Abstract:

Tartary buckwheat （Fagopyrum tataricum） belongs to the Polygonaceae， and originated in the southwest of China， northern India， Bhutan， and Nepal. Most Tartary buckwheat is grown in hilly and mountainous areas， where mechanized farming is still underdeveloped. Lodging is a serious problem in Tartary buckwheat grown in hilly and mountainous areas， and this greatly restricts the development of the Tartary buckwheat industry. Because the appropriate use of agricultural machinery can increase agricultural productivity， we conducted a field study to identify the optimal method for mechanical sowing and fertilization of Tartary buckwheat in hilly and mountainous areas. The field study consisted of an L₉3⁴ orthogonal experiment with three factors and three levels conducted in 2016 and 2017. Seeds of Youqiao 5， a moderately lodging-resistant Tartary buckwheat cultivar， were sown at a depth of 2 （A₁）， 3 （A₂）， or 4 cm （A₃）， at a rate of 16.8 （B₁）， 33.6 （B₂）， or 50.4 kg seeds·ha^-1 （B₃）， with fertilizer applied at 150 （C₁）， 300 （C₂）， or 450 kg·ha^-1 （C₃）. The lodging and yield of Tartary buckwheat were determined at different growth stages. Of the three factors， sowing depth had the strongest effect on lodging rate， followed by the amount of seeds and then the amount of fertilizer. As the sowing depth increased， the lodging period was delayed， and the lodging level and the lodging rate decreased and then increased. The lodging level and lodging rate increased as the amount of seeds and fertilizer increased. The length， diameter， fresh weight， and bending resistance of the second internode of the stem base gradually increased from flowering to maturity. Compared with sowing depth and amount of fertilizer， the amount of seeds had a greater effect on the diameter， fresh weight， and breaking force of the second internode of the stem， but not on the length of second internode. With increasing sowing depth， the diameter， fresh weight， and bending force of the second internode initially increased and then decreased， and the length of the second internode initially decreased and then increased. With increasing amounts of seeds sown， the diameter， fresh weight， and bending strength of the second internode decreased gradually， and the length of the second internode first decreased and then increased. With increasing amounts of fertilizer， the length， diameter， fresh weight， and bending resistance of the second internode increased gradually. The activity of 4-coumarate：CoA ligase （4CL）， phenylalanine ammonia-lyase （PAL）， and cinnamyl alcohol dehydrogenase （CAD） increased and then decreased from flowering to maturity， and the lignin content gradually increased. The lignin content and the activities of 4CL， PAL， and CAD in the second internode of the stem were most strongly affected by the amount of seeds sown， followed by sowing depth and then fertilizer amount. The lignin content and the activities of 4CL， PAL， and CAD first increased and then decreased with increasing sowing depth； gradually decreased with increasing amounts of seeds sown； and increased with increasing amounts of fertilizer. Yield， grain number per plant， and number of plants （but not 1000-grain weight） were most strongly affected by the amount of seeds sown， followed by sowing depth and then fertilizer amount. As the amount of seeds sown increased， the yield and number of plants increased， and the number of individual plant grains and 1000-grain weight decreased. As the amount of fertilizer increased， the yield and number of plants were not significantly affected， but the individual grain number and 1000-grain weight gradually increased. Overall， the combination of A₂B₂C₃ （sowing depth of 3 cm， seed sowing rate of 33.6 kg·ha^-1， fertilizer amount 450 kg·ha^-1） was found to be beneficial for growing Tartary buckwheat with a high yield and strong lodging resistance in hilly and mountainous areas.

Key words: mechanization sowing, tartary buckwheat, lodging resistance, yield