Lesquerella fendleri response to different sowing dates in northern Mexico

Lesquerella fendleri (Gray) Wats. is a Brassicaceae native to northern Mexico and southern United States. The seeds contain an oil similar to castor oil that may be used for a wide array of industrial products. The U.S. imports 41,000 t of castor oil per year. Thus, Lesquerella oil may be an economic replacement for castor oil. The Mexican growers in the semiarid lands have the potential for cultivating Lesquerella if the crop can be grown in the native regions. The object of this study is to determine the effect of sowing date on seed yield and oil content in Lesquerella grown at Saltillo located in northern Mexico. The plants were sown at three different dates (23 October 2003, 16 December 2003, and 17 March 2004) and harvested in 2004 on 15 May, 24 June, and 27 August, respectively. Irrigation was applied for germination and seedling establishment and to maintain soil moisture. The experimental design was a complete randomized block design with eight replications. Plant morphological variables as well as yield characteristics were measured and related to sowing dates and climatic conditions. The longer period for crop development was due to shorter photoperiod. Plant densities were highest when the crop was sown in December and March, although the densities of three sown dates were within the reported limit for high yield. Seed yield was highest when the crop was sown in December and the oil content increased in the March planting when the mean temperature during seed formation was highest. Infrared spectra of the seeds crude extracts showed different functional groups that varied with climatic conditions.     

Effects of the erect/bushy habit, single/double pod and late/early flowering genes on yield and seed size and their stability in chickpea

The development of ascochyta blight resistant chickpea lines has allowed autumn sowing of this crop, and increased seed yields as result of higher biomass production than the traditional spring sowing in the Mediterrranean region. A second step in the chickpea yield improvement could be to increase harvest index. In this sense, the effect of the erect/bushy habit, single/double pod and late/early flowering genes on yield and seed size and their stability was studied using eleven F_6:7 ascochyta blight resistant chickpea lines. These lines were derived from a cross between an erect, single podded and late flowering line and a bushy, double podded early line. Six lines out of eleven were erect and late flowering (three being single and three double podded), two were single podded, bushy and late flowering, two double podded, bushy and early flowering, and finally one single podded, bushy and early flowering. A multilocation trial during four and 3 years under autumn and spring sowing, respectively, in the south of Spain was performed for yield and seed size. The stability of these lines was studied by AMMI analysis. Our results suggest that the double pod gene has no effects on both yield and seed size, although, confers a higher yield stability than the single pod gene. The mean yield of the lines with bushy growth habit, across all environments, was higher than that of the erect habit lines; 208.1 and 179.8 g/m² in autumn and 120 and 101.4 g/m² in spring sowing, respectively. Mean yield of the early lines, across all environments was higher than that of late lines; earliness was more important under spring sowing with yields of 130.2 and 102.3 g/m² for early and late lines, respectively. Thus, for developing new chickpea cultivars under Mediterranean conditions, breeding programs should consider that (i) for spring sowing, early flowering and bushy types are the characters with greater influence on yield and yield stability, respectively, and (ii) for autumn sowing, the important characters are bushy habit on yield and double pod and earliness on yield stability.     

Growth,PAR use efficiency,and yield components of field-grown Vicia faba L. under different temperature and photoperiod regimes

N-fixing legume crops may be a good component of a general plan to improve cropping system efficiency. For this purpose, crop suitability to specific environments must be established. To estimate the yield potential we examined the growth and yield response of faba bean (Vicia faba L.) crops to different thermal and photoperiod regimes. Irrigated field experiments were conducted in northwest Spain for 3 years (2004–2007) with cv. ‘Alameda’ sown on five different dates in each year from mid-autumn to mid-spring. Environmental conditions experienced by plants across sowing dates were largely different. Sowing date had a great influence on biomass, grain yield and its components. This effect was associated with changes in PAR captured, PAR use efficiency (PUE) and biomass allocation to the different organs. Critical leaf area index (LAI_cr) tended to increase and the extinction coefficient, k, to decrease as the sowing date was delayed. Earlier sowing dates intercepted more radiation over the whole season than the spring sowing dates. Greatest crop growth treatments (2nd and 3rd sowing dates) had the highest values of PAR use efficiency probably due to more adequate temperatures for photosynthesis and a large number of reproductive sinks. The highest grain yield (7733 kg ha⁻¹) was obtained with the mid-February sowing date, which produced the most pods and seeds per m², the largest harvest index (62.0%), and large maximum leaf area index (5.41). Low yields of mid-autumn (1st) and mid-spring (5th) sowing dates were associated with reduced pods and seeds per m². Temperature and photoperiod had a large impact on faba bean growth, development, and yield. Best yields were obtained when abundant assimilate supply and moderate temperatures were available during pod set.     

