INFLUENCE OF NITROGEN ON GROWTH AND PHOTOSYNTHESIS OF A C-3 CEREAL, ORYZA-SATIVA, INFECTED WITH THE ROOT HEMIPARASITE STRIGA-HERMONTHICA
INFLUENCE OF NITROGEN ON GROWTH AND PHOTOSYNTHESIS OF A C-3 CEREAL, ORYZA-SATIVA, INFECTED WITH THE ROOT HEMIPARASITE STRIGA-HERMONTHICA
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DOI：
10.1093/jxb/45.7.925
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发表时间：
1994-07-01
影响因子：
6.9
通讯作者：
PRESS, MC
中科院分区：
文献类型：
--
作者：
CECHIN, I;PRESS, MC
独脚金是一种半寄生的被子植物，原产于非洲半干旱热带地区。它是C-4谷物的主要杂草，但在当地它也是C-3植物水稻（Oryza sativa）的重要杂草。当生长在两种不同的硝酸铵浓度，1和3摩尔m（-3），感染的水稻植株产生的总生物量的17%和42%的未感染的植物。S.在两种氮浓度下，hermonthica都阻止了谷物生产。在较低的浓度下，没有头部产生。在较高浓度下，头重仅为未感染对照的6%。S. hermonthica也改变了干物质在植物各部分之间的分配，使得枝生长比根生长降低的程度更大。因此，受感染植物的根冠比是未受感染对照植物的根冠比的约5倍。在低氮和高氮条件下，受感染植株的光饱和光合速率分别为未感染对照的56%和70%。感染也导致气孔导度值较低，虽然气孔下CO2浓度不受影响。分析光合作用对气孔下CO2浓度的响应（A/C-i曲线）表明，较低的光合速率不能完全归因于较低的气孔导度。较低的初始斜率和渐近速率表明，羧化和过程控制再生的核酮糖-1，5-二磷酸减少感染。并讨论了S.与水稻的情况相反，氮营养导致寄生虫对宿主的影响显著减轻。
Striga hermonthica is a root hemiparasitic angiosperm native to the African semi-arid tropics. It is a major weed of C-4 cereals but locally it is also an important weed of the C-3 plant, rice (Oryza sativa). Infected rice plants produced 17% and 42% of the total biomass of uninfected plants when grown at two different ammonium nitrate concentrations, 1 and 3 mol m(-3), respectively. S. hermonthica prevented grain production at both concentrations of nitrogen. At the lower concentration no heads were produced. At the higher concentration head weight was only 6% of uninfected controls. S. hermonthica also altered the partitioning of dry matter between plant parts, such that shoot growth was reduced to a greater extent than root growth. As a consequence the root-to-shoot ratio of infected plants was approximately five times greater than that of uninfected control plants. Light saturated rates of photosynthesis in infected plants were 56% and 70% of those of uninfected controls, at low and high nitrogen, respectively. Infection also led to lower values of stomatal conductance although the substomatal CO2 concentration was unaffected. Analysis of the response of photosynthesis to substomatal CO2 concentration (A/C-i curves) demonstrated that lower rates of photosynthesis could not be solely attributed to lower stomatal conductances. Lower initial slopes and asymptotic rates suggest that both carboxylation and processes controlling regeneration of ribulose-1,5-bisphosphate are reduced by infection. The data are discussed with respect to the influence of S. hermonthica on the growth and photosynthesis of C-4 hosts, where in contrast to the situation with rice, nitrogen feeding results in a marked alleviation of the effects of the parasite on the host.