Lodging is an important constraint limiting buckwheat yield and quality by bending or breaking culm on buckwheat production worldwide. This study was conducted with Ningqiao 01, a moderate lodging resistance cultivar of buckwheat, to determine whether lignin synthesis and lodging resistance of buckwheat are affected by nitrogen fertilizer and planting density. The results showed that the lignin content at the bottom of the 2nd internode was significantly and negatively correlated with lodging index and lodging percentage, but significantly and positively correlated with snapping resistance. The snapping resistance rose and then fell with the increase of nitrogen fertilizer. The snapping resistance decreased with the increase of planting density. The lodging index increased with the increase of nitrogen fertilizer and planting density. The lignin content and its related enzymes activities decreased with the increase of nitrogen fertilizer and planting density. These results suggested that the lignin content is closely related to the lodging resistance of buckwheat, and a higher lignin content could strengthen the lodging resistance of buckwheat. The increase of nitrogen fertilizer and planting density significantly increased the risk of lodging by decreasing the lignin content and its related enzymes activities at the bottom of the 2nd internode.Key words: Buckwheat, Lignin, Lodging, Nitrogen fertilizer, Planting density.Buckwheat (Fagopyrum esculentum), which belongs to the family Polygonaceae, genus Fagopyrum, is commonlyconsumed in arid and cold regions in the world (Koyama et al., 2013). Buckwheat species native to China have been systematically classified since 1913 and it has been praised as one of the most faddish green function in the 21st century (Guo et al., 2007). Buckwheat grains are an important source of macroelements such as K, Ca, Mg, and Na as well as microelements such as Mn, Zn, Se, and Cu (Wei et al., 2003), and they contain rutin, riboflavin, pyridoxine, thiamine, lysine, methionine, arginine, and threonine (Fabjan et al., 2003). The starch of buckwheat includes numerous compounds that have been identified to have beneficial effects on human health, including lowering both blood lipid and sugar levels (MendlerDrienyovszki et al., 2013).Lodging, the permanent displacement of stems from an upright position due to internal and external factors (Pinthus, 1973), is an important constraint limiting crop yields and quality (Crook and Ennos, 1994). Severe lodging destroys plant morphology, resulting in the reduction of photosynthetic ability, grain yield, grain filling, and harvesting efficiency (Berry and Spink, 2012). Enhancing the physical strength of the culm is important for lodging resistance. In spite of the vast research performed to reduce lodging in major cereal crops, such as wheat and rice, lodging is still a dominant contributor to yield reduction (Athwal, 1971;Murakami et al., 2012). Lodging caused a 14.3% loss in rice production in coastal regions of Jiangsu China (Zhang et a...

Waxy wheat (Triticum aestivum L.) is grown throughout the world for its specific quality. Fertilization and planting density are two crucial factors that affect waxy wheat yield and photosynthetic capacity. The objectives of the research were to determine the effects of fertilization and planting density on photosynthetic characteristics, yield, and yield components of waxy wheat, including Yield, SSR, TGW, GNPP, GWPP, PH, HI, Pn, Gs, Ci, E and WUE using the method of field experiment, in which there were three levels (150, 300, and 450 kg ha -1 ) of fertilizer application rate and three levels (1.35, 1.8, and 2.25 × 10 6 plants ha -1 ) of planting density. The results suggested that photosynthetic characteristics, yield, and yield components had close relationship with fertilization levels and planting density. Under the same plant density, with the increase of fertilization, Yield, SSR, TGW, GNPP, GWPP, HI, Pn, Gs, E and WUE increased and then decreased, PH increased, but Ci decreased. Under the same fertilization, with the increase of plant density, Yield, SSR, TGW, GNPP, GWPP, HI increased and then decreased, PH, Pn, Gs and E increased, PH and WUE declined. The results also showed that F2 (300 kg ha -1 ) and D2 (1.8 × 10 6 plants ha -1 ) was a better match in this experiment, which could obtain a higher grain yield 4961.61 kg ha -1 . Consequently, this combination of fertilizer application rate and plant densities are useful to get high yield of waxy wheat.