Effect of chloride in irrigation water and form of nitrogen fertilizer on Virginia (flue-cured) tobacco

One of the main sources of considerable amounts of chloride to soils is irrigation water. The responses of tobacco (Nicotiana tabacum L.) to chloride are varied and inconsistent depending on the tobacco type, variety and methods of fertilization, cultivation and harvesting used. In this work, the impact of the interaction between four chloride levels (10, 20, 40, 80 mg L⁻¹) in irrigation water and three nitrogen fertilizer forms (NO₃–N 100%, NH₄–N 100% and NO₃–N 50%:NH₄–N 50%) on growth, agronomic and chemical characteristics of Virginia tobacco was evaluated over 2 years (1999, 2000) in an outdoor pot experiment. The results showed that the adverse influence of chloride in irrigation water on plant height and number of leaves per plant was already substantial above 40 mg L⁻¹, within 30 days after transplanting. In this period, visual toxicity symptoms of chloride appeared on the lower leaves of plants treated with ammonium nitrogen. In addition, the effect of chloride on flowering time, chlorophyll content of leaves, aboveground fresh weight of plant, total cured product yield and chemical characteristics, depended on the form of nitrogen, with nitrate nitrogen restricting the detrimental effects of chloride in irrigation water up to 40 mg L⁻¹. The reduced yield of cured product at 80 mg L⁻¹ was the result of the adverse effects of chloride on the leaves of the middle and upper stalk position. Leaf chloride concentration was highest in the upper leaves and increased linearly with the increase of chloride level in irrigation water at each leaf position on the stalk and this increase was more rapid as ammonium nitrogen percentage was increased. Chloride increased the concentration of reducing sugars in cured leaves at each leaf position, in all nitrogen forms and nicotine mainly in plants treated with nitrate nitrogen. The changes in total nitrogen and ash content are considered as minimal. We conclude that the optimum chloride level in irrigation water is below 20 mg L⁻¹, whereas the level of 40 mg L⁻¹ in combination with nitrate nitrogen fertilizers can be considered as the upper threshold to avoid adverse effects on Virginia tobacco.     

不同硫肥用量对烤烟光合作用和产量的影响

采用盆栽试验研究了不同硫肥用量对烤烟光合作用和产量的影响。结果表明,当硫肥用量为0.12 g.kg-1时,烤烟叶片的叶绿素a、叶绿素b、叶绿素总量、类胡萝卜素的含量最高,分别为1.62、0.82、2.44、0.33 mg.g-1;不同硫肥用量对烤烟叶片的叶绿素a/b值影响不大;上、中、下部叶片的净光合速率也以硫肥用量为0.12 g.kg-1时最高。硫肥用量为0.12和0.18 g.kg-1时,烤烟的总生物量、根量、茎量和叶量均较高。     

不同陈化条件下烤烟褐变与氨基酸含量变化关系

通过分光光度法测定不同陈化时间和不同温度、湿度、真空度等陈化条件下烤烟烟叶中氨基酸含量和颜色的变化,并探讨烤烟褐变与氨基酸含量变化间的相互关系。结果表明,烤烟云烟85和翠碧在有氧陈化条件下温度越高、湿度越大,氨基酸含量越低,褐变度越大。因此烤烟在陈化过程中适当保持低温、低湿和隔离空气可减少烟叶褐变。     

Influence of liming and form of nitrogen fertilizer on nutrient uptake,growth, yield,and quality of Virginia (flue-cured) tobacco

