Phosphorus use efficiency enhancers as plant growth promotors

A method for promoting plant growth comprising utilizing a compound of the general formula (I)

• with the following definitions:
• R1 hydrogen, NH2, OH, C1-30-hydrocarbon residue which can contain one to three halogen atoms and/or one to six heteroatoms, selected from the group consisting of nitrogen, oxygen and sulfur,
• preferably R1 is hydrogen, NH2 or a C1 to C4 hydrocarbon or C1 to C4 carboxy or carbonyl group, even more preferably, R1 is NH2,
• R2, R3 independently hydrogen, C1-12-hydrocarbon residue which can contain one or two halogen atoms and/or one to three heteroatoms, selected from the group consisting of nitrogen, oxygen and sulfur, it also being possible for R2 and R3 to be covalently linked to form a 5- to 8-membered heterocyclic ring, which can contain 1 or 2 halogen atoms and/or one to three further heteroatoms in addition to the heteroatoms N and O already part of the heterocyclic ring,
• preferably R2 is hydrogen or a C1-C4 hydrocarbon, even more preferably R2 is hydrogen or a C1-C2 hydrocarbon,
• preferably R3 is a C1-C4 hydrocarbon, and even more preferably, R3 is CH3,
• R4 independently hydrogen, halogen, NO2, C1-12-hydrocarbon residue which can contain one or two halogen atoms and/or one to three heteroatoms, selected from the group consisting of nitrogen, oxygen and sulfur, preferably R4 is hydrogen or CH3,
• n 0;
• 1;
• 2 or 3,
• as plant growth promotor, wherein the plant growth promotor is used for
• biomass and/or crop yield increase,
• for mitigating and/or reducing the phosphate starvation stress of plants or for improving,
• the phosphorus or phosphate use efficiency of plants or
• the phosphorus or phosphate uptake of plants,
• the root hair development,
• root system architecture,
• drought resistance development,
• nutrient uptake efficiency of plants,
• the phosphate availability for plants,
• water or nutrient uptake of plants,
• beneficial symbiotic interactions of plants,
• soil microbiome or
• phosphorous or phosphate availability from phosphate rock or organic phosphate.