India occupies a prime position in Tropical, subtropical and temperate fruits production in the world. Temperate fruit cultivation is spread over 350,000 hectares with an annual production of nearly 1.6 million MT. Apple occupies 50% of this area. It is followed by pears, Japanese plums, peaches, apricots, seedling walnuts and almonds. These are mainly grown in the North-Western Indian States of Jammu and Kashmir, Himachal Pradesh and in Uttarakhand. The North-Eastern Hills region, comprising of the States of Arunachal Pradesh, Nagaland, Meghalaya, Manipur and Sikkim also grows some of the deciduous fruits on a limited scale. But, in terms of productivity, it ranks far below many countries because of improper nutrient and plant health management. Production problems and challenges faced by the grower need to be addressed constantly and urgently to keep up production levels from falling. Among micronutrients, zinc deficiency is widespread in the temperate region causing economic losses in fruit crops. This is because Zn play an active role in the plant metabolism process and helps in the uptake of major nutrients and it is estimated that more than 60 enzymes are activated by the element Zn. Equally it is important as a human nutrient. Hence application of zinc is becoming an absolute necessity. Here we give description of basic information on the zinc fertility status of soils in apple, peach and plum orchards, visual symptoms of Zinc deficiencies as well as their management and is an attempt to fill these gaps and help farmers, planners and researchers in their endeavor to improve soil health, fruit quality and fruit yield in temperate orchard crops
Crop Boundary: Eight states covering 48 districts were identified as prime temperate fruits producing states of India. The crop boundary map of temperate fruits was prepared using district maps of respective leading producing states(Fig 1.)
Figure 1. Major Apple growing areas in India
Deficiency symptoms:
One of the most critical periods that a zinc shortage may seriously impair tree performance is between bud break and fruit set. A zinc shortage at this time often results in poor growth of the leaves and new shoots as well as abnormal development of pollen tubes, ultimately resulting in poor fruit set.
Leaf symptoms are not strong in apples, peach and plums compared to other fruit trees. Symptoms occur in the spring and include chlorosis of the youngest shoot leaves, which are stunted and narrower than normal giving a “little leaf” appearance. Zinc deficiency may also cause brown spots of dead tissue on the leaves and chlorosis between the leaf veins. The leaves may be deformed near the tips, may show a wavy margin and bunch together to form rosettes. Blind bud and rosetting can also occur. There may be some dieback of new shoots. Fruit may be smaller than normal and with lower yields than normal. Extreme deficiency results in shoot defoliation (Plate 1A,1B) and the production of misshapen and poorly coloured apples.
Plate 1. Zinc deficiency in apple showing (1A) chlorosis of younger leaves and typical little leaf symptoms and (1B) reduced leaf size on the branches and expression of a dieback like symptom
The zinc fertility map of apple, peach and plum(Figure 2) prepared using the DTPA zinc status of Indian soils shows that out of 49 districts growing these crops, only seven districts viz., Leh, Kargil, Srinagar, Pulwama, Shopian, in J & K, and Krishnagiri, Nilgiris and Dindigul showed deficiency in soil available zinc. Soils in 31 districts are reported to be well supplied with zinc. However, 23% of the apple growing districts (11 districts) do not have information on soil available zinc status.
Management of Zinc in Apple, Peach and Plum:
Zinc is not readily mobile within the tree and applications must be thorough and timely for optimal response. Zinc applied to the soil is usually ineffective for fruit trees because it is not mobile in the soil and does not reach the roots at the rates required by trees. Soil applications need to be applied or banded around the root zone, but uptake is limited and doesn’t occur until 4/5 leaves are unfolded in the spring. Zinc deficiency is usually corrected by applying annual sprays of zinc sulphate heptahydrate to the bark when the trees are dormant. Care is needed in choosing the right form of foliar-applied zinc so as to minimize damage to young leaves and the fruit. Both inorganic forms such as ZnSO4 and EDTA chelates are effective. The dormant spray is a safe treatment for bearing trees as foliar zinc sprays applied in spring may cause rosseting of the fruit. If the deficiency is mild, a zinc-based fungicide normally used for scab control like -zineb, ziram, mancozeb or metiram generally applied up to three times during the growing season, may correct the deficiency. As a late-dormant Sprays farmers may give zinc sulfate at 2 to 2.5 kg per 500 liters of water as a dilute spray. This may supply adequate zinc for growth during bud break to silver tip stage.
Figure 2. Zinc fertility status of apple growing regions of India
Image Credits : depositphotos.com
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