Description of Sunflower Growth Stages¹

TLDR

Sunflower development requires a standardized, accurate, and user‑friendly description system. The study aimed to develop a simple yet accurate staging system for sunflower development. Plants were classified into vegetative and reproductive phases, with vegetative stages defined by true leaf count and reproductive stages split into nine phases based on inflorescence development from emergence to seed maturity. The resulting staging method is rapid, accurate, and simplifies existing approaches, applicable to both single‑ and branched‑inflorescence sunflower.

Abstract

A standardized, accurate, and easy system is needed to describe sunflower ( Helianthus annuus L.) plant development. The objective of this study was to develop and describe stages of sunflower plant development in a manner which is simple but accurate. Plants were divided into either Vegetative (V) or Reproductive (R) stages of plant development. Vegetative development is divided into two phases, emergence and true leaf development. The latter stages are determined by the number of true leaves in excess of 4 cm in length. The number of vegetative stages is dependent upon the number of true leaves formed by the plant, making the method flexible but accurate. The reproductive development was divided into nine stages based on the development of the inflorescence from its initial appearance through anthesis to physiological maturity of the seed. This method of describing the stages of development in sunflower is rapid, accurate, greatly simplifies current methods, and can be used to determine plant development for either single or branched inflorescence sunflower.