Growth, P uptake and rhizosphere properties of intercropped wheat and chickpea in soil amended with iron phosphate or phytate

Intercropping has been shown to increase total yield and nutrient uptake compared to monocropping. However, depending on crop combinations, one crop may dominate and decrease the growth of the other. Interactions in the soil, especially in the rhizosphere, may be important in the interactions between intercropped plant genotypes. To assess the role of the rhizosphere interactions, we intercropped a P-inefficient wheat genotype (Janz) with either the P-efficient wheat genotype (Goldmark) or chickpea in a soil with low P availability amended with 100 mg P kg⁻¹ as FePO₄ (FeP) or phytate. The plants were grown for 10 weeks in pots where the roots of the genotypes could intermingle (no barrier, NB), were separated by a 30 μm mesh (mesh barrier, MB), preventing direct root contact but allowing exchange of diffusible compounds and microorganisms, or were completely separated by a solid barrier (SB). When supplied with FeP, Janz intercropped with chickpea had higher shoot and grain dry weight (dw) and greater plant P uptake in NB and MB than in SB. Contact with roots of Janz increased shoot, grain and root dw, root length, shoot P concentration and shoot P uptake of chickpea compared to SB. Root contact between the two wheat genotypes, Janz and Goldmark, had no effect on growth and P uptake of Janz. Shoot and total P uptake by Goldmark were significantly increased in NB compared to MB or SB. In both crop combinations, root contact significantly increased total plant dw and P uptake per pot. Plant growth and P uptake were lower with phytate and not significantly affected by barrier treatment. Differences in microbial P, available P and phosphatase activity in the rhizosphere among genotypes and barrier treatments were generally small. Root contact changed microbial community structure (assessed by fatty acid methyl ester (FAME) analysis) and all crops had similar rhizosphere microbial community structure when their roots intermingled.     

Phosphorus uptake and rhizosphere properties of intercropped and monocropped maize, faba bean, and white lupin in acidic soil

Little information is available on phosphorus (P) uptake and rhizosphere processes in maize (Zea mays L.), faba bean (Vicia faba L.), and white lupin (Lupinus albus L.) when intercropped or grown alone in acidic soil. We studied P uptake and soil pH, carboxylate concentration, and microbial community structure in the rhizosphere of maize, faba bean, and white lupin in an acidic soil with 0–250 mg P (kg⁻¹ soil) as KH₂PO₄ (KP) or FePO₄ (FeP) with species grown alone or intercropped. All plant species increased the pH compared to unplanted control, particularly faba bean. High KP supply (>100 mg P kg⁻¹) significantly increased carboxylate concentration in the rhizosphere of maize. The carboxylate composition of the rhizosphere soil of maize and white lupin was significantly affected by P form (KP or FeP), whereas, this was not the case for faba bean. In maize, the carboxylate composition of the rhizosphere soil differed significantly between intercropping and monocropping. Yield and P uptake were similar in monocropping and intercropping. Monocropped faba bean had a greater concentration of phospholipid fatty acids in the rhizosphere than that in intercropping. Intercropping changed the microbial community structure in faba bean but not in the other corps. The results show that P supply and P form, as well as intercropping can affect carboxylate concentration and microbial community composition in the rhizosphere, but that the effect is plant species-specific. In contrast to previous studies in alkaline soils, intercropping of maize with legumes did not result in increased maize growth suggesting that the legumes did not increase P availability to maize in this acidic soil.     

Brassica genotypes differ in growth, phosphorus uptake and rhizosphere properties under P-limiting conditions

