玉米与籽粒苋不同种植模式下植物生长及Cd累积特征

为实现Cd污染农田边生产边修复的目标,采用田间原位修复的方式,将玉米与籽粒苋在Cd污染农田中以5种不同的间作模式种植: 交替宽窄行玉米宽行间作单行籽粒苋(T₁)、交替宽窄行玉米宽行间作双行籽粒苋(T₂)、等行距双行玉米间作单行籽粒苋(T₃)、等行距双行玉米间作双行籽粒苋(T₄)、玉米/籽粒苋等4行距间作(T₅),并以玉米(CK₁)和籽粒苋(CK₂)单作种植作为对照,探究不同间作结构配置对作物与超富集植物生长及Cd累积特征的影响.结果表明: 1)与CK₁相比,各间作模式单株玉米的籽粒产量呈增加趋势;T₁间作模式玉米的籽粒产量较CK₁增加10.5%,T₄和T₅间作模式玉米的籽粒产量较CK₁分别减少6.3%和5.4%,T₂和T₃间作模式基本稳产;间作籽粒苋地上部单株生物量及单位面积产量较CK₂分别显著减少69.5%～95.7%和83.9%～96.9%. 2)各间作模式玉米籽粒Cd含量较CK₁呈减少趋势,而间作籽粒苋Cd含量较CK₂呈增加趋势. 3)与CK₂相比,各间作模式籽粒苋的富集系数、转运系数、有效转运系数均呈增加趋势;间作籽粒苋地上部Cd的单株及单位面积提取量较CK₂分别显著减少40.4%～86.7%和70.4%～88.9%;各间作模式玉米与籽粒苋地上部Cd的单位面积提取总量高于单作玉米,但低于单作籽粒苋. 4)各间作模式玉米根际土有效态Cd含量及籽粒苋根际土总Cd、有效态Cd含量分别较单作玉米及单作籽粒苋呈增加趋势,但对非根际土没有显著影响.本研究中,T₁间作模式有利于玉米籽粒产量的提高,T₅间作模式有利于籽粒苋Cd提取量的最大化.     

Row Ratios of Intercropping Maize and Soybean Can Affect Agronomic Efficiency of the System and Subsequent Wheat

Intercropping is regarded as an important agricultural practice to improve crop production and environmental quality in the regions with intensive agricultural production, e.g., northern China. To optimize agronomic advantage of maize (Zea mays L.) and soybean (Glycine max L.) intercropping system compared to monoculture of maize, two sequential experiments were conducted. Experiment 1 was to screening the optimal cropping system in summer that had the highest yields and economic benefits, and Experiment 2 was to identify the optimum row ratio of the intercrops selected from Experiment 1. Results of Experiment 1 showed that maize intercropping with soybean (maize || soybean) was the optimal cropping system in summer. Compared to conventional monoculture of maize, maize || soybean had significant advantage in yield, economy, land utilization ratio and reducing soil nitrate nitrogen (N) accumulation, as well as better residual effect on the subsequent wheat (Triticum aestivum L.) crop. Experiment 2 showed that intercropping systems reduced use of N fertilizer per unit land area and increased relative biomass of intercropped maize, due to promoted photosynthetic efficiency of border rows and N utilization during symbiotic period. Intercropping advantage began to emerge at tasseling stage after N topdressing for maize. Among all treatments with different row ratios, alternating four maize rows with six soybean rows (4M:6S) had the largest land equivalent ratio (1.30), total N accumulation in crops (258 kg ha^-1), and economic benefit (3,408 USD ha^-1). Compared to maize monoculture, 4M:6S had significantly lower nitrate-N accumulation in soil both after harvest of maize and after harvest of the subsequent wheat, but it did not decrease yield of wheat. The most important advantage of 4M:6S was to increase biomass of intercropped maize and soybean, which further led to the increase of total N accumulation by crops as well as economic benefit. In conclusion, alternating four maize rows with six soybean rows was the optimum row ratio in maize || soybean system, though this needs to be further confirmed by pluri-annual trials.     

