Coordinated responses of leaf and nodule traits contribute to the accumulation of N in relay intercropped soybean

Maize(Zea mays L.)-soybean(Glycine max L.Merr.)relay intercropping provides a way to enhance land productivity.However,the late-planted soybean suffers from shading by the maize.After maize harvest,how the recovery growth influences the leaf and nodule traits remains unclear.A three-year field experiment was conducted to evaluate the effects of genotypes,i.e.,supernodulating(nts1007),Nandou 12(ND12),and Guixia 3(GX3),and crop configurations,i.e.,the interspecific row spacing of 45(I45),60(I60),75 cm(I75),and sole soybean(SS),on soybean recovery growth and N fixation.The results showed that intercropping reduced the soybean total leaf area(LA)by reducing both the leaf number(LN)and unit leaflet area(LUA),and it reduced the nodule dry weight(NW)by reducing both the nodule number(NN)and nodule diameter(ND)compared with the SS.The correlation and principal component analysis(PCA)indicated a co-variability of the leaf and nodule traits in response to the genotype and crop configuration interactions.During the recovery growth stages,the compensatory growth promoted soybean growth to reduce the gaps of leaf and nodule traits between intercropping and SS.The relative growth rates of ureide(RGR_U)and nitrogen(RGR_N)accumulation were higher in intercropping than in SS.Intercropping achieved more significant sucrose and starch contents compared with SS.ND12 and GX3 showed more robust compensatory growth than nts1007 in intercropping.Although the recovery growth of relay intercropping soybean improved biomass and nitrogen accumulation,ND12 gained a more significant partial land equivalent ratio(pLER)than GX3.The I60 treatment achieved more robust compensation effects on biomass and N accumulation than the other configurations.Meanwhile,I60 showed a higher nodule sucrose content and greater shoot ureide and N accumulation than SS.Finally,intercropping ND12 with maize using an interspecific row spacing of 60 cm was optimal for both yield advantage and N accumulation.

Effect of Limited Single Irrigation on Yield of Winter Wheat and Spring Maize Relay Intercropping

A field experiment was conducted during the 2002/2003 cropping season of winter wheat （Triticum aestivum） and spring maize （Zea mays） to evaluate the effect of limited single drip irrigation on the yield and water use of both crops under relay intercropping in a semi-arid area of northwestern China. A controlled 35 mm single irrigation, either early or late, was applied to each crop at a certain growth stage. Soil water, leaf area, final grain yield and yield components such as the thousand-grain weight, length of spike, fertile spikelet number, number of grains per spike, and grain weight per spike were measured, and water use efficiency and leaf area index were calculated for the irrigated and non-irrigated relay intercropping treatments and sole cropping controls. The results showed that yield, yield components, water use efficiency, and leaf area index in the relay intercropping treatments were affected by limited single drip irrigation during various growth stages of wheat and maize. The total yields in the relay intercropping treatment irrigated during the heading stage of wheat and the heading and anthesis stage of maize were the highest among all the treatments, followed by that irrigated during the anthesis stage of wheat and silking stage of maize; so was the water use efficiency. Significant differences occurred in most yield components between the irrigated and non-irrigated relay-intercropping treatments. The dynamics of the leaf area index in the relay-intercropped or solely cropped wheat and maize showed a type of single-peak pattern, whereas that of the relay intercropping treatments showed a type of double-peak pattern. Appropriately, limited single irrigation and controlled soil water content level could result in higher total yield, water use efficiency, and leaf area index, and improved yield components in relay intercropping. This practice saved the amount of water used for irrigation and also increased the yield. Therefore, heading stage of wheat and heading and anthesis stage of maize were suggested to be the optimum limited single irrigation time for relay-intercropped wheat and maize in the semi-arid area.