Soil acidity is a limiting factor affecting the growth and yield of many crops all over the world. It is recognized that liming is the most common management practice of profitable crop production on acid soils. On the other hand, it is well-known that the form of nitrogen may affect tobacco yield and quality. In this work, the impact of the interaction between three hydrated lime (HL, Ca(OH)₂) rates (0, 1.5 and 3 t HL ha⁻¹) and three nitrogen fertilizer forms (NO₃-N 100%, NH₄-N 100% and NO₃-N 50% plus NH₄-N 50%) on growth, yield and quality characteristics of Virginia (flue-cured) tobacco was investigated in a 4-year (1995–1998) field experiment established in an acid soil (pH_{water 1:1} 5.3) located in Northern Greece. Lime was applied only once in December 1994, while nitrogen fertilizer was applied annually before transplanting. The results showed that the effect of liming on tobacco growth was not dependent on time, weather conditions and form of nitrogen fertilizer. Liming increased soil pH, enhanced the early growth of tobacco (within 30 days after transplanting (DAT)) and finally increased the total gross and trade yield of tobacco proportionally to the amount of HL added. However, the quality index (organoleptic characteristics) of the cured product was improved only at the HL application rate of 3 t HL ha⁻¹. Furthermore, liming significantly increased Ca and P concentrations but decreased K concentration in cured tobacco leaves. Tobacco yield increase was attributed to the increase of P uptake. Liming also increased the ash content of cured leaves, whereas it did not significantly affect nicotine, total nitrogen and reducing sugars. The use of ammonium N in fertilizer delayed the early growth of tobacco, reduced the nicotine concentration and increased the reducing sugars concentration of the cured product. Total-N, P, K and Mg concentrations of cured leaves were not significantly affected by the form of nitrogen fertilizer used. The results suggested that an initial application of hydrated lime at a rate of 3 t HL ha⁻¹ may ameliorate soil acidity and increase the yield and quality characteristics of Virginia tobacco at least over a 4-year period after application, independent of the form of N fertilizer used.     

2010年南平市异常气候对烤烟生长发育和产量的影响

通过分析2010年南平市烤烟生长发育期间气温、降水、日照3个主要气候因子对烤烟生产的影响,结果表明：3月平均气温、光照和降雨正常,但出现的冰雹对部分烤烟造成灾害;4月低温多雨,不利于烟株早生快发;5月多剧烈天气,冰雹、大风、强雷电等强对流天气多发,灾情较严重,对烤烟造成重大不利影响;6-7月光照不足,低温多雨不利于干物质累积,影响品质;6月中、下旬南平市出现持续性暴雨、大暴雨、局部特大暴雨,各县市均出现严重的洪涝灾害,给烤烟生产造成了严重损失。总体来说,2010年南平市烤烟生产的农业气候条件较差,烟叶产量和质量都下降。     

Effect of rainfall and temperature on yield of Vicia sativa under rainfed Mediterranean conditions

The productivity of Vicia sativa grown in rotation with barley under rainfed Mediterranean conditions was examined at two locations over several years (eighteen location × year situations). Rainfall during the growing season ranged from 200 to 500 mm. Vetch relied on indigenous rhizobia for nodulation and N fixation while for phosphorus it was fertilized with 20kgPha⁻¹. Harvesting took place at the beginning of pod formation. The dry matter (DM) yield reached 6·6t ha⁻¹ and the N offtake 215 kg ha⁻¹. The highest yields were obtained when rainfall exceeded the 350 mm level. The N concentration of the forage was not influenced by rainfall or by the productivity of the plants. Yield of DM was related to the number of days of ground frost in January but not in February and March. Monthly minimum and maximum temperature was not related to the DM yield. The combination of monthly rainfall and temperature explained over 95% of the variation in yield.     

灌水对大豆产量及化学品质的影响

采用田间小区试验,研究灌水对高油大豆和高蛋白大豆品种产量和品质的影响.试验结果表明,灌水使高油大豆的产量略有提高,较对照增产1.9%,对高蛋白大豆产量未表现出增产效果.灌水对不同品质的大豆蛋白质和脂肪含量影响不同,灌水可提高高油大豆品种脂肪含量,降低蛋白质含量.相反,灌水提高高蛋白大豆品种蛋白质含量,降低脂肪含量.     