Variability of root length density and its contributions to seed yield in chickpea (Cicer arietinum L.) under terminal drought stress

The importance of root systems in acquiring water has long been recognized as crucial to cope with drought conditions. This investigation was conducted to: (i) evaluate the variability on root length density (RLD) of chickpea in the vegetative growth stage; (ii) estimate the effect of RLD on seed yield under terminal drought conditions; and (iii) set up a procedure to facilitate the screening of chickpea genotypes with large RLD. Twelve diverse chickpea genotypes were grown in tall PVC cylinders with two different soil water treatments in 2000 and 2001, and in field under water deficit conditions during 2000/2001 and 2001/2002. In field trials, the mean RLD at 35 days after sowing showed a significant positive correlation with seed yield in both years. Similarly, the RLD in the 15–30 cm soil depth had significant positive effects to the seed yield in both years. The importance of the root trait was particularly relevant in 2001/2002, a more severe drought year, when the RLD in deeper soil layer, 30–60 cm depth, showed a significant positive relationship with seed yield. Also, the RLD at deeper soil layer, 30–60 cm depth, was higher in 2001/2002 than in 2000/2001, in particular in tolerant genotypes. The PVC cylinder trials were set up to facilitate the screening of chickpea genotypes with large RLD. RLD of plants grown in cylinders with 70% field capacity was correlated with RLD in the field trials (r = 0.731; p = 0.01). This work highlights the importance of roots in coping with terminal drought in chickpea. The cylinder system offers a much easier procedure to screen chickpea genotypes with large RLD.     

Effects of broad-leaf crops and their sowing time on subsequent wheat production

Lupin, field pea, lentil, chickpea, canola, linseed, and barley were sown at different times (late April-early July) to study their effects on subsequent wheat production on a red earth at Wagga Wagga, New South Wales. The cultivars of field pea (Pisum sativum) included Dunn, Derrimut, Maitland and Dinkum; narrow-leaf lupin (Lupinus angustifolius) cultivars were Danja, Geebung and Gungurru, and either the L. angustifolius line 75A/330 (1989–1990) or the broad-leaf lupin L. albus cv. Ultra (1991–1992). Only one cultivar of the other crops was grown in any year and after 1989 lentil (Lens culinaris cv. Aldinga) was replaced by chickpea (Cicer arietinum cv. Amethyst). The canola (cv. Shiralee (1989–1991), cv. Barossa (1992)) and linseed (cv. Glenelg) rotations received annual applications of 40–50 kg N/ha as urea.Compared to barley and the oilseeds, grain legumes increased soil mineral N supply to the following wheat crop. Over 4 years the mean wheat grain yield response to a broad-leaf crop, relative to barley, was 115% for lupin, 84% for field pea, 88% for linseed and 86% for canola. However, the effects of the various crops on subsequent wheat grain yields and grain protein varied markedly with season. The main advantage of lupin over field pea occurred in years when disease reduced growth of field pea crops. In high rainfall years, wheat yields following lentil and chickpea were lower than those following lupin. The narrow-leaf cultivars of lupin promoted greater wheat yields than either the reduced branching line 75A/330 or the broad-leaf albus cultivar Ultra. Delayed sowing of lupin reduced yield and grain protein of wheat, except when low rainfall curtailed growth of either crop in the rotation. There was little effect of field pea sowing date on wheat grain yield but sowing in late June combined with a dry spring, reduced mineral N supply and grain protein. Late sowing of oilseeds had no consistent effect on wheat grain yield but increased grain protein in most years. Late sowing of barley typically increased wheat grain yield but had little effect on grain protein. The effects of sowing time were mainly attributed to effects on soil N supply and for barley on disease incidence in the subsequent wheat.     