Effects of maize-soybean relay intercropping on crop nutrient uptake and soil bacterial community

Maize-soybean relay intercropping is an effective approach to improve the crop yield and nutrient use efficiency,which is widely practiced by farmers in southwest of China.To elucidate the characteristics of different planting patterns on crop nutrient uptake,soil chemical properties,and soil bacteria community in maize-soybean relay intercropping systems,we conducted a field experiment in 2015–2016 with single factor treatments,including monoculture maize(MM),monoculture soybean(MS),maize-soybean relay intercropping(IMS),and fallow(CK).The results showed that the N uptake of maize grain increased in IMS compared with MM.Compared with MS,the yield and uptake of N,P,and K of soybean grain were increased by 25.5,24.4,9.6,and 22.4%in IMS,respectively,while the N and K uptakes in soybean straw were decreased in IMS.The soil total nitrogen,available phosphorus,and soil organic matter contents were significantly higher in IMS than those of the corresponding monocultures and CK.Moreover,the soil protease,soil urease,and soil nitrate reductase activities in IMS were higher than those of the corresponding monocultures and CK.The phyla Proteobacteria,Acidobacteria,Chloroflexi,and Actinobacteria dominated in all treatments.Shannon’s index in IMS was higher than that of the corresponding monocultures and CK.The phylum Proteobacteria proportion was positively correlated with maize soil organic matter and soybean soil total nitrogen content,respectively.These results indicated that the belowground interactions increased the crop nutrient(N and P)uptake and soil bacterial community diversity,both of which contributed to improved soil nutrient management for legume-cereal relay intercropping systems.

Soil mineral nitrogen and yield-scaled soil N2O emissions lowered by reducing nitrogen application and intercropping with soybean for sweet maize production in southern China

The increasing demand for fresh sweet maize （Zea mays L. saccharata） in southern China has prioritized the need to find solutions to the environmental pollution caused by its continuous production and high inputs of chemical nitrogen fertilizers. A promising method for improving crop production and environmental conditions is to intercrop sweet maize with legumes. Here, a three-year field experiment was conducted to assess the influence of four different cropping systems （sole sweet maize （SS）, sole soybean （SB）, two rows sweet maize-three rows soybean （S2B3） intercropping, and two rows sweet maize-four rows soybean （S2B4） intercropping）, together with two rates of N fertilizer application （300 and 360 kg N ha-1） on grain yield, residual soil mineral N, and soil N2O emissions in southern China. Results showed that in most case, inter- cropping achieved yield advantages （total land equivalent ratio （TLER=0.87-1.25） was above one）. Moreover, intercropping resulted in 39.8% less soil mineral N than SS at the time of crop harvest, averaged over six seasons （spring and autumn in each of the three years of the field experiment）. Generally, intercropping and reduced-N application （300 kg N ha-1） produced lower cumulative soil N20 and yield-scaled soil N20 emissions than SS and conventionaI-N application （360 kg N ha-l）, respectively. $2B4 intercropping with reduced-N rate （300 kg N ha-~） showed the lowest cumulative soil N20 （mean value=0.61 kg ha-1） and yield-scaled soil N20 （mean value=0.04 kg t-1） emissions. Overall, intercropping with reduced-N rate maintained sweet maize production, while also reducing environmental impacts. The system of S2B4 intercropping with reduced-N rate may be the most sustainable and environmentally friendly cropping system.

Effect of intercropping on maize grain yield and yield components

Smallholders in developing countries commonly use intercropping to produce crops with higher yield and value. Many intercropping studies have been conducted under experimental conditions, but few studies have been performed in farmers’ fields. We conducted a 4-year study using data from real farms to examine the relationships between yield and yield components of intercropped maize in the North China Plain. Three field experiments were conducted to compare the suitability of different maize varieties in intercropping. In the farm study, the grain yield of maize intercropped with watermelon was reduced by more than one third as compared to maize in wheat-maize double cropping, mainly due to lower ear density and lower 100-grain weight. Under real farm conditions, the yield of intercropped maize increased with increasing ear density and 100-grain weight, while yield of sole maize increased with increasing grain number per ear and 100-grain weight. In the field experiments, the maize cultivars commonly used in double cropping gave similar yields when grown in the intercropping system and their yields were closely related to ear density and 100-grain weight. Our results demonstrated that ear density, rather cultivar, was a key factor affecting the productivity of intercropped maize. Therefore,maintaining high ear density is a practical way for promoting productivity of maize in farmers’ intercropping practices.