Compared to other crops, Brassicas are generally considered to grow well in soils with low P availability, however, little is known about genotypic differences within Brassicas in this respect. To assess the role of rhizosphere properties in growth and P uptake by Brassicas, three Brassica genotypes (mustard, Brassica juncea cv Chinese greens and canola, Brassica napus cvs Drum and Outback) were grown in an acidic soil with low P availability at two treatments of added P: 25 and 100 mg P kg⁻¹ as FePO₄ (P25 and P100). The plants were harvested at the 6-leaf stage, at flowering and at maturity. Shoot and root dry weight (dry weight) and root length increased with time and were lower in P25 than in P100. In P25, shoot dry weight was lowest in Outback and highest in Chinese greens. In the P100 treatment, Chinese greens had a higher shoot dry weight than the two canola cultivars. Chinese greens had a lower root dry weight and root length at flowering and maturity than the canola genotypes in both P treatments. Irrespective of P treatment, shoot P concentration was lower in Chinese greens than in the two canola genotypes. Specific P uptake (μg P m⁻¹ root length) decreased with time. In P25, Chinese greens had the lowest specific P uptake at the 6-leaf stage but it was higher than in the two canola genotypes at flowering and maturity. In P100, Outback had the lowest specific P uptake. Available P in the rhizosphere (resin P) decreased over time with the greatest decrease from the 6-leaf stage to flowering. In P25, resin P in the rhizosphere was greatest in Chinese greens at the 6-leaf stage and flowering and smallest in Outback at flowering. Microbial P and acid phosphatase activity changed little over time, were not affected by P treatment and there were only small differences between the genotypes. The rhizosphere microbial community composition [assessed by fatty acid methyl ester (FAME) analysis] of Outback and Chinese greens differed from that of the other two genotypes at the 6-leaf stage and flowering, respectively. At maturity, all three genotypes had distinct microbial communities. Plant traits such as production of high biomass at low shoot P concentrations as well as the capacity to maintain high P availability in the rhizosphere by P mobilisation can explain the observed differences in plant growth and P uptake among the Brassica genotypes.     

Growth,P uptake and rhizosphere properties of wheat and canola genotypes in an alkaline soil with low P availability

The aim of the present study was to assess the role of soil type on growth, P uptake and rhizosphere properties of wheat and canola genotypes in an alkaline soil with low P availability. Two wheat (Goldmark and Janz) and two canola genotypes (Drum and Outback) were grown in a calcareous soil (pH 8.5) at two P levels [no P addition (0P) or addition of 200 mg kg⁻¹ P as Ca₃(PO₄)₂ (200P)] and harvested at flowering or maturity. Shoot and root dry weight, root length and shoot P content were greater in the two canola genotypes than in wheat. There were no consistent differences in available P, microbial P and phosphatase activity in the rhizosphere of the different genotypes. Shoot P content was significantly positively correlated with root length, pH and phosphatase activity in the rhizosphere. The microbial community composition, assessed by fatty acid methylester analysis, of the canola genotypes differed strongly from that of the wheat genotypes. The weight percentage bacterial fatty acids, the bacteria/fungi (b/f) ratio and the diversity of fatty acids were greater in the rhizosphere of the canolas than in the rhizosphere of the wheat genotypes. In contrast to the earlier studies in an acidic soil, only small differences in growth and P uptake between the genotypes of one crop were detected in the alkaline soil used here. The results confirmed the importance of root length for P uptake in soils with low P availability and suggest that the rhizosphere microbial community composition may play a role in the better growth of the canola compared to the wheat genotypes.     

Intercropping promotes the ability of durum wheat and chickpea to increase rhizosphere phosphorus availability in a low P soil

Cereal–legume intercropping can promote plant growth (i.e. facilitation) through an increase in the amount of phosphorus (P) taken up, especially in low P soils. The aim of this study was to test the hypothesis that these positive interactions are supported by rhizosphere processes that increase P availability, such as root-induced pH changes. In neutral and alkaline soils legumes are assumed to increase inorganic P availability by rhizosphere acidification due to N₂ fixation which benefit to the intercropped cereal. Growth, P uptake, changes in inorganic P availability and pH in the rhizosphere of intercropped species were thus investigated in a greenhouse pot experiment with durum wheat and chickpea either grown alone or intercropped. We used a neutral soil from a P fertilizer long-term field trial exhibiting either low (−P) or high (+P) P availability. Phosphorus availability was increased in the rhizosphere of both species, especially when intercropped in −P. Such increase was associated with alkalization. Rhizosphere pH changes could not fully explain the observed changes of P availability though. Low rates of N₂ fixation may explain why no rhizosphere acidification was observed. Increases in P availability did not lead to enhanced P uptake but growth promotion was observed for durum wheat intercropped with chickpea in −P soil. Our hypothesis of an increase in inorganic P availability in intercropping as a consequence of root-induced acidification by the legume was not validated, and we suggested that root-induced alkalization was involved instead, as well as other root-induced processes. Thus, the cereal through rhizosphere alkalization may also enhance P uptake and growth of the intercropped legume. Facilitation can thus occur in both ways.     

