Effect of Iron Chelate Application on Yield, Fruit Quality, and Nutrient Status of Clementine in Alkaline Soil Across High- and Low-Production Seasons
摘要
Reasonable iron (Fe) availability is a major concern in citrus grown in alkaline soils. This study aimed to investigate variations in the effects of chelated iron (Fe-EDDHA) soil application on yield, fruit quality, and nutrient status of alternate-bearing clementine. Six Fe-EDDHA application rates were tested (0 or control, 5, 10, 15, 20, and 30 g tree−1) over five consecutive seasons (2016–2020) in a 9-year-old commercial orchard of clementine (cv. ‘Sidi Aissa’) grafted onto Carrizo citrange rootstock. The experiment followed a randomized complete block design with five replications. The studied soil was alkaline (pH 8.8) with an Fe content of 6.3 mg kg−1 (diethylenetriaminepentaacetic acid [DTPA] extraction). The results indicated that the positive effect of Fe-EDDHA application on fruit yield was recorded during the low-yield seasons (2017, 2019, and 2020), likely due to the greater availability of carbohydrates required for the setting and growth of fruits. The highest fruit yield increase (+ 43%) was recorded in 2020 at Fe-EDDHA rates ≥ 20 g tree−1 compared to the control. The fruit diameter was generally enhanced by Fe-EDDHA. The Fe content of the leaves remained consistently above 100 mg kg−1 for different Fe treatments throughout all five experimental seasons. The fruit quality traits (juice content, total acidity, and total soluble solids) were optimal without Fe-EDDHA application. These parameters and the soil’s available Fe content were not affected by Fe-EDDHA applications. These findings suggest that for low fruit load seasons, Fe-EDDHA application in alkaline soil is advisable to ensure sufficient Fe nutrition of clementine and improve fruit yield.