How panicle angle and panicle position in the canopy determine pollination and seed set in rice (Oryza sativa L.)

Aung Win,Takashi S T Tanaka,Tsutomu Matsui

doi:10.1080/1343943x.2020.1730702

Aung Win, Takashi S T Tanaka + Show 1 more

Open Access

https://doi.org/10.1080/1343943x.2020.1730702

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Abstract

ABSTRACT We examined the effect of panicle position relative to canopy and of panicle angle on pollination and floret sterility in rice at anthesis in a paddy field. We set panicles of pot-grown rice at the flowering stage either upright (0°) or inclined (30°), either above or at canopy height (Experiment 1) and either beneath or at canopy height (Experiment 2), in three replications each. In Experiment 1 and Experiment 2, panicle inclination at 30° increased the percentage of florets with <20 total pollen grains on the stigma (TP20) by 21% and 27%, increased the percentage of florets with <10 germinated pollen grains on the stigma (GP10) by 21% and 30%, and increased floret sterility by 10% and 26%, respectively. Floret sterility was correlated with GP10 in all trials. GP10 was correlated with TP20. The effect of position on floret sterility was not significant. We conclude that panicle inclination at 30° significantly increased floret sterility even under the canopy condition. Uprightness of panicles should be an important objective in rice breeding and production. Abbreviations TP20, percentage of florets with <20 total pollen grains on the stigma; GP10, percentage of florets with <10 germinated pollen grains on the stigma.

Highlights

Rice is the primary staple food for more than half of the world’s population (FAO, 2014)
In Experiment 1, we set the panicle at 25 cm above the canopy surface and at the height of the canopy surface to detect the effect of canopy on the relationship between panicle angle, pollination and floret sterility
In Experiment 2, we set the panicle around 40 cm below the canopy surface and at the height of the canopy to know the effect of depth of the panicle in the canopy on that relationship

Summary

Introduction

Rice is the primary staple food for more than half of the world’s population (FAO, 2014). Its pollination is indispensable for seed set. Anthesis of rice occurs in late morning in many cultivars under normal condition. Each flower opens once for around 1 h. At the start of the floret opening, anther dehisces right above the stigma and pollen grains drop from the anther dehiscence to the stigma (Hoshikawa, 1993). There is seemingly little risk of disruption of rice pollination by direct external factors

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