Timing and splitting of nitrogen fertilizer supply to increase crop yield and efficiency of nitrogen utilization in a wheat–peanut relay intercropping system in China

Agronomically optimizing the timing and rates of nitrogen(N) fertilizer application can increase crop yield and decrease N loss to the environment. Wheat(Triticum aestivum L.)–peanut(Arachis hypogaea L.) relay intercropping systems are a mainstay of economic and food security in China. We performed a field experiment to investigate the effects of N fertilizer on N recovery efficiency, crop yield, and N loss rate in wheat–peanut relay intercropping systems in the Huang-Huai-Hai Plain, China during 2015–2017. The N was applied on the day before sowing, the jointing stage(G30) or the booting stage(G40) of winter wheat, and the anthesis stage(R1) of peanut in the following percentage splits: 50-50-0-0(N1), 35-35-0-30(N2), and 35-0-35-30(N3), using 300 kg N ha-1, with 0 kg N ha-1(N0) as control. ^(15)N-labeled(20.14 atom %) urea was used to trace the fate of N in microplots. The yields of wheat and peanut increased by 12.4% and 15.4% under the N2 and N3 treatments, relative to those under the N1 treatment. The ^(15)N recovery efficiencies( ^(15)NRE) were 64.9% and 58.1% for treatments N2 and N3, significantly greater than that for the N1 treatment(45.3%). The potential N loss rates for the treatments N2 and N3 were23.7% and 7.0%, significantly lower than that for treatment N1(30.1%). Withholding N supply until the booting stage(N3) did not reduce the wheat grain yield; however, it increased the N content derived from ^(15)N-labeled urea in peanuts, promoted the distribution of ^(15)N to pods, and ultimately increased pod yields in comparison with those obtained by topdressing N at jointing stage(N2). In comparison with N2, the N uptake and N recovery efficiency(NRE) of N3 was increased by 12.0% and 24.1%,respectively, while the apparent N loss decreased by 16.7%. In conclusion, applying N fertilizer with three splits and delaying topdressing fertilization until G40 of winter wheat increased total grain yields and NRE and reduced N loss. This practice could be an environment-friendly N management strategy for wheat–peanut relay intercropping systems in China.

Relay-intercropping soybean with maize maintains soil fertility and increases nitrogen recovery efficiency by reducing nitrogen input

Optimized nitrogen(N)management can increase N-use efficiency in intercropping systems.Legume-nonlegume intercropping systems can reduce N input by exploiting biological N fixation by legumes.Measurement of N utilization can help in dissecting the mechanisms underlying N uptake and utilization in legume-nonlegume intercropping systems.An experiment was performed with three planting patterns:monoculture maize(MM),monoculture soybean(SS),and maize-soybean relay intercropping(IMS),and three N application levels:zero N(NN),reduced N(RN),and conventional N(CN)to investigate crop N uptake and utilization characteristics.N recovery efficiency and 15N recovery rate of crops were higher under RN than under CN,and those under RN were higher under intercropping than under the corresponding monocultures.Compared with MM,IMS showed a lower soil N-dependent rate(SNDR)in 2012.However,the SNDR of MM rapidly declined from 86.8%in 2012 to 49.4%in 2014,whereas that of IMS declined slowly from 75.4%in 2012 to 69.4%in 2014.The interspecific N competition rate(NCRms)was higher under RN than under CN,and increased yearly.Soybean nodule dry weight and nitrogenase activities were respectively 34.2%and 12.5%higher under intercropping than in monoculture at the beginning seed stage.The amount(Ndfa)and ratio(%Ndfa)of soybean N2 fixation were significantly greater under IS than under SS.In conclusion,N fertilizer was more efficiently used under RN than under CN;in particular,the relay intercropping system promoted N fertilizer utilization in comparison with the corresponding monocultures.An intercropping system helps to maintain soil fertility because interspecific N competition promotes biological N fixation by soybean by reducing N input.Thus,a maize-soybean relay intercropping system with reduced N application is sustainable and environmentally friendly.

