Large scale cultivation of Cynara cardunculus L. for biomass production—A case study

Large scale cultivation of the cardoon Cynara cardunculus L. for biomass production was installed using common agricultural practices and machinery in a total of 77.4 ha in southern Portugal in a region characterized by very hot and dry summers. This species is a perennial with an annual growth cycle. Installation by sowing was successful in spite of the extreme drought that occurred during this first cycle (221 mm), and the plants developed well during the second cycle (with 556 mm rainfall) with a mean density of 27 thousand plants per ha. Aerial photographs showed that 45.8 ha of the field had over 50% of ground cover by cardoon plants. The observed differences in soil occupation could be explained by rock outcrops, soil heterogeneity and land topography. The field biomass yield was estimated at 7.5 t ha⁻¹ and the plants at harvest had on average 2.1 m height and 2.2 cm stalk diameter, with 5.3 capitula per plant. Stalks represented 59.1% of total dry biomass. The capitula contain small oil seeds with an average of 126 seeds per capitulum and weighing 32 g per 1000 seeds. The mean seed yield was 603 kg ha⁻¹. The results of this experiment confirm that Cynara crops are suitable for biomass production in Mediterranean regions and that large scale operation can be applied including whole plant harvest or field fractionation for seed recovery. Careful attention to cultural practices was deemed important for field homogeneity and production. The observed plant variation, namely in oil seed production, suggests potential improvements through breeding.     

Genotype by environment interaction of seed and oil yield in vernonia (Vernonia galamensis variety ethiopica)

Vernonia (Vernonia galamensis variety ethiopica) is a potentially novel renewable source of natural epoxy oil. The objective of this study was to determine the genotype by environment interaction and to identify superior and stable genotypes of vernonia with high seed and oil yield. Field experiments were conducted during 2006, 2007 and 2008 at two localities namely, Gabaza and Syferkuil. Ten selected genotypes of vernonia were evaluated for seed yield, oil content and oil yield using the randomized complete block design with three replications. Significant interactions (P ≤ 0.05) were detected among genotype by location for seed yield, oil content, oil yield and genotype by year for seed and oil yield. Genotype Vge-18 had the highest seed yield ranging between 3095 and 3337 kg/ha followed by Vge-17 yielding 3006-3137 kg/ha at Gabaza. These genotypes were also the best performers at Syferkuil where Vge-17 yielded 2915-3217 kg/ha followed by Vge-18 with 2819-3152 kg/ha. The superiority statistics allocated Vge-17 and Vge-18 as best yielding and stable genotypes. In both locations Vge-4 had increased seed oil contents at 43% (Gabaza) and 35% (Syferkuil). Other promising genotypes with high seed oil content were Vge-33 at Gabaza (40-43%) and Vge-3 at Syferkuil (34-35%). Genotypes with the highest oil yields were found to be Vge-18 (1117-1370 kg/ha) at Gabaza and Vge-4 with yields of 885-922 kg/ha at Syferkuil. Overall, Vge-17 and Vge-18 were identified as having the highest seed yield, while Vge-4 and Vge-3 yielded the highest seed oil content with average stability. These genotypes could be used for direct large scale production or strategic breeding of vernonia in these or similar environments.     

Effects of plant density and nitrogen and potassium fertilization on cotton yield and uptake of major nutrients in two fields with varying fertility