Breeding prospects of Lunaria annua L.

Lunaria annua is a biennial cruciferous oil seed crop. The seeds contain 30–35% oil, which consists of 67% long chain fatty acids (44% erucic acid, C22:1, and 23% nervonic acid, C24:1). The oil is suitable as lubricant. In addition, recent developments indicate that nervonic acid may be used as raw material for the production of a medicine against multiple sclerosis. The biennial character of Lunaria is a main constraint for an economically feasible production of Lunaria oil. The crop has to be sown early in the summer to achieve vigorous plant development required for vernalization during the winter. It would be a great advance when Lunaria could be sown later in the summer after an early harvested crop. From 1993, breeding research in Lunaria has been performed at CPRO-DLO, Wageningen, The Netherlands. A collection of 76 accessions was maintained and evaluated for agronomic performance. In 1995, a selection of 24 accessions were sown at four sowing dates, from end June until end of August and in 1996, 12 promising accessions were sown again at 15 and 30 July. Three accessions showed suitability for delayed sowing until beginning of August. Delay in sowing time caused also delay of flowering and seed ripening. Seed yield amounted to 1200 kg/ha in 1996 and 1700 kg/ha in 1997. Seed oil content varied from 30–38%. Severe infection of Albugo candida and Alternaria occurred and might have reduced seed yield in both years. Most accessions sustained severe winter frost of−17°C very well. It is concluded that within the evaluated gene pool promising variation is available to select for ability for late sowing, to improve the disease resistance and to increase seed yield and seed oil content.     

Evaluation and improvement of CROPGRO-soybean model for a cool environment in Galicia,northwest Spain

This paper describes the evaluation and improvement of the CROPGRO-soybean model for a cool environment in northwest Spain. The model was evaluated with a soybean (Glycine max L.) 1994 field data set with three cultivars and three planting dates. The original model proved to underestimate biomass and seed yield, so modifications were made to the temperature functions affecting N₂ fixation and photosynthesis, in order to fit better to the experimental data. The modified model was then tested, i.e., validated, with independent experimental data collected in 1995 at the same site with the same cultivars and four planting dates. Comparing observed with simulated data in 1994, the modified model decreased the root mean square error (RMSE) for biomass at harvest and seed yield from 1714 to 466 and from 940 to 333, respectively. For 1995, the validation year, RMSE for biomass decreased from 1366 to 352, although the yield was now overestimated with no significant change in RMSE. The average simulated harvest index (HI) for 1995 was greater than for 1994, the reverse of the measured values. Nevertheless, the modified model was more reliable in predicting crop performances under these cool conditions than the original model. Moreover, the predictions of the modified model for a warm climate (Gainesville, FL) were quite acceptable. We conclude that the modified model can be used successfully over a wider range of climates than the original version.     

The competitive ability of different chickpea (Cicer arietinum) genotypes against Polygonum aviculare under field conditions

