The Tropical Fruit Forum

MULTIPLE ROOTSTOCKS    The practice of grafting additional rootstocks to a tree is called inarching and was developed hundreds of years ago to give plants longevity.  Its commercial utilization in large scale was pioneered by Brazilian citrus growers to prevent tree losses caused by the disease Citrus Sudden Death. Citrolima nursery trees now have 2 rootstocks as a standard. The objective is to maintain the excellent qualities of our most common rootstock, Rangpur lime ( broad soil adaptability, rapid initial development, drought resistance, early bearing and high productivity), combined with disease resistance (foot rot, nematodes, blight, sudden death) of another rootstock like Swingle citrumelo. Inarching of additional rootstocks is utilized in some areas of the world to attain more vigorous and long living fruit trees. Citrus trees with 2 rootstocks survive Citrus Sudden Death even on the susceptible rootstock Rangpur lime. There are orange trees over 100 years old that lived through foot rot and who knows what else by the use of the multiple rootstocks technique. The best timing for adding a second rootstock is during the nursery tree stage. Costs are lower and successful rates higher. Citrolima developed special techniques that allow for the addition of a second rootstock to its citrus nursery trees efficiently and economically.

There's a difference between a runt and a potential dwarfing root stock.  Runts are quite common with some mango cultivars.  Maha Chanok is a prolific runt seedling producer.  Also poly embryonic seedlings are often runts. Runts have no vigor and are poor choices for root stocks as they just don't grow.  A dwarfing root stock is one that is vigorous and strong, yet doesn't get much height. There can be a fine line between the two and it is probably too early to draw a conclusion that what you have is or isn't a potential dwarfing root stock.

Quote from: shaneatwell on January 27, 2014, 04:18:26 PM

But isn't dwarfing good for commercial production? Or are runts the ones that are short, but also small leaved, sickly, leaf burned? Cause my runt has lots of big healthy leaves, just short internodes and overall height.

Dwarfing is even better for backyard growers.  Seedlings can vary in size, shape, height a lot when they are small.  Most polyembryonic seedlings have a dominant surrounded by "runts" that potentially can be true to type.  Its really hard to tell how large a tree will become at the early stages, if it were breeding would be a lot easier!  Your runt may in fact be a dwarf, or even a giant, no way to tell.  Either way, healthy is good! Keep it growing if you have space!

A lot of planted mango seeds are slow developing.  I have about 150 in 1 gallon pots that I went through this weekend, I disposed of about 30 "runts".

2. La Verne is experimenting with Turpentine rootstock.
Manila seedling is currently used for rootstock.  I was told that LaVerne uses the largest/healthiest sprout for rootstock of grafted varieties.  From literature, I recall that the largest sprout tends to be the zygote and not the clone.  I hope they don’t do this with the plants they sell as Manila.

Most of citrus varieties (there are only very few exceptions, like for example citrus grandis - pomelo) can produce  nucellar seedlings, which are as you said in fact clones of the mother plant.

and by the way:  we recognize phenotype and genotype! . So, I do not believe that seedling from heirloom tree is necessary identical (clone)  to its grandparent, because  genes are influenced by growing conditions for each generation.