Incidence and severity of foliar diseases of sesame (Sesamum indicum L.) intercropped with maize (Zea mays L.)

This study evaluates the effects of different row arrangements on incidence and severity of Cercospora leaf spot (CLS) and Alternaria leaf blight (ALB) diseases and seed health of sesame intercropped with maize. Row arrangements were: sesame intercropped with maize in alternate pair of rows (2:2), two rows of sesame intercropped with one row of maize (2:1), sesame intercropped with maize in single alternate rows (1:1) with sole sesame as control. Intercropping maize with sesame reduced the incidence and severity of diseases. Sesame intercropped with maize in a (1:1) ration recorded a significantly lower number of infected leaves by CLS and ALB incidence than other row arrangements. ALB lesion number was between 17 and 20 in the (1:1) arrangement relative to 65–104 and 28–43 in the sole crop and other row arrangements, respectively. ALB lesion size was also reduced in the (1:1) than other row arrangements. Fungal infection of harvested sesame seeds was significantly reduced in the intercrop relative to the sole crop. CLS incidence was significant and negatively correlated with seed weight while defoliation was significant and positively correlated with ALB or CLS incidence. Rainfall was significant and positively correlated with CLS or ALB incidence while intercropping induced microclimatic effects that influenced disease incidence. Grain yield, weight of 1000-seed, number of capsules/plant and weight of seed/plant were significantly higher in the (1:1) row arrangement than the sole crop or other row arrangements. The study demonstrates that intercropping sesame with maize in a single alternate row (1:1) arrangement can be used to reduce foliar diseases of sesame.     

不同种植密度下玉米与豌豆间作对群体总产量的影响

于2014和2015年在黄土高原半干旱区全膜覆盖种植技术下,研究了不同种植密度下玉米行内间作豌豆对作物群体总产量的影响.结果表明: 2014年,当玉米株距为40和50 cm时,与不插播相比,在玉米株间插播2株豌豆显著提高了作物群体籽粒总产量;而在株距60 cm情况下,插播豌豆对作物群体总产量无显著影响.2015年,玉米株距40和50 cm情况下,与对应株距的单作玉米相比,在玉米株间插播2株豌豆对群体籽粒总产量无显著影响;但是在玉米株距60 cm的情况下,株间插播2株豌豆使作物群体籽粒总产量显著增加.导致两个试验年份之间玉米行内间作豌豆的产量效应差异的主要原因是生长季降水量在2014年较2015年充沛.综合比较,玉米株距40 cm、株间插播2株豌豆间作形式的籽粒总产量最高.此外,在玉米单作和行内间作中,籽粒总产量均随玉米株距的增大而减小.     

Nitrogen Fixation of Faba Bean (Vicia faba L.) Interacting with a Non-legume in Two Contrasting Intercropping Systems

A field experiment was carried out to quantify biological nitrogen fixation (BNF) using the ¹⁵N isotope natural abundance method in maize (Zea mays L.)/faba bean (Vicia faba L.) and wheat (Triticum aestivum L.)/faba bean intercropping systems. Faba bean was yielding more in the maize/faba bean intercropping, but not in the wheat/faba bean intercropping. Biomass, grain yield and N acquisition of faba bean were significantly increased when intercropped with maize, and decreased significantly with wheat, irrespective of N-fertilizer application, indicating that the legume could gain or lose productivity in an intercropping situation. There was yield advantage of maize/faba bean intercropping, but no in wheat/faba bean intercropping. The grain yield of the faba bean intercropped with maize was greater than that of faba bean monoculture due to increases of the stems per plant and the pods per stem of faba bean. N fertilization inhibited N fixation of faba bean in maize/faba bean and wheat/faba bean intercropping and faba bean monoculture. The responses of different cropping systems to N-fertilizer application, however, were not identical, with competitive intercropping (wheat/faba bean) being more sensitive than facilitative intercropping (maize/faba bean). Intercropping increased the percentage of N derived from air (%Ndfa) of the wheat/faba bean system, but not that of the maize/faba bean system when no N fertilizer was applied. When receiving 120 kg N/ha, however, intercropping did not significantly increase %Ndfa either in the wheat/faba bean system or in the maize/faba bean system in comparison with faba bean in monoculture. The amount of shoot N derived from air (Ndfa), however, increased significantly when intercropped with maize, irrespective of N-fertilizer application. Ndfa decreased when intercropped with wheat, albeit not significantly at 120 kg N/ha. Ndfa was correlated more closely with dry matter yield, grain yield and competitive ratio, than with %Ndfa. This indicates that that total dry matter yield (sink strength), not %Ndfa, was more critical for the legume to increase Ndfa. The results suggested that N fixation could be improved by yield maximization in an intercropping system.     

