Growth Trend, Nutritional Response, and Tolerace of Teroyer Citrange in Calcareous Soils

The area under citrus cultivation in Mazandaran Province amounts to 120,000 ha. The soils in the area contain calcium carbonate (lime) that increases as we move from the central to the eastern stretches of the province. Moreover, the citrus rootstock in the region (sour orange) is sensitive to the CTV disease. These considerations require a substitute rootstock that is not only tolerant or resistant to the disease but is also adaptable to calcareous soils. The present study was conducted to evaluate the vegetative and nutritional responses as well as tolerance of Troyer citrange to different levels of calcium carbonate (lime) in the soils in this region. More specifically, the study was conducted in a randomized complete block design to determine the response of Satsuma mandarin on Teroyer Citrange rootstock to the calcareous soils in eastern Mazandaran. The highest average dry shoot and root weights were obtained for soils with total and active lime contents of 14% and 5%, respectively. The highest leaf chlorosis levels were recorded for soils with active lime contents of 14% and 16% and total lime contents of 30 and 45%, respectively. Also, the highest and lowest increments in diameter were obtained with soils containing 9% and 25% lime, respectively. Soils with total lime contents of 14% and 30% yielded the highest total iron concentrations in the root. Mean total iron, manganese, and zinc concentrations, respectively, in the root were about 12.5, 8, and 4.6 times their concentrations in the leaves, indicating their accumulation and precipitation, especially iron and manganese, in the roots. Average leaf Mn concentrations were less than adequate in all the plants grown in all the soils, while available manganese in most soils was higher than optimal for citrus trees. Based on the results obtained, calcium and magnesium from among the high consumption elements recorded the highest while sulfur and phosphorus exhibited the least root to leaf transfer efficiencies. From among the low consumption elements, iron and manganese exhibited the least root to leaf transfer efficiency. In general, Teroyer Citrange is a semi-tolerant rootstock for calcareous soils and may not be recommended for cultivation in soils with total and active lime contents beyond 20% and 10%, respectively.