The tomato is a major
vegetable crop that has achieve tremendous popularity over the last
century. It is grown in practically every country of the world - in
outdoor fields, greenhouses and nethouses. The tomato plant is very
versatile and the crop can be divided into two categories; fresh
market tomatoes, which we are concerned with and processing
tomatoes, which are grown only outdoors for the canning industry and
mechanically harvested. In both cases, world production and
consumption has grown quite rapidly over the past 25 years.
aside from being tasty, are very healthy as they are a good
source of vitamins A and C. Vitamin A is important for bone
growth, cell division and differentiation, for helping in the
regulation of immune system and maintaining surface linings of
eyes, respiratory, urinary and intestinal tracts. Vitamin C is
important in forming collagen, a protein that gives structures
to bones, cartilage, muscle and blood vessels. It also helps
maintain capillaries, bones and teeth and aids in the absorption
Tomatoes are also an excellent
Lycopene is a very powerful
antioxidant which can help prevent the development of many forms of
cancer. Cooked tomatoes and tomato products are the best source of
lycopene since the lycopene is released from the tomato when cooked.
A raw tomato has about 20% of the lycopene content found in cooked
tomatoes. However, raw or cooked tomatoes are considered the best
source for this antioxidant.
Currently the tomato has a higher consumption rate
in more developed countries and is often referred to as a luxury
crop. In Israel, for example, the tomato is such an important part
of the diet that it is a major part of the food basket, which is
used when calculating the consumer price index. In other words, a
scarcity of tomatoes can cause the CPI to rise and influence the
inflation rate. In developing countries the tomato is becoming a
more important part of the food basket but the goal of the farmer is
to produce quantity not quality so people can eat.
As varieties improve and new cultivars with better resistance to
various diseases are developed, it will become easier to grow the
crops in more marginal conditions and the tomato will become a more
important part of the diet in poorer countries as well.
Determinate and semi-determinate tomatoes and fresh
market tomatoes in the outdoor fields are grown either with
determinate bush tomato varieties, (which grow on the ground without
staking), or with semi-determinate varieties using the stake and
string method. The latter method involves the use of wooden stakes
placed within the row of plants and running a number of parallel
pieces of string or wire from stake to stake and trapping the new
growth of the plant between the strings. This keeps the plants in an
upright position preventing the fruit from touching the ground.
Determinate tomatoes require very little plant care and
have a predetermined number of clusters, which is not
very high. Their yields and quality are usually not very
high but the inputs are very low. This type of crop is
more popular in developing countries where prices are
lower and quality is not a major concern.
Semideterminate varieties usually grow to a height
between 1 - 2 metres and have more clusters and hence
yield than the determinate varieties. The quality is
much better because the tomatoes do not lie on the
ground. However, neither method involves the removal of
side shoots, while the semideterminants require only a
minimum of leaf removal. In both of these types the
fruit is irregular in shape. i.e. They are more
beefsteak than round in shape.
Indeterminate tomatoes are traditionally grown
in greenhouses, which are either glass or plastic. However, since
greenhouse tomatoes are considered to have the best quality, the
indeterminate tomato is often cultivated in net houses and open
fields. Indeterminate tomatoes do not have a pre-determined number
of fruit clusters as do the determinate and semi-determinate types.
The indeterminates can be, and very often are grown for periods of
up to 12 months and over 30 clusters.
In greenhouses they can be grown in the ground or
in soilless media which is often referred to as hydroponics. There is
a crop wire above the plants at a height of 2.5 to 3.2 m. String is
tied to the wire and then the plant, which is then twisted around the
string as it grows. Side shoots or suckers and some leaves are removed
on a regular basis. The flower clusters are pruned to a pre-determined
number, usually 3 - 5 so as to help the plant maintain balance between
the vegetative and generative states. The resulting fruit is more even
in size and usually bigger
than it would be if all the flowers were
left to fruit. The fruit itself maintains size and shape better than
the other two types. Most indeterminate are rounder in shape but
there are beefsteak varieties because the American and some European
Markets prefer greenhouse beefsteak tomatoes.
Indeterminate varieties thus require more work than the other two
types but the monetary returns can be much higher.
As greenhouse indeterminate varieties gained popularity (the fruit
gets higher prices and demand is constantly growing), people started
growing these varieties outdoors using the indoor methods where
possible. In many places of the world such as Australia, Sinaloa, and
Mexico the growers are highly successful. Nevertheless, there are many
circumstances where growing indoor varieties outdoors is very
difficult. The climatic conditions may not be good enough or there may
be too much insect pressure both resulting in diseases and low quality
The cost of building proper
greenhouses may be prohibitive or the problems are such that
greenhouses are not necessary and a net house will often suffice.
Net houses can be of two types; (a) an insect proof house with 50
mesh net which prevents many insects from entering and has
approximately 17 to 20 % shade and (b) an
ordinary black or white
net of approximately 25 to 35 % shade. Both types of houses protect
the crops from the elements, which include wind, blowing sand, hail,
excessive sunshine and insects, although the insect proof is far
superior when protecting against some of the major pests such as
white fly. There is definitely a worldwide
trend to covered cropping especially in tomatoes. When consumers
demand better quality they are really saying that they want
indeterminate type tomatoes. When a farmer starts to build
net-houses and greenhouses his investments and growing costs
increase dramatically. He must learn how to optimize revenues and
minimize expenses so as to attain the maximum profits.
Why extension help is necessary and who would use it
It is clear that growing tomatoes can be a
complicated business. Today's hybrids require more knowledge and skill
than ever before. A hybrid variety can be compared to a thoroughbred
racehorse. They are high strung, strong and ready to move. However, an
inexperienced jockey does not ride a winning race the first few times
out and is actually very likely to finish last in the race. It takes
time, experience, a large investment, a good teacher and a lot of
patience. Growing new hybrid tomato varieties is very similar.
When a farmer or a grower has a sizable investment
in something like a new variety of tomato in a covered structure they
want to be sure that they achieve the best possible return for their
investment. The learning curve for this can turn out to be very
expensive as it can take a long time to learn the ins and outs of a
new system. Government extension services, which in the past were well
organized and able to help growers in these kinds of situations, have
had budgets slashed and today have very limited services to offer.
Growers making the switch to new
hybrids and new technologies can often get the help they need from the
seed companies, local private extension and advisory services and from
consulting companies on the internet. The young jockey learning to
ride the thoroughbred race horse always has a trainer to help him. The
same logic applies to growers trying new varieties and methods. The
grower, with proper help and advice, will shorten the time needed to
complete the learning curve. He will be able to maximize his profits
much quicker by using good professional help and like the well-trained
jockey on the thoroughbred, the grower will be well ahead of the pack.
Zvi Howard Wener is well know to farmers in Australia and New Zealand,
and as an online crop consultant can be contacted through