Simultaneous enhancement of maize yield and lodging resistance via delaying plant growth retardant application

Context

Plant growth retardants (PGRs) have been widely used to improve lodging resistance in crops like maize. However, unsuitable PGRs concentration and application stage always caused yield penalty.

Objectives

This study delayed PGR application time and increased the PGR concentration to simultaneously enhance lodging resistance and grain yield. We aimed to propose a model for maize production regulation and dwarf breeding.

Methods

A four-year field experiment was conducted by applying EC (a mixture of ethephon and cycocel) at V7 (7th leaf collar is visible; TV7) and V14 (TV14) stage, respectively. Lodging resistance, leaf area, florets, internode length, carbon isotope distribution, and grain yield were evaluated.

Results

The results showed that both TV7 and TV14 significantly improved stalk bending strength and lodging-resistant index compared to the control (CK). TV7 reduced basal internodes length and leaves area, while TV14 shortened the internodes above ear without affecting leaf size. Notably, the decreased stem in TV14 facilitated assimilates allocation to the ear from the leaves above ear traced by ¹³C isotope, which could promote kernel set when the number of fully developed florets of each treatment was similar. Indeed, the kernel number per ear was increased by 7.6 % for TV14 but reduced by 7.3 % for TV7 compared to CK, leading to a yield increase of 8.1 % for TV14 and a decrease of 8.1 % for TV7.

Conclusion

Hence, delaying the application of EC from V7 to V14 stage can effectively enhance both maize lodging resistance and grain yield. Finally, a model for optimizing the utilization of assimilates by PGRs is proposed, which provides an insight for maize production regulation and dwarf breeding in the future.