Effects of winter grazing on spring production of lucerne under Mediterranean conditions

The effects of one severe winter‐grazing of lucerne were studied over 3 years in an experiment in the Ebro Valley, Spain. In this region the crop is harvested six to seven times per season and winter grazing is a traditional practice. On average, winter‐grazing reduced the yield at the first harvest in spring by 200 kg dry matter (DM) ha^?1. This limited yield reduction of 0·06 was accompanied by an increase in the proportion of lucerne in the herbage DM from 0·54 to 0·62, a reduction in the proportion of weeds from 0·39 to 0·36, and a reduction in the proportion of dead material from 0·06 to 0·02. The crude protein concentration and the in vitro DM digestibility increased by 20 g kg^?1 DM and 0·03, respectively. The traditional practice, i.e. of grazing lucerne with sheep once in the winter season, results in only a limited reduction in yield in the spring. In addition, the spring crop has a higher nutritive value.     

膜下滴灌追肥种类对花生生长和产量的影响

为明确不同肥料种类及其相互配合追施提高花生产量的效应,确定适宜的追施肥料种类和配施方式,为花生科学施肥提供理论依据。在大田覆膜滴灌条件下,于花针期设置追施氮、钙、硼肥及其相互配施处理,研究了不同处理对花生生长和产量的影响。结果表明,与单独追施氮、硼、钙肥相比,三种肥料配合施用后单株果针数、结果数和荚果干重分别增加了18.61%~24.0%,12.50%~23.00%和12.13%~21.60%,进而提高了产量,且氮、钙和硼肥配合施用促进了花生的地上部干重、主茎高和分枝数,有利于各器官干物质积累,故以花针期追施一定比例的氮硼钙肥或氮钙肥能够有效促进花生营养生长并提高产量。     

Growth and chemical composition of wild oat (Avena fatua) under Mediterranean conditions

Wild oat (Avena fatua) is an annual cool‐season species that grows in areas with a Mediterranean climate and has potential as a forage source in Jordan. A field experiment was conducted during the growing seasons of 1999–2000 and 2000–2001 under sub‐humid Mediterranean conditions at Samta in the Ajloun Mountains, Jordan. Data on seasonal herbage mass, morphology and chemical composition of wild oat were collected at 60, 80, 100, 120 and 140 days after emergence. Plant height increased rapidly beyond 100 days after emergence. The increase in herbage mass of dry matter was gradual and peaked at 140 days after emergence. The lowest concentration of crude fibre was at 60 and 80 days after emergence, with a range of 201–263 g kg^?1 DM. Crude fibre concentrations (610–630 g kg^?1 DM) peaked at 140 days after emergence (maturity). In contrast to concentrations of crude fibre, concentrations of crude protein decreased gradually with age. The calcium and phosphorus concentrations were sufficient to meet the maintenance requirements of ewes.     

Integrated management of Ascochyta blight (Didymella fabae) on faba bean under Mediterranean conditions

Integrated disease management options (two sowing dates, three fungicides and 3–6 faba bean genotypes) in managing Ascochyta blight affecting faba bean were evaluated for three cropping seasons (2006/07–2008/09) in northern Syria for their effects on disease parameters, seed infection and dry seed yield. The combined results of the three seasons on disease parameters showed that sowing dates significantly affected final disease severity and area under the disease progress curve (AUDPC); faba bean genotypes significantly affected final disease severity, rate of disease development and AUDPC. The highest AUDPC (255% days) was observed in early than late planted (168% days) faba bean genotypes. The mean AUDPC of faba bean genotypes ranged from 189% days on genotype 1053–1325 to 234% days on ILB-1814. Only faba bean genotypes and fungicides showed significant interactions in affecting final disease severity and AUDPC. Fungicide sprays significantly affected mean percent pod infection and rate of disease development but not mean percent seed infection. Faba bean genotypes showed significant differences in dry seed yield and the yield ranged from 1.7 t ha⁻¹ in cv. Ascot to 2.4 t ha⁻¹ in faba bean genotype 945-105. Improved varieties with Ascochyta blight resistance are not currently released and available for farmers in northern Syria and the integration of early planting (November–December) with one foliar fungicide spray at vegetative stage can help to reduce Ascochyta blight severity, pod and seed infections. Chlorothalonil and azoxystrobin are widely used fungicides to manage Ascochyta blights on food legumes in many countries and one of them could be used depending on their availability and costs to managing faba bean Ascochyta blight in Syria and other Mediterranean type environments.     

