Variation of floret fertility in hexaploid wheat revealed by tiller removal.

Zifeng Guo,Thorsten Schnurbusch

doi:10.1093/jxb/erv303

Abstract

Grain number per spike, which is greatly influenced by floret fertility, is an important trait of wheat (Triticum aestivum L.) yield. Maximum floret primordia, fertile floret, and final grain number per spikelet are three crucial factors of floret fertility. Floral degradation plays a critical role in determining these three floret fertility-related traits. Twelve hexaploid spring wheat genotypes were selected to investigate the influence of detillering on floral degradation and floret fertility-related traits in the field and greenhouse. Notably, the green anther stage was found to consistently have the maximum floret primordia number. Visible floral degradation, however, was observed to occur at several floral developmental stages, specifically from green anther stage to anthesis. Detillering was able to delay floral degradation in most cases and was evidently highly associated with increased maximum floret primordia, fertile floret, and final grain number per spikelet, with only a few exceptions. Thermal time required for each floral developmental stage was overall not influenced by detillering. These data hereby reveal a predominant spikelet fertility pattern along the spike in which the number of fertile florets per spikelet at anthesis becomes developmentally confined.

Highlights

Grass spikelets produce reproductive structures called florets; the determination of floret number per spikelet is a primary factor of spikelet architecture in the grass family
The indeterminate nature of wheat (Triticum aestivum L.) spikelets may enable more than eight florets to be formed within one spikelet, which is in contrast with other cereals that have a fixed number (Oryza sativa and Zea mays) (Skibbe et al, 2008; Yoshida and Nagato, 2011) or effectively are fixed to one floret (Hordeum vulgare, barley) (Bonnett, 1967)
Comparisons between control and tiller removal experiments were conducted to show the effects of detillering on the timing of floral degradation, maximum floret primordia number, fertile floret number, and final grain number

Summary

Introduction

Grass spikelets produce reproductive structures called florets; the determination of floret number per spikelet is a primary factor of spikelet architecture in the grass family. After reaching the maximum number of floret primordia, representing wheat’s yield potential, a floral degradation process is initiated determining the fertile florets at anthesis. González et al (2011) reported the initiation of floret death when F1 ranged from W8 to W9 As far as it could be ascertained, the only work to determine the onset of floral degradation following the Kirby scale was conducted by Kirby and Appleyard. It is necessary to determine the effects of detillering on the maximum number of floret primordia, fertile floret number, final grain number, and floral degradation under field and greenhouse growth conditions. Comparisons between control and tiller removal experiments were conducted to show the effects of detillering on the timing of floral degradation, maximum floret primordia number, fertile floret number, and final grain number

Materials and methods

Results

Discussion