Soil and leaf nutritional profiling of declined citrus orchards of Punjab, Pakistan

Citrus tree decline (CTD) is the subject of substantial research worldwide. CTD is a complex problem, involving both biotic and abiotic factors, and causing huge yield losses in citrus. Malnutrition is also playing significant role in citrus decline and its low yield. Objective of this study was to assess nutritional status and other parameters of rhizosphere soil together with nitrogen (N) and phosphorous (P) levels in leaves collected from healthy, partially healthy and declined trees. For samples collection, comprehensive surveys were conducted and soil and leaves samples were collected from declined, partially declined and healthy trees, from four sides and middle of the orchards. Determination of soil pH was done with glass electrode pH meter and Organic matter (OM) was determined by multiplying the organic carbon (OC) with factor 1.724. The total nitrogen (N) in soil samples was measured by Kjeldahl procedure, soil phosphorous (P) was measured using spectrophotometer, while Potash (K) content was measured with flame photometer by using K filters. The N and P level in leaves were determined using standard procedures. The results showed that electrical conductivity (EC) and pH were higher in declined orchards compared to healthy while organic matter, phosphorous, potassium, nitrogen and zinc were low in declined orchards compared to healthy. Significant variation was found in nitrogen and phosphorous levels of leaves collected from healthy and declined citrus trees. The current findings will lead in devising effective management strategies of citrus decline in Punjab.