being new to citrus and after reading this thread, would the following statements be correct?
rooting citrus is finicky and takes a long time
citrus seeds are true to type making it faster and easier to grow from seed or to graft(or air layer?).
named fruiting varieties should still be grafted onto named rootstock varieties for temp hardiness/disease and pest resistance/vigor.
if youre going to graft a named variety(X) onto a named variety(Y) that is on a different rootstock(Z), would you graft X onto a branch of Y, the trunk of Y, or the trunk of Z?
I’m not sure about other citrus but I find lemons are extremely easy to propagate by cuttings. I’ve done it with Meyer and Pink Variegated varieties. I’ve given away a lot of lemon plants to friends and family. Those cuttings usually produce fruits by the 2nd or 3rd year. I’ve not tried it with kumquats since my trees are fairly small but will soon.
I have chip bud grafted onto the trunk of Y in this example. I would have done it onto trunk of Z but the tree is 6+ft tall and 8+ wide so I don’t think the bud that would would have enough vigor. Although I’m putting buds on z this spring to one day perhaps cut down the variety Y due to its very low bearing, unless this year it bears a lot. It’s my largest citrus so far by a good measure but has only bore 5 fruits total. My owari had that many season 2 and 9 fruits it’s second season. None however this year as that was too many fruits for its second year bearing. However it sized up drastically due to it being third year in ground and no fruit or flowers so all its energy was into foliage and branches. Basically it’s a case by case basis, citrus grafts take pretty easily in my limited experience.
Rootstock is usually from seed, which is why varieties that are highly nucellar (clonal seed, ie true to type) are preferred.
In general, most citrus varieties you’ll normally encounter are mostly true to type even when cross pollinated. Basically all oranges, limes, and grapefruits are, most lemons except for Meyer are, most tangelos and similar hybrids except for honeybelle, and most mandarins except for clementines, and most trifoliate hybrids except for some rare ones. On the other hand, most kumquats except for Meiwa, most pumelos, and most citrons are not true from seed and will form hybrids when cross pollinated.
There are various exceptions to the above, like Kiyomi tangor or ichang papeda or smooth flat Seville, but you’re not likely to come across those varieties.
Then how do we create so many hybrids i always thought if cross pollinated then genetic lottery as with most other plants as well. Is there something I’m missing?
It’s because some Citrus produce a high percentage of seeds which are nucellar. Nucellar seeds are formed from clonal tissue rather than from a combination of two parents. These types generally still produce a small amount of seeds which are zygotic (which is what you typically expect seeds to be from most plants). Zygotic seeds will be different from the parent even if self-pollinated since self-pollinated plants will have a recombination of their parent’s genes and might become homozygous for certain genes that the parent was only heterozygous for. The only way for self-pollinated plants of any species to reliably be “true” from seed (if they actually produce zygotic seed) is if they are already inbred enough to be mostly homozygous in the majority of their genes to make variation among seedlings negligible (except for when mutations or accidental cross-pollinations happen).
It’s centered around cold hardy citrus, but I’ve found this useful: Table of citrus cold hardiness and %zygotic seed
The first column is frequency of zygotic seedlings (i.e. how not-true-to-type a cultivar is). So lower the better if you want to a tree of whatever seed you’re planting. Much thanks to @a_Vivaldi for putting it together.
i always thought if cross pollinated then genetic lottery as with most other plants as well. Is there something I’m missing?