As the most important cultural practices for cotton production, the single effects of plant density and [nitrogen (N) and potassium (K)] fertilization on yield and yield components are well documented but their combined effects on Bt cotton are poorly understood. Using a split–split plot design with four replications, we conducted a two-year field experiment in two fields, one with lower fertility and the other with higher fertility, in the Yellow River Valley of China. The aim was to evaluate both the individual and combined effects of plant density and nitrogen and potassium fertilization on yield, yield components and uptake of major nutrients. The main plots were assigned to plant density (4.5 and 7.5 plants/m²), while nitrogen (0 and 240 kg N/ha) and potassium fertilization (0 and 150 kg K/ha) were assigned to the sub- and sub–subplots. Lint yield was improved with high plant density (7.5 plants/m²) in the lower fertility field, particularly without N and K application, but not in the higher fertility field. Nitrogen or K application also increased lint yield, and a combination of high plant density, N and K application further improved lint yield in the lower fertility field, while only K application increased lint yield in the higher fertility field. Lint percentage was not affected by any of the variables studied. Thus, the yield increase due to plant density, fertilization or their combinations was attributed to increases in boll number or boll weight. The ratio of seed cotton to stalk (RSS) was linearly correlated with harvest index, and thus can be a simple indicator of dry matter allocation to reproductive structures. Increased yield due to plant density and fertilization was mainly attributed to the enhanced biological yield in the lower fertility field, while the yield increase due to K fertilization was mainly due to increased RSS in the higher fertility field. The plants used approximately equal N and P to produce 100 kg lint in both fields, but the uptake of K to produce 100 kg lint in the higher fertility field was about 21% more than that in the lower fertility field. Ratios of N:P:K were 1:0.159:0.604 in the lower fertility field and 1:0.159:0.734 in higher fertility field. This study suggests that K fertilization was extremely important for maintaining high yield, although luxury consumption occurred in the higher fertility field; N was applied more than required in the highly fertile field, and increased plant density would be beneficial to cotton yield in the lower fertility field.     

Effects of nitrogen,phosphorus and vermicompost on groundnut yield in Babile District,eastern Ethiopia

Groundnut is a major cash crop for smallholder farmers in several districts of eastern Ethiopia with low yield. Little or no fertilizer was applied for the crop possibly because no generic or recommended fertilizer and technology were available. Therefore, field experiments were conducted for 2 consecutive cropping seasons in Babile District, to investigate effects of applying mineral N and P fertilizer and vermicompost (VC) on seed yield and oil content of groundnut using an improved variety ‘BaHa-Gudo’. Treatments consisted of nitrogen (0,23 and 46 kg N/ha), phosphorus (0,46 and 92 kg P2O5/ha) and VC (0,2.5 and 5 t VC/ha). Results revealed that yield attributes, seed yield and seed oil content were significantly (p < 0.01) affected by fertilizers. Seed yield after combined application of 46 kg N, 46 kg P2O5 and 2.5 t VC/ha increased by about 113% compared to seed yield without any fertilizers. Enhancement in seed oil content at the aforementioned rate was 7.0%. It could, thus, be concluded that applying the aforementioned fertilizers would enable farmers to increase seed yield and oil content of groundnut for enhancing their income and livelihoods in the study area.     

Dry matter and nitrogen accumulation,partitioning, and retranslocation in safflower (Carthamus tinctorius L.) as affected by nitrogen fertilization

Safflower (Carthamus tinctorius L.) is a deep-rooted crop which can tolerate water stress and can be grown in rotation with other crop species. Nitrogen is one of the most important nutrients for the growth and development of safflower; however, the effect of N level on dry matter, accumulation, partitioning, and retranslocation has not been extensively studied. A 2-year field study was therefore conducted with the objective to determine the effect of N fertilization on crop phenology, dry matter, N accumulation, partitioning and retranslocation of safflower grown under rain-fed conditions. Three rates of N were used (0, 100, and 200 kg N ha⁻¹) and two hybrids (CW9048 and CW9050) of safflower were selected. The experiment was conducted during the 2003–2004 (2004) and 2004–2005 (2005) growing seasons on a calcareous sandy loam (Entisols, Orthents, Typic Xerorthent) at the experimental farm of the Aristotle University of Thessaloniki, in Northern Greece. During 2004 spring was quite mild with significant rainfall whereas during 2005 spring was hotter with lower rainfall. Our study found that N fertilization increased biomass at anthesis by an average of 24% and at maturity by an average of 25% compared with the control. Total above ground biomass increased after anthesis in both years, in both hybrids and for all fertilizer treatments. N fertilization increased the dry matter partitioning in leaves + stems and heads at anthesis and also in leaves + stems, seeds, and head vegetative components at maturity. Dry matter translocation was not affected by N fertilization but lower values were found during the second year. N content was affected by the fertilization treatments and increased in those plants treated with fertilizer compared with the controls. In addition, N fertilization increased N retranslocation from the vegetative parts of the plant to the seed, but it did not affect N gain. During the second year, which was drier, there were significant N losses but also greater N translocation efficiency and higher contribution of pre-anthesis N to seed. Seed yield was correlated with the dry matter and N translocation indices, and was higher for the fertilized plants, compared with the control. The present study indicates that N fertilization promoted the growth of safflower and increased the dry matter yield, N accumulation, translocation and seed yield under rain-fed conditions.     

