Periodical Nutrient Dynamics in ‘Blood Red' Sweet Orange as Affected by Fungicides Soil Drenching

Ailing root system of sweet oranges in Punjab, Pakistan, has been suspected to affect nutrient uptake due to rough lemon (Citrus jambhiri Lush.) rootstock susceptible to soil born fungal diseases and might be one of the main reasons of low productivity of sweet oranges. A block of ‘Blood Red’ sweet orange (Citrus sinensis L. Osbeck) grafted on rough lemon (Citrus jambhiri Lush.) rootstock,  with low yielding (200–250 fruit/tree) trees ranging between 12–15 years age, was selected for this research work growing at Experimental Fruit Garden Sq. #9, Institute of Horticultural Sciences, University of Agriculture, Faisalabad, Punjab, Pakistan. The main objective of the research was to induce the sweet oranges in main streamline of citrus industry by improving their root health by fungicides treatments ultimately enhancing mineral nutrient uptake from soil. The experiment was laid out according to RCBD replicated thrice, taking single tree as a treatment unit. The fungicides used in the experiment were Ridomil Gold (Matalyxl) and Alliette (Fosetyl-Al) alone, in combination with each other and Copper sulphate (CuSO₄) making 9 treatments including control. Periodic changes in nutritional status of tree leaf macronutrients (N, P, and K) as well as micronutrients (Mg, Fe, Mn, Cu, and Zn) from flowering through fruit set were monitored at fortnight intervals in relation to different fungicides treatments. During two years trials a detailed data was collected. The fungicides treatments improved nutrient uptake by correcting the health of root system and had profound effect on health and vigor of trees under trial. It was further revealed by enhancement of fruit quality and yield of treated trees compared with control. It was concluded from the trial that best management practices could improve yield and quality of sweet oranges emphasizing on health of root system.