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.     

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.     

High productivity of wheat intercropped with maize is associated with plant architectural responses

Mixed cultivation of crops often results in increased production per unit land area, but the underlying mechanisms are poorly understood. Plants in intercrops grow differently from plants in single crops; however, no study has shown the association between plant plastic responses and the yield advantage. Here, we assessed the productivity of wheat–maize intercropping as compared to sole wheat and sole maize, and the associated differences in wheat shoot and leaf traits. In two field experiments, intercrop wheat and maize were both grown in alternating strips consisting of six rows of wheat and two rows of maize. The traits of wheat plants in border rows of the strips were compared to the traits of plants in the inner rows as well as those in sole wheat. Leaf development, chlorophyll concentration and azimuth, as well as the final leaf and ear sizes, tiller dynamics of wheat and yield components of both crops were determined. The relative densities of wheat and maize in the intercrop were 0.33 and 0.67, respectively, but the corresponding relative yields compared to the respective monocultures were 0.46 for wheat and 0.77 for maize. Compared to wheat plants in the inner rows of the intercrop strips as well as in the monoculture, border‐row wheat plants in the intercrop strips had (a) more tillers owing to increased tiller production and survival, and thus more ears, (b) larger top leaves on the main stem and tillers, (c) higher chlorophyll concentration in leaves, (d) greater number of kernels per ear and (e) smaller thousand‐grain weight. Grain yield per metre row length of border‐row wheat was 141% higher than the sole wheat, and was 176% higher than the inner‐row wheat. The results demonstrate the importance of plasticity in architectural traits for yield advantage in multispecies cropping systems.     

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.     

基于产量效应的间作紫花苜蓿/禾本科牧草光能利用特征

为探究紫花苜蓿/禾本科牧草间作下光能利用特性、光能利用诸因素的产量效应及其调控机理,通过2017—2019年3年田间试验,以紫花苜蓿、饲用小黑麦(C3植物)、饲用玉米(C4植物)3种单作模式为对照,研究了紫花苜蓿/小黑麦和紫花苜蓿/玉米两种间作模式下的产量效应、光能利用各因子对产量形成的影响、光能利用特征差异及机理。结果表明: 两种间作模式的土地当量比均大于1,表明两种间作模式的土地利用率都高于单作,均有高于单作的产量效益,且增产潜力较大的是紫花苜蓿/小黑麦间作模式。光能利用各因子对产量的贡献依次是: 叶面积指数(1.531)＞净光合速率(0.882)＞胞间CO₂浓度(0.282)＞蒸腾速率(-0.229)＞冠层开度(-0.291)＞光合有效辐射截获率(-0.681)＞气孔导度(-0.751)。其中,叶面积指数不仅是表征光合能力的重要指标之一,更是以收获营养体为目标的牧草作物产量的重要构成因子,光合特性诸因素中净光合速率是影响产量的主要因子。与单作相比,间作下紫花苜蓿、小黑麦、玉米的净光合速率均存在差异,且表现为相同的规律。间作下净光合速率提高的主要途径为: 小黑麦和玉米通过增强CO₂的羧化固定能力,提高对强光的利用能力,从而提高净光合速率,促进产量增加;而紫花苜蓿则是通过提高功能叶的叶绿素b含量,改变叶绿素构成,增强对光能的收集和传递,从而提高净光合速率,促进其在弱光下光合能力的提高和正常生长。     