Polygonum aviculare L. is a troublesome weed in chickpea cultivated in the Mediterranean environment of Central Italy. A 2-year field study was carried out to evaluate the competitive ability and the yield response of different chickpea genotypes against P. aviculare. Experimental treatments consisted in six chickpea genotypes (Alto Lazio, C1017, C133, C134, C6150 stable lines and cultivar Sultano) cultivated in weed-free conditions and with P. aviculare at four densities (4, 8, 16, 32 plants m⁻²). The competitive ability of chickpea against P. aviculare was assessed on the basis of (i) the relative biomass total (RBT); (ii) the competitive balance index (Cb), and (iii) the competitive index (CI). The chickpea seed yield in weed-free conditions ranged from 2.6 to 2.1 t ha⁻¹ of DM and was higher in C6150 and Sultano. P. aviculare caused an average chickpea seed yield loss of 14, 46, 74 and 88% at the density of 4, 8, 16, 32 plants m⁻² compared to the weed-free crop. The relationship between the P. aviculare density and the percentage of chickpea yield loss was described by the rectangular hyperbola model with the asymptote constrained to 100% maximum yield loss. The estimated coefficient I (yield loss per unit density as density approaches zero) was lower in C133, Sultano, and C1017. RBT was higher than 1 in all chickpea genotypes at 4 plants m⁻² of P. aviculare, while at higher P. aviculare densities it was similar to 1 suggesting that there is no resource use complementarity between chickpea and the weed. Generally, at the density of 50 plants m⁻² the chickpea crop was more competitive than P. aviculare at 4 plants m⁻² (Cb > 0), equally competitive at 8 plants m⁻² (Cb = 0), and less competitive at 16 and 32 plants m⁻² (Cb < 0). No chickpea genotype achieved the objective of combining a high seed yield potential and a great competitive ability against P. aviculare. C6150 and Sultano had a high seed yield production in weed-free conditions, but they were poorly competitive against P. aviculare at intermediate and high weed infestation, while C1017 showed a satisfactory level of Cb and CI at all P. aviculare densities although its seed yield was the lowest in weed-free conditions. However, the results suggest that, from an agronomical point of view, P. aviculare plant density should be less than 4 plant m⁻² in order to prevent severe chickpea seed yield loss in field conditions.     

Rice crop duration and leaf appearance rate in a variable thermal environment.: I. Development of an empirically based model

Variable crop duration is a major constraint to rice double cropping in arid irrigated environments, such as the Sahel. Photoperiodism and low air and water temperatures during the cool season are the major causes of variability, and cultivars are needed whose photothermal response provides a more stable crop duration. A previous study analyzed cultivar photothermal constants on the basis of progress to flowering. The present study sought to identify, on the basis of leaf appearance rates, the phenological stages that are most sensitive photothermally, and to explore technical options to screen germplasm for stable crop duration. Three Oryza sativa, indica-type rice cultivars (Jaya, IKP, IR64) were sown in the field at 15-day intervals during the dry season of 1995 (11 sowing dates) and 1996 (5 sowing dates) in Ndiaye, Senegal, under full irrigation and wide spacing to reduce microclimate variability. Mean daily water temperature (T_w) varied from 13 to 35°C. After seed soaking, the rate at which the first leaf (L₁) appeared was linearly related with T_w, with a base temperature (T_base) of about 10°C. Appearance rates of the subsequent three leaves (L₂–L₄) had a similar T_base, and presented a distinct temperature optimum (T_opt) at about 23°C, beyond which development rates decreased. Errors were too large to determine differences among cultivars in thermal constants. No significant temperature response was observed for the leaf appearances between L₅ to the flag leaf (L₁₂ to L₂₀). Crop duration to flowering varied by 45 (IR64) and 63 days (Jaya). These variations were associated with highly variable leaf numbers in all cultivars, including photoperiod-insensitive IKP. One-third of the variable duration was hypothesized to be due to a variable basic vegetative phase (BVP), caused by variable germination and leaf appearance rates, and two-thirds to variable duration of panicle induction after BVP. Water temperature was the main determinant of both sources of variability. A simulation model, describing these temperature and photoperiod effects on leaf number, growth duration and leaf appearance rates, was developed using the 1995 data, and satisfactorily validated with the 1996 data. The model was used to identify phenological-stage and cultivar-specific causes of variable crop duration.     

晚播对菜用大豆根系、干物质积累及鲜食产量的影响

播期是大豆高产栽培管理的重要手段.利用正常大豆播种期为对照,研究了三个相对晚播日期对菜用大豆物候期、根系、干物质及鲜食产量的影响.结果表明:晚播明显缩短生育期,播期越晚,播种到出苗的时间越短,整个生育日期越短,晚播能促进营养生长,增加苗期干物质的积累,但显著降低苗期根表面积和减少根长,根冠比下降.晚播也显著增加地上干物质的积累,6月14日播种R6期的干物重最高为:51.1g·株-1.适当的晚播可有利于菜用大豆的鲜荚产量形成.6月4日和6月14日播种R6期后10 d鲜荚产量最高,可作为哈尔滨地区的菜用大豆的适宜播期.     

