Abstract
The nutrients removed by the fruit harvest, pruning, and fallen leaves in pear orchards are meaningful to creating reasonable suggestions regarding fertilizer recommendations. Thus, we determined the biomass as well as the concentrations of macroelement [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] and microelements [iron (Fe), manganese (Mn), cuprum (Cu), zinc (Zn) and boron (B)] of the pruned branches of different ages, fallen leaves, and mature fruit of four 15-year-old interspecific hybrids and Asian pears cultivars,
Pyrus bretschneideri
Rehd. cv. Huangguan (HG),
Pyrus bretschneideri
Rehd. cv. Zhong Li No. 1 (LBS),
Pyrus pyrifolia.
cv. Yuanhuang (YH), and
Pyrus bretschneideri
Rehd. (YL), growing in the same orchard. The nutrient abundance was Ca > N > K > Mg > P in the pruned branches and fallen leaves of all four cultivars; however, it was K > N > P > Ca > Mg in the fruit. The N, K, and P concentrations decreased with increasing age of the pruned branches. The Ca and Mg concentrations in the fallen leaves were 58% and 100% higher, respectively, than those in the pruned branches, but they were 44-fold and 6-fold higher, respectively, than those in fruits. The annual losses of N, P, K, Ca, and Mg from pear trees by pruning, leaf abscission, and fruit harvest were 241, 26, 118, 307, and 36 kg/ha, respectively; of these, 37% to 78% was attributable to pruning. Of the total loss, the percentages of N, Ca, and Mg lost via fallen leaves were higher than those lost via fruit (approximately 15%–46% in fallen leaves and 6%–16% for N, 0.9%–1.2% for Ca, and 5.7%–8.7% for Mg in fruit). However, the losses of P and K via fallen leaves (approximately 6%–24% and 22%–38%, respectively) were less than those via fruit. Among the cultivars tested, HG trees exhibited the greatest loss in nutrients through pruning, leaf abscission, and fruit harvest, followed by LBS. However, YL lost more N, K, Ca, and Mg through falling leaves than did LBS. Therefore, there is great variation in the amount of mineral nutrients lost from different cultivars of pear trees during the growing season, and fertilizers should be applied appropriately to compensate for this variation.