Plant architectural responses in simultaneous maize/soybean strip intercropping do not lead to a yield advantage

Maize/soybean strip intercropping is a commonly used system throughout China with high crop yields at reduced nutrient input compared to sole maize. Maize is the taller crop, and due to its dominance in light capture over soybean in the intercrop, maize is expected to outperform maize in sole cropping. Conversely, soybean is the subordinate crop and intercropped soybean plants are expected to perform worse than sole soybean. Crop plants show plastic responses in plant architecture to their growing conditions to forage for light and avoid shading. There is little knowledge on plant architectural responses to growing conditions in simultaneous (non-relay) intercropping and their relationship to species yields. A two-year field experiment with two simultaneous maize/soybean intercropping systems with narrow and wide strips was conducted to characterise architectural traits of maize and soybean plants grown as intercrop and sole crops. Intercropped maize plants, especially those in border rows, had substantially greater leaf area, biomass and yield than maize plants in sole crops. Intercropped soybean plants, especially those in border rows, had lower leaf area, biomass and yield than sole soybean plants. Overall intercrop performance was similar to that of sole crops, with the land equivalent ratio (LER) being only slightly greater than one (1.03–1.08). Soybean displayed typical shade avoidance responses in the intercrop, such as greater internode elongation and changes in specific leaf area, but these responses could not overcome the consequences of the competition with the taller maize plants. Therefore, in contrast to relay intercrop systems, in the studied simultaneous maize/soybean system, plastic responses did not contribute to practically relevant increases in resource capture and yield at whole system (i.e., intercrop) level.     

玉米/花生间作行比和施磷对玉米光合特性的影响

试验于2014—2015年设玉米/花生间作2∶2(R₁)、2∶4(R₂)和2∶8(R₃)三种间作模式,研究了间作行比和施磷对玉米冠层光照日变化、功能叶的SPAD值、光合-光强响应曲线和光合-CO₂响应曲线的影响,以探究间作玉米适应强光的光合机理.结果表明: 间作玉米冠层日均光照表现为R₃>R₂>R₁;大口期至灌浆期,间作玉米穗位叶的SPAD值、表观量子效率(AQY)、光补偿点(LCP)、光饱和点(LSP)、光饱和时的最大净光合速率(LSP_n)、羧化效率(CE)、最大电子传递速率(J_max)、磷酸丙糖利用率(TPU)、气孔导度(g_s)、蒸腾速率(T_r)和净光合速率(P_n)均表现为R₃>R₂>R₁,胞间CO₂浓度(C_i) 则为R₁>R₂>R₃;蜡熟期R₃间作玉米的AQY、LSP_n、g_s、CE、J_max和TPU均低于R₂间作玉米;施磷能提高AQY、LSP_n、CE、V_{c max}、J_max和TPU等光合参数.这说明间作玉米g_s、AQY、CE、V_{c max}、J_max和TPU随着光强增加逐渐提高是其增强利用强光能力的关键,但超过一定光强易早衰,施磷肥有助于增强玉米对强光的利用和延缓叶片衰老.     

不同基因型玉米间作对叶片衰老、籽粒产量和品质的影响

 采用大田试验, 研究了不同基因型玉米(Zea mays)间作对叶片衰老、籽粒产量和品质的影响。结果表明, ‘豫玉19’(YY19)与‘周单 041’(ZD041)、‘郑单958’(ZD958)与‘鲁单981’(LD981)间作, 可提高叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)的活 性, 降低丙二醛(MDA)含量, 延缓叶片衰老。具体表现为, 在吐丝后10 d, 4个玉米品种叶片中的SOD和POD活性均有所提高或显著提高, ZD041和 ZD958叶片中的CAT活性提高或显著提高, YY19和LD981变化不显著; 4个玉米品种叶片中的MDA含量降低。在吐丝后40 d, SOD和POD活性及MDA含 量的变化与吐丝后10 d基本一致, CAT活性均有所提高, 其中以YY19较为显著。研究还表明, 间作增加了复合群体产量, 土地当量比(Land equivalent ratio, LER)均大于1, 籽粒品质也有所改善。     

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.     