小麦蚕豆间作施氮对小麦氮素吸收、累积的影响

田间试验研究了小麦蚕豆间作及4种施氮水平(0、90 kg·hm^-2、180 kg·hm^-2和270 kg·hm^-2)对小麦植株体内氮含量、小麦地上部氮素累积及氮素养分吸收速率的影响。结果表明: 间作显著增加了小麦地上部植株的氮含量, 与单作相比, 分蘖期、拔节期、抽穗期和成熟期不同施氮处理间作小麦植株的氮含量平均比单作提高20.0%、21.9%、21.4%和17.1%; 抽穗期和成熟期间作小麦叶、茎和穗中的氮含量均高于单作; 间作显著提高了小麦植株的氮素累积量和氮素吸收速率, 与单作相比整个生育期间作小麦氮素累积量增幅为15.5%~30.4%。无论单作还是间作, 小麦植株氮含量和氮素累积量随氮肥用量的增加而增加, 施氮对单作小麦植株氮含量、氮素累积量和氮素吸收速率的影响大于间作, 随着氮肥用量的增加, 间作优势逐渐减弱; 单作小麦植株的氮素吸收速率随氮肥用量的增加而增加, 间作小麦植株的氮素吸收速率随氮肥用量的增加呈先增后降的趋势。本研究表明, 间作和施氮促进了小麦对氮素的吸收利用, 间作优势与施氮水平密切相关, 间作体系中氮素养分的合理投入是发挥间作优势的关键。     

Influences of intercropping and nitrogen supply on flavonoid exudation in wheat roots

Abstract

Soil and hydroponic experiments were carried out to examine the influences of intercropping and nitrogen supply on flavonoid exudation in wheat roots. Both experiments comprising three cropping patterns (wheat intercropped with faba bean, monocropped wheat, and monocropped faba bean) and three N supply levels (deficient, adequate, and excessive) with three replicates in a randomized complete block design. Across two experiments, intercropping increased but N fertilization decreased flavonoids of wheat roots frequently. Intercropping variably increased secretion of naringenin from 0.5 to 1.9 folds (P?<?0.5) in wheat roots at all three N levels, but rarely increased secretion of genistein and hesperetin in wheat at the deficient N level. Intercropped wheat secreted more flavonoids than monocropped wheat at its tillering (60^th d) and flowering (95^th d) stages; after the flowering stage, however, the differences between intercropping and monocropping were not significant at any N level. Secretion of flavonoids in wheat roots decreased with increased N supply. Interspecies and N supply altered the contents and proportions of flavonoids in wheat root exudations under wheat and faba bean intercropping. These results indicate facilitative root–root interactions and provide insight into cereal promote nodule of legume in intercropping system.     

小麦蚕豆间作对红壤有效磷的影响及其与根际pH值的关系

在云南红壤上采用田间小区试验,通过测定分蘖～拔节期、孕穗～抽穗期、灌浆～乳熟期不同土层深度小麦根际土壤有效磷(available phosphorus)含量和根际pH值,比较研究了小麦蚕豆间作对小麦根际土壤有效磷含量和pH值的影响,探讨了间作小麦根际pH与根际土壤有效磷之间的相互作用.结果表明,与小麦单作相比,小麦蚕豆间作显著地促进了小麦产量的提高.同时,小麦蚕豆间作促进了小麦根际土壤有效磷含量的提高,分蘖～拔节期、孕穗～抽穗期0-10 cm、10-20 cm土层单、间作差异显著;间作显著降低了分蘖～拔节期10-20 cm土层、孕穗～抽穗期0-10 cm、10-20 cm、20-30 cm土层小麦根际土壤pH.分蘖～拔节期、灌浆～乳熟期,单、间作小麦根际土壤有效磷含量与根际pH呈负相关关系.试验表明,在红壤上间作小麦根际土壤有效磷含量的提高与间作降低根际pH有密切关系.     

间作小麦、蚕豆的产量和竞争力对供水量和化感物质的响应

为了寻求解决间作群体受化感物质抑制作用的理论依据, 本研究通过盆栽试验, 探讨了不同供水水平下(田间持水量的45%、60%和75%), 小麦根系分泌物间甲酚对单作小麦、单作蚕豆、小麦间作蚕豆生物产量、经济产量和两种作物共生期间竞争力的影响。结果表明: 60%和75%供水水平下, 间作小麦生物产量和经济产量较单作显著提高, 45%供水水平下间作小麦经济产量低于单作; 不同供水水平下, 间作蚕豆的生物产量与相应供水水平的单作相比, 增加显著。间甲酚对小麦、蚕豆的产量均具有化感负效应, 间作具有一定弱化间甲酚对蚕豆化感负效应的作用。45%、60%和75%供水水平下, 间甲酚使间作小麦相对于蚕豆的竞争力较无间甲酚处理时分别提高24.82%、19.26%和79.30%; 增加供水可弱化间作小麦的相对竞争力, 无间甲酚和间甲酚处理间作小麦的相对竞争力在75%供水水平下较45%供水水平分别降低158.08%和79.67%。     

