For a successful watermelon production, a lot of care must be taken in order to achieve that. Some of the management practices which enables the proper growth and production of watermelon includes:
1) Quality Seeds
The quality of the seed used for planting is the most crucial factor as the other factors are based on this. The rate of germination and production yield of your watermelon farm is largely dependent on the type and quality of the seed planted.
Therefore you are always encouraged to purchase only high quality seeds for your watermelon planting as it goes a long way on determining the successful rate of your watermelon farming.
2) Climatic Factors
Watermelons require long warm growing periods as the plants are susceptible to frost, and also note that low temperatures can cause growth abnormalities, poor setting and hollow fruit.
Crisis like Sunburn can be a very big problem for the fruit particularly in the ‘ground spot’ area if the fruit are placed upside down after harvest. According to study, Light green and grey-green melons are less likely to sunburn than the darker green or striped varieties.
3) Soil Factors
With a well prepared soil, watermelons can be grown on a wide range of soil types since the main requirement is good drainage.
Good irrigation management is required when growing on heavy soils in order to minimize plant losses from root rot and Mud sticking to the harvested fruit can also make them unsightly and can lead to reduction in market acceptance.
4) Establishment and Care for the Watermelon Plant
A cover crop is highly recommended before you plant watermelons and If root-knot nematodes are a problem, then try to avoid legumes only use cereal crops like forage sorghum instead. Ensure that all cover crop residues have been broken down completely before planting the watermelon crop.
Ripping may be required to improve drainage on shallow or compacted soils and laser leveling before planting is also recommended. Since watermelons are often used as a quick rotational crop, you are encouraged to carry out a research on the cropping history of the ground you are planting on to ensure no carry-over herbicides have been used.
In the case of sugar-growing districts, you should notify surrounding cane farmers of the crop’s presence to prevent damage from herbicide spray drift.
Plastic mulch, as well as drip irrigation and containerized seedlings, is widely used in watermelon production. The plastic mulch used can vary from 0.9 to 1.2 m in width and is used to cover the plant row.
Soil in the rows is usually raised about 10 cm in height and the drip tape laid down the centre of the row or slightly to the side then both the bedding up and laying of the drip tape can be carried out during or prior to the laying of the plastic.
5) Planting Factors
Watermelon planting is carried out by direct seed sowing in the field or with the use of containerized seedlings. Since most of the commercial varieties of watermelon seeds are hybrids, the latter technique is preferred because of the high cost of hybrid seeds.
Wherever plastic mulch is used then the direct seeding machines on waterwheel planters are also used thereby punching the seed or seedlings directly through the plastic mulch and for direct sowing then approximately 1.5-2 kg/ha of seed is required.
Pre-germinated seeds can be used to re-plant anyone that did not germinate, the row spacing varies from 1.5m-3.0m and the plant spacing varies from 0.75m-1.5m. Seedless melons require a standard variety in close proximity to provide pollen in order to enable fertilization to occur.
Also note that without pollinators, fruit will not set and do not plant more than two rows of the seedless variety to every one row of a standard variety and always ensure the seedless type is distinguishable from the standard variety. Watermelon seeds take 4-14 days to germinate and the required soil temperature should be at least 11°C as at the time of planting.
6) Nutritional Factors
Soil analysis is highly recommended and in the absence of a complete soil analysis, a complete fertilizer should be applied through spreading and incorporate with (sandy soils) or drilling (red soils). Also use NPK mixes at 700-1200 kg/ha of 5:6:4 or 300-500 kg/ha of 14:14:12 or similar mixtures, and nitrogen side-dressings.
Avoid late applications or excessive nitrogen use in cold weather, as hollow melons may result. Excessive nitrogen application also favors the development of male flowers and where drip irrigation is used, side dressings are applied through the drip system.
Depending on the results of soil or sap analysis, you can apply side dressings of calcium nitrate alternated with potassium nitrate every two weeks from early running. Apply both fertilizers at 20-40 kg/ha.
Apply magnesium sulphate at the rate of 20 kg/ha after every 2-3 applications of the calcium or potassium nitrate. Plant tissue analysis can indicate the crop’s nutrient status throughout the season.
In the aspect of Nutritional disorders, Note that Molybdenum deficiency is common in areas with a low pH. Symptoms include stunting of plant growth and mottling, yellowing and rolling of leaves.
This deficiency can be remedied by a foliar spray of sodium molybdate at the four leaf stage, repeated if necessary at the runner stage of growth. Zinc, copper and boron deficiencies may also occur but are most likely in leached, strongly acidic, sandy soils or where large quantities of liming materials are present.
Hence, zinc and boron deficiencies are also common on the alkaline soils of the Lockyer and Fassifern Valleys.
Manganese toxicity is also another problem associated with acidic soils (pH 5.8 or less). Seedlings suffering from manganese toxicity exhibit stunted growth and yellowish crinkled leaves.
Older plants can have an unhealthy pale green cast, and affected plants may have pinhole-sized brown lesions occurring in clusters between the leaf veins.
These symptoms are often confused with infectious diseases, such as gummy stem blight. You can prevent manganese toxicity by maintaining soil pH between 6.0 and 6.5.
7) Irrigation Factors
Water can be applied to the crop through overhead, furrow, or drip irrigation. Drip irrigation enables the most efficient use of available water and is compatible with fertigation which is the application of soluble fertilizers in the irrigation water.
Depending on the time of the year and the soil type, the amount of water used to grow a crop will vary. Meanwhile, the following figures can serve as a useful guide:
- When using overhead sprinkler system= 4-5 ML/ha
- Using furrow/flood= 4-5 ML/ha
- Using Drip= 3 ML/ha.
Note: Overwatering should be avoided when the plants are young but quantities should increase as the plant grows. The highest water requirements are during fruit set and fruit fill. Water quality is very important, particularly if overhead irrigation is used.
Study has shown that Electrical conductivity (EC) readings much greater than 1.3-1.4 dS/m could cause leaf burn and yield reduction and with furrow or drip systems, irrigation water with EC readings up to 2.0 dS/m can be used with care.
Beyond this figure, losses from a disorder known as blossom end rot may occur. Avoid overhead irrigation at 7-11 am during flowering and fruit set, as this may deter bees from pollinating flowers.
8) Pollination Factors
Watermelons produce separate male and female flowers. Male flowers are produced initially, followed by the production of both sexes usually at a ratio of 1 female to 7 males.
Watermelons, pumpkins, cucumbers and zucchinis can be planted side by side. Cross-pollination can occur between cultivars of the same crop (e.g. watermelons and watermelons) but not between different crops (e.g. watermelons and pumpkins).
Bees are necessary for pollination. Bees need to be present and active in the crop. If bees are not plentiful, then import at least 2 hives/ha, spread them around the field perimeter and check to ensure that male flowers are producing pollen.
Flowers are most receptive to pollination during the morning hours when bee activity is usually the highest. Bee activity is related to climate and is lower in cooler weather.
Spraying and irrigation should be coordinated to occur when bees are least active and If possible, use chemicals with minimal bee toxicity.