Effect of nitrogen rates on yield and quality of fennel (Foeniculum vulgare Mill.) accessions

Nitrogen rates and plant genotypes effects yield and quality of medicinal plants therefore, this experiment was conducted in order to determine the effects of nitrogen rates on fennel accessions quality and quantity. The experimental design was a split plot with nitrogen rate (0, 40, 80, 120 and 160 Kg N ha⁻¹) as main and accession (Isfahan, Tehran, Yazd and EU11486) as sub plots and replicated four times. The experiment was conducted at the Isfahan University of Technology Experimental Station, Isfahan, Iran during 2008-2009. Plant height, number of umbel per plant, 1000seed weight, number of seeds per umbel, seed yield, seed essential oil yield, seed and foliage essential oil contents and seed ash, protein and fiber contents were measured. Nitrogen fertilization increased all measured traits, but reduced ash content. On average, the highest seed and foliage essential contents and seed essential yield were produced at 160 kg per N ha⁻¹ and EU11486 was a superior cultivar for these traits. However, there was an interaction between N rate and accession on all traits. Isfahan (11.65 kg ha⁻¹), EU11486 (38.26 kg ha⁻¹), Tehran (15.32 kg ha⁻¹) and Yazd (22.06 kg ha⁻¹) produced the highest seed essential oil yield under application of 160, 80, 160 and 120 kg N ha⁻¹, respectively. Foliage of the accessions contained 0.45-0.91% essential oil and seeds of accessions contained 17.6-18.2% protein and 8.9-9.4% ash suggesting that foliage of fennel also is a good source of essential oil and seeds of fennel are good sources of protein and minerals. The results showed that N fertilization and accession can affect yield and quality of fennel and accessions responded differently to N fertilization rates, thus selection among the accessions and N rates for better fennel production is possible.     

Nitrogen utilization efficiency of safflower hybrids and open-pollinated varieties under Mediterranean conditions

The identification of the factors determining nutrient utilization of safflower (Carthamus tinctorius L.) is useful for the successful introduction of the crop to the cropping system of a region. A field study was conducted to compare and analyze the relative importance of the various component traits causing variation in nitrogen utilization efficiency (NUE) of safflower under Mediterranean conditions. Ten genotypes, four hybrids and six open-pollinated varieties, were grown for two growing seasons without irrigation, on a silty clay (Typic Xerorthent) soil. Seed yield varied greatly among genotypes and ranged from 923 to 3391 kg ha⁻¹. Hybrids showed a mean seed yield superiority of 12.5% against varieties. Seed yield was the most important component of seed N yield and its contribution to the total variation in seed N yield among genotypes was at least 53%. NUE for biomass production during the seed-filling period was lower compared to that during the vegetative period. Genotypes differed in NUE for seed production (NUE_s) and the differences followed those of nitrogen harvest index (NHI). The contribution of NHI to the total variation in NUE_s among genotypes was much greater compared to that of yield per unit seed nitrogen and accounted for more than 79%. NUE_s is positively correlated with seed yield, suggesting that high yield was probably associated with more efficient exploitation of nitrogen. NUE_s is negatively correlated with (leaf + stem) N concentration at maturity, meaning that low straw N concentration may be indication of higher NUE_s. Results indicated that selection for NUE in safflower should be based on multiple criteria rather than just one criterion and also should be accompanied by evaluation for seed yield to ensure an improvement in both traits.     

