玉米,小麦与花间作改善花生铁营养机制的探讨

采用土培盆栽方法模拟研究了玉米／花生、小麦／花生间作对花生铁营养状况的影响及其作用机制。结果表明,禾本科作物与花生间作对花生的铁营养显著影响;当花生与玉米或小麦分别间作时,花生新叶叶色正常,而花生单作则表现出严重的缺铁花化现象,间作花生新叶活性铁、叶绿素含量明显高单作,途中瞳作花生各部位铁含量和吸收量明显高于单作,间作灶促进了铁向花生地上部的转移;在单作花生表现缺铁症状１４ｄ的时间范围内,其根系质     

不同禾本科作物与花生混作对花生根系质外体铁的累积和还原力的影响

采用土培盆栽方法模拟玉米／花生、大麦／花生、燕麦／花生、小麦／花生、高粱／花生5种种植方式,研究混作对花生根系质外体铁的累积和还原力的影响．结果表明,当花生与5种分泌植物铁载体能力不同的禾本科作物混作时,花生新叶叶色正常,而单作花生则表现出严重的缺铁黄化症状,混作花生各部位的含铁量明显增加．与麦类作物(大麦、燕麦、小麦)混作的花生其各部位铁含量高于与玉米、高粱混作的花生,说明麦类作物改善花生铁营养的能力强于玉米、高粱,而两个玉米品种之间的能力差异不大。这主要是由于麦类作物分泌植物铁载体能力高于玉米、高粱．在花生生长至第50、60和70d时,混作花生根系质外体铁含量也随着逐渐增加,并始终高于单作花生．同时,混作明显地提高了花生根际土壤有效铁的含量,花生根系还原力也逐步提高．混作花生逐渐提高的还原力和介质中不断供给的易被花生还原吸收的铁。在改善花生的铁营养方面起了重要的作用．     

不同禾本科作物与花生混作对花生根系质外体铁的累积和还原力的影响

采用土培盆栽方法模拟玉米/花生、大麦/花生、燕麦/花生、小麦/花生、高粱/花生5种种植方式,研究混作对花生根系质外体铁的累积和还原力的影响.结果表明,当花生与5种分泌植物铁载体能力不同的禾本科作物混作时,花生新叶叶色正常,而单作花生则表现出严重的缺铁黄化症状,混作花生各部位的含铁量明显增加.与麦类作物(大麦、燕麦、小麦)混作的花生其各部位铁含量高于与玉米、高粱混作的花生,说明麦类作物改善花生铁营养的能力强于玉米、高粱,而两个玉米品种之间的能力差异不大,这主要是由于麦类作物分泌植物铁载体能力高于玉米、高粱.在花生生长至第50、60和70d时,混作花生根系质外体铁含量也随着逐渐增加,并始终高于单作花生.同时,混作明显地提高了花生根际土壤有效铁的含量,花生根系还原力也逐步提高.混作花生逐渐提高的还原力和介质中不断供给的易被花生还原吸收的铁,在改善花生的铁营养方面起了重要的作用.     

间作对植株生长及养分吸收和根际环境的影响

通过盆栽实验研究了线辣椒和玉米间作对其植株生长、矿质养分吸收、根际环境以及铁载体分泌的影响,以探索间作促进铁、磷等养分吸收利用的可能生理机制.结果表明:(1)与单作相比,间作线辣椒地上部干重降低23.0%,根系干重增加44.2%,玉米地上部和根系的干重分别增加8.7%和22.9%;间作线辣椒根冠比和根系活力分别显著提高86.4%和29.8%;间作线辣椒、玉米叶绿素含量分别显著提高12.6%和7.8%.(2)与单作相比,间作线辣椒的铁、锌、锰含量分别增加1.50倍、1.39倍和1.34%,而间作玉米则无显著变化;间作线辣椒和玉米的钙含量都显著低于相应单作,氮含量没有显著变化,但磷、钾含量显著增加.(3)间作线辣椒和玉米的根际土、非根际土的酸性磷酸酶活性及根系酸性磷酸酶活性都显著高于相应单作,而其根际土和非根际土的pH值无显著变化;间作玉米根系的铁载体分泌比单作减少32.8%,间作线辣椒根系的铁还原酶活性是单作的1.10倍.研究发现,线辣椒/玉米间作能通过影响根际生物学特征和化学过程提高植株的铁、锌、磷和钾养分水平,缓解养分胁迫,是一种很有推广价值的种植模式.     