不同磷水平下小麦蚕豆间作对根际有效磷及磷吸收的影响

【目的】探明不同磷水平下小麦–蚕豆间作对根际有效磷含量及作物磷吸收量的影响,提高磷肥利用率。【方法】2015—2016和2016—2017两季田间试验在云南农业大学试验基地耕作红壤上进行,供试小麦品种为云麦-52,蚕豆品种为玉溪大粒豆。设施P2O5 0 (P0)、45 (P45)和90 kg/hm^2 (P90)三个水平,和单作(M,包括小麦单作MW和蚕豆单作MF)和间作(I)两种种植模式。每季在小麦分蘖期、拔节期、抽穗期、灌浆期和成熟期,蚕豆分枝期、开花期、结荚期、籽粒膨大期、收获期采取根际土样测定有效磷含量。在小麦蚕豆收获期测定单、间作小麦、蚕豆产量,并测定作物地上部磷含量。计算土地当量比(LER)来衡量间作优势,并用磷肥农学利用率来反映磷肥的吸收效率。【结果】与单作相比,在P0、P45、P90水平下,2016年间作种植显著提高了小麦籽粒产量12.5%、21.7%和17.3%,2017年间作蚕豆产量较单作分别降低了16.8%、11.7%和8.2%。三个磷水平下,小麦–蚕豆间作具有产量优势,土地当量比(LER)为0.95~1.18。与常规施磷水平(P90)下的单作相比,小麦–蚕豆间作条件下,磷肥减施1/2 (P45)并未降低小麦和蚕豆产量。间作种植对小麦根际有效磷含量无显著影响(除2016年成熟期外),但2017年,在蚕豆分枝期、开花期、结荚期,间作则分别降低蚕豆根际有效磷含量20.8%、44.5%和18%。与P90单作相比,间作P45处理几乎不会降低小麦、蚕豆根际有效磷含量。小麦、蚕豆磷吸收量主要受磷水平的调控,种植模式对小麦和蚕豆磷的吸收量及磷肥农学利用率均没有影响。【结论】在本试验条件下,小麦–蚕豆间作提高了小麦籽粒产量,降低了蚕豆产量;间作种植主要是改变了蚕豆生育前期根际有效磷含量,但对作物的磷吸收量没有影响。小麦–蚕豆间作具有减施磷肥、维持作物产量和根际土壤有效磷的潜力。     

间作对分蘖洋葱与番茄根际土壤磷转化强度及磷细菌群落结构的影响

【目的】间作分蘖洋葱能缓解番茄连作障碍,提高番茄养分吸收。本试验主要研究间作后分蘖洋葱和番茄根际土壤中磷细菌群落结构及活性的变化,以揭示该间作体系磷细菌改善作物磷营养的生物学机制。【方法】盆栽试验选用茄科连作8年的设施土壤,番茄品种为‘东农708’,分蘖洋葱品种为‘五常红旗社’。设番茄单作、分蘖洋葱单作、分蘖洋葱与番茄间作及无苗对照等4个处理。在定植23 d、30 d和37 d取样,测定植株干重及磷浓度。同时用抖根法取番茄和分蘖洋葱根际土,测定土壤中磷细菌数量及磷细菌的转化强度。采用PCRDGGE方法测定磷细菌的群落结构。【结果】1)间作后,番茄地上和地下干重增加,分蘖洋葱地上和地下干重减少,在37 d差异达到显著水平。2)间作后,番茄根际土壤中无机磷和有机磷细菌的数量增加,在23 d和37d差异达到显著水平;分蘖洋葱根际土壤中无机磷细菌数量在23 d时显著降低,有机磷细菌数量在间作37 d时显著升高。间作期间分蘖洋葱和番茄根际土壤中无机磷和有机磷细菌的数量均显著高于无苗对照。间作23d时,番茄根际土壤中无机磷和有机磷细菌的转化强度均显著升高,分蘖洋葱根际土壤中无机磷和有机磷细菌的转化强度均显著降低;而间作37 d时,分蘖洋葱根际土壤中无机磷和有机磷细菌的转化强度均显著升高,且间作期间番茄和分蘖洋葱根际土壤中无机磷和有机磷细菌的转化强度均显著高于无苗对照。3)间作37 d番茄和分蘖洋葱根际土壤pH显著升高,EC值显著降低,且各处理土壤pH均高于无苗对照,土壤EC值均低于无苗对照。间作30 d时番茄根际土壤中速效磷含量显著升高,间作37 d时显著低于单作。间作期间分蘖洋葱根际土壤速效磷含量变化不显著,番茄根际土壤速效磷含量均低于无苗对照,而分蘖洋葱均高于无苗对照。间作后番茄植株磷浓度和磷吸收量显著高于单作处理,分蘖洋葱植株磷浓度显著高于单作处理,而磷吸收量显著低于单作处理。4)间作后番茄根际土壤中无机磷细菌的条带数、香农多样性指数和均匀度指数显著高于其单作处理,而间作分蘖洋葱显著低于其单作处理。间作后番茄根际土壤中有机磷细菌的条带数、香农多样性指数和均匀度指数前期显著高于单作番茄,后期显著低于单作。而间作分蘖洋葱与对应单作比较差异不显著。【结论】间作分蘖洋葱通过改变番茄根际土壤中磷细菌数量和群落结构,提高了磷细菌的转化强度,增加了番茄根际土壤中速效磷含量,促进植株磷浓度和磷吸收量增加,改善了番茄磷营养。     