不同带宽行比对玉米/大豆带状间套作群体产量和氮素效率的影响

为明确玉米/大豆带状间套作的最优配置,大田试验条件下,以单作玉米(MM)和单作大豆(MS)为对照,设置5种不同带宽行比:2 m带宽玉豆行数比为2∶2(T1)、2.4 m带宽玉豆行数比为2∶3(T2)、2.4 m带宽玉豆行数比为2∶4(T3)、2.8 m带宽玉豆行数比为2∶3(T4)、2.8 m带宽玉豆行数比为2∶4(T5),研究不同带宽行比对玉米/大豆带状间套作群体产量和氮素利用效率的影响。结果表明,玉米籽粒产量总体上随着带宽增加呈现逐渐减少的趋势,大豆籽粒产量总体上随着带宽增加呈现逐渐增加的趋势;相同带宽条件下,随着玉米大豆行比增加,玉米籽粒产量下降,大豆籽粒产量增加;玉米和大豆的植株氮素吸收利用效率变化规律与籽粒产量基本相一致。与对照相比,T2有提高玉米和大豆的收获指数,增加氮素在玉米和大豆籽粒的分配比例、降低在茎秆的分配比例的趋势。综合产量、经济效益以及群体氮素吸收、分配和利用效率的表现,2.4 m带宽下种植2行玉米3行大豆为鄂西南山区玉米/大豆的最优间套作模式。

施氮与种间距离下大豆/玉米带状套作作物生长特性及其对产量形成的影响

为明确施氮和种间距离下套作作物生长特性及其对产量形成的影响。本文以大豆/玉米带状套作系统为研究主体,探究不同氮水平(施氮与不施氮)与种间距离(玉豆间距30、45、60和75 cm、单作100 cm)下作物生长率、干物质积累与分配及产量差异,并对作物干物质积累过程进行拟合,综合分析作物生长规律和产量效益。结果表明:玉米生长率在抽雄期至乳熟期达最大,不施氮下以间距30 cm(MS30)最高,较玉米单作(MM100)高出34.99%。套作大豆生长率在初花期前显著低于单作(SS100),而初花期后高于SS100,以间距60cm(MS60)最高,盛花期—盛荚期在不施氮下较SS100高出78.91%。Logistic方程可较好的拟合玉米、大豆的干物质积累过程,且R2均在0.95以上。与不施氮相比,施氮推迟了玉米干物质积累高峰,提高了干物质积累量;套作大豆生育前期干物质积累慢于单作,而生育后期间距45cm(MS45)、MS60干物质积累逐渐与单作持平甚至超过单作。施氮提高了玉米籽粒干物质分配率而显著提高产量,2年间玉米产量分别提高10.05%、40.90%。随种间距离增加套作大豆产量呈先增后减趋势,以MS60最高,MS30最低,MS60两年间在不施氮与施氮下较MS30分别平均高出23.88%、31.77%。套作下土地当量比均在1.35以上,其中以施氮下MS60最大(1.89)。适宜的种间距离(间距60 cm)可实现套作下玉米和大豆协同生长,提高作物生长率、促进干物质积累与分配、提高系统产量和土地当量比。

玉米-大豆带状套作对土壤肥力的影响

【目的】明确玉米大豆带状套作对土壤肥力、酶活性、团聚体含量的影响以及作物产量的变化。【方法】以“登海605”为供试玉米品种,以“南豆12”为供试大豆品种,设置玉米-大豆带状套作、玉米单作和大豆单作3个处理,系统研究不同处理对土壤有机质、全氮、全磷和有效磷、全钾和速效钾含量,pH、容重,脲酶、蔗糖酶、酸性磷酸酶、硝酸还原酶活性、团聚体含量和作物产量的影响。【结果】玉米-大豆带状套作显著提高了玉米和大豆带土壤的有机质、有效磷、速效钾等养分含量,其中玉米带增幅分别为18.1%、14.9%和21.8%,大豆带有机质和速效钾增幅分别为17.7%和34.9%,而有效磷增幅较小且不显著,并保持了全氮、全磷、全钾含量和pH的稳定。玉米带土壤容重显著下降3.3%,大豆带则显著增加4.7%。带状套作显著提高了土壤蔗糖酶和脲酶的活性,玉米带增幅为16.3%和20.5%,大豆带增幅为133.7%和66.2%,酸性磷酸酶和硝酸还原酶活性保持稳定。带状套作促进了大粒径团聚体的形成,套作玉米和大豆带>2 mm团聚体分别显著提高18.8%和22.2%,其他各粒级的小团聚体不同程度下降。带状套作玉米较单作千粒重、穗粒数、有效株数和产量均无显著差异。带状套作大豆有效株数、单株粒数分别较单作显著下降12.9%、26.5%,百粒重无显著差异,最终使大豆产量达到单作的60.9%。【结论】玉米-大豆套作模式提高了土壤肥力,显著增加了有机质、速效钾、有效磷等的含量,维持了土壤中全氮、全磷、全钾含量和pH的稳定,并显著提高了土壤脲酶和蔗糖酶的活性,从而有利于土壤养分转化和植物吸收利用。带状套作还促进微小团聚体向稳定的大团聚体转化,从而提高了土壤的通透性和保水保肥能力,一定程度上影响土壤的化学性质,满足了玉米和大豆生长需要。因此,玉米-大豆带状套作可以改善土壤的化学性质和物理性质,提高土壤肥力,保持与单作相当的玉米产量,并能额外收获相当于单作产量60.9%的大豆。

