Seedling growth of four pear rootstocks and changes in mineral elementsin their leaves, shoots and roots during growing seaso

Abstract:【Objective】Pear is one of the most important deciduous fruits in the world. Several species of Pyrus are commercially used as rootstocks for cultivated pear cultivars. Rootstocks may affect the performance of growth and fruiting of the scion cultivars through uptake and transportation of the mineral elements. The purpose of this study was to determine the contents of mineral elements in different organs of different pear rootstock seedlings during the growing season in order to understand the effect of rootstockon scion performance.【Methods】Two-year-old seedlings of P. ussuriensis Maxim,‘Xiaoxiangshui’(P.bretschnederi Rehd.) and two local types (Hebei Duli and Hubei Tangli) of P. betulaefolia Bunge from twolocations were selected as materials to study the growth potential and mineral contents in these Pyrus seed⁃lings. 30 seedling plants were randomly selected for each species or local types for the measurements ofshoot length and plant height, and 10 plants for the measurements of the contents in mineral elements inthe leaves, shoots and roots. N content was determined with a semi micro Kjeldahl N method, P using vanadium molybdate yellow colorimetric method, and K with a flame photometer. The determination of theother mineral elements was carried out with an atomic absorption spectrophotometer. All the data were analyzed using DPS v3.01 statistical software.【Results】The shoot growth patterns of the two P. betulaefolia Bunge were similar, and that of P. bretschnederi var.‘Xiaoxiangshui’was similar to that of P. ussuriensis Maxim. The cessation of shoot growth of P. bretschnederi‘Xiaoxiangshui’and P. ussuriensis Maxim oc⁃curred earlier than that in the two local types of P. betulaefolia Bunge. The growth of the two P. betulaefolia Bunge showed a typical“S”pattern. The order of shoot length was Hebei Duli (P. betulaefolia Bunge)＞Hubei Tangli (P. betulaefolia Bunge)＞‘Xiaoxiangshui’(P. bretschnederi Rehd) ＞Shanli (P. us⁃suriensis Maxim). The height of the trunk of‘Xiaoxiangshui’was similar to those of two local types of P.betulaefolia Bunge due to longer growing time. The levels of N, P, K, Fe, Cu and Zn elements in differentorgans were positively correlated with the shoot growth during the rapid growing period. The contents ofCa and Mg were negatively related to the shoot growth, while Mn had no obvious correlation with thegrowth of shoots. The contents of removable mineral element, such as N, P and K in the leaves and shootsof the four different pear seedlings decreased with leaf age, while the contents of immovable mineral ele⁃ments, such as Ca and Mg in the leaves decreased with leaf age. The content of Ca in the shoots of‘Xiaoxi⁃angshui’was similar to that of Shanli, but the content of Ca in the shoots of the two P. betulaefolia Bunge.increased and reached a peak in mid-June. Among the tested seedlings, the contents of N and K in theleaves of Hebei Duli were the highest, and those of Shanli were the lowest. The contents of P in the leavesand shoots were quite similar in the four roostocks, and those in the roots were slightly different. The con⁃tents of Ca in the leaves and shoots of‘Xiaoxiangshui’and Shanli were significantly higher than the twoP. betulaefolia Bunge. The content of Mg in the leaves of Hebei Duli was the lowest. The contents of allmineral elements except for K and Mg in the roots of Shanli were higher than those of the other pear seed⁃lings. The contents of Fe in the leaves of the two P. betulaefolia Bunge were similar and higher than thoseof‘Xiaoxiangshui’and Shanli. The change pattern and contents of Cu in the seedlings of the four root⁃stocks were similar. The levels of Mn in the leaves of‘Xiaoxiangshui’and Shanli steadily increased; thecontents of Mn in the two P. betulaefolia Bunge fluctuated and were similar. The contents of Zn in theleaves of the two P. betulaefolia Bunge had little difference and were lower than those of‘Xiaoxiangshui’in the growing season.【Conclusion】The shoots of the 2 kinds of P. betulaefolia Bunge were significantlylonger than those of P. bretschnederi‘Xiaoxiangshui’and P. ussuriensis Maxim. The height of the trunk of P. ussuriensis Maxim was obviously shorter than those of the other pear seedlings due to the early endingof the trunk growth. The contents of mineral elements in different seedlings were different while the chang⁃es in the contents of N, K, Ca, Fe, Fe, Mn and Zn in the leaves and shoots of the two local types of P. betu⁃laefolia Bunge were quite similar.