施磷水平对玉米大豆间作系统氮素吸收与分配的影响

  【目的】  研究施磷对玉米大豆间作系统氮素吸收、分配和间作优势的影响,为优化玉米与大豆间作系统氮、磷养分管理提供参考。  【方法】  两年盆栽试验设置3种种植方式:玉米单作、大豆单作、玉米与大豆间作;4个P₂O₅施用水平:0、50、100、150 mg/kg,分别以P0、P50、P100和P150表示。在玉米小喇叭口期、大喇叭口期、孕穗期、成熟期及大豆分枝期、开花期、结荚期、成熟期进行采样,分析玉米、大豆各器官氮素吸收、分配以及氮吸收间作优势对施磷的响应。  【结果】  与单作相比,在P0、P50、P100和P150水平下,2019年间作玉米和大豆籽粒生物量分别显著提高了38.2%～111.8%和22.2%～31.4%,2020年分别显著提高了38.2%～121.1%和13.0%～31.1%。在4个磷水平下,玉米大豆间作土地当量比 (LER) 为1.31～1.72。与P100水平下单作处理相比,在磷肥减施1/2 (P50水平) 条件下,玉米大豆间作并未降低玉米和大豆的籽粒生物量。间作种植提高了玉米与大豆叶、茎、根与籽粒等各器官氮素吸收量,显著提高了间作体系氮素吸收量,并促进了氮素向玉米籽粒的分配,却降低了氮素向大豆籽粒的分配。与P0水平相比,施磷进一步提高了间作体系玉米与大豆各器官的氮素吸收量,提高了间作体系氮吸收量与氮吸收间作优势,并促进了氮素向玉米籽粒的分配。与P100水平的单作相比,间作P50水平不会降低玉米与大豆植株的氮素吸收量与利用率。  【结论】  玉米与大豆间作具有明显的产量优势,土地当量比介于1.31～1.72之间。施磷可显著提高间作玉米和大豆的氮吸收量,并促进氮素向玉米籽粒的分配,具有明显的氮吸收间作优势。施磷水平调节玉米和大豆对养分的竞争能力,适宜的磷肥水平可缓解二者之间对氮素营养的竞争,获得更高的氮肥利用率。     

Comparison of Rhizosphere Impacts of Wheat (Triticum aestivum L.) Genotypes Differing in Phosphorus Efficiency on Acidic and Alkaline Soils

A glasshouse study was conducted to compare the rhizosphere characteristics of two wheat genotypes, Xiaoyan54 (XY54) and Jing411 (J411) on two soils. The results showed that supplying phosphorus (P) increased the biomass and P content of two wheat lines significantly on alkaline soil, but P fertilization altered their biomass and P content on acidic soil only slightly. XY54 decreased rhizosphere pH more significantly than J411 on Fluvo-aquic soil without P addition, but similar acidity ability was shown when P applied. On red soil, two wheat genotypes showed similar rhizosphere pH. Two wheat lines showed similar rhizoshphere phosphatase activity on alkaline soil, whereas XY54 demonstrated greater rhizoshphere phosphatase activity than J411 on acidic soil. Rhizoshphere phosphatase activities of two wheat lines on acidic soil were greater than alkaline soil. Therefore, stronger acidity on alkaline soil and greater phosphatase activity on acidic soil are principal rhizosphere mechanisms for XY54 to adapt to low-P soils.     