Seed and oil yields of Moringa oleifera variety Periyakalum-1 introduced for oil production in four ecosystems of South America

Moringa oleifera Lam. is a member of Moringaceae family which grows throughout most of the tropics, and is native to sub-Himalayan tracts of north west India, Pakistan, Bangladesh and Afghanistan. Moringa seed concentrates 35-45% oil which is considered a great natural cosmetic emollient almost total natural absence of color and odor, and high oleic acid concentration (>73%). To assess their production potential in the Arid Chaco, The Yungas Tropical Forest, Tropical Lowland Forest, and in the Sub-Humid Chaco Ecosystems of South America, a comparative trial was undertaken to determine their seed yield and oil content. Arid Chaco Ecosystem: significant (P < 0.05) difference in seed yields among years were found, with 176.17 and 481.25 kg/tree recorded for 1- and 2-year-old trees, respectively. Sub-Humid Chaco Ecosystems: the difference in seed yield and oil percentage between years was significant (P < 0.05). Comparison between years showed significantly (P < 0.05) higher seed yields, and significantly (P < 0.05) lower oil percentage for the two years old trees, than for the one year old trees. The oil/tree content was significantly (P < 0.05) higher for two years old trees than for one-year-old trees. Yungas Tropical Forest Ecosystem: seed oil percentage was significant (P < 0.05) higher in one-year-old trees than in seeds of two years old trees. Overall: over the tree years, oil percentage was significantly (P < 0.05) higher for seeds produced at the Arid Chaco than at the Sub-Humid Chaco. The seed/tree yields and the oil/tree content were no significantly (P < 0.05) different among the three ecosystems. However, when oil percentage per tree and seed yield/tree were combined trees from Sub-Humid Chaco and from Yungas Tropical Forest yielded significantly (P < 0.05) higher oil content compared to that from Arid Chaco trees.     

Narrow row spacing and high plant population to short height castor genotypes in two cropping seasons

Castor plant (Ricinus communis L.) produces a very important oil for chemical and biofuel industries. However, doubts remain about what the best plant arrangement is to obtain the maximum yield of seeds and oil from short height castor genotypes cultivated in higher plant population. This study evaluated two castor genotypes (FCA-PB and IAC 2028) in 5 plant arrangements (row spacing × in-row spacing): 0.90 m × 0.44 m (traditional), 0.90 m × 0.20 m, 0.75 m × 0.24 m, 0.60 × 0.30 m, and 0.45 m × 0.40 m, in spring-summer and fall-winter cropping seasons in Botucatu, São Paulo State, southeastern Brazil. The traditional plant arrangement comprised an initial plant population of 25,000 plants ha⁻¹, while the others comprised 55,000 plants ha⁻¹. The IAC 2028 genotype presented the greatest plant height, first raceme insertion height, basal stem diameter, number of fruits per raceme and 100 seed weight; however, seed yield and seed oil content were equal between genotypes. Wider stems and higher number of racemes per plant and fruits per raceme were observed with a 0.90 m × 0.44 m plant arrangement, but due to the lowest plant population (25,000 plants ha⁻¹) in this plant arrangement, the higher values of the yield components mentioned above did not result in higher yield. The higher plant population (55,000 plants ha⁻¹) by narrower row spacings (0.45 or 0.60 m) combination produced a higher castor seed yield. The effect of plant arrangement was more intense in the spring-summer cropping season.     

Genetic variability and interrelationship among various morphological and quality traits in quinoa (Chenopodium quinoa Willd.)

