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Development of planting

Planting time Irrigation Transplanting Fertilization Gender-altered planting Weeds or brushwood control Bud removing Shedding of leaves Guard rail installing Climate effects on flowering Fruit removing Supporting

Planting time

During all seasons, papayas can be grown. However, it is important to take into account the following factors:

• To avoid pest impacts, which transmit diseases and virus, because these pests hinder optimal growing and production.
• Especially hot summers produce flowering alteration. Hence it is important to avoid flowering during this season.
• During all the year, there are fluctuations in fruit prices, so this is a special factor to be considered in accordance with the target market.

Irrigation System

For papaya growing, it is necessary to use irrigation because this variety has a radical superficial system. Consequently, soil needs an optimal humidity level which allows papaya to have a continual stem elongation and new leaves growth in whose axillaries fruits are produced.

Lack of water slows the papaya's growth and it also causes fruit or flower abortion. Irrigation problems provoke more problems in papaya growing than in any other planting.

Immediately after transplanting, a swift irrigation must be done. It is necessary to do it again 3 or 4 days later so that papaya growing can perfectly acclimate to the new environment and it does not suffer temperature changes or alterations.

Some of the factors, which are essential to determine the water quantity that should be used, are: plant age, soil type, temperature, wind and light. From planting until flowering, irrigation frequency must be carried out from 3 to 5 days by using a 4-12 liter standard per plant. From the beginning of flowering to the 6 forthcoming months after planting, irrigation frequency must be carried out from 5 to 10 days by using a 15-20 liter standard per plant. Finally, from 6 months onward, irrigation frequency must be done from 5 to 12 days by using a 20-40 liter standard per plant.

It is very important to keep the required humidity level needed during the entire growing cycle. One of the indicators to know whether an appropriate water quantity is being irrigated is to keep soil in good conditions and to avoid flooding.

Transplanting

Four or seven days after transplanting, in all areas where transplanting was not successful and there were plant losses, it is necessary to sow other plants, that is why seed calculation has to be between 5 to 10 % overestimated, if not calculated in this way, there may be homogeneity problems in the orchard.

Fertilization

Papaya is a fast and continually growing plant which has a relatively lengthy growing cycle. Among all fruit trees, papaya is the one which has fast growth and early production. Consequently it has high requirements of nutritional values during the whole cycle.

Maradol papaya reacts well to the use of chemical fertilizers and organic matter.

The Fertilization program aims at restoring or providing nutritional elements to the soil in accordance with growing needs. Some factors, which should be considered, are:

• Plant age
• Quantity of nutritional elements on soil
• Expected yield
• Losses by lixiviation and volatilization
• How to use it · Type of irrigation
• Frequency of application

Notwithstanding the fact that previously mentioned factors must be taken into account, it is very important to do soil studies and foliage analysis to measure nutritional requirements of the growing to the planting.

The use of fertilizers must be controlled in order to avoid losses by lixiviation and volatilization. The fertilizer can be applied manually by using fertilizer plunger-type knapsack sprayers (or any other fertilizer machine) or by using microspraying or drip irrigation. Irrigation should be applied in the dripping area.

The most important nutritional elements absorbed by papaya plant are: nitrogen, phosphorus, calcium, potassium, magnesium, sulphur, boron, but also Manganese, Iron, cinc.

There are different nutrient extraction studies of plants. Here we offer three publications about plant behavior in this respect:

Studies by Cunha, Hiroce and collaborators.

 

	Cunha(80)*		Hiroce and collaborators **
Element	Kg/ton	Kg/ha/año	Kg/ton	Kg/ha/año
Macronutrients (kg)
Nitrogen	1.77	86.55	1.70	85.16
Phosphorus	0.20	9.99	0.258	12.60
Potassium	2.12	103.40	1.23	61.30
Mesonutrients (kg)
Calcium	0.35	17.07	0.23	11.55
Magnesium	0.18	9.61	0.22	11.05
Sulphur	0.20	9.99	0.14	7.25
Micronutrients (gr)
Boron	0.989	48.32	0.90	45.00
Copper	0.330	16.11	0.30	15.00
Iron	3.364	164.28	2.60	130.00
Manganese	1.847	90.19	0.90	45.00
Molybdenum	0.008	0.38	0.0045	0.225
Cinc	1.385	87.85	1.00	50.00

Notes:

* female plant density of 1480 per acre and 33 kg yield per plant is 48 840 per acre.

** Female papaya yield is 50, 000 kg per acre.

Nutrient extraction studies (Kg/ha) regarding 2000 plant density per acre and 150 ton yield per acre and finally, 540-day cycle:

Element	Aerial part	Fruits	Total
Nitrogen	133	337	470
Phosphorus	40	80	120
Potassium	400	888	1288
Calcium	300	600	900
Magnesium	110	216	326
Sulphur	15	22	37
Sodium	15	n/a	15
Boron	15	15	30
Iron	80	92	172
Copper	8	34	42
Cinc	24	31	55
Manganese	30	27	57

 

Recommendations about the use of fertilizer according to plant age and a 2000 plant population per acre (figures in kilograms per acre).

Source: Haifa Química de México S.A. de C.V.
Haiquim, information about papaya

Recommendations about the use of fertilizer according to plant age and a 2000 plant population per acre (figures in kilograms per acre).