小麦蚕豆间作体系氮素吸收累积动态及其种间氮素竞争关系

  【目的】  通过研究小麦//蚕豆间作地上部的氮含量和吸收量，明确不同氮水平下小麦//蚕豆间作的氮吸收累积特征，解析间作小麦和蚕豆种间氮素竞争关系。  【方法】  田间试验采用两因素随机区组试验设计，设置3个种植模式 (单作小麦，单作蚕豆及小麦//蚕豆间作) 及4个氮水平 (N0，N1，N2，N3)，其中小麦的4个施氮量依次为0、90、180、270 kg/hm2，蚕豆的4个施氮量依次为0、45、90、135 kg/hm2。测定了单间作小麦和蚕豆的产量、地上部氮累积含量，利用Logistic模型模拟小麦蚕豆的氮吸收关键参数及氮吸收动态，分析了间作小麦和蚕豆的氮素竞争关系。  【结果】  小麦//蚕豆间作整体平均提高小麦产量33.4% (除N3外)、降低蚕豆产量20.7%，N0和N1水平下，间作具有显著产量优势。通过Logistic模型分析发现，间作条件下小麦的氮吸收高峰比蚕豆晚12～19天。4个氮水平下，间作主要提高了小麦最大氮累积量 (A)、最大氮吸收速率 (R_max) 和初始氮吸收速率 (r)，却降低了蚕豆的A、达到最大氮吸收速率所需的时间 (T_max) 和R_max。在营养生长阶段，小麦的氮素竞争力低于蚕豆，施氮可提高小麦的氮素吸收量。从施氮水平和种植模式共同作用角度分析，N0、N1和N2水平下，间作分别提高小麦的R_max 34.1%、44.6%和21.0%。因此，当小麦达到氮吸收高峰后，间作分别提高小麦氮吸收速率和氮素累积量15.1%～48.4%和9.2%～28.9%，却降低蚕豆氮吸收速率和氮素累积量7.3%～28.4%和7.9%～14.0%。此时，间作小麦氮素竞争力大于蚕豆，在N1水平下小麦的氮素竞争力最强。  【结论】  小麦//蚕豆间作提高了小麦的初始及最大氮素吸收速率 (r和R_max)，提高了小麦生殖生长阶段的氮素吸收和累积，是间作小麦产量优势的基础。优化氮肥投入量，可调控小麦和蚕豆的种间竞争及互补关系，是小麦//蚕豆间作体系产量优势形成、氮素高效吸收利用的关键。     

Nodulation and root growth increase in lower soil layers of water‐limited faba bean intercropped with wheat

Below‐ground niche complementarity in legume–cereal intercrops may improve resource use efficiency and root adaptability to environmental constraints. However, the effect of water limitation on legume rooting and nodulation patterns in intercropping is poorly understood. To advance our knowledge of mechanisms involved in water‐limitation response, faba bean (Vicia faba L.) and wheat (Triticum aestivum L.) were grown as mono‐ and intercrops in soil‐filled plexiglass rhizoboxes under water sufficiency (80% of water‐holding capacity) and water limitation (30% of water‐holding capacity). We examined whether intercropping facilitates below‐ground niche complementarity under water limitation via interspecific root stratification coupled with modified nodulation patterns. While no significant treatment effects were measured in intercropped wheat growth parameters, water limitation induced a decrease in shoot and root biomass of monocropped wheat. Likewise, shoot biomass and height, and root length of monocropped faba bean significantly decreased under water limitation. Conversely, water limitation stimulated root biomass of intercropped faba bean in the lower soil layer (15–30 cm soil depth). Similarly, total nodule number of faba bean roots as well as nodule number in the lower soil layer increased under intercropping regardless of water availability. Under water limitation, intercropping also led to a significant increased nodule biomass (48%) in the lower soil layer as compared to monocropping. The enhanced nodulation in the lower soil layer and the associated increase in root and shoot growth provides evidence for a shift in niche occupancy when intercropped with wheat, which improves water‐limited faba bean performance.     

