Shade Effects on Phaseolus vulgaris L. Intercropped with Zea mays L. under Well-Watered Conditions

Field experiments were carried out under unstressed conditions of soil water during two summer crop growing seasons (1998–99 and 1999–2000 seasons) in a South African semi‐arid region (Bloemfontein, Free State, South Africa). The aim of this study was to investigate shade effects on beans intercropped with maize in terms of plant mass and radiation use. The experimental treatments were two cropping systems (no shading/sole cropping and shading/intercropping) and two row orientations (north–south and east–west). At the top of bean canopies shaded by maize, incident radiation was reduced by up to 90 %. Shading reduced total dry matter of beans by 67 % at the end of the growing season, resulting in yield losses. The dry matter partitioning into leaf and stem (the ratios of leaf and stem to total biomass) was about 50 % higher in intercropping than sole cropping. In contrast, intercropped beans had 40 % lower dry matter partitioning into pod (the ratio of pod to total biomass). Fraction of radiation intercepted by sole‐cropped beans steeply increased until canopy closure (0.9) and then slowly decreased, while fraction of radiation intercepted by intercropped beans remained constant between 0.0 and 0.2 throughout the growing seasons. However, intercropped beans had 77 % higher radiation use efficiency (RUE) than sole‐cropped beans. In contrast, for maize, no effect of intercropping (shading) was found on growth, partitioning, yield, radiation interception or RUE. Consequently, lower bean yield losses can be attained in association with late shading rather than early shading. This can be controlled by growing crops with different temporal and spatial treatments. As regards row treatment, no effect of row direction was found on growth, partitioning, yield, radiation interception or RUE.     

夏闲菜田间套作糯玉米产量优势分析

以单作糯玉米和单作蔬菜为对照,探讨了蔬菜间、套作糯玉米体系下作物干物质积累和产量差异。结果表明,间、套作糯玉米一直处于优势位,干重显著高于单作糯玉米,具有间、套作增产优势;间作青刀豆产量较单作低,造成间作体系减产;套作西兰花前期植株小、结球晚,后期加快生育进程,产量与同期单作西兰花相比无明显差异,套作体系增产10.93%~11.57%。     

Intercropping Maize with Climbing Beans, Cowpeas and Velvet Beans

When one of the crops is a legume, intercropping has potential to reduce fertilizer nitrogen (N) needs and increase food quality. Total dry matter (DM) and grain yields of different plant populations of intercropped maize ( Zea mays L.) and climbing beans ( Phaseolus vulgaris L.), cowpeas ( Vigna unguiculata [L.] Walp.), or velvet beans ( Mucuna pruriens [L.] DC. var utilis [Wight] Bruck.) were compared in two experiments. Maize populations were 40,400 and 50,500 plants ha⁻¹ in combination with climbing bean populations of 0, 20,200, 40,400 and 80,800 plants ha⁻¹ in Experiment 1. In the second experiment, climbing beans, cowpeas and velvet beans at 215,200 plants ha⁻¹ were intercropped with maize at 64,600 plants ha⁻¹. Climbing beans contributed up to 5% to total DM yields in the first experiment. In the second experiment legume contributions to total DM were 20% for climbing beans, 12% for cowpeas and 8% for velvet beans. Increasing populations of maize and climbing beans increased grain and DM yields. Dry matter yield of maize was lowered by intercropping. However, DM yields of the intercrop were not different to maize sole cropped. Maize/cowpeas produced more total DM than maize/climbing beans. Cowpeas increased the total yield of crude protein by over 15% without lowering total DM yield of the intercrop compared to maize alone and are promising as a legume for intercropping with maize. Climbing beans show little promise as a possible legume for intercropping with maize.     

