Seeding and Propagation/rootstock for pomrgrenate
I am starting a large project to plant 700 pomegranates "wonderful variety".
the nursery people tell me they have them (20 inches long) grafted on rootstock. is there any advantage in buying grafted pomegranate trees (much more expensive than grown from cuttings). how about the in-vitro grown?
Thanx for your question. This is really a question for a professional and I will give you some contacts below. I am just a hobbyist and not university-trained but I am self-taught and I do know a little bit about agriculture and growing things.
Basically, most commercially grown fruit come from hybrid trees that are grafted onto hardier rootstock. The reasons for this are many. Many hybrids are not as robust and strong as are open pollinated varieties. Even most hobby fruit growers grow trees that are from grafted stock because the plant is more reliable. The hardy rootstock provides a firm base on which the hybrid can grow as many hybrids tend to be weak, but, they can also be prone to disease and effects of cold weather. In the U.S., it looks like most of our pomegranates grown in California are grown on their own rootstock.
Now, the other consideration is, if you are growing the stock from seed, you have to find open pollinated varieties otherwise, the progeny will be variable and usually inferior in quality because of the instability of the genetics in hybridization. 'Wonderful' is a cultivar meaning it was developed through hybridization and its seeds if planted, will result in variability in the progeny and most likely to an inferior level. This is the reason to graft because a graft is a clone of the parent plant and carries all of the genetic characteristics with it only using the graft (such as an organ transplant in a human) in order to nourish itself and survive.
Now, you can make cuttings as you mentioned. This can be very economical AND, cuttings are clones too, except you are rooting them in a rooting medium instead of grafting them to an existing, living rootstock. Cuttings are relatively easy to root and if you have the time and space to root cuttings then yes, that would be the most economical way to go. You can use cuttings from suckers coming up from the roots and last years growth in the canopy no longer than 8 inches (20 cm).
So, if you are growing a commercial project, a project to make profit, it is reasonable to say that growing grafted root stock in the end is the more judicious approach. You plant the root stock and wait about 2 years for the first fruit. Planting by cuttings could take a little longer. Cuttings will take time to root and the cuttings must go through a juvenile stage before reaching adult sexual maturity (when they start blooming and producing fruit). Your grafted root stock is ready to go in the ground. However, if expense is your main consideration and you don't mind a little time investment, cuttings would be the more judicious and advantageous approach, and economically sound approach.
I hope this helps.
University of Florida - cutting information
University of California-Davis - Pomegranate information
Remember, you can e-mail experts at both of these universities for more assistance.