2018 ASHS Annual Conference

Potassium (K) is one of the most important mineral nutrients limiting fruit growth and development and is known as a ‘quality element’. The results from the study showed K fertilization improved the development of the vascular bundles in pear petioles and fruit peduncles and enhanced the synergistic effect of the genes involved in nutrients and sugar transport. Magnesium (Mg) concentrations in the leaves, petioles and fruit peduncles were significantly lower under the K treatments than under the control treatment, but the concentrations of K, calcium (Ca), and Mg in the fruit gradually increased as the K application rate increased. Leaf Mg and Ca were antagonistic to K, and this phenomenon may be related to the up-regulated expression of Mg transporters (MRS2-1 and MRS2-3) under low K treatment. The concentrations of sorbitol, sucrose and total sugar in the leaves and fruit at maturity significantly increased in response to K supply. The improvement of sugar concentration was closely related to the up-regulation of the expression of sucrose transporter (SUT) and sorbitol transporter (SOT) genes. In turn, these effects promoted the transport of nutrients and sugar from sources (leaves) to sinks (fruit) to increase the accumulation of sugar in the fruit.