Interrelationships between cropping systems for pod and seed quality components and breeding implications in common bean

Breeding programmes in common bean (Phaseolus vulgaris L.) have mainly focused on performance under monoculture conditions. Interactions among cultivars and cropping systems do occur and genotypes bred for pure cropping may not be suitable for intercropping. This study was undertaken to obtain estimates of genetic parameters of quality traits for bush bean landraces grown in two cropping systems, and the interrelationships of these traits between pure cropping and intercropping with maize (Zea mays L.). Field experiments were conducted at two locations for two years. Expression of most traits was not strongly influenced by genotype × environment interactions. Heritability estimates were similar in both cropping systems for most pod and seed quality traits. Positive correlations were observed between pure cropping and intercropping for pod characters (weight, length, width and texture) and seed characters (dry and imbided weight, length, hardness, coat proportion, water absorption and crude protein). Use of a selection index is suggested for breeding for seed size, water absorption,coat proportion and crude protein for both cropping systems. However, larger gains would be expected in pure cropping for most traits. Bean accessions PHA-0267, PHA-0285, PHA-0286 and PHA-0299 should be used for developing acceptable culinary and high protein breeding lines for either cropping system. This revised version was published online in August 2006 with corrections to the Cover Date.     

Participatory plant breeding approach for host plant resistance to bean fly in common bean under semi-arid Kenya conditions

Common bean (Phaseolus vulgaris L.) is the most important legume crop in Kenya. It is cultivated across a wide range of agro-ecologies which include high potential and marginal areas. Eastern Kenya alone, largely semi-arid, accounts for 35% of the country’s total bean production. Bean farmers mainly small-scale have limited access to quality seed, chemical pesticides and fertilizer. Therefore, bean yield under on-farm conditions still remains below 500 kg ha⁻¹ while the potential is about 1,200 kg ha⁻¹ under semi-arid conditions. To asses the farmers’ views on bean varieties and a key insect pest and associated constraints contributing to yield loss, research was undertaken. The research included survey to quantify the yield loss and Participatory Rural Appraisal to determine the level of adoption and criteria for variety choice in semi-arid eastern Kenya (SAEK). The results show that farmers consider drought and insect pest problems as main causes for low yields. The adoption rate for improved varieties is high but self sufficiency in beans stands at 23% in the dry transitional (DT) agro-ecology and at 18% in the dry mid-altitude (DM) agro-ecology, respectively. This could be attributed to low adaptability since most of the improved varieties grown were selected for high potential areas but now found in marginal areas. Drought, earliness, yield stability, and insect pest resistance are the main reasons for choice of varieties by farmers. Bean fly (Ophiomyia sp.) was identified as one of the key crop pests of beans limiting yield. Besides, African bollworm (Helicoverpa armigera) and bean aphid (Aphis fabae) were ranked higher. Due to limitations of the conventional breeding approach, a participatory plant breeding approach is suggested so as to provide an opportunity to develop insect pest resistant varieties adapted to the SAEK region.     

Yields and Land-Use Efficiency of Maize-Cowpea Crop Rotation in Comparison to Mixed and Monocropping on an Alfisol in Northern Ghana

Results reported in the literature with regard to productivity of intercropping systems in comparison to sole cropping are very inconsistent. A field experiment was therefore conducted in the northern part of the Guinea Savanna in Ghana to compare the productivity of maize/cowpea mixed cropping, maize/cowpea relay intercropping with maize/cowpea rotation and maize monocropping over a 4-year period. The treatments included two levels of nitrogen (0 and 80 kg of N ha⁻¹ y ⁻¹ as urea) and two levels of phosphorus application (0 and 60 kg of P ha⁻¹ y⁻¹ as Volta phosphate rock). At all levels of N and P application, maize yields of the intercropping systems, especially of maize/cowpea mixed cropping, were significantly lower than in sole cropping. Highest maize yields were obtained in maize/cowpea rotation, which in contrast to the other cropping systems did not show any reductions in yields over years. Cowpea yields were generally less affected by the cropping system, but were notably depressed when cowpea was relay-intercropped with maize. In treatments without fertilizer application (N and P) Land Equivalent Ratios (LER) and Area x Time Equivalency Ratios (ATER) generally indicated lower productivity of the intercropping systems as compared to sole cropping, with the maize/cowpea rotation showing the highest productivity. Conversely, fertilizer application resulted in higher productivity of the intercropping systems over the 4-year period. Productivity on the basis of ATER was generally lowest in maize/cowpea relay-intercropping as a consequence of the long time of land occupation. All of the parameters indicate low productivity of maize monocropping, clearly demonstrating that crop sequence as well as fertilizer application must be considered as important for maintaining high production levels at this site.     