生姜应答间/套作的生理生化研究进展

生姜(Zingiber officinale Roscoe)是重要的药食两用作物,有较高的经济价值。生姜喜阴,生产中常采用遮阴栽培,合理的生姜间/套作可以提高光能利用率及土地利用率,增加经济效益,在现代农业生产中具有一定的推广价值。本研究综述了间/套作对生姜生长和生理生化等方面的影响,旨在为构建简易、高产、高效、可持续发展的生姜产业提供参考;提出了生姜间/套作在分子生物学机制、根际微生态协调等方面需要进一步研究的问题,并对生姜在间/套作的未来研究方向进行了展望。

Crop Diversity for Ecological Disease Control in Potato and Maize

本文针对中国西南山区作物病害发病高峰与降雨高峰重叠难以防治的难点,进行了生态调控马铃薯与玉米种植结构避雨避病的试验。试验结果表明,时间上提前和推后马铃薯种植避开了降雨高峰,平均降低晚疫病病情指数44.3%。空间上行距拉宽株距缩小,通风透光减轻病害,套种玉米的大斑病平均降低病情指数为14.8%,小斑病平均降低22.5%。本试验的另一重要结果表明,通过调整马铃薯种植结构可以大幅度提高耕地产出率,马铃薯与玉米套种,提前和推后种植马铃薯分别提高土地利用率1.738-1.766。本文研究结果对作物病害的生态防治和增加粮食产量有重要现实意义。通过时空优化作物与环境的配置,合理利用农业生态结构,适应最佳生态环境,实现优质高产高效。

河西走廊玉米与豆科作物间作田化学除草及对作物安全性的研究

玉米与豆科作物复合种植是河西走廊地区重要的粮经作物栽培模式,杂草危害是该复合种植体系中普遍存在的重要问题。本文采用田间裂区试验设计的方法研究了5种除草剂(或配方)对玉米与3种豆科作物-大豆Glycine max、赤小豆Vigna umbellata和菜豆Phaseolus vulgaris间作田杂草的防除效果和对两类作物的安全性。结果表明,除草剂对杂草的防效为81.67%~91.55%,显著高于当地常规玉米单作的化学除草处理(P<0.05),5种药剂处理对苗期玉米无明显药害,而对3种豆科作物幼苗均有不同程度的不利影响。玉米收获期900 g/L乙草胺EC、900 g/L乙草胺EC+87.5%2,4-滴异辛酯EC和900 g/L乙草胺EC+10%唑嘧磺草胺SC 3种药剂处理条件下三种间作组合的玉米+豆科作物总产量均高于空白对照,且与各自的人工除草处理相当或更优;本试验5种药剂处理条件下玉米与3种豆科作物间作组合的玉米+豆科作物总产量均与玉米单作常规化学除草处理相当或更优。研究结果可为西北河西走廊地区玉米与豆科作物间作模式下田间杂草的安全、高效化学防除提供技术参考。

