Pollen Analysis in Onions

Why is it Important to Analyze Onion Pollen Quality?

The analysis of onion pollen quality improves breeding and seed production processes and enables better decisions based on data. The onion chip with automated data analysis makes these analyses even easier: 

  • Select those lines with high pollen viability and low number of aberrant cells 
  • Select those lines with high amount of viable pollen cells 
  • Know the impact of abiotic stress for crop placement 

Ensuring high pollen viability and a substantial pollen quantity is crucial for achieving a robust seed set, making it an indispensable factor in cost-effective seed production. The early identification and understanding of effective pollinator lines during the breeding process not only streamline efforts in breeding but also result in time and resource savings in subsequent production research and seed production. 

As a biennial crop, onion breeding and seed production are lengthy processes and gains in efficiency have a significant impact. Knowing the properties of onion lines with respect to reproduction can help to save a lot of effort and resources and to improve the result. 

Our specific onion chip facilitates automated data analysis of pollen viability and quantity. It delivers instantaneous results, offering a time and resource-efficient solution for routine quality control and systematic pollen screening. 

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Characterization of onion pollen quality in breeding 

  • Identify the best pollinator lines 
  • Optimize sampling and sample preparation process 

Improvement of onion seed production 

  • Avoid poor seed set by knowing the pollinator properties  
  • Use the right tools to ensure efficient manual pollination 

Characterization of Pollen Quality in Breeding

Viable pollen in a sufficient amount is a basic requirement for successful plant reproduction. However, viability and quantity show significant variation among different onion lines. Amphasys’ technology with automated data analysis offers a fast, reliable, and cost-efficient solution for line characterization.  

Sampling and sample preparation

For the determination of pollen viability and pollen quantity, flowers in an open stage should be used. Closed flowers or older flowers at the end of the flowering period should not be used. The best time for flowers or anther collection is about lunch time or early afternoon. 

For sample preparation, several flowers should be collected to have enough pollen to measure. Using 4 to 5 open flowers shows the best result. The pollen of the flowers is shaken out by moving the tube with the flowers over a rack (“rack method”). Sample preparation instructions are provided on the Ampha P20 instrument using the onion chip. 

If stored onion pollen is used, a 30-minute rehydration time is recommended to obtain the best results.  

Onion pollen should be equilibrated for two minutes in the measurement buffer. Pollen is stable in the buffer for more than one hour without loss of viability.  

Onion umbels and flowers

Identify the best pollinators - Systematic Line Screening

Large scale screening measurements show that pollen viability of onion is rather moderate compared to other crops. The better pollinator lines show around 50% pollen viability only, bad pollinator lines produce less than 10% viable pollen, and the variability between the lines is also quite high. 

Percentage of viable and aberrant pollen cells of different onion lines 

In addition, a line dependent variation of aberrant cells can be observed, ranging from low occurrence of below 10% to above 70%! All these results show the importance of proper line selection during onion breeding to prevent later issues in seed production. 

Improvement of Onion Seed Production

Knowing the impact factors for crop placement, determining the optimum female to male ratio, having the right pollen storage protocol in place – these are important success factors for seed production. For onion seed production this is specifically important as the preconditions are already poor: low pollen viability, relatively high content of aberrant cells, and high variability between lines. In addition, the amount of pollen grains per flower can vary a lot between lines. 

Number of pollen cells per flower of different onion lines 

In the event that low viability comes along with low amount of pollen cells, reproduction of this line becomes a great challenge. But also in case of high amount of pollen, the success of reproduction can be limited by a high percentage of aberrant cells. Investigation of abiotic stress factors is then indispensable and relocation of production or changes in the production pattern are recommended. 

Our Onion chip, equipped with automated data analysis, enables swift and systematic screening of numerous lines, delivering instant results. Testing pollen quality and determining the pollen quantity per flower can be done in less than a minute. When coupled with our pollen analyzers, Ampha P20 and Ampha Z40, the Onion chip enhances the efficiency of breeding and seed production processes. 

Amphasys Pollen Analyzers

Amphasys Pollen Analyzers provide pollen quality metrics which enable you to improve your plant breeding and seed production processes:

The Ampha Z40 is a high-end laboratory device. It offers full flexibility for all pollen quality related research tasks and predefined templates for routine quality control.

The Ampha P20 is a mobile high-tech instrument for greenhouses and fields. With its easy handling and automated data analysis you get immediate results on site.

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