肉桂酸对蚕豆枯萎病发生的影响及间作缓解机制

采用盆栽试验,研究了肉桂酸不同浓度(C0(0.0 mg kg~(-1))、C1(14.0 mg kg~(-1))、C2(28.0 mg kg~(-1))和C3(56.0 mg kg~(-1)))处理对蚕豆枯萎病发生的影响及小麦与蚕豆间作对肉桂酸自毒效应的缓解机制。结果表明:(1)蚕豆单作条件下,肉桂酸处理显著降低了根系的过氧化物酶(POD)活性并增加了丙二醛(MDA)含量,导致根系脂质过氧化伤害加剧;肉桂酸处理降低了根际微生物的活性(AWCD值)、香农(Shannon)多样性指数(H)和丰富度指数(S)并改变了微生物群落结构;肉桂酸处理显著增加蚕豆根际土壤中镰刀菌数量,提高了枯萎病病情指数并降低根系干重。(2)肉桂酸胁迫下,与单作蚕豆相比,小麦与蚕豆间作提高了蚕豆根系的POD活性,降低了MDA含量,提高了根际微生物对碳源的利用能力及根际微生物的H和S,明显改变了根际微生物群落结构;间作显著降低了蚕豆根际土壤中镰刀菌数量及枯萎病病情指数,显著增加了蚕豆地上部干重和根系干重。表明小麦与蚕豆间作一方面提高蚕豆对枯萎病菌的生理抗性,另一方面有效调节根际微生物活性和多样性,从而缓解了肉桂酸引起的枯萎病危害,促进了蚕豆生长,但间作减轻枯萎病危害的效果受肉桂酸处理浓度的影响。因此,利用非寄主作物小麦的化感效应而采取的间作模式是缓解蚕豆自毒效应的有效措施。     

间作分蘖洋葱对番茄氮素吸收和根际土壤微生物多样性的影响

  【目的】  间作分蘖洋葱能缓解番茄连作障碍,提高番茄养分吸收。本研究通过解析间作分蘖洋葱条件下番茄根际土壤中氮吸收和微生物多样性的变化,旨在揭示间作对番茄氮营养改善的生物学机制。  【方法】  设计田间和盆栽两个试验,田间试验设番茄单作、分蘖洋葱(农安)与番茄间作和分蘖洋葱(五常)与番茄间作共3个处理,测定番茄的生长指标、氮吸收量及产量,阐明间作对番茄养分吸收、分配及产量的影响。盆栽试验设番茄单作、分蘖洋葱(五常)单作、分蘖洋葱与番茄间作及无苗对照等4个处理。对番茄及分蘖洋葱的根际土壤中铵态氮、硝态氮含量及土壤酶活性测定,并采用Miseq高通量测序技术分析土壤细菌和真菌多样性变化,旨在阐明间作对根际土壤养分环境的影响。  【结果】  1) 间作后,番茄株高显著增加,番茄产量提高了8.49%～16.92%。2) 间作分蘖洋葱两品种番茄各测定指标表现为相似的变化规律。间作60天,番茄干重显著增加,间作后番茄干物质向根分配指数降低,而向地上分配指数增加,其中向茎叶分配指数降低,而向果分配指数增加。间作90天,均显著提高了氮养分向根和茎分配,而降低了氮养分向叶中分配。3) 间作37天后,番茄根际土壤中铵态氮含量显著增加,硝态氮含量显著降低,间作改变土壤铵态氮和硝态氮比例,促进了番茄的氮吸收。番茄根际土壤中脲酶和脱氢酶活性显著高于单作和无苗对照,间作分蘖洋葱根际土壤脱氢酶活性显著高于单作和无苗对照。4)间作分蘖洋葱处理提高了放线菌纲、拟杆菌纲 、黄杆菌纲、绿菌纲、绿弯菌纲、厌氧绳菌纲、异常球菌纲、芽孢杆菌纲、梭菌纲、柔膜菌纲、浮霉菌纲、α-变形菌纲、丰佑菌纲的丰度,其中间作分蘖洋葱提高了番茄根际土壤芽孢杆菌属(Bacillus)、假单胞菌属(Pseudomonas)和鞘氨醇单胞菌属(Sphingomonas)等细菌的相对丰度。间作提高了番茄根际土壤青霉菌属(Penicillium)、曲霉菌属(Aspergillus)和毛壳菌属(Chaetomium)等真菌的丰度,但却降低了散囊菌属(Eurotium)和梭孢壳属(Thielavia)的丰度。间作番茄根际土壤微生物菌群结构的改变可能是促进番茄氮养分吸收的关键因素之一。  【结论】  间作两种分蘖洋葱均增加了番茄株高和干重,间作提高了番茄的氮吸收量和产量,降低了氮养分向叶中分配,而升高了氮养分向根和花果中分配,提高氮的利用。同时,间作分蘖洋葱通过改变番茄根际土壤细菌和真菌菌群结构,改善了土壤氮有效性,促进了番茄的氮吸收,为番茄产量的提高奠定了营养基础。     

Intercropping with garlic alleviated continuous cropping obstacle of cucumber in plastic tunnel

