Effects of Nitrogen Fertilizer and Planting Density on the Lignin Synthesis in the Culm in Relation to Lodging Resistance of Buckwheat

Abstract

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...

Effects of uniconazole or gibberellic acid application on the lignin metabolism in relation to lodging resistance of culm in common buckwheat (Fagopyrum esculentum M.)

“…Various workers also reported that lignin is an important factor for lodging resistance of wheat (Berry & Spink, ; Ma, ; Peng et al., ), rice (Ookawa & Ishihara, , ) and Arabidopsis (Jones, Ennos, & Turner, ). In the present study, our results suggested that the lignin accumulation is closely related to the lodging resistance of common buckwheat, and higher lignin accumulation could strengthen the lodging‐resistant ability of common buckwheat, which was consistent with the previous study (Wang, Hu, et al., ; Wang, Ruan, et al., ).…”

“…It was also reported that the lignin content and its related enzymes activities were significantly related to lodging resistance of culm in common buckwheat and buckwheat cultivars with high lodging resistance usually have large culm quality and short second internode length (Wang, et al. ; Wang, Hu, et al., ; Wang, Ruan, et al., ).…”

“…Wang, Ruan, et al. () reported that uniconazole significantly decreased the risk of lodging occurred by increasing the lignin content and its related enzymes activities of culm in common buckwheat. The treatment of seed dressing with 200 mg/kg uniconazole powder or foliar spraying with 75 mg/L uniconazole solution could optimize the culm structure, improve the culm quality, reduce the lodging risk and enhance the yield of common buckwheat (Liu et al., , ; Wang, Hu, et al., ).…”

“…It has long been proposed that lignin metabolism might be closely related to lodging resistance of culm in wheat (Baker et al, 1998;Chen et al, 2011;Peng et al, 2014;Welton, 1928;Zhu et al, 2004), rice (Ookawa & Ishihara, 1992 and rapeseed (Huang et al, 2013). Hu et al (2015) found that the common buckwheat cultivar with lodging resistance showed high lignin content in the stem, the PAL, 4CL, C4H, CAD, CCoAOMT and CCR genes play a crucial role in the pathway of lignin synthesis, and full bloom stage is the critical period in lignin synthesis of stem in common buckwheat.…”

“…Previous studies have shown that the uniconazole has been used to regulate the lodging in various crops production (Dong et al, 2008;Han et al, 2011;Wang & Xu, 1996;Yan et al, 2010;Zhang et al, 2011). Wang, Ruan, et al (2015) reported that uniconazole significantly decreased the risk of lodging occurred by increasing the lignin content and its related enzymes activities of culm in common buckwheat. The treatment of seed dressing with 200 mg/kg uniconazole powder or foliar spraying with 75 mg/L uniconazole solution could optimize the culm structure, improve the culm quality, reduce the lodging risk and enhance the yield of common buckwheat (Liu et al, 2015(Liu et al, , 2016Wang, Hu, et al, 2015).…”