Picture of the Biggest Fruit in the world

What is the largest fruit there has ever been, and
just how big is it possible for fruit to get?
The answer to the first is reasonably
straightforward.
This recording breaking feat triggered a
discussion about how it is possible to grow
such large fruit
The answer to the second, however, is much juicer,
attracting the attention of some of the world’s
leading plant biologists.
They have just published new research into what
influences the extreme size fruit can grow to.
This new research not only reveals something
about what goes on inside these giant fruits, it also
confirms how much we still have to understand
about how plants produce their fleshy, often sweet
bounty.
Record breakers
So far, the largest known fruit was a pumpkin,
grown by a human, rather than naturally in the
wild. Produced in 2014, it weighed more than a
tonne, topping the scales at a mouth-watering
1056kg.
The Atlantic Giant variety used today is likely
a descendent of the award winning Mammoth
pumpkin that held the world record from 1904
to 1976
This freakish fruit is not quite as outlandish as it
may first seem.
Indeed records for the largest fruit varieties are
broken so often that scientists at Harvard
University in Massachusetts, US, decided to
research them further to see what could be
learned.
“A colleague of ours, Kaare Jensen, brought to our
attention in 2012 that nearby in Topsfield,
Massachusetts, a new world record was set with a
2009 lb (913kg) pumpkin,” Dr Jessica Savage , at
Harvard’s Arnold Arboretum, told BBC Earth.
“This recording breaking feat triggered a
discussion about how it is possible to grow such
large fruit.”
Descendants of giants
Most giant pumpkins descend from a few known
varieties.
“Competitively grown pumpkins were originally
bred from Hubbard Squash and their lineage can
be traced back through a series of varieties, each
progressively increasing in size,” explained Dr
Savage.
Some people eat them but they are more
often used for decorations or novelty items
including boats
“In fact, the Atlantic Giant variety used today is
likely a descendent of the award winning Mammoth
pumpkin that held the world record from 1904 to
1976.
“However, in the intervening years, seeds from this
pumpkin were crossed with many other Mammoth
varieties and the exact parentage of older plants is
often unknown.”
Novelty items
These giants of the fruit world have limited uses.
Being around 98% water, they contain relatively
little sugar and starch, and may lack in taste as a
result.
“Some people eat them but they are more often
used for decorations or novelty items including
boats that are used for racing,” said Dr Savage.
For giant pumpkins, the solution was simple,
build more single-laned roads
Because giant varieties are pruned to grow a single
fruit per plant, and are heavily fed and watered, it
is uneconomical to grow them for agriculture.
“Producing large fruits, especially giant pumpkins
and squash, does not always lead to a greater
yield per unit of land,” said Dr Savage.
“But they do serve as a great tool for studying fruit
growth.”
Pumpkin highways
Dr Savage and colleagues did exactly that by
comparing the anatomy and physiology of giant
pumpkin varieties to an ancestral variety, with the
goal of determining why giant pumpkin plants can
produce enormous fruit.
They were particular interested in the plant’s
vascular system, the channels within that transport
water and sugar.
“We focused on the phloem because it is the part
of the vascular system that delivers sugars, which
provide the carbon used during fruit growth.”
The scientists discovered that larger fruits didn’t
change the structure of their phloem, or the rate at
which nutrients passed through them.
It is difficult to say whether it is possible to
predict the upper limit of fruit size
Instead they grew more.
“You can think about how giant and non-giant
pumpkin varieties differ in their phloem transport
by thinking about it in terms of traffic on a road,”
Dr Savage explained.
“If more cars travel between two cities, there either
needs to be more roads or higher capacity roads
with more lanes. For giant pumpkins, the solution
was simple, build more single-laned roads, which
in the phloem means building more conduits to
transfer fluid.
“The actual structure of the phloem cells did not
change but the total amount of phloem increased.”
Outer limits
The fact that giant pumpkins create more phloem
to transport vast amounts of carbon to their huge
fruits sheds light on how plants move carbon
around their bodies, and how much of it they
allocate to different parts, such as leaves or roots.
What remains unclear is whether there is a limit to
how many phloem a plant can produce, report the
scientists in the journal Plant, Cell & Environment.
We also do not know, yet, just how big fruits can
get.
“It is also difficult to say whether it is possible to
predict the upper limit of fruit size, because we do
not know what determines when the fruit stops
expanding,” said Dr Savage.
While the phloem limits the fruit’s rate of growth,
some other factor may finally kick in to stop it
growing at a certain size, an unseen barrier that
extreme fruit breeders will be keen to test.