Impact of the Cropping Systems of a Minor Dry Season on the Growth, Yields and Nitrogen Uptake of Maize (Zea mays L) Grown in the Humid Tropics during the Major Rainy Season

A field study evaluated the residual effect of a cropping system in two minor (dry) seasons on the productivity pattern and nitrogen utilization of a maize crop grown in the subsequent major (wet) seasons. The cropping systems established in the minor seasons, where evaporation exceeds rainfall, were either monocultures of maize (Zea mays L), or maize intercropped with either common bean (Phaseolus vulgaris L) or sunhemp (Crotolaria juncea L). In addition, monocultures of two green manures, namely sunhemp (Crotolaria juncea) or Tithonia (Tithonia diversifolia), were established. The residues of maize and beans and the green manures were incorporated at the end of the minor season; at the onset of rains in the major season, maize crops were established on the same plots. Germination of maize was not affected by the previous cropping system. In contrast, crop growth and yields of maize and nitrogen utilization were affected by the previous cropping system. Optimum growth and highest yields were procured in maize that was grown after a green manure crop. Similarly, although the yields were high, the planting of a green manure crop reduced nitrogen utilization by maize in the major season, thereby indicating its potential contribution to sustainability, due to its lower mining of soil nitrogen. On the basis of the results of this two‐year study, the impact of cropping systems in minor seasons on the productivity of maize, a very important highland cereal in the tropics, grown under rain‐fed conditions in a major season, is presented.     

Variation in traits affecting nodulation of common bean under intercropping with maize and sole cropping

Common bean (Phaseolus vulgaris L.), an important food crop in Europe, America, Africa and Asia, is thought to fix only small amounts of atmospheric nitrogen. It contributes significantly to the sustainability of traditional cropping systems because of the predominance of small-scale farmers who cultivate beans in those areas. The objectives of this work were to evaluate bush bean varieties under common agronomic cropping systems and to evaluate breeding lines under low N-fertility sole cropping and intercropping systems. The purpose of the study was to characterize the genotype and cropping system's variability in symbiotic and plant characters and to identify the most suitable genotypes to establish an effective symbiosis with indigenous strains of Rhizobium. No significant differences among the bush bean varieties evaluated under typical fertilization practices were observed for N₂-fixation and plant traits except for seed nitrogen. Significant differences among the bean lines studied under low N-fertilization conditions were detected for plant growth,plant component and N₂-fixation traits. A significant interaction of bean genotype x cropping system was found for number of nodules per plant and nodule moisture on the bush bean varieties studied, and for days to emergence, days to flowering, end of flowering, shoot length, root dry weight and shoot nitrogen on the bean lines evaluated. Nodulation parameters were correlated positively with the yield components, shoot and root parts and duration of flowering, and correlated negatively with seed crude protein, pod and seed dimensions and seed dry weight. These observations indicate that it may be possible to increase both the symbiotic N₂-fixation and seed yield through plant breeding. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genotype × cropping system interaction in climbing beans (Phaseolus vulgaris L.) grown as sole crop and in association with maize (Zea mays L.)

