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                                | 31 October 2025 |  |  | മലയാളം |  |  | 
               
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                | Agriculture > 
                        Plantation Crops > Rubber (Hevea brasiliensis) |  
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                        Crop
                            Management |  
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                        Nutritional disorders 
                        Magnesium 
                     
                        The characteristic symptom of magnesium deficiency is the development of chlorosis
                        (yellowing) in the inter-veinal areas on exposed mature leaves giving rise to a
                        herringbone pattern. The pre-coagulation of latex on the tapping panel has been
                        found to be due to excessive supply of magnesium to rubber. 
                        Potassium 
                        The characteristic symptom is the development of marginal chlorosis, which is followed
                        by marginal necrosis. Only older leaves exhibit the deficiency symptoms. Size reduction
                        of the leaves and the absence of herringbone pattern of yellowing allow potassium
                        deficiency symptoms to be distinguished from those of magnesium deficiency. 
                        Zinc 
                        This causes interveinal chlorosis of leaves. The laminae become much reduced in
                        breadth in proportion to their length and the young leaflet becomes incurved towards
                        one another and present a hooked or claw appearance. The cause of deficiency appears
                        to be heavy application of phosphatic fertilizers resulting in poor availability
                        of zinc. 
                        Manganese 
                        This results in overall paleness and yellowing of the leaf with bands of green tissue
                        outlining the midrib and main veins. 
                        Also, there are indications to believe that unbalanced nutrition can cause excessive
                        drainage of latex resulting in the dryness of trees. |  
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