Li Dongxiao, Mo Shaojing, Batchelor William D, Cheng Ruiting, Wang Hongguang, Li Ruiqi
State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Crop Growth Regulation of Hebei Province/College of Agronomy, Hebei Agricultural University, Baoding, China.
Auburn University, Auburn, Alabama, United States of America.
PeerJ. 2021 Nov 29;9:e12473. doi: 10.7717/peerj.12473. eCollection 2021.
Optimal nitrogen (N) application and plant growth regulators can improve wheat productivity. This can help to improve yield level and ensure food security with limited resources in the Huang-Huai-Hai Plain of China (HPC).
A 2-year field experiment was conducted using a randomized block design with four treatments (TS-N topdressing at pseudostem erection stage ; TPS-N topdressing combined with paclobutrazol application at pseudostem erection stage; TJ-N topdressing at jointing stage; TPJ-N topdressing at combined with paclobutrazol application at jointing stage) in 2011-2013.
The grain number per ear, thousand kernel weight and yield for the TJ and TPJ treatments were higher than those of the TS and TPS treatments. Grain number per ear, yield, and thousands kernel weigh for the TPJ treatment were significantly higher than for the TS and TPS in 2011-2012 (9.82% and 7.27%, 10.23% and 8.99%, 6.12% and 5.58%) and in 2012-2013 (10.21% and 11.55%, 8.00% and 6.58%, 0.00 and 0.00), respectively. Thousands kernel weight under TJ were significantly higher than those under TS and TPS by 13.21% and 14.03%, respectively in 2012-2013. The floret number, significantly correlated with cytokinin content, was also significantly increased under TJ and TPJ at connectivum differentiation stage. For TPJ treatment, the floret number was significantly higher than for the TS, TPS, and TJ by 19.92%, 10.21%, 6.10% in 2011-2012; it was higher than for the TS and TPS by 28.06% and 29.61% in 2012-2013, respectively. The relative expression level of cytokinin oxidase/dehydrogenase gene () was improved during flowering, when cytokinin content was at high level and was also inhibited by paclobutrazol with different degrees.
Therefore, nitrogen topdressing at jointing stage had increased grain number per ear, thousand kernel weight, and grain yield of wheat. Paclobutrazol could delay spike differentiation and promote cytokinin accumulation that induced expression of , maintaining hormonal balance and affecting wheat spike morphogenesis.
优化施氮量和使用植物生长调节剂可提高小麦产量。这有助于在中国黄淮海平原（HPC）有限资源条件下提高产量水平并确保粮食安全。
2011 - 2013年进行了为期两年的田间试验，采用随机区组设计，设置四个处理（TS - 在假茎拔节期追施氮肥；TPS - 在假茎拔节期追施氮肥并喷施多效唑；TJ - 在拔节期追施氮肥；TPJ - 在拔节期追施氮肥并喷施多效唑）。
TJ和TPJ处理的穗粒数、千粒重和产量均高于TS和TPS处理。2011 - 2012年，TPJ处理的穗粒数、产量和千粒重显著高于TS和TPS处理（分别高9.82%和7.27%、10.23%和8.99%、6.12%和5.58%）；2012 - 2013年，分别高10.21%和11.55%、8.00%和6.58%、0.00和0.00。2012 - 2013年，TJ处理的千粒重显著高于TS和TPS处理，分别高13.21%和14.03%。在小花分化期，TJ和TPJ处理下与细胞分裂素含量显著相关的小花数也显著增加。对于TPJ处理，2011 - 2012年小花数显著高于TS、TPS和TJ处理，分别高19.92%、10.21%、6.10%；2012 - 2013年分别高于TS和TPS处理28.06%和29.61%。细胞分裂素氧化酶/脱氢酶基因（）的相对表达水平在开花期细胞分裂素含量处于高水平时升高，且不同程度地受到多效唑的抑制。
因此，拔节期追施氮肥增加了小麦的穗粒数、千粒重和籽粒产量。多效唑可延缓穗分化并促进细胞分裂素积累，诱导基因表达，维持激素平衡并影响小麦穗形态建成。