不同沼肥用量对烤烟产量和质量的影响研究

通过田间试验,比较了不同沼肥施用量以及施用方法对烤烟生长发育、产量和质量的影响,结果表明:移栽15 d前,施用沼肥对烟草生长具有明显促进作用.在7个处理中,处理4单产和均价都最高,分别为2 868.0 kg/hm2和10.67元/kg,比对照提高10.39%和10.68%.处理7和6的烟碱含量适中,糖碱比协调,处理5的烟碱含量较低,糖碱比不协调;各处理的氯离子含量正常.评吸结果为中部烟叶以处理3,6,7较好,其次为处理4,处理1和5较差,上部烟叶也以处理6,5,7较好.综合结论以处理4即每公顷施用沼渣30 000kg,专用基肥360 kg,专用追肥150kg,硝酸铵25.5 kg,硝酸钾150 kg为最佳.     

Alfalfa (Medicago sativa L.) seed yield and quality under different forage management systems and irrigation treatments in a Mediterranean environment

Alfalfa (Medicago sativa L.) is widely grown as a forage crop due to its good quality characteristics and high adaptability. However, seed yield is generally considered to be of secondary importance and is characterized by fluctuating yields with often poor seed quality. A field experiment using five alfalfa cultivars (Equipe, Iside, Lodi, Robot, Romagnola) was carried out in 1995, 1996 and 1997 at Foggia (southern Italy) to evaluate the effects of four defoliation practices (H1: crop mown during early plant growth; H2: plant desiccation by chemical agent at the end of February; H3: crop mown at early flowering; H4: never cut) and two irrigation treatments (I: irrigation applied from April to beginning of seed filling; NI: non-irrigated control) on seed yield, seed yield components and seed quality (as determined by seed germination with and without accelerated ageing (AA)). The relationships between yield components (stems per m², pods per stem, seeds per pod, 1000-seed weight) were determined by path-coefficient analysis. Irrigation significantly increased seed yield; on average doubling the control yield over the three seasons. However, the potential seed yield (calculated from seed yield components) was, on average, five times the actual seed yield. The two mowing treatments produced consistently higher seed yields than either desiccated or untreated swards. Cultivar differences were evident for seed yield, with Equipe having the highest value (40% higher than the mean of the other cultivars). Irrigation improved the yield primarily because it led on average a greater than four fold increase in the density of stems (the most influential yield component). By contrast, seeds per pod and 1000-seed weight increased in the absence of irrigation. Defoliation treatments had little effect on stems per m², seeds per pod and seed weight, whereas pods per stem were reduced by desiccation. Path analyses calculated across irrigation treatments and years revealed that stems per m² had the largest positive direct effect on alfalfa seed yield under each harvest management (path-coefficient values ≥0.89), and its indirect effects on seed yield via other traits were negligible. Seed quality, as measured by germination percentage both before and after AA, remained relatively consistent across both defoliation and irrigation treatments and cultivars, but was anomalously low in the 1997 irrigated crops. Overall, the highest seed yields were obtained under irrigated conditions when crops were mown during early growth or at early flowering. The potential seed yield of alfalfa varieties is sufficient to guarantee a profitable seed harvest. However, the harvest efficiency of the combine-harvester was low (20% of the potential seed yield); thus, more appropriate harvest techniques should be used.     

