Effects Of Nitrogen Fertilizer Levels On The Photosynthetic Characteristics Of Waxy Maize Inbred Lines And Hybrid

In this paper, the differences in photosynthetic characteristics and yield of waxy maizeinbred lines and hybrid under different nitrogen conditions were comparatively studied toprovide basis for high quality cultivation of waxy maize in Tianjin area. The parent inbredlines (Hei943and Jin872) and their hybrid (Jinheinuo6) were used as materials and thenwere treated with three nitrogen fertilizer levels (low N, middle N, and high N). Leaf areaindex, leaf photosynthetic rate, leaf transpiration rate, GS, intercellular CO2concentration,Chlorophyll fluorescence characteristics and Chlorophyll content were measured in thegrowth period and yield traits were estimated after harvest.1. Leaf area index in hybrid was higher than in parent inbred lines, which reflected hybridvigor. Leaf area index of the female parent and hybrid of increased with increasing nitrogenlevels, and LAI of waxy maize inbred lines and hybrids basically reached the maximum onAugust20.2. The increase of nitrogen fertilizer could enhance photosynthetic accumulation of parentinbred lines but had no significant effects on hybrid variety. Under low nitrogen conditions,the photosynthetic accumulation was higher in hybrid variety than parent inbred lines, whichsuggested that this hybrid had advantages in low nitrogen adaptation. In addition, water useefficiency of parent inbred lines was higher under middle nitrogen conditions while hybridvariety had higher WUE in low nitrogen conditions.3. F0value of waxy maize inbred lines and hybrid combination was higher on August3and September12than tin other growth stages. The maximum fluorescence value of maleparent under middle nitrogen condition and hybrid under high nitrogen condition, achievedthe maximum on August17, but besides Fmvalue reached the maximum on August25.Photochemical efficiency (Fv/Fm) and photochemical activity (Fv/F0) of waxy maize inbredlines and hybrids at different grouth stages reached the maximum on August25.4. There were two situations for chlorophyll index at different growth stages underdifferent nitrogen levels: One was a single peak curve, such as parent inbred lines undermiddle nitrogen levels; the other was a bimodal curve, such as parent inbred lines under highnitrogen level. But in general, there existed slight differences in chlorophyll index among under different nitrogen levels.5.Grain number per row and1000-kernel weight of hybrid were higher than parentinbred lines, suggesting that this hybrid had obvious yield advantages. In conclusion,Jinheinuo6has yield advantages and relatively lower nitrogen fertilizer requirements.