Grain Filling Physiology in Cereal Crops

Grain filling in cereals encompasses a dynamic interplay between assimilate production, transport and deposition in the developing endosperm. This process determines final yield and quality in staple crops such as rice, wheat, maize and barley. Grain filling commences with a phase of endosperm cell division followed by starch and protein accumulation, primarily through sucrose translocation from photosynthetic tissues and remobilisation of non-structural carbohydrate reserves. Enzymatic activities, including those of ADP-glucose pyrophosphorylase and starch synthases, mediate sucrose-to-starch conversion, while hormones such as abscisic acid and cytokinins regulate both metabolic and developmental aspects. Source–sink coordination is modulated by environmental cues including water availability and temperature, which can alter phloem loading and unloading capacities. Genetic variation underpins differences in sink strength and vascular efficiency, explaining asynchronous filling of superior and inferior spikelets in large-panicle rice and variable kernel setting in wheat. Insights into molecular networks governing grain filling underpin breeding strategies and agronomic practices aimed at enhancing yield stability and nutritional quality under changing climates.

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Grain Filling Physiology in Cereal Crops publication trend

The graph below shows the total number of articles in grain filling physiology in cereal crops across all publications each year (not limited to Nature Index journals).

Technical terms

Grain Filling: The phase of endosperm cell division and deposition of starch and protein in developing cereal grains.

Source–Sink Relationship: The balance between sites of carbohydrate production (sources) and storage or growth organs (sinks).

Sink Strength: The capacity of developing grains to attract and utilise assimilates from source tissues.

Non-structural Carbohydrates (NSC): Soluble sugars and starch reserves in vegetative tissues that can be remobilised during grain filling.

Sucrose-to-Starch Conversion: The enzymatic pathway by which imported sucrose is transformed into starch polymers within the endosperm.

Abscisic Acid (ABA): A plant hormone that regulates stress responses and development, playing a key role in coordinating grain filling processes.

References

1. Transcriptomic analysis of grain filling in rice inferior grains under moderate soil drying. Journal of Experimental Botany (2019).
2. Abscisic acid synergizes with sucrose to enhance grain yield and quality of rice by improving the source-sink relationship. BMC Plant Biology (2019).
3. The Initiation of Inferior Grain Filling is Affected by Sugar Translocation Efficiency in Large Panicle Rice. Rice (2019).