Comparing pollination bag types and the effect of environmental conditions on seed set in Miscanthus crosses

Three bag types, i.e., PBS International (duraweb®), a Paper-&-Plastic bag, and Glassine were compared for their relative efficiency in producing a successful cross in Miscanthus under two environments of glasshouse and isolation chamber conditions. Crosses were attempted in 2013 at the Institute of Biological Environmental and Rural Sciences (IBERS), Aberystwyth University. ANOVA: The effect of two climatic conditions (glasshouse and isolation chambers) was non-significant on seed set and success of crosses. Bag type and Type of cross, however, had significant effect on seed setting upon pollination. None of the interactions were significant. Bag type effect: While the Glassine and Paper-&-Plastic types did not differ significantly, the PBS International bags were superior to the combined effect of other two types of bags with 12% higher rate of success of crosses. The success rate of crosses with PBS’ duraweb® bags was the highest at 45%, which exceeded Glassine by 15% and Paper-&-Plastic over 7%. The Z-test revealed highly significant higher mean rate of success for the duraweb® bags than the combined mean success rate of Glassine and Paper-&-Plastic type of bags. Cross type effect: The success rate of crosses was significantly higher when crosses involved genotypes of the same Miscanthus species than when they represented different species. The mean success of crosses was 47% from intraspecific crosses which was 13% higher than the interspecific crosses. Seed traits: Seeds produced within PBS bags were significantly bolder (heavier) and presumably healthier for better seedling establishment under stress environments. Economic analysis: Average cost of a cross using different bags was computed from the actual spend. The most economical bags are those of PBS International duraweb® type which are cheaper by £55 pounds than glassine and £19 than Paper-&-Plastic type for a cross. The duraweb® bags give relative gain of 33% over glassine and 15% over Paper-&-Plastic type. Considering many crosses attempted in a breeding programme our simulations showed that for 1000 crosses, the duraweb® bags result in saving of £55,000 over Glassine and £19,000 over the Paper-&-Plastic type of bags. Even when 500 crosses are attempted the saving still remains very significant. Reuse: The PBS International bags stood up well to the different climatic conditions and were easy to re-use with an autoclave cycle in between. The Paper-&-Plastic bags were unable to withstand an autoclave cycle and so for single use bags were too costly. They were also a bit too short for use with Miscanthus species. The glassine bags became brittle under the different climatic conditions and as such were only usable once. Both of the glassine and the paper and plastic bags were damaged by slugs and were broken by the continued growth of the Miscanthus stems. These problems were not observed in the PBS bags.