Breeding

by Donald Smith
January 1995

Over the past few years I have had moderate success with the intersectional cross (Paeonia lactiflora x lutea hybrids) obtaining 75-100 seeds per year. The majority of these seeds have come from the cross Paeonia lactiflora 'Martha Washington' x Paeonia 'Golden Era' (lutea group) pairing originally discovered by Roger Anderson. During this period I have kept accurate records on the development, germination, and first year growth of the seeds and seedlings resulting from this cross. A summary of the results for 1993 is shown in Table 2 below. All seeds were germinated indoors in plastic bags containing damp sphagnum moss (natural long fibered - not milled). Results were checked and recorded about once per week. On average, these seeds germinated in approx. 10 weeks and (after about 18 wecks in the refrigerator) grew into strong, healthy, and vigorous plants averaging 8 cm tall with light green foliage measuring 6.5 cm x 8 cm across. All seedlings were grown indoors under artifical lights, each in a separate 10 cm plastic pot. Although the first year foliage varied markedly from individual to individual, nearly all exhibited clear indications of their tree peony heritage. The leaf structure of a typical intersectional hybrid seedling is shown below.

 

0397ZF01, Blattform

Leaf structure of a intersectional hybrid seedling

The results so far for 1994 are quite similar to those for 1993 except that the percentage of ruptured seeds was significantly higher at 25 %. Amoug the seeds of the cross Paeonia lactiflora 'Martha Washington' x Paeonia 'Golden Era' (lutea group) the percentage of ruptured seeds was even higher at 33 %. Do not discard these ruptured seeds when they appear along with the "good" ones from the intersectional cross, as a few of these seeds (5-10 %) will germinate and grow with no special care or handling, so long as they are started immediately upon harvest. They can not be allowed to dry-out. I believe that many of the resulting plants from these seeds may turn out to be tetraploids. I will explain why I believe this to be true and give some ideas for how to bring more of these "special" seeds to successful germination in a subsequent article.

Table 1
Intersectional hybrid seed development, germination and first year growth summary 1993 results