Abstract

Continuous cropping obstacle is prevalent for protected cultivated cucumber in China. Intercropping garlic may effectively relieve this obstacle due to its allelopathic and antimicrobial effects. A two-growing season investigation was carried out during autumn 2009 to spring 2010 in plastic tunnel to determine the effects of intercropped garlic and green garlic on the overall growth of cucumber and soil biological properties. Results showed that green garlic exhibited the inhibitory effect on the growth of cucumber in spring cultivation 2010. Garlic–cucumber intercropping system increased yield of cucumber differently depending on garlic cultivars, with only cv. G005 showing significant increase (13.4%). Intercropping systems were evaluated as a greater net benefit system as compared to monoculture cultivation. Populations of soil bacteria and actinomyces were stimulated, while fungi were inhibited under intercropping system. Activities of soil invertase, urease, and alkaline phosphatase were encouraged under intercropping system in spring cultivation 2010 compared with monoculture. The promotion effect of intercropped garlic on urease and alkaline phosphatase maintained till garlic harvest. These results suggest that intercropping system can improve soil biology environment and alleviate continuous cropping obstacle of cucumber at different levels.     

Effects of Nitrogen and Phosphorus Fertilizers and Intercropping on Uptake of Nitrogen and Phosphorus by Wheat,Maize, and Faba Bean

Abstract

One‐third of all the cultivated land area is used for multiple cropping and half of the total grain yield is produced with multiple cropping in China. There have been numerous studies on nutrient acquisition by crops in legume/non‐legume intercropping systems, but few on nutrient uptake in cereal/cereal intercropping. This paper describes a field experiment in which integrated wheat/maize and maize/faba bean systems were compared with sole wheat and sole faba bean cropping to assess the effects of intercropping on nutrient uptake by wheat, maize, and faba bean under various application rates of nitrogen (N) and phosphorous (P) fertilizers. Results show that both N and P fertilizers and intercropping enhanced N uptake by wheat, while only P fertilizer and intercropping increased P acquisition by wheat. The advantage of N uptake by border rows of wheat intercropped with maize declined with increasing N fertilizer application rate, but that of P acquisition was not affected by P fertilizer. The amounts of both N and P taken up by maize intercropped with faba bean were much higher than those by maize intercropped with wheat throughout the period of intercropping. Both fertilization and intercropping did not influence the N and P uptake by faba bean.     

间作小麦和接种AM真菌协同提高蚕豆抗枯萎病能力和根际微生物碳代谢活性

【目的】接种丛枝菌根 (arbuscular mycorrhizal,AM) 真菌和间作均是防治蚕豆枯萎病的有效方法,从土壤微生物学角度研究两者协同减轻蚕豆枯萎病的机理,对控制蚕豆枯萎病传播具有重要意义。【方法】利用盆栽试验方法,进行了间作和接种AM真菌摩西管柄囊霉 (Funneliformis mosseae,Fm) 和扭形球囊霉 (Glomus tortuosum,Gt) 试验。设蚕豆单作对照 (MF)、蚕豆小麦间作 (IF)、蚕豆单作接种Fm (MFFm)、蚕豆小麦间作接种Fm (IFFm)、蚕豆单作接种Gt (MFGt)、蚕豆小麦间作接种Gt (IFGt) 6个处理。于蚕豆开花期 (生长70天) 取土壤样品,测定蚕豆幼苗生长、枯萎病发生、根际镰刀菌数量和微生物碳代谢活性。【结果】间作显著增加蚕豆幼苗干重93.0%、降低蚕豆枯萎病病情指数71.4%,接菌显著增加蚕豆幼苗干重55.3%、降低病情指数76.6%,其中接种Fm真菌对蚕豆幼苗干重的影响更大,对病情指数的抑制效果更好。间作接菌显著增加蚕豆幼苗干重100%、降低病情指数89.8%。Biolog微平板测试结果显示,间作提高根际微生物碳代谢活性32.3%;接菌提高微生物活性85.4%;间作接菌提高微生物活性122%。主成分分析结果表明,间作和接菌均明显改变了根际微生物的群落结构,并主要改变了对碳水化合物类、氨基酸和羧酸类碳源的利用。相关性分析结果显示,枯萎病发病率和病情指数与根际镰刀菌数量呈极显著正相关关系,与AWCD值、Shannon多样性指数和丰富度指数均呈极显著负相关。【结论】蚕豆与小麦间作和接菌对抑制蚕豆枯萎病和促进蚕豆生长均具有积极效应,间作显著提高了AM真菌的定殖率,二者协同提高了根际微生物活性,改变了微生物群落结构,并抑制了病原菌增殖,进而控制蚕豆枯萎病发生。