The selection of cultivars for the predominant cropping systems of small farms in the tropics depends to a large extent on the information obtained by testing their performance across the different systems. The main objective of this experiment was to measure the genotype × cropping system (G × CS) interaction for yield and selected agronomic traits of climbing beans (Phaseolus vulgaris L.) grown as sole crop and intercropped with two morphologically contrasting maize (Zea mays L.) cultivars. A secondary objective was to identify the most efficient and productive bean–maize intercrop combinations. Seven climbing bean genotypes were grown as sole crop and intercropped with two maize varieties, BH 140 (Mix. 1) and Guto (Mix. 2), in a factorial arranged Randomized Complete Block Design with three replications at Bako Agricultural Research Center in western Ethiopia. Main effects due to genotype and cropping system (except days to flowering) were significant for all bean traits considered. The genotypes × cropping system interaction terms were also significant for the number of seeds per pod, 100-seed weight, harvest index and seed yield. While bean seed yield significantly correlated with the number of seeds per pod (in Mix. 1) and with harvest index (in both mixtures), positive and significant correlations occurred with the number of pods per plant and 100-seed weight under sole cropping system. The correlation between bean seed yields of Mix. 1 and Mix. 2 and between Mix. 2 and sole crop were positive and significant. No such relationship was found between Mix. 1 and sole crop. The results suggest that selection of suitable climbing bean cultivars for intercropping with maize varieties predominantly grown in the area should be made under the associated culture of the two crops. Intercropping contributed to a significant reduction in seed yield of the bean genotypes due mainly to its adverse effects on the numbers of pods per plant and seeds per pod. The index tLER₁ identified most bean–maize genotype combinations of Mix. 2 as biologically more efficient system than Mix. 1. On the other hand, tLER₂ values of more than 1.00 for all treatments of Mix. 2 demonstrated higher overall productivity of the intercrop system when the bean genotypes were grown in association with a late-maturing and high yielding maize hybrid BH 140.     

箭筈豌豆、玉米产量对间作和施氮水平的响应

研究不同施氮水平下箭筈豌豆、玉米产量对单作和间作的响应,对于优化栽培措施、提高作物产量具有重要意义。本试验于2017年在甘肃河西绿洲灌溉区进行,重点研究是不同施氮水平下箭筈豌豆、玉米在单作及间作模式中干物质累积、产量构成、产量表现。结果表明,间作箭筈豌豆干物质累积量与单作相比在不施氮(N0)、减量施氮(N1)和常规施氮(N2)处理下分别提高44.0%、36.7%和37.2%;施氮水平间,间作模式下N1比N2和N0提高9.1%和25.5%,单作模式下提高9.4%和32.1%。间作玉米干物质累积量与单作相比在N0、N1和N2处理下分别提高23.3%、22.5%和23.0%;施氮水平间,间作模式下N1比N2和N0提高9.3%和19.8%,单作模式下提高9.9%和20.7%。间作模式下箭筈豌豆豆荚数和玉米穗数较相应单作分别增加7.6%和14.5%,两者的产量较单作分别提高34.9%和27.0%。由通径分析可知,箭筈豌豆产量决定次序是豆荚数>粒重>单荚粒数,玉米产量决定次序是穗数>粒重>穗粒数。间作结合施氮量240 kg/hm²能获得较高干物质积累量和产量,是河西灌溉区玉米间作箭筈豌豆适宜的施氮水平。     

施磷对不同间作体系间作优势与磷肥利用的影响

为了探明施磷水平对不同间作体系产量间作优势和磷肥利用的影响,在河北曲周主要研究了施磷对玉米‖蚕豆、玉米‖大豆和玉米‖油菜3种间作体系土地当量比(LER)、磷吸收量、磷肥吸收效率和磷间作优势的影响。结果表明：玉米‖蚕豆的LER是1.24~1.31,玉米‖油菜的LER是1.20~1.24,玉米‖大豆的LER是1.11~1.15,均大于1,具有明显的间作优势;3个磷水平下,吸磷量表现为玉米‖大豆>玉米‖蚕豆>玉米‖油菜,除玉米‖油菜间作体系外,比单作玉米分别高21.5%%~40.2%和13.3%~22.9%,且均随着施磷量的增加而增加,但增加幅度降低;3种间作体系均具有明显的磷间作优势,除玉米‖大豆间作体系外,施磷后均降低;磷肥吸收效率除玉米‖蚕豆在施磷90 kg/hm²外均低于单作玉米,并且随着施磷量的增加而降低。这表明,通过活化磷能力强的作物与玉米间作可以提高土壤难溶性磷的利用,玉米‖大豆和玉米‖蚕豆比玉米‖油菜效果好,适宜的施磷量为90 kg/hm²。     

Linkage analysis among loci for RAPDs, isozymes and some agronomic traits in Brassica campestris L.