Effect of winter cover crop species and planting methods on maize yield and N availability under irrigated Mediterranean conditions

Under semiarid Mediterranean conditions irrigated maize has been associated to diffuse nitrate pollution of surface and groundwater. Cover crops grown during winter combined with reduced N fertilization to maize could reduce N leaching risks while maintaining maize productivity. A field experiment was conducted testing two different cover crop planting methods (direct seeding versus seeding after conventional tillage operations) and four different cover crops species (barley, oilseed rape, winter rape, and common vetch), and a control (bare soil). The experiment started in November 2006 after a maize crop fertilized with 300 kg N ha⁻¹ and included two complete cover crop-maize rotations. Maize was fertilized with 300 kg N ha⁻¹ at the control treatment, and this amount was reduced to 250 kg N ha⁻¹ in maize after a cover crop. Direct seeding of the cover crops allowed earlier planting dates than seeding after conventional tillage, producing greater cover crop biomass and N uptake of all species in the first year. In the following year, direct seeding did not increase cover crop biomass due to a poorer plant establishment. Barley produced more biomass than the other species but its N concentration was much lower than in the other cover crops, resulting in higher C:N ratio (>26). Cover crops reduced the N leaching risks as soil N content in spring and at maize harvest was reduced compared to the control treatment. Maize yield was reduced by 4 Mg ha⁻¹ after barley in 2007 and by 1 Mg ha⁻¹ after barley and oilseed rape in 2008. The maize yield reduction was due to an N deficiency caused by insufficient N mineralization from the cover crops due to a high C:N ratio (barley) or low biomass N content (oilseed rape) and/or lack of synchronization with maize N uptake. Indirect chlorophyll measurements in maize leaves were useful to detect N deficiency in maize after cover crops. The use of vetch, winter rape and oilseed rape cover crops combined with a reduced N fertilization to maize was efficient for reducing N leaching risks while maintaining maize productivity. However, the reduction of maize yield after barley makes difficult its use as cover crop.     

Effect of irrigation frequency and amount on water use efficiency and yield of sesame (Sesamum indicum L.) under field conditions

The water-use characteristics of sesame (Sesamum indicum L.) were studied in the field under furrow irrigation. Irrigation water quantities were based on pan evaporation (E_pan) from a screened class-A pan. Treatments consisted of three irrigation intervals (I₁: 7 days; I₂: 14 days, I₃: 21 days), and four pan coefficients (K_cp 1: 0.60; K_cp 2: 0.80, K_cp 3: 1.00 and K_cp 4: 1.20). Average irrigation values for each treatment varied from 467 to 857 mm in 2003 and 398 to 654 mm in 2004. The highest seasonal evapotranspiration was obtained from the I₃K_cp 4 treatment in 2004 (1019 mm); the lowest value was observed in the I₁K_cp 1 treatment in the same year (598.0 mm). Data collected in 2003 and 2004 showed that the amount of irrigation water applied significantly the affected seed yield. However, the effects of irrigation interval on yield were not significant. On average, the K_cp 3 treatment gave the highest seed yield (1.915 t ha⁻¹), whereas K_cp 1 treatment gave the lowest (1.538 t ha⁻¹). Seasonal yield response factors (k_y) were 1.01 and 0.54 in 2003 and 2004, respectively. ET/E_pan ratios for each treatment varied from 0.3 to 1.3 in 2003 and from 0.1 to 1.1 in 2004. In conclusion, the K_cp 3 plant-pan coefficient is recommended for sesame grown under field conditions in order to maximise yield.     

追肥结束期对烤烟生长发育及产质量的影响

以K326为材料，在南昌进行了3个追肥结束期对烤烟生长发育和产质量影响的研究。试验结果表明，追肥结束期早(栽后25d)有利于提高烟株的株高、总叶数、有效叶数、单株叶面积及上部10叶的叶面积和产量；追肥结束期中(栽后35d)有利于提高上等烟比例、均价和产值；追肥结束期晚(栽后45d)有利于提高平均单叶重及上中等烟比例。认为烤烟追肥结束期以栽后25～35d为宜。     

盐分胁迫下滴灌时间对棉花生长和产量的影响

为研究盐分胁迫下不同滴灌时间对棉花生长状况和产量的影响,在石河子大学农学院试验站进行了盐池试验,设计3个盐分处理（土水质量比为1∶5时的电导率分别为0.230、0.904、1.910 dS·m^－1）和2个灌溉时间处理（5月25日、6月5日）,测定棉花株高、干物质积累量、叶绿素含量、光合指标、产量等。结果表明,提前灌水使棉花株高增长的拐点提前,可以使棉花生长发育提前,棉花株高、干物质积累量及产量随着灌水时间的提前呈上升趋势。提前灌水对盐胁迫下的棉花生长有促进作用。     

