by133.53%,112.13%,85.26%,119.90%and104.84%, respectively; while under the high N level(N2), it increased by126.03%,116.18%,112.45%,96.18%and99.71%. The grain yield of the five years varieties between low N level (N1) and the high N level (N2) had no significant difference. The above-ground biomass and spike length significantly increased with the increasing rate of N application. The plant height, spike number, spikelet number, ears and kernel number per ear all showed decreasing trends, while the1000kernel weight decreased with N application rate increasing.(2) The mineral elements concentration of grains and flour due to N level and elements types with the succession of winter wheat cultivars. Some mineral concentrations (Zn, Fe, Mn, P) in grains first increased and then decreased along with with the succession of winter wheat cultivars, while others (concentrations of Ca, Mg and Cu)showed different change trends under different N fertilizer levels, but trended to decline overall. Similarly, all mineral elements concentrations of flour showed different change trends under different N fertilizer levels, but trended to decline overall. The concentrations of Zn, Fe, Mn, Ca and Cu in winter wheat grains and flour of which from different eras increased with N application rate increasing, while P decreased. The concentrations of Mg varied because of their eras.(3) The content of total starch, amylopectin and the amylopectin/amylose value in flour first increased and then decreased along with the succession of winter wheat cultivars, and the maximum were1970s and1980s varieties which had significant differences with the other three ears. The content of amylose in flour showed the same trends as the three (total starch, amylopectin and the amylopectin/amylose value), which minimum were1970s varieties, and the minimum were1960s varieties. The content of protein, glutenin, ash content in flour and the protein, wet gluten content in grains decreased along with the succession of winter wheat cultivars. The content of total starch, amylose and amylopectin in flour of winter wheat varieties which from different eras decreased with the application of N fertilizer, but the content of protein, glutenin, ash content in flour and the protein, wet gluten content in grains significantly increased along with N application rate increasing.(4) With the succession of winter wheat cultivars, there were no significant differences between the new cultivars and the old ones of stem and leaves N content at maturity, but the grain N content showed different change trends under different N fertilizer levels. The N harvest index of varieties which followed1990s was significantly higher than the varieties before1990s. N use efficiency first increased and then decreased along with the succession of winter wheat cultivars. N content of grain, stem and leaves all significantly increased along with N application rate increasing, while N agronomic efficiency and N partial factor productivity significantly decreased. With N application rate increasing, N harvest index of1960s and2000s varieties tended to decrease, but had no significant effects on N harvest index of1970s,1980s and1990s varieties. N use efficiency tended to decrease with the increasing rate of N application.