	2 a 6 months	6 a 12 months	1 a 2 years	total
N	20 - 40	40 - 60	60 - 120	120 - 220
P2O5	30 - 60	80 - 120	140 - 180	250 - 360
K2O	20 - 30	30 - 60	100 - 140	150 - 230
MgO	10 - 20	20 - 40	40 - 80	90 - 140
Zn	-	0 - 1	2 - 4	2 - 5
Cu	-	0 - 0.5	1 - 3	1 - 3.5
Mn	-	0 - 1	2 - 3	2 - 4
Fe	0 - 2	2 - 3	2 - 4	4 - 9
B	-	0 - 0.5	0.5 - 1	0.5 - 1.5

Source: Chirinos, Hamlet. 1999 Fertilización de papaya
INFOAGRO Año I, N° 5 Laboratorios A y L de México S.A. de C.V.

Gender-altered planting

This growing practice is performed by growers looking for hermaphrodite plant percentage increase. Accordingly, the production of long-shaped fruits can be assured, instead of rounded fruits (coming from female plants).

Hermaphrodite fruits are preferred because these fruits have more marketability and they also use less room in the size unit. It represents an advantage for shipping, above all in the long transportation process to foreign countries.

Gender-altered planting consists of planting 2 or 3 plants per position and when flowering, plant gender is distinguished. Selecting one plant and eliminating the rest (cut them off), if all plants are female, is necessary to choose plants in better conditions.

Certified seeds guarantee 66% of hermaphrodite plants and 33% of females ones. By sowing in two positions, the hermaphrodite plants percentage is increased to 85% and in three positions, 93%.

By increasing the number of plants per position, seed costs, workforce and tree nursery expenses will be obviously increased. Additionally, plants tend to grow very closely to each other in a period of 60 days.

Weeds or brushwood control

Weeds compete for nutrients such as light and water. These plants can house pests and harmful diseases for papaya growing, especially papaya ringspot virus. So it is important eliminate weeds from the crop during all cycle.

There are some ways of cleaning the orchard:

• Manually using a billhook
• Mechanically using a rake tractor
• Chemically using weed killers, making sure these chemical products do not get in contact with growing. The most common products are:
  • Glifosato in 1.25 to 2.5 liters per 100 water liters
• Paraquat in 1.5 to 2 liters per acre.

The amount depends on weed size and it is recommendable to use an additional device for a more efficient application

Bud removing

During growing, papaya produces axilary shoots or buds which have to be cut off because it is not profitable to let them grow and absorb nutrients.

The smaller axilary shoots are cut off, the less damage they cause to the plant. This method should be done when bud elongation becomes visible and frequently all visible shoots must be cut off.

Shedding of leaves

Older leaves of the plant must be eliminated because they can house pests and diseases. During rainy season, these leaves can create a perfect microclimate for disease growth and they can also hinder fumigation activities towards the fruiting branch.

Only the leaf blade is cut off from the leaf and the petiole remains, stuck to the stem, so that it falls off later. Neither knives nor scissors must be used because they can transmit virus or disease to healthy plants, so this activity must be done manually.

Leaves must be cut off at a height when they do not permit that sunbeams fall directly to fruits because it can cause burns.

Cut leaves must be taken out of the orchard or they can be sprayed with fungicide such as sulphur among others.

Guard rail installing

Papaya growing is seriously damaged by virus diseases which can reduce yields to 5% even total losses of 100% in the plantation.

Aphid insects can be disease transmitters from any surrounding infected orchards, weeds or any plant in the same orchard.

Once a plant has been infected, there is no available treatment. Therefore some measures must be taken to reduce the impact of the disease in the orchard.

A very practical measure that can be taken is to sow fodder sorghum put in the plantation, but also it is recommendable to sow a hibiscus flower around the orchard because its coloration repels insects.

Guard rails can be installed before or during planting

Climate effects on flowering

Hermaphrodite plants are sexually changeable and also very sensitive to the environment factors.

Warm or dry climates can damage the plant ovary. Consequently, hermaphrodite plants can become sterile. This is because some hermaphrodite plants are fruitless or do not produce fruits. High temperature and soil humidity at night can produce estaminated flowers. They can also cause damage to the plant ovary if these temperature conditions continue in several weeks.

Cold climate is a limiting factor which can slows plant growth and its fruit ripening. Cold temperatures in the night during winter can transform stamen into a fleshy structure such as carpels (Carpeloid). These variations cause a wide range of deformed fruits. However, it also happens during constant temperatures above 36°C.

This phenomenon also happens under frequent rainy conditions in which high relative humidity (70 to 85%) and high temperatures are common.

Fruit removing

When two or three fruits grow in the same pedicel, it is recommendable to keep one fruit and cut off the rest. When fruits are very close to each other, it is important to be careful not to damage them. Instead of risking damage, it is much better not to touch them.

Deformed fruits must be eliminated because of carpeloid, small and unhealthy caracteristics. Fruit removing should be practiced 2 or 3 weeks and this allows the rest of fruits to grow healthy and scattered.

Supporting

When plants are overloaded, and soil is soft because of rains and irrigation, plants can tilt or even fall off. In order to solve this problem, supports should be installed, such as sticks and wood trunks, or a cord can be used to fasten stake-supported plants.

Another practice is to support tree's anchoring by placing soil to the stem, especially in adult trees, due to the fact that if this practice is done during the very first stages of growing, it can provoke rotting in the stem.

 

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