MICRO-NUTRIENTS AND PAPAYA !!!

         The nutrient elements which are required comparatively in small quantities are called as micro or minor nutrients or trace elements. Micro-nutrients are essentially as important as macro-nutrients to have better growth, yield and quality in plants. The requirement of micro-nutrients (boron, iron, copper, zinc, manganese, chloride and molybdenum) is only in traces, which is partly met from the soil or through chemical fertilizer or through other sources. The major causes for micro-nutrient deficiencies are intensified agricultural practices, unbalanced fertilizer application including NPK, depletion of nutrients and no replenishment.

                    Horticultural crops suffer widely by zinc deficiency followed by boron, manganese, copper, iron (mostly induced) and Mo deficiencies. Cl, Cu, Fe and Mn are involved in various processes related to photosynthesis and Zn, Cu, Fe, and Mn are associated with various enzyme systems; Mo is specific for nitrate reductase only. B is the only micro-nutrient not specifically associated with either photosynthesis or enzyme function, but it is associated with the carbohydrate chemistry and reproductive system of the plant. The significance of micro-nutrients in growth as well as physiological functions of horticultural crops fruits are briefed here nutrient wise.

1. IRON

          Plants need iron to produce chlorophyll and to activate several enzymes including those involved in the oxidation /reduction processes of photosynthesis and respiration.

             Iron concentrations of 50-100 ppm are often quoted as satisfactory leaf analysis values for most crops. But leaf analysis is not a reliable guide as there is poor mobility between tissues. Iron deficiency is rarely caused through insufficient iron in the soil but usually because it is rendered unavailable for the uptake by alkaline soil conditions or an excess of manganese or phosphorous. Iron deficiency is a problem of high pH calcareous soils and is often described as lime induced chlorosis. Custard apples are relatively sensitive suffering from iron deficiency while other crops such as bananas are usually not affected much. This sensitivity appears to be related to crop’s poor ability to absorb or utilize iron. The common deficiency symptoms include development of light green chlorosis of all the tissues between the veins. A distinctive pattern results from the network formed by the midrib and veins, which remain green for example, custard apples. If the chlorosis is severe and persistent, yellowing increases to the point of bleaching and burns can develop within this chlorotic area. Because iron does not move easily within the plant, older leaves can remain green while flushes of new growth are chlorotic. In pine apples, chlorosis is strongest towards the margins of young inner leaves. The fruits are small, reddish in color, hard and prone to cracking. The effects of iron deficiency in different fruit crops are discussed below.

2. ZINC

             Zinc deficiency is the most widespread and limiting growth and yield in fruit crops. It commonly affects banana, custard apple and mangoes. Problems often appear in spring when crops are growing quickly but have difficulty in absorbing nutrients from cold soil.

    Zinc is important for the formation and activity of chlorophyll and in the functioning of several enzymes and the growth hormone, auxin. The severe stunting of leaves and shoots, which is so typical of zinc deficient crops is a consequence of low auxin levels in tissue. Young leaves are usually the most affected and are small, narrow, chlorotic and often rosette due to failure of the shoot to elongate. Bloom spikes are small, deformed and drooping. In young pine apple plants, zinc deficiency is indicated by the young heart leaves bunching together and then tilting horizontally. This condition is commonly called crook neck. Older plants may develop yellow spots and dashes near the margins of older leaves that eventually coalesce into brown blister like blemishes giving the leaf surface n uneven feel. The symptoms and corrective measures for zinc deficiency in different tropical fruit crops are mentioned below.

3. BORON

                Boron is much required for cell division and development in the growth regions of the plant near the tips of shoots and roots. It also affects sugar transport and appears to be associated with some of the functions of calcium. Boron affects pollination and the development of viable seeds which in turn affect the normal development of fruit. A shortage of boron also causes cracking and distorted growth in fruit. Boron does not easily move around the plant and therefore the effects of deficiency appears first, and are usually most acute in young tissues, growing points, root tips, young leaves and developing fruit. The fruits of boron deficient papaya are deformed and bumpy due to the irregular fertilization and development of seeds within the fruit. Ripening is uneven and the developing fruit secrete pinkish white to brown latex. Premature shedding of male flowers and impaired pollen tube development can lead to poor fruit set. Growth is ceased at the growing point.