大豆根系质外体铁库的累积及其在缺铁时被利用的规律

采用营养液培养法研究了在不同程度的缺铁条件下,大豆（Ｇｌｙｃｉｎｅｍａｘ（Ｌ．）Ｍｅｒｒ．）根系质外体铁库累积与利用的规律,及其在缓解植物缺铁胁迫方面的作用。结果表明,缺铁处理下,大豆根系质外体铁库不断被再利用直至枯竭,根系还原力与过氧经物酶活性呈升降有序的周期性变化,从而一定程度上缓解缺铁胁迫,延缓植株缺铁症状的出现,新叶叶绿素和活性铁含量缓慢下降,而低铁条件下（供应１０＾－６ｍｏｌ／ＬＦｅＥＣ     

玉米/花生间作对土壤微生物和土壤养分状况的影响

通过大田试验,研究了玉米/花生间作对玉米和花生根区土壤微生物和土壤养分状况的影响.结果表明：与单作相比,间作能显著提高玉米和花生根区的土壤细菌数量;间作花生根区土壤真菌和放线菌数量与单作无显著差异;间作玉米根区土壤真菌和放线菌数量比单作明显提高;间作作物根区微生物群落功能多样性和代谢活性比单作有所改善.玉米/花生间作不同程度提高了整个间作系统根区的土壤碱解氮、速效磷、有机质含量及EC值,其中,间作玉米根区土壤养分的增加更为明显,说明玉米/花生间作可以较明显地改善两种作物根区的微生物和养分状况,土壤微生态环境的改善又会促进作物地上部的生长.     

小麦与蚕豆间作体系根系形态与磷吸收的定量解析

豆科与禾本科作物间作能够改变作物根系生长,但不同施磷水平下间作-根系形态-磷吸收之间的关系尚未明确.本研究通过田间定位试验和根箱模拟试验,研究不同种植模式(小麦单作、蚕豆单作和小麦-蚕豆间作)和不同磷水平下小麦和蚕豆的产量、生物量、磷吸收及根系形态特征,分析探讨不同施磷条件下小麦-蚕豆间作对根系形态和磷吸收的影响.结果...     

石灰性土壤上HCO3-诱导花生缺铁失绿机制

采用土壤-营养液结合的分根培养方法,研究了部分根系供应HCO- 3或铁对花生铁营养的调控及其作用机制。结果表明,对花生部分根系供应HCO- 3或铁可以调控花生的铁营养,仅供HCO- 3可以诱导缺铁,而只供铁能矫正失绿,同时供应HCO- 3和铁时则不引起失绿。在花生新生叶失绿和复绿的过程中,其中的活性铁含量和全铁含量也有相应的消长。当花生表现缺铁失绿症状时,地上各部分的全铁含量显著降低,而土中根的全铁含量不降低、质外体铁含量升高。在HCO- 3存在的条件下,不同部分根系的铁( )还原酶活性因其生长介质而不同,营养液中根系的铁( )还原酶活性降低而土中根的铁( )还原酶活性不受影响。当花生表现缺铁失绿症状时,土壤中HCO- 3含量升高,有效铁含量不高,p H值无变化。因此,本试验证实了石灰性土壤上的高HCO- 3含量,主要是降低了花生地上部的铁含量而引起失绿,而且花生缺铁失绿又导致土壤HCO- 3含量升高     

潜在性缺铁条件下大豆根系质外体铁库的积累与利用

用营养液培养方法研究了在不同供铁条件下,大豆根系质外体铁库的积累与活化利用。结果表明：1、供应难溶性Fe（OH）3,大豆根系质外体铁库呈现出积累与亏缺的节律性变化。与之相应出现根系还原力的降低与升高的节律性变化,但地上部总铁含量和新叶叶绿素含量均无变化。说明了根系质外体铁库的利用,维持了大豆正常生长需铁。2、对缺铁植株脉冲供铁后,大豆根系质外体铁库首先出现明显积累,随后一直处于下降状态,与此同时根系还原力表现出相应的变化,前期下降,后期有波动。地上部总铁含量与新叶叶绿素含量的变化与前两者密切联系,出现升高、降低不同趋势的变化。     

