Hi Folks
Somehow the wrong button got pushed and instead of putting this into
draft it got posted incomplete. My apologies. I have just copied it back
and will now try to finish it off properly.
Jim Worstell wrote
Actually bread wheat and spelt are the same species, both Triticum
aestivum.
You may be thinking of emmer which has the same genomes as
dicoccoides.
By the way, dicoccoides is a source of high protein genes. I've seen
lines as high as 30% protein.
Hi Folks
Just to enlarge on Jim's information a little I looked up my ancient
University notes and this is what I found:-
Like corn, none of the quite large number of species (races) of
cultivsted wheat also occur in the wild, but unlike corn which has no
very close wild
relation, there are two wild Triticum species, growing naturally in the
East Mediterranean area which are generally reckoned to have between
them given rise to all the cultivated forms.
Triticum aegilopoides. This species occurs mainly in the Balkans and>
Asia minor. While the individual spikelets on the flowering stem may be
two-flowered only one ever produces a grain.
It is thought that only one cultivated plant has ever arisen from this
species :-
T. monococcum (Small Spelt). This is not much of an improvement on the
wild species, having the single-grained spikelets which shatter at
maturity, so gathering the grain is quite difficult and threshing to get
rid of the chaff even more so. It is also late ripening, has a miniscule
yield and is poor for bread making. Not surprisingly it is not grown as
a crop any more, but was the common grain in the area of its parent in
prehistoric times (fossil grains are for instance found in Swiss Lake
Dwelling sites).
The second wild species is the important one in the story of wheat.
Triticum dicoccoides (Wild Emmer)
Occurs widely in the western Mediterranean, reaching inland as far as
Iran.
As the name suggests each spiklet sets two grains.
It is thought by one school at least that all the different types of
wheat we know today arose from this species mainly by selection, which
quite unintentionally was enhanced by polyploidy. For those not familar
with this concept, the wild form is a simple diploid, that is a plant
whose cells contain just one set of chromosomes from each parent, but in
the case of wheat, in the most useful of the resulting descendents,
these have somehow become doubled or even tripled, so that for instance
the common bread wheat (T. aestivum) has no less than three double sets
making it a hexaploid.
Polyploides can now be produced by breeders at will using certain
chemicals and other methods, but this was certainly not known in
earlier times. However they can also arise spontaneously due to some
natural hiccup in cell division during reproduction, and that is
obvously what happened on more than one occasion as the early farmers
began to select the best individuals from their crops for seed. They
would have started no doubt at the very beginning just growing the
wild species deliberately in little beds or fields and picking the best
individuals as seed parents each year. Improvement would of course have
been very slow to start with, maybe one useful change in thirty or so
generations, but this is only a guess, I have no real infomation on the
likely rate. As cultivation increased so did the chance of a change in
the growing plants.
The big point about polyploids is that the majority are stouter and
higher-yielding than the simple diploid ancestor from which they
sprung, moreover the change is a permanent one, unlike say the
advantages from growing in a richer soil.
So farmers would have certainly noticed these exceptional plants
standing above the rest of the crop and often with denser heads than the
parents, and those with any sense at all would have defintely selected
their seed for planting, so that in time they would have had some
better-yielding forms, often with other advantages also, to improve
their crop. Of course polyploidy was not the only change in the plants
which produced the improved forms, minor changes due to crossing of
different strains and sometimes to favourable mutatuons would have also
played their part.
You have to understand though that this was not modern purposful
breeding and the establishment of all the various types of wheat
cultivated today took hundreds if not thousands of years of fairly
random and not by any means always successful selection (this is
equally true of course of the history of domestication of any plant in
ancient times, not just wheat)
Anyway, by early last century there was plenty to classify when
Professor Percival at Reading University gathered up every wheat variety
he could find and eventually produced a vast monograph entitled (if I
remember correctly)The Wheat Plant. By the time I got to Reading he was
a very ancient Professor Emeritus of the Ag. Botany Department in which
I studied for my degree, but a large part of his wheat collection was
still preserved there, along with his magnum opus, an impressive
publication indeed..
It was his opinion that T. dococcoides had given rise to no less than 11
very distinct races, which I guess are also considered by some to be
different enough to be termed species. Some of these are really weird
like the hedgehog wheat or confined to restricted areas, where no doubt
by now mny will have died out, but there are four which are of
particular interest and definitely still around.
T. dicoccum (Emmer)
Is the most primitive and a diploid like its wild relation. Percival
recognise two types one from Europe an the other from Ethiopia.
The European type (Maybe extinct by now) has the primitive features of
both a fragile stalk which breaks into sections at maturity and also
grains firmly held in the chaff and one of the Ethiopean forms is
similar, but the other is msot interesting as it shows the much more
modern and useful features of a firm stalk and a grain which naturally
separates from the chaff when threshed.
This wheat was cultivated in Europe from the time of the Bronze Age and
was much used in Ancient Egypt and Babylonia. It has been ousted almost
everywhere by better varieties such as Spelt, but may be useful in
breeding because of both the non-shattering head and the high protein
content mentioned by Jim.
T spelta (large Spelt or Dinkel)
One of whose major advantages is great cold hardiness, but it is also
very disease resistant and its yield on good soils is nearly as good as
the bread wheat (T aestivum), while it will also yield an adequate crop
in much poorer conditions.
It seems to have originated among the ancient Germanic races living just
north of the Alps and has long been grown in that region. It would
appear to have come back into popularity in recent times becase it has
certain dietary advantages for people who can't take ordinary wheat..
It's one major problem is that it has the primitive characteristic of
brittle ears and so needs special threshing methods.
Only two other races/species heed to be considered, but between them
they cover almost the entire world wheat production. They are:-
T durum (Macaroni Wheat). This one is a tetraploid with correspondingly
fuller ears than the foregoing. Varieties are often known as "hard"
wheats from their tough flinty grain which is particlarly suited to
making pasta. Though occasionally use for bread making they are not very
successful for this, due to excess gluten.
They first appeared in Egypt in classical times and in 18th century
Britain were nearly as popular as ordinary bread wheat, but with the
onset of the Little Ice Age the climate there became to cold for them.
Today they are mostly confined to the hotter and more arid
wheat-growing areas as they are resistant to both drought (needing
rainfall in the range from 10-18" only) and also rusts and smuts.
T. aestivum (T vulgare) Is the bread wheat.
This has very stout and full ears due to being a hexaploid. Ther are
numerous varieties, some of which are planted before winter and others
in spring. Many countries breed their own to get the best match with
their particular conditions. It can be very high yielding but in general
requires a higher rainfall than durum types, At the same time though it
is also considerably more cold resistant.
This species has the unfortunate the disadvantage of being prone to a
number of diseases. especially rusts, and some breeding effort is alway
directed towards increasing resistance to these.
There is a lot more that might be said, but I will refrain.
Moira
--
Tony & Moira Ryan
Wainuiomata NZ,
where it's Summer in January and Winter in July.