4. COPPER

                 Generally copper deficiency appears to be minimal in tropical fruit crops. Copper is essential for photosynthesis, for the functioning of several enzymes, in seed development and for the production of lignin which gives physical strength to shoots and stems. The deficiency symptoms include restriction of terminal growth, die back of twigs, death of growing points and sometimes resetting, and multiple buds form at the end of twigs. Foliage can be chlorotic in bananas or darker than normal or dull and brownish in color. In pineapple, growth is severely stunted and leaves are narrow, U shaped in section, and curved downward at their tips. Tip necrosis occurs in some young leaves. Since foliar application of copper can result in burning of foliage, soil application of copper sulphate @ 30 kg/ha is recommended to correct the deficiency.

5. MANGANESE

                    Manganese is necessary for chlorophyll formation for photosynthesis, respiration, nitrate assimilation and for the activity of several enzymes. The concentration of manganese in leaves can range widely from 10-15ppm when deficient and in thousands of ppm when it is toxic. Manganese is only moderately mobile in plant tissues so symptoms appear on younger leaves first, most often in those leaves just reaching their full size. Manganese availability is reduced in high pH calcareous soils but is often very high in the acid soils commonly chosen for tropical fruit production. Over liming of the soils particularly well drained, poor, coastal sandy soils can induce deficiency. Manganese deficiency causes a light green mottle between the main veins. A band of darker green is left bordering the main veins while the interveinal chlorotic areas become pale green or dull yellowish color. Soil application of manganese can be ineffective due to immobilization especially in heavier soils or soils which have been over limed. Two to three sprays of 0.1 % manganese sulphate can be recommended.

6. MOLYBDENUM

                       Molybdenum functions in enzyme nitrate reductase which is responsible for reduction of nitrate to nitrite during N assimilation in plants. Although molybdenum deficiency is observed in many soils and pasture legumes, vegetables and occasionally cereals, it is very rare in fruit crops. There are few reports that molybdenum deficiency called as yellow spot is observed in citrus. Soil application of molybdenised single superphosphate @ 250-500 kg/ha is the usual means of satisfying the need for 2-5 years.

                             Although general recommendations are available for most of the nutritional disorders in horticultural crops, application of micro-nutrients based on soil and plant nutrient status, at the critical stages of crop growth is absolutely necessary to achieve higher yield and quality.

"THE ASPECTS OF PAPAYA FARMING"

 Site selection:-

The three major environmental factors to consider in selecting a site to grow papayas are temperature, moisture (rainfall and soil drainage), and wind. The hermaphrodite papaya plant preferred for commercial orchards is more sensitive to the growing environment than the female papaya plant, and therefore selection of a suitable site is critical. Another condition to consider is the amount of sunlight the site receives to support plant growth and fruit production. Insufficient sunlight results in low yields and fruits with inadequate sugar and encourages plant diseases affecting papaya production.

 Temperature:-

The temperature of the site is the most important factor. Commercial papaya production in Hawaii is generally limited to low-elevation areas where the minimum temperature is above 60°F. Temperatures below 60°F cause carpeloidy, which results in “cat-face” deformity when floral stamens develop abnormally into fleshy, carpel like structures.

 Moisture:-

A minimum monthly rainfall of 4 inches (100 mm) and an average relative humidity of 66 percent are suggested as “ideal” for papaya growth and production. In low rainfall areas irrigation should be provided via drip-type or mini-sprinkler irrigation systems.

Papaya requires good soil drainage. Where soil drainage is restricted, papaya is susceptible to fungal root diseases. The plants are severely affected by water logging and can be killed when subjected to puddle conditions for even a few hours.

 Wind:-

Papaya plants must be protected from wind. Plants exposed to constant wind develop deformed, crinkled leaves. When wind stress damage is excessive, the plants have reduced growth, fruit set, fruit quality, and productivity. Wind-blown dust can cause sap bleeding that harms fruit appearance.

Land preparation:-

After existing vegetation is cleared, soil samples should be collected and analyzed to determine if there are any problems. Based on analysis results, recommendations are provided on adjusting soil pH and the amounts of soil amendments required to correct any deficiencies. Papaya grows well at a soil pH between 5.5 and 6.5.

Seedling production:-

Papaya can be either seeded directly or transplanted into the new field. The seeds are planted in a trench approximately 6 inches long dug parallel to the planting row. In soil areas, transplanting allows growers to place a larger plant (4 –8 inches tall) into the field. Seeds are direct-seeded into individual cells (2 x 2 inches) placed in full sunlight. The potting media should be sterile and well drained to minimize root rot.