Effects of rhizobial inoculation, cropping systems and growth stages on endophytic bacterial community of soybean roots

Interspecific interactions and soil nitrogen supply levels affect intercropping productivity. We hypothesized that interspecific competition can be alleviated by increasing N application rate and yield advantage can be obtained in competitive systems. A field experiment was conducted in Wuwei, Gansu province in 2007 and 2008 to study intercropping of faba bean/maize, wheat/maize, barley/maize and the corresponding monocultures of faba bean (Vicia faba L.), wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and maize (Zea mays L.) with N application rates of 0, 75, 150, 225 and 300 kg N ha^?1. Total land equivalent ratios (TLER) were 1.22 for faba bean/maize, 1.16 for wheat/maize, and 1.13 for barley/maize intercropping over the 2-year study period. Maize was overyielding when intercropped with faba bean, but underyielding when intercropped with wheat or barley according to partial land equivalent ratios (PLER) based on grain yields of individual crops in intercropping and sole cropping. There was an interspecific facilitation between intercropped faba bean and maize, and interspecific competition between maize and either wheat or barley. The underyielding of maize was higher when intercropped with barley than with wheat. Fertilizer N alleviated competitive interactions in intercrops with adequate fertilizer N at 225 kg ha^?1. Yield advantage of intercropping can be acquired with adequate nitrogen supply, even in an intensive competitive system such as barley/maize intercropping. This is important when using intercropping to develop intensive farming systems with high inputs and high outputs.     

Interspecific complementary and competitive interactions between intercropped maize and faba bean

Interspecific complementary and competitive interactions between maize (Zea mays L. cv. Zhongdan No. 2) and faba bean (Vicia faba L. cv. Linxia Dacaidou) in maize/faba bean intercropping systems were assessed in two field experiments in Gansu province, northwestern China, plus a microplot experiment in one treatment of one of the field experiments in which root system partitions were used to determine interspecific root interactions. Intercropping effects were detected, with land equivalent ratio values of 1.21–1.23 based on total (grain+straw) yield and 1.13–1.34 based on grain yield. When two rows of maize were intercropped with two rows of faba bean, both total yield and grain yield of both crop species were significantly higher than those of sole maize and faba bean on an equivalent area basis. When two rows of pea (Pisum sativum L. cv. Beijing No. 5) were intercropped with two rows of faba bean, neither total yield nor grain yield of faba bean was higher than of sole faba bean on an equivalent area basis. Interspecific competition between maize and faba bean was relatively weak, with mean relative crowding coefficients of 0.99–1.02 for maize and 1.55–1.59 for faba bean. The microplot experiment in which partitions were placed between root systems showed a significant positive yield effect on maize when the root systems intermingled freely (no partition) or partly (400 mesh nylon net partition) compared with no interspecific root interaction (plastic sheet partition). This revised version was published online in June 2006 with corrections to the Cover Date.     

留茬方式对小麦间作玉米产量和水分利用效率的影响

小麦/玉米间作是河西绿洲灌区主要间作模式,但传统间作和套种需水量大,使该地区水资源紧张.2010年在甘肃河西走廊石羊河绿洲灌区进行大田试验,研究传统小麦秸秆焚烧、秸秆翻还和秸秆立茬3种留茬方式对小麦/玉米间作作物籽粒产量、水分利用效率(WUE)和经济效益的影响.结果表明： 与焚烧和翻还的籽粒产量相比,立茬小麦单作分别增加7.2%和5.1%,立茬小麦间作分别增加6.2%和5.1%,立茬玉米单作分别增加4.7%和2.5%,立茬玉米间作分别增加7.2%和3.3%;与焚烧和翻还的WUE相比,立茬小麦单作分别增加20.4%和16.2%,立茬小麦间作分别增加17.9%和14.6%,立茬玉米单作分别增加16.7%和10.9%,立茬玉米间作分别增加11.8%和17.0%.就单作小麦、单作玉米和小麦/玉米平均值而言,焚烧、翻还、立茬处理的纯收益分别为10946、11471和13454元·hm^-2.从籽粒产量、水分利用效率和纯收益等方面考虑,立茬种植方式为甘肃省河西绿洲灌区小麦/玉米最佳种植模式.     