Common bean, Phaseolus vulgaris L. is intercropped or relay cropped with maize in many Andean highlands of Colombia and Peru. Breeding beans for the target multiple cropping systems is essential for the development of productive and sustainable agriculture for the Andean smallholders. Outline of the breeding programme should follow the farming system approach with the establishment of on-farm trials and early farmers involvement. Bean breeding is oriented to minimize intercrop competition and to stabilize complementarity with maize. Genetic traits needed for improved varieties are divided as follows : traits not interacting with the cropping systems, traits specific to intercrops and traits related with socioeconomic and seed quality aspects. Screening, prebreeding and recombination nursery are better made under sole cropping while varietal improvement and on-farm trials are conducted under the target multiple cropping systems. Breeding schemes may involve recurrent, pedigree and bulk hybrid selection. The given application concerns the genetic improvement of P. coccineus, P. polyanthus and interspecific hybrids of P. vulgaris for both simultaneous and relay intercropping in Colombia and Peru. Earliness, cold tolerance, resistance to fungus diseases (mainly Ascochyta leaf blight and anthracnosis) and seed yield potential were the major objectives of the bean improvement programme. Priority has been given to the exploitation of the large diversity available in the secondary gene pool of common bean. This revised version was published online in July 2006 with corrections to the Cover Date.     

间作和双接种对玉米和菜豆生长的影响

为了验证菜豆玉米间作的可行性及双接种丛枝菌根真菌和根瘤菌在此间作体系中的影响。通过采用盆栽试验的方式,测定了不同栽培及接种方式下玉米和菜豆的一些生理指标如：生物量、氮磷钾元素的含量及吸收量、叶绿素SPAD值、菌根侵染率等。结果表明：单接种时,单作下的玉米和菜豆的总生物量分别是间作下的3.26 倍和1.25 倍;双接种时也分别达到了3.08 倍和1.25 倍。然而单接种时玉米和菜豆间作后每盆的吸氮量和吸磷量分别是间作下的1.11 倍和1.05 倍;双接种时则均为1.16 倍。接种丛枝菌根真菌后玉米及菜豆的生物量、氮磷钾元素的含量及吸收量、叶绿素含量等差异均不显著,而菜豆的根瘤数却降低了。试验研究表明：间作抑制了菜豆及玉米的生长,但促进了二者对氮磷元素的吸收利用;接种丛枝菌根真菌对玉米及菜的生长无促进作用,对二者吸收利用氮磷钾元素也无明显促进,而且还抑制了根瘤菌侵染菜豆。     

Nutritional and culinary quality of bush bean populations intercropped with maize

Summary The intereropping of common bean (Phaseolus vulgaris L.) and maize (Zea mays L.) is a common practice in the Northwest of the Iberian Peninsula. In this experiment, 25 populations of bush bean were evaluated for nutritional and culinary traits of dry seed and immature pod in sole crop and in intercrop in two years and in two locations, in order to determine whether selection of bush bean in sole crop can result in genetic progress for intercrop.There were no differences in the population means between cropping systems. Significant differences were detected among populations for all traits tudied except starch content, crude ash, water absorption and coat proportion. Population x environment interaction was significant for pod thickness. Bean populations did not interact with cropping systems for any trait, although there were differences between cropping systems for crude protein. These results suggest that a sole crop system provides sufficient information to select bean populations efficiently for the bush bean-maize intercropping system, although the advanced generations of the breeding program should be tested for quantitative traits such as protein content in the appropriate cropping system (intercropping) to know the competitive ability with the associated species. This would permit to choose bush bean populations which complement more efficiently and would be less competitive with the maize population.     

