Growth and nutrient demand for major minerals in Cuiguan pear

【Objective】This study aimed to systematically investigate the growth dynamics of new aerial organs in Cuiguan pear, the main sand pear cultivar in the southeastern coastal region of China, and the patterns of absorption, accumulation, and distribution of major mineral elements (N, P, K, Ca and Mg) in these organs. Through correlative analysis between tree growth and nutrient demand, the research aimed to establish a precision fertilization regime based on phenological stages, providing a scientific basis for improving quality and efficiency in local pear production.【Methods】The study was conducted in 2024 in a standardized pear orchard in Simen town, Yuyao municipal, Zhejiang province, using 8-year-old Cuiguan pear trees as plant material. Five uniformly growing sample trees were selected, and the growth dynamics of three types of aerial organs (leaves of rosette-short shoots, vegetative shoots, and fruit) were systematically monitored from bud burst on March 28th to fruit harvest on July 20th. Periodic determination of leaf number and fresh weight per leaf on rosette-short shoots was conducted; length, basal diameter, shoot fresh weight, and the fresh weight of attached leaves on vegetative shoots were recorded; and changes in fruit vertical diameter, horizontal diameter, and single fruit weight were traced. Organ samples were collected simultaneously, and the contents of major mineral elements were analyzed using standard methods (NY/T 2017—2011 for N, P and K; GB/T 23375—2009 for Ca and Mg). Combined with dry matter rate measurements, the accumulation of each element per plant was calculated. Significance of differences was analyzed using DPS V9.50.【Results】① Organ growth dynamics. The development of rosette- short shoot leaves was completed earliest, with single leaf weight reaching 1.26 g by April 20th and remaining constant thereafter, averaging approximately 5.5 leaves per shoot. The elongation growth of vegetative shoots essentially ceased by June 10th, reaching an average length of 96.69 cm; however, their diameter continued to increase until harvest, growing from 4.82 mm on April 10th to 12.90 mm on July 20th. Fruit development showed distinct stages: slow growth before June 10th, followed by a rapid expansion phase where single fruit weight increased sharply from 59.20 g on June 10th to 395.50 g on July 20th, yielding 30.69 kg per plant. ②Nutrient demand characteristics. Nitrogen demand was highly concentrated in the early to mid-stages, with accumulation from April to May accounting for 89.69% of the total growth period. Leaves were the main nitrogen sink, constituting 63.91% of the total aerial N on July 30th. Phosphorus demand was relatively evenly distributed across growth stages, with fruit accounting for 51.82% of P at maturity. The peak demand for potassium occurred during the fruit rapid expansion phase (June 20th-July 10th), with accumulation in this phase accounting for 40.16% of the total period; fruit was the primary sink for potassium. Calcium and magnesium were mainly accumulated in the aerial vegetative organs, with leaf Ca and Mg contents reaching 47.92 g·plant-1 and 7.62 g·plant-1 , respectively, on July 20th, while the maximum fruit Ca content was only 1.09 g·plant-1 . ③Growth-nutrient correlation. The study found a significant stage-specific correlation between tree growth and nutrient uptake: the vigorous vegetative growth period from late April to mid-May corresponded to the rapid accumulation phase of N and P; after vegetative growth slowed in early June, the focus of nutrient allocation shifted to fruit, with a sharp increase particularly in potassium accumulation; the continuous accumulation of calcium in leaves coincided with the thickening growth of shoots, reflecting its important role in maintaining cell structure and enhancing stress resistance.【Conclusion】Both the growth of newly formed aboveground organs and the demand for mineral elements in Cuiguan pear exhibited obvious stage-specific characteristics, with a close correlation between the two. On this basis, a stage-targeted precision fertilization strategy suitable for sand pear production areas in the southeastern coastal region of China was proposed: From April to May, nitrogen fertilizer should be applied predominantly, combined with phosphorus, potassium and foliar magnesium and calcium fertilizer to promote early vegetative growth; from May to June, the proportion of potassium fertilizer should be appropriately increased, and foliar calcium fertilizers should be supplemented for fruit expansion; from June to July, potassium fertilizer should be heavily applied, phosphorus fertilizer applied moderately, and nitrogen input controlled. This study systematically revealed the dynamic relationship between tree growth and mineral nutrient demand in Cuiguan pear for the first time, providing important theoretical and practical guidance for scientific fertilization in sand pear producing areas.