高原气候下西藏不同熟期甘蓝型春油菜光温资源利用效率比较分析

为了充分协调产量潜力与气候资源高效利用的关系,研究高原气候下不同熟期甘蓝型春油菜的光温利用效率,选用3个不同熟期甘蓝型春油菜品系,设置4个播期,分析不同播期下西藏甘蓝型春油菜的生长发育及产量形成规律。结果表明：随着播期的推迟,参试油菜生育期间的温度升高,达到有效积温的天数较少,参试油菜生育期缩短;其中苗期、蕾薹期和花期较早播呈缩短趋势,角果成熟期有延长趋势。晚播油菜的茎秆伸长期雨热充足,参试油菜的株高较早播有增加,而茎粗有降低;晚播造成参试油菜前期营养生长不足,成熟期干物质积累较早播下降。晚播油菜生育后期遇持续降雨造成成熟期油菜的有效分枝数、单株有效角果数和单株粒重的降低,较早播油菜明显减产。播期改变了参试油菜的光、温利用效率,早熟品系NY16在B2播期（2021年3月15日）下光、温利用效率较高,分别为0.081 g·MJ^-1和1.017 kg·hm^-2·℃^-1;中熟品系NY28和晚熟品系NY52均在B1播期（2021年3月8日）下光、温利用效率较高,分别为0.1 g·MJ^-1 、1.282 kg·hm^-2·℃^-1和0.134 g·MJ^-1、1.712 kg·hm^-2·℃^-1。同一播期下中晚熟品系的光、温利用效率大于早熟品系。因此,适时早播可促进甘蓝型春油菜光温利用效率的提高,促进产量形成,早熟品系在3月15-22日,中晚熟品系在3月8-15日播种适宜。西藏一年一熟种植制度下,为充分协调生态条件与生产潜力关系,一定无霜期范围内,中晚熟品系的选育和利用可有效提高甘蓝型春油菜产量。     

不同品种及播期对丘区套作大豆产量的影响

在"麦/玉/豆"模式下,研究了不同品种与播期对丘区套作大豆产量的影响.结果表明,品种间产量差异极显著,以晚熟品种(贡选1号)的产量最高,达1375.11 kg/hm2,中熟品种(乐豆1号)次之,早熟品种(浙春3号)最低.与早中熟品种比较,晚熟品种表现为营养生长期较长,与玉米的生殖共生期为零,植株较高,茎粗增加0.13～0.16 cm,分枝多0.38～0.89个,主茎节数多4.47～7.12个,单株有效荚数、每荚粒数极显著高于早中熟品种,适合套作.播期间产量也有差异,以播期6月7日的产量最高.品种不同,表现略有差异.中晚熟品种的适宜播期为6月7日,表现为单株荚数、荚粒数较高;早熟品种以6月14日的产量较高,表现为单株荚数、荚粒数和百粒重较高.     

Simulation of soybean growth and yield in near-optimal growth conditions

SoySim is a new soybean (Glycine max, L. Merr) simulation model that combines existing approaches for the simulation of photosynthesis, biomass accumulation and partitioning with several new components: (i) flowering based on floral induction and post-induction processes, (ii) leaf area index based on logistic expansion and senescence functions, (iii) integration of canopy photosynthesis using a beta function, and (iv) yield simulation based on assimilate supply and seed number. Simulation of above ground dry matter (ADM) and seed yield by SoySim were validated against data from field studies at Lincoln (NE), Mead (NE), Whiting (IA), and West Lafayette (IN) that included 147 site-year-cultivar-planting date-plant-plant population combinations. In each of the four field studies, agronomic management other than planting date and plant population was optimized to achieve growth with minimal limitation from pests, nutrients, or other controllable factors. SoySim requires just two genotype-specific and two crop management-specific input parameters and yet provides reasonable accuracy in simulating growth and yield under optimum growth conditions across a wide range of sowing dates, plant population, and yield (2.5–6.4 Mg ha⁻¹) in the North-Central U.S. Corn Belt. Simulated seed yield had a RMSE of 0.46 Mg ha⁻¹. Few cultivar-specific parameter input requirements, lack of requirements for specification of key developmental stages, and mechanistic treatment of phenological development, canopy photosynthesis, and seed dry matter accumulation give several advantages to SoySim for use in research and for use as a decision-support tool to evaluate the impact of crop management options on yield potential in favorable environments.     