Evaluation of Intercropping Cassava/Corn/Beans (Phaseolus vulgaris L.) in Northeast Brazil

Cassava, corn and drybeans were tested under sole cropping and under all possible intercropping combinations in Paraiba State, Northeast Brazil. The crops were planted with and without fertilizer (N, P, K), which generated fourteen cropping systems. Yields of beans were not affected by either intercropping systems or fertilization. Yields of corn and cassava were affected by intercropping systems, fertilizer, and cropping systems fertilizer interaction. LER values were significantly different among cropping systems but were not affected by fertilization. This indicates that the advantage of intercropping was not improved by the addition of nutrients.     

Dry Peas (Pisum sativum L.) Grown in Mixtures with Faba Beans (Vicia faba L.)—A Rewarding Cultivation Alternative

Two semi-leafless pea cultivars and two highly lodging-resistant faba bean cultivars were grown in a series of replacement trials conducted on a highly fertile loam soil near Gottingen from 1992 to 1995. Cultivation as well as harvesting of mixed crops of both species proved possible. In spite of the delayed harvest of the mixed crop stands determined by the later pod ripening of the faba beans (varying between seasons from -f 5 to +21 days), noticeable seed losses due to pod shattering were not observed for the overripe peas. Standing ability of the peas was considerably improved by mixed cropping. Lodging began later and was less severe at harvest. Within mixtures with 50 % or more faba bean proportions at sowing (relative to the seeding rate of the pure stands) the peas, n i most cases, remained nearly upright until harvest and instead of the usual 'Plattlager', i.e., prostrate but upright top, frequently a more highly inserted 'Hohllager', i.e., upright but collapsed at higher nodes, was observed. In contrast to these remarkably synergistic effects for standing ability, such effects proved to be only small and nonsignificant for grain yield (−1.5–2.9%). Yield stability of the mixed crops was higher than that of the pure stands of both species. Estimates of the stability parameters, ecovalence, deviation from regression and environmental variance were at least halved. Yield proportions of peas and faba beans in the harvested seed of the mixtures did not correspond with the seed proportions at sowing. They differed considerably between seasons and cultivar combination. Higher yield proportions of faba beans were observed under wet and cold weather conditions and for the cultivar combination Victor/Disco, whereas higher yield proportions of peas were found under dry and warm weather conditions and for the cultivar combination Mythos/Baroness .     

机械化条件下“豆玉”不同行距配置和减肥对作物产量及大豆光合特性的影响

研究大田机械化条件下不同玉米-大豆间作模式下的群体产量及大豆的光合特性,为筛选适合河南省玉米-大豆的行距配置和减肥施用提供理论基础。设置行比和减肥2个因素,玉米单作、大豆单作为对照,其中行比设置玉米大豆行比2:4间作(2/4J)、玉米大豆行比4:4间作(4/4J)2个处理,减肥处理在上面行比处理上减量20%(2/4N、4/4N),研究了不同行距配置及减肥条件下的作物产量及大豆LAI、干质量、SPAD值及叶片光合速率的影响。2年试验结果表明,玉米处理2/4J、4/4J、2/4N、4/4N比单作减产,LAI、干物质、SPAD值和叶片光合速率均显著低于单作,但减氮前后比较,除LAI指标外,干质量、叶片光合速率(Pn)和SPAD值没有显著差异。建议河南玉米-大豆间作模式行距配置和施肥管理中,玉米大豆间作行比2:4(2/4J)减氮20%处理2/4N更增加光合产物积累,从而提高大豆产量,提高间作效益。     