种间距对不同结瘤特性套作大豆根瘤生长及固氮潜力的影响

为充分挖掘套作大豆的固氮潜力,本试验以玉米/大豆带状套作系统为对象,研究了不同玉豆间距(30 cm、45 cm、60 cm和75 cm)下不同结瘤特性大豆品种(贡选1号、桂夏3号和南豆25号)的根瘤生长及固氮潜力差异。结果表明,与单作相比,带状套作可延缓大豆根瘤数目和鲜重峰值出现的时间:玉豆间距60 cm处理下,各品种大豆根瘤数目和鲜重显著高于其他间距处理,并在达到峰值期后高于单作大豆;品种间表现为:南豆25号>桂夏3号>贡选1号。带状套作相对于单作会降低始粒期(R5)前大豆根瘤的单株固氮潜力,但玉豆间距60 cm处理下,R5期贡选1号、桂夏3号和南豆25号的单株固氮潜力2年平均较单作提高8.53%、16.40%和13.70%。不同大豆品种根瘤侵染细胞内含物积累过程差异较大,相较单作,玉豆间距60cm处理下,R5期类菌体数量增多,其中聚-β-羟基丁酸盐颗粒(PHB)增加,以南豆25号表现最优。因此,带状套作下适宜的种间距(玉豆间距60cm)可增加R5期大豆根瘤数目和鲜重,提高大豆根瘤类菌体和PHB的数量,增强大豆根瘤的固氮潜力,以强结瘤品种南豆25号效果最好。

玉米行向配置对带状套作大豆光合特性、叶片结构及产量的影响

玉米-大豆带状复合种植技术具有提高土地利用率,扩大大豆生产面积,提高大豆产量的作用,而田间配置直接影响大豆生长发育和产量形成。本研究通过分析玉米-大豆带状套作模式行向配置对大豆形态、光合生理参数及产量的影响,确定南方区域玉米-大豆带状套作模式的最优行向。试验采用单因素随机区组设计,玉米大豆行比为2∶2,带宽2 m,设置6个处理:玉米西北-东南行向净作(CKm)、大豆西北-东南行向净作(CKs)和4种行向的玉米-大豆带状套作[东-西(A1)、南-北(A2)、西北-东南(A3)、东北-西南(A4)],分析套作大豆光环境、株高、叶面积指数、光合色素、光合参数、叶片结构特性、粒叶比及产量等对复合种植系统行向的响应。结果表明,东-西行向和西北-东南行向处理的大豆前期受荫蔽程度显著低于南-北行向和东北-西南行向处理(P<0.05);东-西行向种植,套作大豆受光量最大。与净作大豆西北-东南行向处理相比,带状套作各处理大豆叶面积指数、地上部生物量、光合色素含量、净光合速率、叶片生产能力、叶片厚度、气孔密度显著降低,整体趋势为东-西行向>西北-东南行向>南-北行向>东北-西南行向处理。东-西行向处理各生育时期大豆叶面积指数、地上部生物量、光合色素含量、净光合速率以及大豆叶片厚度、气孔密度、气孔长度和气孔开度均显著高于其他带状套作处理。在产量和效益方面,东-西行向处理的大豆产量和整株粒叶比、1~5节位粒叶比及3~4节位粒叶比分别为1932.66 kg∙hm^(-2)和1074.25 g∙m^(-2)、498.50 g∙m^(-2)及207.59 g∙m^(-2),高于其他带状套作处理(P<0.05)。与玉米净作处理相比,南-北行向、西北-东南行向和东北-西南行向处理玉米实际产量显著降低,而东-西行向处理玉米产量增加1.67%。东-西行向处理下玉米产量贡献率最高(79.44%),土地当量比为1.66。在中国南方地区,东-西行向种植能显著发挥玉米-大豆套作复合种植模式的优势。

西南地区玉米-大豆带状套作成本及综合效益分析

为了探究玉米-大豆带状套作模式在西南地区的推广价值,采用比较分析法和主成分分析法,对4种种植模式,即玉米-大豆带状套作(SRI)、玉米-大豆单行套作(RI)、单作玉米(MM)和单作大豆(MSB)的产量、产值、成本、成本构成及综合效益进行了分析。与单作相比,SRI模式显著提高土地复种指数,提高了土地利用率,具有良好的产出效果,不同地区SRI模式的平均纯收益为13422.17元/hm^(2),较RI、MM和MSB模式分别高24.15%、32.86%和554.98%;SRI总成本为13252.70元/hm^(2),较MM和MSB模式分别高31.99%和100.72%,较RI模式低1.87%。总成本中用工费用所占的比例最高,较MM和MSB模式分别增加21.51%和76.28%,较RI模式低2.85%;就综合效益而言,川南-仁寿、川中-乐至和川西-雅安地区的SRI模式综合效益排名均位于各地区第一,川南和川中丘陵地区的综合效益最好,其次为川西盆周山区。玉米-大豆带状套作模式是西南地区提高经济效益和综合效益较为理想的种植模式,其在丘陵地区的推广价值要高于盆周山区。

