This study aims to explore the low phosphorus (P) tolerance of saplings from different
Gleditsia sinensis
Lam. families. It also seeks to screen for
Gleditsia sinensis
families with strong low P tolerance and identify key indicators for evaluating their tolerance. This research provides a foundation for the breeding of superior families of
Gleditsia sinensis
and the study of mechanisms underlying low P tolerance. Using saplings from 30
Gleditsia sinensis
families as the research subjects, a sand culture pot experiment was conducted. This study set up low P treatment (0.01 mmol L
−1
) and normal P treatment (1 mmol L
−1
). Twenty-five indicators including growth morphology, biomass, root morphology, and P content were measured. The low P tolerance coefficient was used as the basic data for assessing the low P tolerance of
Gleditsia sinensis
. The fuzzy comprehensive evaluation method was employed to comprehensively assess the low P tolerance types of
Gleditsia sinensis
a stepwise regression model was established to identify the key evaluation indicators for low P tolerance. The results indicate that low P stress reduced plant height, stem diameter, and biomass in most
Gleditsia sinensis
families, but increased the root morphological indicators, root-shoot ratio and PUE of various organs. Principal component analysis transformed the 25 indicators into 6 independent comprehensive indicators, with a cumulative contribution rate of 86.743%. The fuzzy comprehensive evaluation method calculated a comprehensive evaluation value (D value), enabling the screening of
Gleditsia sinensis
families into low P tolerant and low P sensitive types. Cluster analysis grouped the 30
Gleditsia sinensis
families into 4 types. Among them, F13, F10, F9, F18, F15, and F28 were classified as low P tolerant types; F6, F23, F3, F17, F20, F2, F12, F11, F16, F8, F5, F27, F1, and F26 were categorized as intermediate types; F30, F7, F22, F4, F19, F29, F24, F14 and F25 were considered low P sensitive types, and F21 was classified as extremely low P sensitive types. The stepwise regression analysis identified the indicators stem diameter, total root volume, shoot dry weight, total root projection area, and leaf P content as the key factors for discriminating the low P tolerance of
Gleditsia sinensis
. The regression model is as follows: D=-0.005 + 0.323 stem diameter *+0.154 * total root volume + 0.196* shoot dry weight + 0.139* total root projection area − 0.112* leaf P content. In summary, low P stress inhibited the growth of
Gleditsia sinensis
saplings, but it increased the root morphological indicators, root-shoot ratio and PUE of various organs to cope with low P environments. The screening identified F13, F10, F9, F18, F15, and F28 as low P to...