供磷水平对间套作物根系酸性磷酸酶活性的影响

选择小麦／大豆和小麦／玉米２种模式,用盆栽法和根系栽培法研究了不同供磷水平对间套作物根系酸性磷酸酶（ＡＰase)活性的影响,试验得出：间套种植种植根系Ａpase的分泌量,套作大表兄弟经单作大豆平均提高３５．９％,而小麦和玉米在间套种植时也有不同程度地提高,说明间套种植有利于土壤有机磷向有效化方向转化,大豆不论单作还是间套作其根系ＡＰase都远高于相应小麦,而小麦又高于玉米,说明大豆利用土壤的潜在的能力大于小麦,而小麦又高于玉米,可见,禾谷类的小麦与大豆间套后不但能改善小麦的氮素营养状况还使磷素营养也得以好转。     

玉米/花生混作改善花生铁营养对花生根瘤碳氮代谢及固氮的影响

研究了石灰性土壤上玉米 (Zea mays L.) /花生 (Arachishypogaea L.)混作改善花生铁营养对花生光合速率、光合产物的运输、花生各部位糖类含量、固氮酶活性以及根瘤内碳氮代谢及其有关酶活性的影响。结果表明 ,玉米 /花生混作改善花生铁营养能够明显增强固氮酶活性 ,进而增加了间作花生根瘤氨基酸的含量 ,这主要是由于玉米 /花生混作改善花生铁营养促进了花生光合作用 ,提高光合产物数量 ,增加光合产物由地上部向地下部的运输 ,但是处理间花生根瘤蔗糖和可溶性糖含量变化不大 ,单作花生根瘤还积累较多淀粉 ,说明不是光合产物的供应导致了花生固氮活性的差异。玉米 /花生混作对花生根瘤碳水化合物代谢水平影响较大 ,混作花生根瘤异柠檬酸脱氢酶 (IDH)、苹果酸脱氢酶 (MDH)、琥珀酸脱氢酶活性明显高于单作 ,而磷酸烯醇丙酮酸羧激 (PEPCK)活性低于单作花生 ,表明混作花生根瘤内三羧酸循环代谢水平较高 ,形成类菌体直接吸收利用的能量物质苹果酸和琥珀酸多 ,能够满足类菌体的固氮需求 ,因此 ,玉米 /花生混作改善花生铁营养增强根瘤碳水化合物代谢水平是提高花生固氮作用的重要原因之一     

Effect of peanut mixed cropping with gramineous species on micronutrient concentrations and iron chlorosis of peanut plants grown in a calcareous soil

To gain a better understanding of the mechanisms of improvement of iron nutrition of peanut (Arachis hypogaea L.) intercropped with maize (Zea mays L.) in calcareous soil, both greenhouse and field experiments were conducted to investigate the rhizosphere (phytosiderophores) effects from maize, barley, oats and wheat with different phytosiderophores release rates on iron nutrition and other micronutrients in calcareous soil. Six cropping treatments were examined in a greenhouse experiment: peanut grown separately in monoculture, normal peanut/maize intercropping (two genotypes: Danyu13, Zhongdan12), peanut/barley intercropping, peanut/oats intercropping, and peanut/wheat intercropping. Additionally, we investigated in a field experiment the same five cropping systems as the greenhouse experiment (maize/peanut intercropping not including Zhongdan12). Our results show that the chlorophyll and active Fe concentrations in the young leaves of the peanut in the intercropping system with different gramineous species were much higher than those of the peanut in monoculture. In greenhouse conditions, the Fe concentration in the shoots of peanut plants grown in the intercropping systems of two maize genotypes separately were 1.40–1.44, 1.47–1.64 and 1.15–1.42 times higher respectively than those of peanut plants grown in monocropping at 55, 60 and 70 days. In particular, the Fe concentration in shoots of peanut plants grown in the intercropping systems of barley, oats and wheat were not only higher than those in monocropping but also higher than those in peanut intercropped cropping with maize. In the field, the concentration of Fe in shoot of intercropped peanut plants in rows 1–3 from gramineous species were significantly higher than in monocropping at the flowering stage. Simultaneously with iron nutrition variation in peanut, Zn and Cu concentrations of intercropped grown peanut increased significantly compared to those in monocropping in the greenhouse experiment, and different intercropping treatments generally increased the Zn and Cu content in the shoot of peanut in the field. Systemic mechanisms may be involved in adaptation to nutrient stresses at the whole plant level. The study suggests that a reasonable intercropping system of nutrient efficient species should be considered to prevent or mitigate iron and zinc deficiency of plants in agricultural practice.     