Yield losses of soybean and maize by competition with interseeded cover crops and weeds in organic-based cropping systems

Weed management is a major issue in organic farming systems. Although interseeding cover crops is one alternative to herbicides, cover crops often suppress not only weeds but also main crops. Therefore, using cover crops for weed control without adverse effects on main crop growth is important. To verify the effect of cover crops on competition between main crops, cover crops and weeds in a snowy-cold region, main crops soybean (Glycine max Merr.) in 2005 and maize (Zea mays L.) in 2006 were grown with cover crops winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth), respectively. The cover crops were sown on three sowing dates: before main crop planting (Pre-MC), on the same date of main crop planting (Syn-MC) and after main crop planting (Post-MC). A plot without cover crops (Sole-MC) was used as a control. The dry weight (DW), vegetation cover ratio (VCR), vertical community structure and chlorophyll content were measured to estimate the competition between main crops, cover crops and weeds. Weed DW was suppressed significantly by sowing cover crops in both soybean and maize. This weed suppression was associated with the increase of VCR of main crops plus cover crops at the early growth stage of main crops. Soil seed banks of dominant weed also became lower by sowing cover crops, implying the importance of proper weed management for suppressing weeds successively. In addition, the sowing dates of cover crops had large effects on main crops DW especially in maize, i.e., it was significantly lower in Pre-MC and Syn-MC than in Post-MC. Although the cover crop height was markedly shorter than the main crop height, the chlorophyll content of the main crops was significantly lower when cover crops were sown earlier. These results suggest that the growth inhibition of main crops by cover crops was partly caused by competition for nutrients between main crops and cover crops, and this growth inhibition was alleviated when cover crops were sown after the establishment of main crops. Consequently, soybean yield was the highest in Post-MC and decreased by 29%, 18% and 7% in Sole-MC, Pre-MC and Syn-MC, respectively, and maize yield was also the highest in Post-MC and decreased by 68%, 100% and 24% in Sole-MC, Pre-MC and Syn-MC, respectively. It was concluded that weeds could be controlled effectively by sowing cover crops after planting main crops in organic farming systems in a snowy-cold region.     

Screening of kenaf (Hibiscus cannabinus L.) genotypes for low temperature requirements during germination and evaluation of feasibility of seed production in Italy

Kenaf (Hibiscus cannabinus L.), an annual plant of the family Malvaceae, with potential use as a non-wood fiber source is a relatively new crop in Italy where it can be used in the manufacture of paper and pulp products. Cultivars differ markedly in their response to daylength, but stem growth generally declines rapidly following the onset of flowering such that under Italian conditions sowing for fiber production has to be carried out early to allow maximum growth before floral initiation. Sowing is generally delayed until soil temperature exceeds 12°C (approximately the middle of May), and therefore it is important to evaluate genetic diversity in response to low temperature during the germination stage to determine which kenaf cultivars are suited to early sowing. These trials screened various lines to identify those able to germinate at low temperature and therefore suitable for early sowing. The lines were also grown to evaluate photoperiodic requirements and seed yield in the trial environment (Experimental Centre of Rottaia, Pisa, central Italy, 43°40′N latitude;10°19′E longitude). In addition, the germination characteristics of seed obtained here were tested at low constant temperature (8°C) and at alternating 20–30°C temperature. Seed belonging to 15 lines – produced in Australia and selected for tolerance to low temperature – showed high germination percentage at 8°C in comparison with Tainung 2, a cultivar sensitive to low temperature and produced in USA (75 and 12% as overall mean of lines and Tainung 2, respectively). Lines differed significantly in their response to temperature both in germination percentage and mean germination time. Lines showed a wide range of duration of vegetative period. Flowering took place from 31 July to 23 August in most lines, and they are therefore considered early-maturing-types. Lines differed in duration of the period from emergence to seed maturity (from 134 to 187 days), in seed yield per plant (from 0.9 to 27.7 g plant⁻¹), and harvest index (from 0.3 to 16.6%). In some lines, flowering occurred in mid-August and seed filling was then not completed due to low air temperature and unfavourable moisture conditions. Seed produced in central Italy had low quality due to more rapid deterioration and susceptibility to fungal pathogens. Sensitivity to low temperature during germination was greater in most lines and germination percentages were considerably lower than for seed produced in north-eastern Australia. Environmental conditions in central Italy appear inadequate for seed production.     