Planting:-

Planting in “virgin” lands or fields in which papaya has not been grown before is preferred because of low disease and insect pressure. It is becoming increasingly difficult to find such fields.“Replant” fields in which papaya has recently been grown generally have high levels of Phytophthora palmivora spores due to the decomposition of infected papaya fruit, trunk, and root residues.

                  In fields with mineral soils, residual fungi and nematodes can be controlled with soil fumigants. The fumigant is injected under plastic mulch before planting and allowed to volatilize for 2–3 weeks to ensure that seedlings are not damaged when transplanted. Fumigation reduces the population of nematodes and residual fungi and allows young roots to grow free of pathogenic organisms.

Plant sex selection:-

Seeds from solo varieties produce plants of two reproductive types: female and hermaphrodite. Although there is no difference in the eating quality of fruits from these two types, the commercial market prefers the pear shaped fruits produced by hermaphrodite plants over the rounder fruits of the female plants. Female plants require cross pollination to produce fruit, and there can be gaps in production when pollination does not occur. The desired hermaphroditic plants have flowers that contain both an ovary (female organ) and pollen sacs (male organ); they are self-pollinating. Hermaphroditic flowers are more uniformly tubular than female flowers, which are bulbous at the base and pointed at the end (see illustration). Female flowers contain an ovary but lack pollen sacs, and they need to be pollinated.

Thinning:-

Thinning is done to reduce competition while retaining enough plants to ensure that a hermaphrodite plant is finally obtained. In direct-seeded fields, the plants are thinned three times. First, one month after germination, the number of seedlings is reduced to 6–10 per hole. Second, at three months after germination, the number of seedlings is further reduced to three plants for the standard commercial solo cultivars, which have a sex segregation ratio of 2:1 (two hermaphrodite plants for each female plant), ensuring a 97 percent chance of retaining one hermaphroditic plant.

Soil conditions:-

When papaya is grown in soil, the soil should be sampled in advance of planting to allow for incorporation of any amendments needed. The results will determine the form and application rate of liming material required to adjust the soil pH to the 5.5–6.5 range. Soil should be analyzed annually to determine if current practices are sufficient for maintaining production. If deficiencies are found, recommendations will be given by the soil testing laboratory.

Weed control:-

Weed control is a major cost in papaya production, particular in young fields. In “virgin fields,” the initial weed population may be low, requiring minimal hand weeding. The use of fumigation or the “virgin soil” technique reduces the need for hand weeding in replant fields. Before planting, irrigate fields to germinate weed seeds and then spray the weeds with a systemic herbicide .

It is advisable to shield the young plants when spraying. Older papaya plants with woody trunks are more tolerant of glyphosate-based systemic herbicides such as Roundup, but care in herbicide application should be emphasized. Herbicide applications are usually limited to a bimonthly or quarterly interval in mature orchards, where shading reduces weed growth.

Leaf trimming:-

Leaves of bearing plants should be trimmed to facilitate application of fungicide to the fruit column and minimize fruit scarring from petioles rubbing against the fruits. It is important to retain as many leaves as possible, because they produce the energy that supports the developing fruits. Trim only leaves with petioles that angle below horizontal. Trimming should be kept to a minimum in winter. Petioles should be cut at the halfway point between the leaf blade and base to minimize fungal infection.

Pest management:-

Papaya crops are affected by various disease, insect, and mite problems. Becoming aware of potentially injurious organisms and taking appropriate management measures are important for success. The following sections present a brief overview of the major pests of papaya.

Diseases:-

The diseases of papaya include those caused by a virus, fungi, and nematodes. The papaya ring spot virus (PRV) is the most severe papaya disease and is often the limiting factor in papaya production throughout the world. PRV is widespread on Oahu.

                    Papaya plants infected with PRV must be destroyed to minimize spread of the virus. Virus problems can be avoided by planting genetically resistant cultivars.

                         PRSV is not transmitted via seeds, but it can be spread to areas where it is not present by transporting infected seedlings. To avoid introductions of the virus, do not transport papaya seedlings between islands. On islands where PRV is already present, raise seedlings in nurseries close to the planting site to minimize the possibility of spreading the virus further.

                Fungal diseases are a major problem in papaya production. The strategy for fungal disease management is prevention through the application of fungicides at regular intervals. Proper timing, deposition, and coverage of the pesticide application is critical for effective control. Once the disease is established, the fungicides have minimal impact on control. Under high-rainfall conditions, high-volume sprays (75–100 gallons per acre) are required at 2–3 week intervals. Under drier conditions, low-volume sprays (40–50 gallons per acre) at 3–4 week intervals are adequate to protect the exposed fruit surfaces.

