We conducted a 3-year (2017-2020) field experiment in the wheat base of Jinzhong Agricultural Hi-tech Industries Demonstration Zone, aiming to determine the measures of nitrogen topdressing and the regulatory effect of cycocel in spring to increase wheat yield. Four nitrogen topdressing dates were set up under the condition of cycocel spraying and control (CK) during the rising period: 10 days (D10), 20 days (D20), 30 days (D30), and 40 days (D40) after regreening stage, to analyze the impact of different N topdressing dates on winter wheat yield and the regulation effect of cycocel on stem characteristics, lignin content and related synthetase activities. The results showed that compared to other nitrogen topdressing dates, D30 increased spike number by 1.4%-5.2%, grain number per spike by 0.4%-12.0%, 1000-grain weight by 1.7%-9.4% and yield 8.8%-22.1% respectively. Compared to D10 and D20, D30 significantly improved the activities of phenylalanine ammonia-lyase (PAL) at 0-21 days and 35-42 days after the formation of the second section and increased that of tyrosine ammonia-lyase (TAL) at 0-42 days after the formation of the second section, and increased the lignin content of stem, the internode quality, and the breaking resistance of stem, reduced plant height, and thereby improved the lodging resistance. However, D40 increased grain number per spike by 4.5%-10.1% and yield 0.04%-11.3%, but reduced the activities of PAL and TAL at 0-42 days after the formation of the second internode, reduced the lignin content, weakened the stem strength, and increased the risk of lodging. After spraying cycocel, plant height decreased significantly, the activities of PAL and TAL enhanced, the lignin content in internodes increased, the stem strength advanced, and reached a significant level under D30. Under the condition of nitrogen topdressing combined with cycocel spraying in spring, PAL and TAL activities were significantly positively correlated with lignin content. Lignin content was significantly positively correlated with stem breaking resistance. Stem breaking resistance was significantly positively correlated with lodging resistance index. Yield and its components were significantly posi-tively correlated with internode diameter, weight and breaking resistance, and significantly negatively correlated with plant height and internode length. Overall, nitrogen topdressing combined with spraying cycocel 30 days after regreening could promote the synthesis and accumulation of lignin, and improve stem plumpness, plant lodging resistance and yield.
为明确小麦增产的春季追氮措施及矮壮素的优化调控效应,于2017—2020年在晋中农高区小麦基地开展大田试验,在起身期喷施矮壮素和对照(CK)条件下设置4个追氮时间: 返青后10 d(D10)、返青后20 d(D20)、返青后30 d(D30)和返青后40 d(D40),研究不同追氮时间对冬小麦产量的影响及矮壮素对茎秆特性、木质素含量及相关合成酶活性的调控效应。结果表明: D30较其他追氮时间穗数提高1.4%～5.2%、穗粒数提高0.4%～12.0%、千粒重提高1.7%～9.4%、产量提高8.8%～22.1%。与D10和D20相比,D30显著增强了基部第2节间形成后0～21、35～42 d苯丙氨酸解氨酶(PAL)活性和0～42 d酪氨酸解氨酶(TAL)活性,提高了茎秆木质素含量,增加了节间质量,提高了茎秆抗折力,且降低了株高,提高了抗倒性;而D40较D10和D20穗粒数增加4.5%～10.1%、产量增加0.04%～11.3%,但降低了基部第2节间形成后0～42 d PAL和TAL活性,减少了木质素含量,茎秆强度减弱,增加了倒伏风险。喷施矮壮素后,小麦株高显著降低,PAL和TAL活性增强,节间木质素含量提高,增加了茎秆强度,且在D30达显著水平。春季追氮与喷施矮壮素条件下,PAL和TAL活性与木质素含量呈显著正相关,木质素含量与茎秆抗折力呈显著正相关,茎秆抗折力与抗倒伏指数呈显著正相关;产量及其构成因素与节间直径、质量和抗折力呈显著正相关,与株高和节间长度呈负相关。综上,返青后30 d追氮结合喷施矮壮素,可促进木质素的合成与积累,提高茎秆充实度,提高植株抗倒性和产量。.
Keywords: cycocel; lodging resistance; nitrogen topdressing in spring; winter wheat; yield.