Effects of aromatic plants incorporated as green manure on weed and maize development

A 2-year field experiment was conducted in northern Greece to study the mulch effects of seven annual [anise (Pimpinella anisum L.), sweet fennel (Foeniculum vulgare P. Mill.), sweet basil (Ocimum basilicum L.), dill (Anethum graveolens L.), coriander (Coriandrum sativum L.), parsley (Petroselinum crispum (P. Mill.) Nyman ex A.W. Hill) and lacy phacelia (Phacelia tanacetifolia Benth.)] and three perennial [mint (Mentha X verticillata L.), oregano (Origanum vulgare L.) and common balm (Melissa officinalis L.)] aromatic plants, used as incorporated green manure, on the emergence and growth of barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.], common purslane (Portulaca oleracea L.), puncturevine (Tribulus terrestris L.), common lambsquarters (Chenopodium album L.) and maize (Zea mays L.). In addition, the phytotoxic potential of the abovementioned aromatic plants extracts was determined in the laboratory using a perlite-based bioassay with maize and barnyardgrass. The bioassays indicated that germination, root elongation and fresh weight of barnyardgrass were reduced by the most aromatic plant extracts. However, maize growth parameters were only affected by the extracts of anise, sweet fennel, coriander, common balm and oregano. In the field, emergence of barnyardgrass, common purslane, puncturevine or common lambsquarters was reduced by 11–50%, 12–59%, 26–79% or 58–83% in green manure-treatment plots, respectively, as compared with green manure-free plots (control). On the contrary, maize emergence was not affected by any green manure. At harvest, maize grain yield in green manure-herbicide untreated plots was 10–43% greater than that in the corresponding green manure-free plots. In particular, maize grain yield in anise, dill, oregano or lacy phacelia green manure-herbicide untreated plots was 27–43% greater than that in the green manure-free-herbicide untreated and slightly lower than that obtained in the corresponding herbicide treated plots. These results indicated that green manure of aromatic plants, such as anise, dill, oregano or lacy phacelia could be used for the suppression of barnyardgrass and some broadleaf weeds in maize and consequently to minimize herbicide usage.     

Effects of drip irrigation regimes on potato tuber yield and quality under plastic mulch in arid Northwestern China

Field experiments were conducted to study the effects of drip irrigation regimes on potato (Solanum tuberosum L.) growth, tuber yield and quality, and water use efficiency (WUE) when grown under plastic mulch in an arid area of Northwestern China in 2008, 2009 and 2010. The 2008 experiment consisted of a drip irrigation check without plastic mulch and four different drip irrigation frequency treatments with plastic mulch: once every day, once every 2 days, once every 4 days, and once every 8 days. In 2009 and 2010 the drip check treatment without mulch was irrigated at −25 kPa soil matric potential (SMP) during three potato development stages and four different SMP drip irrigation strategies were compared during the potato development stages (using plastic mulch): S1 (−25 kPa SMP during the three development stages), S2 (−25 kPa SMP during tuber initiation and bulking and −35 kPa SMP during maturation), S3 (−25 kPa SMP during tuber initiation and maturation and −35 kPa SMP during bulking), S4 (−35 kPa SMP during the three development stages). Plastic mulch negatively affected tuber yield, WUE, and tuber quality. In the presence of plastic mulch, tuber yield, specific gravity, starch content, and vitamin C content seemed to be enhanced as the irrigation frequency increased, although the differences were not statistically significant. Irrigation frequency did not affect WUE for potato grown under plastic mulch. Analysis of plant height, tuber yield and WUE showed that a drip irrigation threshold of −35 kPa SMP led to obvious water stress for potato growth in this arid area. Under plastic mulch in 2010, S2 was the optimum drip irrigation regime because of the significantly higher yield than S3 and S4, the highest WUE and significantly firmer tubers than any of the other irrigation regimes tested.