Width of clover strips and wheat rows influence grain yield in winter wheat/white clover intercropping

Cereal–legume intercropping offers potential benefits in low-input cropping systems, where nutrient inputs, in particular nitrogen (N), are limited. In the present study, winter wheat (Triticum aestivum L.) and white clover (Trifolium repens L.) were intercropped by sowing the wheat into rototilled strips in an established stand of white clover.A field experiment was performed in two fields starting in two different years to explore the effects of width of the wheat rows and clover strips on the competition between the species and on wheat yields. The factors were intercropping (clover sole crop, wheat sole crop and wheat/clover intercropping), rototilled band width, sowing width and wheat density in a factorial experimental design that enabled some of the interactions between the factors to be estimated. The measurements included grain yield, ear density, grain weight, grain N concentration, dry matter and N in above-ground biomass of wheat, clover and weeds and profiles of photosynthetic active radiation (PAR) within the crop canopy.Intercropping of winter wheat and clover resulted in wheat grain yield decreases of 10–25% compared with a wheat sole crop. The yield reductions were likely caused by interspecific competition for light and N during vegetative growth, and for soil water during grain filling. N uptake in the wheat intercrop increased during late season growth, resulting in only small differences in total N uptake between wheat intercrops and sole crops, but increased grain N concentrations in the intercrop. Interspecific competition during vegetative wheat growth was reduced by increasing width of the rototilled strips from 7 to 14 cm, resulting in higher grain yields and increased grain N uptake. Increasing the sowing width of the wheat crop from 3 to 6 cm increased interspecific interactions and reduced wheat intraspecific competition during the entire growing season, leading to improved grain yields and higher grain N uptake.     

播期和播量对冬小麦尧麦16群体性状和产量的影响

为确定高产小麦尧麦16的适宜播期和播量,采用田间裂区设计,研究不同播期和播量对该品种群体性状、产量结构及产量的影响。结果表明,随着播期的推迟,小麦营养生长期缩短,成熟期却不推迟。同一播期下,播量对小麦生育进程无影响;早播增加冬前至拔节期总茎数,而对生育后期总茎数无影响。增加播量可显著增加各生育时期总茎数;随着播期推迟,同一播量水平的干物质积累量明显降低。相同播期下,干物质积累量、叶面积指数随播量的增加而递增;相同播量下,随着播期的推迟叶面积指数降低。小麦叶面积指数随生育时期的推进先升高后下降,在抽穗期达到最大。随着播量增加,产量和有效穗数逐渐增加,穗粒数和千粒重呈下降趋势;与播量相比,播期对尧麦16产量及产量结构的影响较大。尧麦16的最佳播期为10月7日,播量为300×10~4粒·hm~(-2);9月27日至10月2日播种,播量为225×10~4粒·hm~(-2),10月12日至10月17日播种,播量为375×10~4粒·hm~(-2),也可以获得较高的产量。     

Environmental effects on seed yield determination of irrigated peanut crops: Links with radiation use efficiency and crop growth rate