Evaluation of seed yield, morphological variability and nutritional quality of 27 germplasm lines of Chenopodium quinoa and 2 lines of C. berlandieri subsp. nuttalliae was carried out in subtropical North Indian conditions over a 2-year period. Seed yield ranged from 0.32 to 9.83 t/ha, higher yields being shown by four Chilean, two US, one Argentinian and one Bolivian line. Two lines of C. berlandieri subsp. nuttalliae exhibited high values for most of the morphological traits but were low yielding. Seed protein among various lines ranged from 12.55 to 21.02% with an average of 16.22 ± 0.47%. Seed carotenoid was in the range of 1.69–5.52 mg/kg, while leaf carotenoid was much higher and ranged from 230.23 to 669.57 mg/kg. Genetic gain as percent of mean was highest for dry weight/plant, followed by seed yield and inflorescence length. All morphological traits except days to flowering, days to maturity and inflorescence length exhibited significant positive association with seed yield. The association of leaf carotenoid with total chlorophyll and seed carotenoid was positive and highly significant. The path analysis revealed that 1000 seed weight had highest positive direct relationship with seed yield (1.057), followed by total chlorophyll (0.559) and branches/plant (0.520). Traits showing high negative direct effect on seed yield were leaf carotenoid (−0.749), seed size (−0.678) and days to flowering (−0.377). Total chlorophyll exerted strongest direct positive effect (0.722) on harvest index, followed by seed yield (0.505) and seed protein (0.245).     

Microscopy techniques and image analysis for evaluation of some chemical and physical properties and morphological features for seeds of the castor oil plant (Ricinus communis)

Ricinus communis seed is a source of protein and oil with a high potential to use as animal's feedstock and biodiesel production. However, the oil yield and the extraction efficiency depend on the process conditions applied, as well as on the physical, chemical and structural properties of the seed, which have not been fully investigated. Hence, the objective of this study was to evaluate some chemical and physical properties of R. communis seed as well as to describe and quantify the macro and microstructure of this raw material by microscopy techniques and image analysis. Chemical analysis confirmed the seeds’ high contents of protein (28.48 ± 0.25%) and fat (51 ± 0.31%). On the other hand, the values of geometric mean diameter (8.95 ± 0.05 mm), bulk density (538 ± 11 kg/m³), and true density (1458 ± 27 kg/m³), among others, were higher than the ones reported about similar oils seeds. Microstructural studies showed that the endosperm cells presented an ovoid shape, as obtained from the aspect ratio results (AR = 1.28 ± 0.17), and a cell density of 570 ± 10 cell/mm², resulting in a porous structure, while the embryo cells had a cell density of 4903 ± 2 cell/mm², and an AR of 2.41 ± 0.48, related to a more compact structure (rectangular form) in this part of the seed. Regarding to lipids bodies (lb), they were only visible in the endosperm cells, showing a circular shape (AR = 1.16 ± 0.1), and a mean cell density of 9.57 ± 2.40 lipid bodies/μm², associated to protein as observed by the mineral presence (K, P, Mg and S) as determined by the energy dispersive X-ray analysis. Microscopy techniques and images analysis were efficient tools for the characterization of macro and microstructure of seeds and the data obtained integrate numerical information that could be useful for thermal and mechanical processing of R. communis seed, as well as for the design process equipment.     

Interactions of sunflower (Helianthus annuus) and sunflower broomrape (Orobanche cumana) as affected by sowing date,resource supply and infestation level

The holoparasitic weed Orobanche cumana (sunflower broomrape) constrains sunflower (Helianthus annuus) production in many countries. The development of efficient control strategies requires an understanding of the processes underlying the complex environment–host–parasite interrelations. Growth and development of O. cumana and sunflower were quantified under field conditions in southeastern Romania. Sunflower hybrid Florom 350 was sown at two dates, in plots infested with 0, 50, 200 and 1600 viable O. cumana seeds kg⁻¹ dry soil, under low-input (rainfed, low nitrogen supply) and high-input (irrigated, high nitrogen supply) conditions. Sunflower shoot biomass reached peak values of 760–1287 g m⁻² between the end of anthesis and physiological maturity. Seed yield varied from 221 to 446 g m⁻². Sunflower biomass and yield were affected by all experimental factors. Seed yield responded positively to delaying sowing from early April to late May as well as to irrigation and fertilisation, and negatively to O. cumana infestation. Yield reductions, which were a product of reduced seed number and size, amounted to 13%, 25% and 37% at parasite seed densities of 50, 200 and 1600 viable seeds kg⁻¹ soil, respectively. Maximum O. cumana attachment numbers, recorded in late-sown high-input crops in 2004, ranged from 11 m⁻² in plots with 50 parasite seeds kg⁻¹ soil to 188 m⁻² with 1600 seeds kg⁻¹ soil. Parasite attachment number was a function of crop sowing date, water and nutrient supply, seedbank density, and sunflower biomass and root length density, via mechanisms of parasite seed stimulation, host carrying capacity and intraspecific competition. Delayed sowing and improved water and nitrogen supply were associated with increases in parasite number that neutralised yield-boosting effects of irrigation and fertilisation at the highest infestation level. Sunflower shoot biomass was significantly reduced by O. cumana infection, with reductions affecting organs in the order head > stem > leaves. Most of the discrepancy between infected and non-infected plants was accounted for by O. cumana biomass. Parasites mainly acted as an extra sink for assimilates during sunflower generative growth and impaired host photosynthesis to a much lesser degree. Results suggest that similar mechanisms govern infection level and host–parasite biomass partitioning across different Orobanche–host systems.     