秸秆还田后少耕对小麦/玉米间作系统中种间竞争和互补的影响

保护性耕作具有提高作物水分利用效率、减少能耗等优点,但能否将该技术集成应用于间作套种,尚需理论研究和具体实验依据。本研究通过2011至2012年度的田间定位试验,探讨不同耕作和秸秆还田方式对小麦间作玉米作物群体竞争、互补作用及产量的影响。试验设3种秸秆还田处理,分别是小麦带25 cm高茬收割立茬免耕(NTSS)、小麦带25 cm高茬等量秸秆覆盖免耕(NTS)及小麦带高茬等量秸秆还田翻压(TIS),以传统耕作(CT)为对照。秸秆还田后少耕间作的土地当量比高于传统耕作间作,且大于1,说明少耕小麦秸秆还田有利于提高间作优势;少耕秸秆还田降低了共生期小麦相对于玉米的竞争力,以NTS处理对小麦竞争力的影响最大,NTSS、NTS和TIS的小麦全生育期相对竞争力分别降低37%~54%、109%~141%和22%~24%。与单作玉米相比,NTSS、NTS、TIS和CT处理间作玉米的相对生长率分别高54%~59%、66%~71%、61%~63%和71%~78%,其中小麦秸秆还田间作处理中NTS更有利于发挥玉米的恢复效应。间作条件下,3种秸秆还田处理的产量较对照高6%~10%(2011年度)和4%~12%(2012年度),其中NTS增产显著。总体来看,间作群体籽粒产量与小麦相对于玉米全生育期的平均竞争力呈二次相关关系,当该竞争力在0.24~0.27时利于获得间作高产。本研究表明,秸秆还田配合少耕是调控种间竞争力的可行途径,其中小麦等量秸秆(小麦留茬25 cm)还田覆盖是优化小麦玉米竞争力的理想耕作措施。     

玉米–大豆带状套作行距配置对作物生物量、根系形态及产量的影响

空间配置是影响间作套种作物生长和产量构成的关键因素之一。本研究固定玉米–大豆套作带宽200 cm,玉米采用宽窄行种植,设置4个玉米窄行行距为20 cm(A1)、40 cm(A2)、60 cm(A3)和80 cm(A4)套作处理,2个玉米和大豆净作对照处理,研究行距配置对套作系统中玉米和大豆生物量、根系及产量的影响。结果表明,套作大豆冠层光合有效辐射和红光/远红光比值均低于净作,且随着玉米窄行的增加而降低。套作系统中大豆地上地下生物量、总根长、根表面积和根体积从第三节龄期(V3)到盛花期(R2)逐渐增加,但随着玉米窄行的增加而降低。套作玉米地上地下生物量从抽雄期到成熟期逐渐增加,根体积却逐渐降低,但这些参数随玉米窄行的变宽而增加。玉米和大豆在带状套作系统中产量均低于净作,且随玉米窄行的变宽,玉米产量逐渐增加,2012和2013两年最大值平均为6181 kg hm–2,而大豆产量逐渐降低,两年最大值平均为1434 kg hm–2,产量变化与有效株数和粒数变化密切相关。此外,玉米–大豆带状套作群体土地当量比(LER)大于1.3,最大值出现在A2处理,分别为1.59(2012年)和1.61(2013年),且最大经济收益也出现在A2处理(2年每公顷平均收益为1.93万元)。因此,合理的行距配置对玉米–大豆带状套作系统中作物的生长、产量构成和群体效益具有重要的作用。     

Winter cover crop: the effects of grass–clover mixture proportion and biomass management on maize and the apparent residual N in the soil

The advantages and disadvantages of varying mixture proportion of crimson clover (Trifolium incarnatum L.) and Italian ryegrass (Lolium multiflorum Lam.), used as winter cover crops, and cover crop biomass management before maize sowing (Zea mays L.) were studied in a series of field experiments in Eastern Slovenia. Pure stands and mixtures of cover crops on the main plots were split into different cover crop biomass management subplots: whole cover crop biomass ploughed down before maize sowing, aboveground cover crop biomass removed before ploughing and sowing, or aboveground cover crop biomass removed before sowing directly into chemically killed residues.Cover crop and cover crop biomass management affected the N content of the whole aboveground and of grain maize yields, and the differences between actual and critical N concentrations in the whole aboveground maize yield. The whole aboveground and grain maize dry matter yields, and the apparent remaining N in the soil after maize harvesting, showed significant interaction responses to cover crop × management, indicating positive and negative effects. Crimson clover in pure stand provided high, and pure Italian ryegrass provided low maize dry matter yields and N content in the yields in all the observed methods of biomass management. However, within individual management, mixtures containing high proportions of crimson clover sustained maize yields and N contents similar to those produced by pure crimson clover. Considering the expected ecological advantages of the mixtures, the results thereby support their use.