In Argentina, delayed sowing causes a decrease in seed yield and in radiation use efficiency (RUE) of peanut crops (Arachis hypogaea L.), but it is not known if RUE reduction is mainly due to reduced temperature during late reproductive stages or to a sink limitation promoted by decreased seed number in these conditions. We analyzed seed yield determination and RUE dynamics of two cultivars (Florman and ASEM) in four irrigated field experiments (Exp_n) grown at three sites and five contrasting sowing dates (between 17 October and 21 December) in three growing seasons. An additional field experiment was performed with widely spaced plants (i.e. with no interference among them) to evaluate the effect of peg removal on RUE and leaf carbon exchange rate (CER). Seasonal dynamics of mean air temperature and irradiance, biomass production (total and pods), and intercepted photosynthetically active radiation (IPAR) were followed. Seed yield and seed yield components (pod number, seeds per pod, seed number and seed weight) were determined at final harvest. Crop growth rate (CGR) and pod growth rate (PGR) were computed for growth phases of interest. RUE values for crops sown until 14 November were 1.89–1.98 g MJ⁻¹ IPAR, within the usual range. RUE decreased significantly for cv. Florman in the late sowing of Exp₁ (29 November) and for both cultivars in Exp₃ (21 December sowing). Across experiments, seed yield (4.5-fold variation relative to minimum) was strongly associated (r² = 0.87, P < 0.0001) with variations in seed number (3.5-fold variation relative to minimum), and to a lesser extent (r² ≤ 0.54, P ≤ 0.001) to variations in seed weight (1.9-fold variation relative to minimum). Seed number was positively related (P < 0.01) to CGR (r² = 0.66) and to PGR (r² = 0.72) during the R₃–R_6.5 phase (seed number determination window), while crop growth during the grain-filling phase (i.e. between R_6.5 and final harvest) was positively associated with grain number (r² = 0.80, P < 0.001). No association was found between RUE and mean air temperature, neither for the whole cycle nor for the phase between R_6.5 and final harvest, which showed the largest temperature variation (16.4–22.4 °C) across experiments. Use of mean minimum temperature records (range between 13.8 and 18.5 °C) did no improve the relationship. However, grain-filling phase RUE showed a positive (r² = 0.69, P = 0.003) linear response to seed number across experiments. This apparent sink limitation of source activity was consistent with the reduced RUE (from 2.73 to 1.42 g MJ⁻¹ IPAR) and reduced leaf CER at high irradiance (from ca. 30 to 15 μmol m⁻² s⁻¹) for plants subjected to 75% peg removal.     

Effects of maturity genes E2 and E3 on yield formation in soybean cultivar Enrei in warm region,Fukuyama in Japan

ABSTRACT

Understanding how maturity genes affect soybean yield formation will provide important information for crop management decisions. This study aimed to reveal how maturity genes E2 and E3 in the soybean cultivar ‘Enrei’ affect yields and yield formation in warm regions of Japan. ‘Enrei’ (e2e3) and three near-isogenic lines of ‘Enrei’ (e2E3, E2e3, and E2E3) were cultivated in 2016 and 2017 in Fukuyama, Japan (34°30′N, 133°23′E). Two sowing dates were set in each year (June sowing and July sowing). E2 extended the period from emergence to R1 and also the period from R1 to R7, whereas E3 extended only the period from emergence to R1. Interaction between E2 and E3 did not affect duration of the period from emergence to R1, but did affect the period from R1 to R7. Although seed yield did not differ between genotypes in the June sowings, the effects of E2 and E3 on seed yield in July sowing were both significant and interaction between E2 and E3 also observed. The total number of nodes increased in E3 genotypes in both sowing dates, especially in E2E3. Pod-set ratio was lower in E2 and E3 genotypes than in e2 and e3 genotypes in the June sowings, but did not differ between genotypes in the July sowings. The high yield of E2E3 genotypes in the July sowings was attributed to increased number of nodes and flower production while maintaining pod-set ratio. Appropriate choice of sowing date is suggested to be essential when using E3 genotypes.Abbreviations: HI: harvest index; NIL: near-isogenic line; RUE: radiation use efficiency; TDM: total above-ground dry matter; TRI: total solar radiation intercepted     

播期对专用高蛋白大豆产量和品质的调节效应

试验设三个播期,探讨了播期对大豆产量、蛋白质含量和农艺性状的调节效应.结果表明,播期对大豆的生育期有调节效应,播期推迟,生育期缩短,但播期对成熟期的调节效应不明显;播期对大豆产量、蛋白质产量有一定影响,但调节效应不显著;播期对大豆籽粒蛋白质含量具有极显著的调节效应;播期不能明显地改变大豆产量构成因素水平,但对空荚率的调节效应却达显著水平;合理应用播期调节措施,对大豆的高产、优质、高效生产有利.