种植方式对玉米-大豆套作体系中作物产量、养分吸收和种间竞争的影响

为探寻玉米-大豆套作体系下作物间的资源竞争关系,揭示玉米-大豆套作系统的增产机理,本研究以玉米-大豆套作系统(简称玉豆套作)为对象,通过2 a大田定位试验,研究了玉豆套作带状连作(A1)、玉豆套作带状轮作(A2)、玉豆套作等行距种植(A3)、玉米单作(A4)、大豆单作(A5)5种种植方式对玉米、大豆的产量、养分吸收及种间竞争能力的影响。结果表明,与单作和等行距种植相比,带状种植的玉米产量降低、大豆产量显著增加,A2的大豆产量分别比A5和A3高25.5%和89.2%。与带状连作相比,带状轮作促进玉米增产和对N、P、K的吸收,玉米籽粒产量及植株N、P、K的吸收总量分别提高7.5%、18.5%、9.1%、14.1%。与大豆单作相比,带状套作显著增加了大豆的经济系数和养分收获指数,A2的经济系数和植株N、P、K收获指数分别增加40.9%、11.9%、20.6%、39.9%。带状种植方式下,玉米对N、P、K的竞争力弱于大豆(Ams<0,CRms<1),但带状轮作提高了玉米的种间竞争力和营养竞争比率。玉米-大豆套作体系下,相对带状连作和等行距种植,带状轮作种植有利于玉米与大豆间的和谐共生,促进了玉米、大豆对养分的吸收,提高了系统的产量和土地当量比率(LER)。

玉米-豆科作物带状间套作对养分吸收利用及产量优势的影响

为明确玉米大豆套作、玉米花生间作养分吸收利用对产量优势贡献的差异。本研究开展了2年大田试验,通过比较间套作与相应单作成熟期植株氮磷钾养分吸收量和利用效率,综合分析了玉米大豆套作、玉米花生间作中养分吸收和利用效率的变化。结果表明:玉米大豆套作土地当量比(land equivalent ratio,LER)为1.16~1.72,具有套作产量优势,玉米花生间作LER为0.89~1.13,无明显间作产量优势。玉米大豆套作体系中,植株氮、磷、钾养分吸收总量比相应单作提高32.60%~54.22%、27.35%~34.64%和17.74%~24.42%,氮素利用效率低于相应单作21.99%~42.07%。氮、磷、钾吸收效率对LER的贡献分别为0.34~0.62、0.31~0.46和0.22~0.32,利用效率的贡献分别为–0.11~–0.35、–0.03~–0.31和–0.11~0.22。玉米花生间作体系中,氮、磷、钾养分吸收总量分别高出相应单作–7.86%~31.58%、23.09%~46.52%和1.60%~55.48%,氮素利用效率高出相应单作7.55~26.60。氮、磷、钾吸收效率对LER的贡献分别为0~0.22、0.05~0.27和–0.11~0.32,利用效率的贡献分别为–0.25~0.19、–0.32~0.11和–0.47~0.32。因此,玉米大豆套作优势在营养方面的基础主要来自于相对于单作养分吸收总量的增加,而玉米花生间作无明显间作优势主要因为养分吸收对产量优势的贡献较小。

不同施氮水平下春夏玉米套作对全株饲用营养价值的影响

【目的】以单作为对照,研究不同施氮水平下春夏玉米套作对全年饲用营养价值的影响。【方法】采用随机区组设计,研究不同施氮水平下套作体系中春玉米、夏玉米及全年生物产量、粗蛋白产量和粗脂肪产量与单作的差异,并从氮素吸收利用、气候因素等方面分析造成差异的原因。【结果】套作显著提高了全年的生物产量和营养价值。套作体系N1(187.5 kg.ha-1)和N2(375 kg.ha-1)条件下的全株粗蛋白产量的土地当量比分别为1.54和1.77,全株粗脂肪产量的土地当量比分别为1.39和2.55。套作条件下,单季作物的生物产量和营养价值一般比单作低。但在N2条件下,春玉米全株粗脂肪产量高于单作,夏玉米全株粗蛋白产量与单作差异不显著。套作体系全年吸氮量显著低于单作,但随着施氮量的增加其吸氮量增幅高于单作。【结论】与单作相比,春夏玉米套作体系利于全年营养价值的提高。这种效应是氮素营养状况及气候因素状况等共同作用的结果。在套作体系中,春玉米营养价值受竞争影响较大,而夏玉米受竞争影响较小,这与竞争发生时作物所处的时期不同有关。合理增施氮肥可以缓解复合群体的竞争而使营养价值显著提高。

