Maistry Pravin M, Muasya A Muthama, Valentine Alex J, Chimphango Samson B M
Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
Funct Plant Biol. 2014 Feb;42(1):52-62. doi: 10.1071/FP14100.
We investigated the physiological basis for tolerance of limiting P supply and for enhanced growth with simultaneous addition of N and P in Aspalathus linearis (Burm. f.) R. Dahlgren. It was hypothesised that increasing N supply would stimulate P acquisition mechanisms and enhance plant growth with high P supply. In sand, plants received 100μM, 300μM, 500μM and 700µM N at a low P level of 10µM and a high P level of 100µM. In solution, plants received 200μM and 500µM N at a low P level of 5µM and a high P level of 15µM. Cluster roots formed only in plants with low P supply. Roots showed greater citrate and malate production and phosphatase activity at 5µM P than at 15µM P. At 10µM P, greater N supply enhanced cluster root formation to 60% of root biomass, and increased the phosphatase activity of noncluster roots and succinate release by both root types. At a high P supply of 15µM, greater N supply stimulated phosphatase activity of roots by 50%, increasing P uptake and plant growth. With increased resource partitioning towards P acquisition due to greater P demand, A. linearis is tolerant of low P supply and highly responsive to combined addition of N and P.
我们研究了线叶香豌豆（Aspalathus linearis (Burm. f.) R. Dahlgren）对有限磷供应的耐受性以及同时添加氮和磷时生长增强的生理基础。我们假设增加氮供应会刺激磷获取机制，并在高磷供应下促进植物生长。在砂培中，植物在低磷水平10μM和高磷水平100μM下分别接受100μM、300μM、500μM和700µM的氮。在水培中，植物在低磷水平5μM和高磷水平15μM下分别接受200μM和500μM的氮。簇生根仅在低磷供应的植物中形成。在5μM磷水平下，根系的柠檬酸和苹果酸产量以及磷酸酶活性高于15μM磷水平。在10μM磷水平下，更高的氮供应使簇生根形成增加至根生物量的60%，并增加了非簇生根的磷酸酶活性以及两种根类型的琥珀酸释放量。在15μM的高磷供应下，更高的氮供应使根系磷酸酶活性提高了50%，增加了磷吸收和植物生长。由于对磷的需求增加，资源分配更多地用于磷获取，线叶香豌豆对低磷供应具有耐受性，并且对氮和磷的联合添加反应高度敏感。