             The use of a surfactant is important to ensure good distribution and adherence of the fungicide spray. Currently, the most effective fungicide for protecting fruits is mancozeb, which can be used in combination with a copper product to increase efficacy.

          Powdery mildew can cause premature loss of foliage, resulting in reduced fruit quality and yield. Wet-table sulfur is effective for powdery mildew control but only when thorough coverage of the foliage is achieved.  Nematodes can be controlled by fumigating the soil before planting.

Insects:-

Insects can be a major problem in papaya production. The Stevens leafhopper can be a serious problem when its populations build to high levels, which can occur under dry conditions. Infestation is recognized by the yellowing of terminal leaves and the exudate from feeding wounds on petioles. The phytotoxic reaction of the plant, termed “hopper burn,” is characterized by the browning (or “firing”) of leaf tips and edges.

            The white peach scale is a recent introduction to Hawaii. The insects can form large populations at the base of the trunk, giving it a whitewashed appearance. They may move up the trunk and invade the fruit column. If this pest is on fruit intended for export, it becomes a quarantine concern.

            Fruit flies are primarily a problem in fruits allowed to ripen on the tree; they are not a major problem when fruits are harvested mature-green for export sale. Papaya fruits for export need to be subjected to approved disinfestations procedures.  

         Mealybugs and white peach scale are occasional pests on the fruits and may lead to rejection at the packing plant. Thorough spray coverage is important in mealybug control, especially at the stem end of the fruit, near the trunk.

                Miticides generally kill only adults and nymphs and have little effect on eggs. Timely chemical applications are necessary to control the emerging young, which can become egg-laying adults in 7–14 days. Proper spray coverage is essential to prevent “escapes” from reestablishing their population to destructive levels.

 

Mites:-

  

          Mite infestation can affect both the fruit and foliage. It becomes a significant problem under hot, dry conditions. Mites usually feed on the underside of leaves and on young, developing tissues. Miticides generally kill only adults and nymphs and have little effect on eggs. Timely chemical applications are necessary to control the emerging young, which can become egg-laying adults in 7–14 days. Proper spray coverage is essential to prevent “escapes” from reestablishing their population to destructive levels.

PAPAYA : AN INTRODUCTION

                     TODAY, PAPAYA IS THE MOST PROFITABLE CROP. PAPAYA IS A REGULAR FRUIT IN INDIAN MARKETS. OUR PRODUCTION RATE IS LOWER THAN OUR DEMAND. PAPAYA HAS POTENTIAL IN MANY SECTORS INCLUDING PHARMACEUTICALS, COSMETICS, LEATHER INDUSTRY, ANIMAL FEED INDUSTRY, FISH FEED INDUSTRY AND DIRECT CONSUMPTION.

                      OUR AIM IS TO PROMOTE FARMERS AND ASSIST THEM IN GROWING PAPAYA ON LARGE SCALE. THE MOST DESIRED BREED FOR INDIAN CLIMATE IS “RED LADY 786 (MADE IN TAIWAN)”. THE MARKET POTENTIAL OF PAPAYA SAYS THE SUCCESS STORY OF PAPAYA FARMING IN INDIA.

                         PAPAYA IS THE MOST SENSITIVE PLANT. IT HAS THE HIGHER POSSIBILITY OF MANY PHYSICAL AND BIOLOGICAL PROBLEMS. ALL THESE PROBLEMS IN PAPAYA FARMING VARIES FROM BREED TO BREED.

             WE HAVE THE TEAM OF EXPERTS FOR CONCERNED CROP AND WE ARE PROVIDING THE CONSULTANCY FOR THE PAPAYA FARMING. WE BELIEVE IN THE WAY WHERE NEWEST BIOTECHNOLOGY TECHNIQUES COME ALONG WITH CONVENTIONAL AGRICULTURE METHODS.

                OUR CONSULTANCY IS THE MORAL AND EXCELLENT ADVICE BEYOND THE COMMERCIAL AND MANY OTHER BARRIERS. OUR ASPECTS ARE VERY SIMPLE AND EFFECTIVE FOR AGRICULTURE AND FARMERS.

                  OUR TARGET IS TO PROVIDE THE MORAL, TECHNICAL, FINANCIAL SUPPORT AND ADVICE TO FARMERS. OUR VISION IS TO GROW AGRICULTURE AND HORTICULTURE AT THE MAXIMUM POSSIBLE LEVEL.