Studies on the improvement in iron nutrition of peanut by intercropping with maize on a calcareous soil

Both rhizobox and field experiments were conducted to investigate nutritional interactions between peanut and maize in intercropping systems for Fe acquistion. Field observations indicated that Fe deficiency chlorosis symptoms in peanut grown in monoculture were more severe and widespread compared to those of peanuts intercropped with maize. This indicated a marked improvement in the iron nutrition of peanut intercropped with maize in the field and was further studied. In experiments with rhizoboxes, roots of maize and peanut were either allowed to interact with each other or prevented from making contact by inserting a solid plate between the root systems of the two species. A field experiment for four cropping treatments were examined: peanut grown separately in monoculture, normal peanut/maize intercropping, peanut/maize intercropping with solid plates between the root systems of the two crop species and peanut/maize intercropping with 30 μm nylon nets between the root systems. The results show that the chlorophyll and HCl-extractable Fe concentrations in young leaves of peanut in the intercropping system with unrestricted interactions of the roots of both plant species were much higher than those of peanut in monoculture. In the nylon mesh treatment, the beneficial effects of the maize extended to row 3. The improvement of Fe nutrition in the intercropping system got reduced but not diminished completely in the treatment with nylon net. It is suggested that the improvement in the Fe nutrition of peanut intercropped with maize was mainly caused by rhizosphere interactions between peanut and maize. This revised version was published online in June 2006 with corrections to the Cover Date.     

Using competitive and facilitative interactions in intercropping systems enhances crop productivity and nutrient-use efficiency

This paper reviews recent research on the processes involved in the yield advantage in wheat (Triticum aestivum L.)/maize (Zea mays L.), wheat/soybean [Glycine max (L.) Merr.], faba bean (Vicia faba L.)/maize, peanut (Arachis hypogaea L.)/maize and water convolvulus (Ipomoea aquatica Forsk.)/maize intercropping. In wheat/maize and wheat/soybean intercropping systems, a significant yield increase of intercropped wheat over sole wheat was observed, which resulted from positive effects of the border row and inner rows of intercropped wheat. The border row effect was due to interspecific competition for nutrients as wheat had a higher competitive ability than either maize or soybean had. There was also compensatory growth, or a recovery process, of subordinate species such as maize and soybean, offsetting the impairment of early growth of the subordinate species. Finally, both dominant and subordinate species in intercropping obtain higher yields than that in corresponding sole wheat, maize or soybean. We summarized these processes as the `competition-recovery production principle'. We observed interspecific facilitation, where maize improves iron nutrition in intercropped peanut, faba bean enhances nitrogen and phosphorus uptake by intercropped maize, and chickpea facilitates P uptake by associated wheat from phytate-P. Furthermore, intercropping reduced the nitrate content in the soil profile as intercropping uses soil nutrients more efficiently than sole cropping.     

氮素形态和铁营养对玉米苗期生长及体内铁分布的影响

以玉米(Zea mays)品种‘豫玉-22’为材料,采用营养液培养方法,研究了低铁和正常供铁条件下供应不同形态氮素对玉米苗期生长及体内铁分布的影响。结果表明:(1)与低铁介质相比,常铁介质增加了各氮素处理玉米幼苗的株高、地上部干重、全株干重,降低了根冠比,其中硝态氮处理表现得尤其突出;与供应硝态氮(NO3--N)相比,增施铵态氮(1/2 NO3--N 1/2 NH4 -N,NH4 -N)能明显促进低铁介质中玉米生长,但在常铁介质下作用不明显。(2)相比于低铁介质,正常供铁显著提高了相应处理玉米新叶叶绿素含量及净光合速率;2种供铁介质中,NH4 -N处理的新叶叶绿素含量以及净光合速率均高于其它氮素处理。(3)相比于低铁介质,正常供铁处理总体上增加了玉米各部分活性铁含量和全铁含量,对NO3--N处理的新叶活性铁含量增加尤其明显;2种供铁介质中,NH4 -N均有利于提高新叶活性铁含量和植株地上部全铁含量。(4)玉米新叶活性铁含量不仅与其叶绿素含量显著正相关(r=0.979**),也与叶片净光合速率显著正相关(r=0.950**)。研究发现,供铁状况显著影响玉米新叶的叶绿素含量及其净光合速率且与供氮形态存在互作;供应铵态氮有利于提高缺铁条件下玉米新叶活性铁含量,增强玉米植株的光合能力,进而促进其正常生长。     

