Al Daini Hussein, Norman Hayley C, Young Paul, Barrett-Lennard Edward G
School of Animal Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
CSIRO Animal, Food and Health Sciences and Sustainable Agriculture Flagship, Private Bag 5, Wembley, WA 6913, Australia.
Funct Plant Biol. 2013 Oct;40(10):1057-1064. doi: 10.1071/FP13060.
Atriplex nummularia Lindl. (oldman saltbush) is a halophytic shrub used widely as a forage for ruminant production in saline farming systems. However, it can contain high concentrations of oxalate in the leaves, which may cause calcium deficiency in grazing animals. We hypothesised that supplying NH4+ instead of NO3- to a clone of this species would decrease oxalate concentrations in the shoots, and also decrease plant growth. Oxalate concentrations were measured in plants in the field, and a glasshouse experiment was conducted in which plants were grown with 10mM NO3- or NH4+, with 50, 200 or 500mM NaCl. The field survey showed effects of site (P<0.001), with average oxalate concentrations in shoots varying between 2.4 and 6.4% dry mass (DM). In the glasshouse, oxalate concentrations and plant growth were both affected by N-source and salinity (P<0.001). Averaged across salinities, plants grown with NH4+ for 24 days had only 43% of the shoot DM but 25% of the oxalate concentration of plants grown with NO3-. We discuss the effects of N-source on oxalate concentrations, the implications of this for halophyte growth, and the opportunity to select halophytes with lower oxalate and higher nutritive value for livestock.
滨藜（Atriplex nummularia Lindl.，即老头盐肤木）是一种盐生灌木，在盐碱地养殖系统中广泛用作反刍动物生产的饲料。然而，其叶片中可能含有高浓度的草酸盐，这可能导致放牧动物缺钙。我们推测，向该物种的一个克隆体供应铵离子（NH4+）而非硝酸根离子（NO3-）会降低地上部分的草酸盐浓度，同时也会减缓植物生长。我们在田间测量了植物中的草酸盐浓度，并进行了一项温室实验，让植物在含有10mM硝酸根离子或铵离子，以及50、200或500mM氯化钠的条件下生长。田间调查显示地点有影响（P<0.001），地上部分草酸盐的平均浓度在干重（DM）的2.4%至6.4%之间变化。在温室中，草酸盐浓度和植物生长均受氮源和盐度的影响（P<0.001）。在不同盐度条件下平均计算，用铵离子培养24天的植物地上部分干重仅为用硝酸根离子培养的植物的43%，但草酸盐浓度仅为其25%。我们讨论了氮源对草酸盐浓度的影响、这对盐生植物生长的意义，以及选择草酸盐含量较低且营养价值较高的盐生植物用于饲养牲畜的机会。