不同玉米-大豆带状套作组合条件下光合有效辐射强度分布特征对大豆光合特性和产量的影响

【目的】发展间种套作大豆是有效解决粮食供需矛盾的重要途径。本文旨在通过优化群体配置,改善群体光分布特征,实现大豆对有效光能的高效利用,为套作大豆高产栽培及群体结构的优化设计提供理论依据和技术途径。【方法】本研究于2011年和2012年,以不同株型玉米杂交种和大豆品种贡选1号为试材,设计登海605/贡选1号(处理A)、川单418/贡选1号(处理B)、雅玉13/贡选1号(处理C)3种玉豆带状套作组合,并以大豆单作作为对照(CK),分析不同玉豆带状套作组合PAR分布特征对大豆光合特性和产量的影响。【结果】(1)不同玉豆带状套作组合的PAR和透光率存在显著差异,且均显著低于CK(P<0.05)。玉豆共生期间,处理A的PAR分别比处理B和处理C高54.4%和90.7%。处理A的透光率分别比处理B和处理C高7.4%和17.7%。处理A的PAR和透光率均显著高于处理B和处理C。这说明登海605/贡选1号的带状套作组合,能够提高套作系统的光合有效辐射强度和透光率。(2)不同玉豆带状套作组合下,处理A大豆叶片Pn显著高于处理B和处理C(P<0.05),处理B和处理C大豆的Pn与处理A相比分别低了14.16%和27.23%。Gs和Ci与Pn变化趋势相同,Pn与Gs存在显著的正相关关系(0.883**),说明气孔限制可能是Pn下降的主要原因。(3)不同玉豆带状套作组合显著提高了大豆叶片的Chla、Chlb、Chl(a+b)含量,降低了Chla/b比值,且均呈显著差异(P<0.05)。在V3、V5和R1期时,处理C大豆叶片Chla含量比处理A和B相比分别高5.42%、10.2%、5.9%和3.08%、4.9%、3.3%。处理C下大豆的Chlb含量比处理A和处理B分别高14.4%、14.9%,11.73%和7.8%、7%和5.74%。处理C大豆叶片Chl(a+b)的含量比处理A和处理B分别高7.27%,11.1%,7%和4.08%,5.35%,3.8%。处理间Chla/b与其呈相反的变化趋势。不同套作组合大豆叶片的叶绿素含量随着遮阴程度的增加而增加,使叶片更有效的捕获有限的光能,对光强降低有一定的补偿作用,增加对有限光能的利用。(4)不同玉豆带状套作组合大豆叶面积指数和干物质重且均显著低于CK。且处理间呈显著性差异(P<0.05),玉豆共生期间,不同玉豆带状套作组合大豆的LAI表现为处理A>处理B>处理C,且处理B和处理C的干物质重分别比处理A低35.4%和57.1%,LAI与干物质重存在显著的正相关关系(0.977**),说明紧凑型玉米削弱了对大豆弱光胁迫的程度,增加了LAI和光能截获量,从而提高了套作大豆群体的物质积累。(5)不同玉豆带状套作组合下,大豆产量及产量构成因素存在显著性差异(P<0.05)。处理A的单株荚数比处理B和处理C高11.28%和32.75%,单株粒数高5.19%和13.34%,每荚粒数高6.4%和22.5%,单株粒重高2.16%和6.22%。不同处理间大豆产量以处理A的产量最高,且分别比处理B和处理C高13.13%和35.6%,说明随着玉米对大豆弱光胁迫程度的加剧,大豆产量呈现降低趋势。【结论】适宜的株型配置可以改善套作大豆生长的光照环境、提高其光合效率和产量。