AhNRAMP1 iron transporter is involved in iron acquisition in peanut

Peanut/maize intercropping is a sustainable and effective agroecosystem to alleviate iron-deficiency chlorosis. Using suppression subtractive hybridization from the roots of intercropped and monocropped peanut which show different iron nutrition levels, a peanut gene, AhNRAMP1, which belongs to divalent metal transporters of the natural resistance-associated macrophage protein (NRAMP) gene family was isolated. Yeast complementation assays suggested that AhNRAMP1 encodes a functional iron transporter. Moreover, the mRNA level of AhNRAMP1 was obviously induced by iron deficiency in both roots and leaves. Transient expression, laser microdissection, and in situ hybridization analyses revealed that AhNRAMP1 was mainly localized on the plasma membrane of the epidermis of peanut roots. Induced expression of AhNRAMP1 in tobacco conferred enhanced tolerance to iron deprivation. These results suggest that the AhNRAMP1 is possibly involved in iron acquisition in peanut plants.     

Molecular evidence for phytosiderophore‐induced improvement of iron nutrition of peanut intercropped with maize in calcareous soil

Peanut/maize intercropping is a sustainable and effective agroecosystem that evidently enhances the Fe nutrition of peanuts in calcareous soils. So far, the mechanism involved in this process has not been elucidated. In this study, we unravel the effects of phytosiderophores in improving Fe nutrition of intercropped peanuts in peanut/maize intercropping. The maize ys3 mutant, which cannot release phytosiderophores, did not improve Fe nutrition of peanut, whereas the maize ys1 mutant, which can release phytosiderophores, prevented Fe deficiency, indicating an important role of phytosiderophores in improving the Fe nutrition of intercropped peanut. Hydroponic experiments were performed to simplify the intercropping system, which revealed that phytosiderophores released by Fe‐deficient wheat promoted Fe acquisition in nearby peanuts and thus improved their Fe nutrition. Moreover, the phytosiderophore deoxymugineic acid (DMA) was detected in the roots of intercropped peanuts. The yellow stripe1‐like (YSL) family of genes, which are homologous to maize yellow stripe 1 (ZmYS1), were identified in peanut roots. Further characterization indicated that among five AhYSL genes, AhYSL1, which was localized in the epidermis of peanut roots, transported Fe(III)–DMA. These results imply that in alkaline soil, Fe(III)–DMA dissolved by maize might be absorbed directly by neighbouring peanuts in the peanut/maize intercropping system.     

Peanut/maize intercropping induced changes in rhizosphere and nutrient concentrations in shoots.

A greenhouse study was conducted to investigate the rhizosphere effects on iron (Fe), phosphorus (P), nitrogen (N), potassium (K), calcium (Ca), zinc (Zn), and manganese (Mn) nutrition in peanut plants (Arachis hypogaea L.) by intercropping them with maize (Zea mays L.). In addition, we studied the release of phytosiderophores and the ferric reductase activity of roots, pH and acid phosphatases in the rhizosphere and bulk soil, and the secretion of acid phosphatases in roots. Our results revealed that shoot yields of peanut and maize plants were decreased by intercropping the plants, as compared to monocultured plants. Growing peanut plants in a mixture with maize, enhanced the shoot concentrations of Fe and Zn nearly 2.5-fold in peanut, while the Mn concentrations of peanut were little affected by intercropping. In the case of maize, the shoot concentrations of Fe, Zn and Mn were not significantly affected by intercropping with peanut. Intercropping also improved the shoot K concentration of peanut and maize, while it negatively affected the Ca concentration. In the intercropping of peanut/maize, the acid phosphatase activity of the rhizosphere and bulk soil and root secreted acid phosphatases were significantly higher than that of monocultured peanut and maize. In accordance, the shoot P concentrations of peanut and maize plants were much higher when they were intercropped with peanut or maize, respectively. The rhizosphere and bulk soil pH values were not clearly affected by different cropping systems. When compared to their monoculture treatments, the secretion of phytosiderophore from roots and the root ferric reducing capacity of the roots were either not affected or increased by 2-fold by the intercropping, respectively. The results indicate the importance of intercropping systems as a promising management practice to alleviate Fe deficiency stress. Intercropping also contributes to better nutrition of plants with Zn, P and K, most probably by affecting biological and chemical process in the rhizosphere.