玉米杂交种正红2号群体结构与密肥优化方案的研究

采用两因素五水平裂区试验设计方法,研究了种植密度和施氮量对玉米新杂交种正红2号的产量及其群体结构的影响,建立了优化栽培模型。结果表明,正红2号产量在7500kg/hm2以上的高产栽培技术方案为:种植密度为58542.2～75474.3株/hm2,施氮量为188.50～336.50kg/hm2。     

种植密度和施氮量对辽单527产量的影响

以玉米杂交种辽单527为试材,研究不同种植密度和氮肥量对产量的影响。结果表明,随着种植密度和施氮量的增加,辽单527的产量呈先升高后下降的趋势。通过建立二元二次回归方程得出,种植密度为61 000株/hm2、施氮量在149 kg/hm2时辽单527理论产量最高,灌浆期穗位层叶面积指数也较高。     

Comparative analysis of local and improved practices used by farmer seed production schools in Vietnam

Farmer seed production schools in combination with participatory field experimentation might be effective instruments to enhance the skills of farmers to produce high-quality seed in the informal seed system in Vietnam. Four hundred twenty nine, unreplicated on-farm experiments were carried out in four different provinces and analyzed by the farmer seed production schools. These experiments consisted of two adjacent seed production plots: one with common local practice and one with improved practice. Differences between the two plots in yield and profit were assessed. Averaged across provinces, yields of the “improved practice plots” were 0.43 Mg ha⁻¹ higher in the wet season and 0.78 Mg ha⁻¹ higher in the dry season than the “local practice plots”. In the Nam Dinh and Nghe An provinces more hills per m², more input of potassium and muck, and fewer seedlings per hill at transplanting contributed to the higher yields in the “improved practice plots”. In the provinces Binh Dinh and Dong Thap, using a drum seeder for sowing, reduced seed rate, less input of nitrogen fertilizer and more potassium contributed to the yield advantage of the “improved practice plots”. The profit of the improved practice plots was 212 US$ ha⁻¹ higher than the profit in the local practice plots. Rice growers can benefit from lower seed rates, better yields and higher prices when grains are sold as seeds. These findings may direct the seed policies and extension approaches in Vietnam.     

种植密度和施氮量耦合对夏玉米干物质积累及氮肥利用率的影响

以郑单958和中单909为试验材料,设4.5万、6.75万、9.0万株/km~2 3个种植密度和0、100、300、500 kg/km~2 4种施氮水平,分析种植密度与施氮量对夏玉米干物质积累量和氮肥利用率的影响。结果表明,玉米在种植密度9.0万株/hm~2,其叶面积指数、群体干物质积累量、总氮素积累量以及产量均显著高于4.5万株/hm~2密度处理。增施氮肥可显著增加玉米叶面积指数、单株干物质积累量、群体干物质积累量、总氮积累量和子粒产量。当施氮量为300~500 kg/hm~2时,叶面积指数、群体干物质积累量及产量不再提加,氮肥利用率和氮肥偏生产力大幅降低。结果表明,郑单958和中单909种植适宜模式为施氮量300~500 kg/hm~2、种植密度9.0万株/hm~2。     