控水对饲草作物间作群体产量、根冠比及水分利用效率的影响

黄土高原半湿润易旱区降水资源短缺且年际分配不均,研究水分供应对饲草作物生长的影响对该区饲草栽培具有重要的指导意义。在遮雨棚中采用盆栽控水的方法,研究了箭筈豌豆单作、燕麦单作、饲用玉米单作、燕麦/箭筈豌豆间作、燕麦/饲用玉米间作5种种植模式在高水(70%田间持水量)、中水(55%田间持水量)、低水(40%田间持水量)3个供水水平下的群体产量、根冠比以及水分利用效率。结果表明: 在高、中、低3个供水水平下,燕麦/箭筈豌豆间作群体的土地当量比分别为1.20、1.21和1.19,燕麦/饲用玉米间作群体的土地当量比分别为1.17、1.11和1.03,均表现为间作优势。同一供水水平下,5种种植模式中单作饲用玉米总干物质产量最高,单作箭筈豌豆最低。单作燕麦的干物质产量和粗蛋白产量均随水分供应量的减少而增加,而单作箭筈豌豆和单作玉米则表现出相反的趋势。在个体水平上,间作提高了燕麦干物质产量和粗蛋白产量,而降低了箭筈豌豆和饲用玉米的产量,燕麦表现为间作优势。燕麦/箭筈豌豆间作群体干物质产量在中水和低水处理下比高水处理分别增加4.1%和4.8%,但差异不显著;而燕麦/饲用玉米间作群体干物质产量在中水和低水处理比高水处理分别显著降低8.0%和13.0%。燕麦/箭筈豌豆间作群体的根冠比在中水和低水处理下分别比高水处理显著增加33.4%和58.4%,中水和低水处理显著降低了燕麦/饲用玉米间作群体的根冠比。燕麦/箭筈豌豆间作群体的水分利用效率在中水和低水处理下分别比高水处理显著增加11.7%和12.9%,而燕麦/饲用玉米间作群体的水分利用效率在中水和低水处理下与高水处理相比变化不显著。单作玉米和燕麦/饲用玉米间作群体的产量较高,但其对水分变化较为敏感、产量稳定性差,燕麦/箭筈豌豆间作群体在水分变化条件下产量稳定、粗蛋白产量占优、水分利用效率较高,建议在研究区使用。     

印度芥菜-苜蓿间作对镉胁迫的生态响应

采用温室盆栽试验,研究了重金属镉（Cd）胁迫对印度芥菜和苜蓿间作下的土壤-植物系统的影响,同时对苜蓿的Cd饲用安全进行了评估.结果表明：在土壤Cd含量为0.37～20.37 mg·kg^-1范围内,与单作印度芥菜和苜蓿相比,间作使印度芥菜生物量降低了0.4%～11.8%,而使苜蓿生物量提高了55.3%~70.0%.土壤有效Cd主要受土壤全量Cd和种植植物种类的影响,种植方式对其影响不大.在土壤Cd含量为5.37 mg·kg^-1时,间作印度芥菜地上部Cd含量较单作提高了14.5%,而间作苜蓿地上部Cd含量较单作降低了57.1%;此时,单作和间作苜蓿地上部Cd含量分别为0.21和0.09 mg·kg^-1,均未超过饲料卫生限定标准(0.5 mg·kg^-1).在土壤Cd含量为10.37～20.37 mg·kg^-1范围内,虽然单作和间作苜蓿Cd含量均超过饲料卫生限定标准,但间作种植方式仍然使苜蓿地上部Cd含量较单作降低了2.8%～48.3%,印度芥菜地上部Cd含量也较单作降低了1.1%～48.6%.不论单作还是间作印度芥菜的Cd转运系数都远高于苜蓿.     

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.