Aluminium tolerance and high phosphorus efficiency helps Stylosanthes better adapt to low-P acid soils.
OBJECTIVE
Stylosanthes spp. (stylo) is one of the most important pasture legumes used in a wide range of agricultural systems on acid soils, where aluminium (Al) toxicity and phosphorus (P) deficiency are two major limiting factors for plant growth. However, physiological mechanisms of stylo adaptation to acid soils are not understood.


METHODS
Twelve stylo genotypes were surveyed under field conditions, followed by sand and nutrient solution culture experiments to investigate possible physiological mechanisms of stylo adaptation to low-P acid soils.


RESULTS
Stylo genotypes varied substantially in growth and P uptake in low P conditions in the field. Three genotypes contrasting in P efficiency were selected for experiments in nutrient solution and sand culture to examine their Al tolerance and ability to utilize different P sources, including Ca-P, K-P, Al-P, Fe-P and phytate-P. Among the three tested genotypes, the P-efficient genotype 'TPRC2001-1' had higher Al tolerance than the P-inefficient genotype 'Fine-stem' as indicated by relative tap root length and haematoxylin staining. The three genotypes differed in their ability to utilize different P sources. The P-efficient genotype, 'TPRC2001-1', had superior ability to utilize phytate-P.


CONCLUSIONS
The findings suggest that possible physiological mechanisms of stylo adaptation to low-P acid soils might involve superior ability of plant roots to tolerate Al toxicity and to utilize organic P and Al-P.
Du
Yu-Mei
YM
Institute of Tropical Crop Genetic Resources, Chinese Academy of Tropical Agriculture Science, Danzhou 571737, China.
Tian
Jiang
J
Liao
Hong
H
Bai
Chang-Jun
CJ
Yan
Xiao-Long
XL
Liu
Guo-Dao
GD