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101.
Plants display an array of classical strategies to maximize phosphate (Pi) acquisition from sparingly soluble P sources. Acclimation to Pi-stress via elegant Pi-starvation induced (PSI) adjustments would reduce our current overreliance on expensive, polluting and non-renewable Pi-fertilizers. Nevertheless, differences in the ability of various species to solubilize sparingly soluble P-sources have been often evidenced; inter-cultivar variations are scarcely documented. Brassica is known as an effective, non-mycorrhizal user of sparingly soluble P-sources. Various growth parameters and biomass accumulation by genetically diverse Brassica cultivars were determined in four experiments using hydroponics and quartz sand culture media. Role of PSI root mediated pH changes, organic anions (OAs) exudation and altered root architecture in mobilization and acquisition of sparingly soluble P-forms [Jordan rock-P (RP) at 2 g l−1 and Ca3(PO4)2 (TCP) at 0.2 g l−1 respectively] was investigated. Cultivars showed considerable genetic variations in biomass accumulation, various growth parameters and root–shoot ratio. Concentration and total uptake of P, specific absorption rate of P, P-transport rate and P-utilization efficiency (PUE) were also significantly (P < 0.001) different for various cultivars and their dry matter was significantly correlated with P-uptake [r = 0.94** (significant at 1% level)]. P-tolerant cultivars showed substantial decrease in solution media pH because of H+ efflux and exuded more carboxylates than low P-sensitive cultivars under P-starvation. P-uptake by cultivars increased linearly with decreasing pH. The amount and types of OAs exuded from the roots of P-starved plants differed from those of plants grown under P-sufficient environment. In split pot study, with TCP and RP supplied spatially separated from other nutrients, efficient cultivars were still able to mobilize RP and TCP more efficiently than inefficient cultivars. In rhizobox study, the elongation rates of primary roots decreased but the elongation rates of the branched zones of primary roots and the length of lateral roots increased under P-starvation. Tested cultivars showed genetic diversity in accessing, mobilization, acquisition and utilization of Pi from sparingly soluble P forms. An arrange marriage of plant traits can explain cultivar’s access to different forms of sparingly soluble P, and in addition to altered lateral root topology and enhanced P-uptake and PUE, enhanced H+ efflux and OAs exudation are key factors in Pi scavenging from extra cellular sparingly soluble P-forms. 相似文献
102.
《Communications in Soil Science and Plant Analysis》2012,43(15-16):2536-2544
Recent soil‐management practices such as no‐tillage and minimal tillage, when applied to the irrigated rice crop, promote changes in soil composition as a result of anaerobic degradation of organic matter. Several short‐chain organic acids are formed, such as acetic acid. The objective of this work was to determine the effect of calcium (Ca) on plant development under stress by acetic acid toxicity. The experiment was conducted in hydroponics by testing different Ca (0.2, 1.0, and 5.0 mmol L?1) and acetic acid (0 and 2.5 mmol L?1) concentrations. The variables evaluated were the root system morphological parameters (total length, radius, area, dry‐matter weight, and main root growth), shoot parameters (shoot dry matter, plant height), and concentration and total accumulated nitrogen (N), phosphorus (P), potassium (K), Ca, and magnesium (Mg) in the plants. The growth of the root system and the shoots of rice plants were not affected by the addition of Ca to the treatments containing acetic acid. 相似文献
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104.
地膜覆盖下豆禾混播草地根系的动态研究 总被引:1,自引:0,他引:1
吴序卉 《甘肃农业大学学报》1999,34(2):120-124
使用差额法连续分层次地对燕麦+豌豆人工草地的根系在地膜覆盖条件下的生长发育动态进行了研究,结果表明:燕麦根系的58%分布浅,豌豆的77%根系分布在10~20cm深,两者混播后,其根系可有效地互补,且在地膜覆盖条件下互补性增强。同时地膜覆盖后,使根系的分布更浅,根量减少。 相似文献
105.
《Plant Production Science》2013,16(4):437-445
abstractNodal root anatomy was compared among twelve upland and lowland rice (Oryza sative L.) varieties with tropical origin which were grown in hydroponic culture and under field conditions. The traditional upland japonica varieties showed the largest diameter of root, stele, and xylem vessel followed by modern upland varieties. There was a clear varietal difference in the ratio of stele to root diameter, which was associated with the genetic group rather than with the ecosystems. The japonica varieties had a significantly larger stele diameter relative to the root diameter than indica and aus varieties. The indica and aus varieties displayed more xylem vessels per unit area of stele than the japonica varieties, but the diameter of xylem vessel was smaller. Equivalent xylem vessel diameter (De) was more dependent on the number of xylem in the indica varieties than in the japonica varieties. Distinctly different types of sclerenchyma anatomy were identified among the varieties. The development of sclerenchyma was classified into four different types based on thickening of cell wall in the outer cortical parenchyma and the number of sclerenchymatous cell layers. Like the xylem anatomy, the varietal differences in sclerenchyma development were more associated with genetic group rather than the ecotype. The japonica varieties had higher frequency of the types which have a doubled cell layer in sclerenchyma with thick cell wall than indica and aus. The difference among the genetic groups was nearly consistent across growing conditions, aerobic and submerged soils. These results indicated that sclerenchyma development is controlled by a genetic factor. 相似文献
106.
《Plant Production Science》2013,16(2):186-191
AbstractAnatomical observations were conducted to clarify some characteristics of the crown root primordia (CRP) formation in wheat stems. Unelongated portions of main stems were sampled from the plant at 3.2 and 7.2 plant age in leaf number, which were adopted as indexes because of the similarity to rice plants. Then, serial cross sections were made to investigate the position of CRP in the unelongated stem taking into consideration the running of vascular bundles in the stem. CRP were formed just outside tissues of the peripheral cylinder of longitudinal vascular bundles. The positions of CRP were not successive along the stem axis. They showed no definite relation to the running of vascular bundles. Diameters of CRP at the upper portion of the stems were larger than those at the lower portion. The positions of CRP along the stem axis were not distinguishable into nodal and internodal position. CRP and emerged CRs were not classified by the well-known ‘nodal root’ or ‘shoot unit root’, or the ‘unit’, which have been applied recently to rice plants. Further studies are necessary to clarify the factors controlling CRP formation anatomically and quantitatively. 相似文献
107.
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110.
Paclobutrazol (2R,3R + 2S,3S)-1-(4 chlorophenyl)-4,4-dimethyl-2-(1,2,4-trizol-1-yl) pentan-3-ol), at 25, 50 and 150 mg active ingredient, was applied as a soil drench or stem application to 1-year-old ‘Topred Delicious’ apples. Root growth measured as relative root surface area was reduced by both soil and stem applications. There was no significant difference in dry weight of the root tissue. The root-to-leaf-area ratio was significantly increased in paclobutrazol-treated plants.Water relations measured as leaf conductance and leaf water potential were significantly influenced by paclobutrazol. Leaf conductance was higher in paclobutrazol-treated plants when the plants were turgid, as well as under some water stress. Leaf water potential was significantly higher in treated plants.There were no significant differences in the total nitrogen, phosphorus, potassium and magnesium levels found in the leaf or root tissue. 相似文献