辽宁省玉米高产潜力探索及创建“超高产田”关键技术研究

2006~2014年,辽宁省粮食丰产科技工程项目组在辽西项目区开展玉米高产潜力探索及小面积超高产田创建工作。对经过严格测产且产量达到和超过15 000 kg/hm2的32个地块的地理分布、种植品种、种植密度、产量和产量构成因素及创建关键技术进行分析。结果表明,从纬度看,高产田均出现在40.82°~42.07°N范围内;从海拔看,高产田出现在1 000 m以下。玉米高产田的平均产量为16 630.5 kg/hm2,75%以上高产田块的种植密度超过6.75×104株/hm2,收获穗数与产量呈正相关关系。辽单565产量为15 025.5~18 822.2 kg/hm2,收获穗数69 800~93 200穗/hm2,穗粒数453~510粒,千粒重422.5~463.9 g,穗粒重190.3~233.6 g。高产关键技术是采用耐密型高产稳产品种,合理提高密度,充足的水肥供给,科学管理和地膜覆盖。     

湖南春大豆高产综合技术研究及其利用开发

本研究以优良品种为材料,采用五元二次正交回归旋转组合设计,通过田间测定参数,对密度(X_1)和氮(X_2)、磷(X_3)、钾(X_4)、硼(X_5)施用量与产量的关系,以及双因素互作的产量效应进行了探讨,研究结果表明:(1)湖南近年育成的春大豆新品种均具有亩产180～230kg的生产潜力;(2)大豆最佳种植密度因品种特性和土壤肥力的不同而有较大差异,一般为2.4～3.6万株;(3)不论稻田或旱土施用氮肥均有明显的增产效果,施用量为每亩5.0～20.0kg;(4)施用磷、钾、硼肥均有一定增产作用,每亩用量分别为过磷酸钙25.0～50.0kg、氯化钾7.5～22.5kg、硼砂0.4～0.8kg;(5)提出了以优良品种为中心的高产综合农艺模式,经大面积示范、推广、高产综合农艺模式亩产130.2～180.0kg,比对照(常规栽培)增产22.78％～73.1％。     

不同氮肥施用量对东北玉米田杂草发生的影响

利用吉林省梨树县黑土区氮肥长期定位试验田(施氮水平为0、60、120、180、240、300 kg/hm2),2019～2020两年调查玉米田杂草种类、密度和生物量及其与玉米生物量和产量的关系.结果表明,试验条件下玉米田杂草主要是禾本科杂草,尤其是水稗草Echinochloa oryzoides.与不施肥相比,60 k...     

Competition and yield in intercrops of maize and sunflower for biogas

Maize (Zea mays L.) is widely used for the production of biogas, but intercrops of maize and sunflower (Helianthus annuus L.) might improve yield as well as the environmental compatibility of biofuel production. We conducted a field study planting both crops in pure stands and intercrops in three intercropping ratios (maize:sunflower with 33:67, 67:33 and 50:50 ratio) at two nitrogen application rates (no fertilizer and 85 kg N/ha as organic fertilizer plus 85 kg N/ha as mineral fertilizer) to determine the competition between the two species and the advantage of intercropping systems at two sites differing in water supply during 2007 and 2009. Dry matter yield of maize and sunflower in mono- and intercropping systems were significantly affected by intercropping ratio, nitrogen fertilizer rate and environments. Sunflower was more competitive than maize especially in intercrops with 67% sunflower. Intercropped sunflower had a higher relative crowding coefficient (K = 1.39) than intercropped maize (0.86). Intercropping with 67% maize had the highest land equivalent ratio (1.11) and relative methane yield advantages (0.94) in one environment and showed high yield stability. It is concluded that the maize component should be dominant (>50%) for intercropping. In regions with more rainfall during the growing season, maize-sunflower intercrops required a sufficient N supply to realize a yield advantage.