Effect of various phosphorus and calcium concentrations on potato seed tuber production

Although the effects caused in plants by the calcium (Ca)–phosphorus (P) interaction in calcareous soils are well documented, very few studies report on such effects in nutritive solutions or hydroponic cultivation. In a sand and perlite (1:1 volume) hydroponic system, effects of various P (21, 42, and 63 ppm) and Ca (120, 180, and 240 ppm) concentrations on potato tuberization were studied. A factorial experiment based on a completely randomized design with three replications was conducted. For maximum tuber yield and tuber number production, 21 and 42 ppm P was sufficient, respectively. Increase in P and Ca concentrations in nutrient solutions in early growing season resulted in an increase in shoot and root weight, leaf area, and shoot length linearly, but tuber yield and tuber number did not follow this trend. The maximum tuber specific gravity and total solid percent were also observed in 42 ppm P. The highest tuber number and tuber yield were observed in 120 ppm Ca concentration.     

Response of potatoes to different nutrient solution management in a closed hydroponic system

Ion control of nutrient solutions to control nitrogen (N), phosphorus (P), and potassium (K) was developed for Superior (medium-to-early maturing) and Atlantic (mid-late) potato cultivars grown in closed hydroponic systems in which solutions were replenished and recirculated. Results were compared with conventional nutrient solution management strategies. In the “solution replacement” treatment, nutrient solutions were completely replaced each week. In the “electrical conductivity (EC) control” treatment, water use by potato plants was compensated by adding ground water to achieve the original volume (water replenishment) and the diluted EC of the solution was adjusted to the target levels using stock solution. In “ion control” treatment, ammonium dihydrogen phosphate (NH₄H₂PO₄) and potassium nitrate (KNO₃) were added to the EC-controlled nutrient solution. The amounts increased with plant age in both cultivars. The concentrations of nitrate (NO₃), P, and K in the ion control nutrient solution could be maintained at target levels. In water replenishment, recycling of nutrient solution resulted in a progressive decrease in EC and an increase in pH. Root activity increased by 93% and 59% in the Superior and Atlantic cultivars, respectively, compared with the nutrient solution replacement. These changes decreased photosynthesis, plant growth, water use, and thus tuber growth in the Superior cultivar. Decreased growth of shoots and tubers occurred without affecting photosynthesis in the Atlantic cultivar. Although there were no significant differences in root activity, photosynthesis, or plant growth between the ion control treatment and the EC control treatment, increased tuber growth was observed in the ion control treatment, possibly as a result of the constant supply of nutrients. High tuber growth and the capability to maintain solution nutrient concentration in the ion control treatment are highly desirable for closed hydroponic systems.     

Potato (Solanum Tuberosum L.) Response to Nitrogen,Phosphorus and Potassium Fertilization Rates

Nitrogen (N), phosphorus (P) and potassium (K) management are critical in optimizing potato yield, which is also influenced by environmental factors, and crop response to these factors may vary with cultivars. Application doses and times of NPK fertilizers and use of tolerant genotypes are the most commonly employed strategies for the amelioration of potato yield. The objective of this work was to assess the response of two potato cultivars distinct by their earliness characters concerning tuber maturation (mid-early and mid-late), to different NPK regimes. Experiments were carried out with Spunta and Daifla cultivars. The impact of deficiency, optimum and excess NPK rates was tested for different tuberization stages. This study has emphasized the importance of the cultivar in potato plants response to NPK fertilization doses. Spunta showed a higher production performance compared to Daifla. Daifla was distinguished by a good vegetation throughout the development cycle but gave a very low tuber yield.

Abbreviation: NPK: Nitrogen (N), phosphorus (P) and potassium (K), DAP: Day after planting, I₂KI: Potassium Iodide, HCl: Hydrochloric acid, P₂O₅: Phosphorus pentoxide, K₂O: Potassium oxide, FW: Fresh weight, OM: Organic matter, C: Carbon, RS: Reducing sugar     

INFLUENCE OF NITROGEN SUPPLY ON CADMIUM ACCUMULATION IN POTATO TUBERS

The effect of different levels and forms of nitrogen (N) fertilizer on cadmium (Cd) concentrations in potato (Solanum tuberosum L.) tubers, a large component of the northern European diet, was investigated with the aim of decreasing the Cd content. A high and a low Cd-accumulating cultivar were used in two field trials and a pot experiment. The N fertilizers tested were balanced N- phosphorus (P)- potassium (K) 11-5-18 + micronutrients, alkaline calcium nitrate and acidic ammonium sulfate at levels of 60, 160, and 240 kg N ha^?1 at planting or (for the higher N doses) split between two or three occasions. The Cd concentration in tubers of both cultivars decreased when increasing the N fertilizer from 60 to 160 or 240 kg N ha^?1, indicating that Cd uptake and translocation are not positively correlated to the growth rate of the potato plant. A strong positive linear correlation was found between the Cd concentration in leaves at 77 days after planting and the Cd concentration in tubers at harvest, irrespective of N treatment, although the Cd concentration was three-fold higher in the leaves. The genetic variation in leaf and tuber Cd accumulation was consistent, regardless of the form of N fertilizer used. Ammonium sulfate decreased soil pH and increased tuber Cd concentration in both cultivars compared with NPK fertilizer, possibly due to increased amounts of plant-available Cd arising from the pH decrease after ammonium sulfate application. The tuber Cd concentration in the low Cd-accumulating cultivar increased when fertilized with calcium nitrate, an effect attributed to Cd availability being influenced by the increased Ca²⁺ concentration.     

马铃薯产量品质与氮磷钾吸收利用的关系

【目的】分析马铃薯品种(系)产量和品质在不同栽培条件下与养分吸收及利用的关系,为马铃薯科学施肥提供理论基础。【方法】在宁夏固原和甘肃定西开展马铃薯品种(系)田间试验,宁夏收集了76份品种(系),甘肃收集了83份,马铃薯试验均采用当地水肥管理技术。成熟期测定产量及产量构成因素,取样分析马铃薯品质和氮磷钾养分含量,以及土壤有机质和速效养分含量。【结果】两地马铃薯块茎产量差异不显著。将马铃薯产量分为<30 t/hm² (低)、30～45 t/hm² (中)和>45 t/hm² (高) 3个等级,宁夏种植的76个品种(系)中低产、中产、高产的占比分别为27.6%、34.2%、38.2%,甘肃种植的83个品种(系)中的占比分别为15.7%、49.4%、34.9%。随着不同马铃薯品种(系)产量的不断增加,干物质和淀粉含量呈现增加趋势,而蛋白质含量则呈现降低趋势。无论产量水平高低,每生产1 t马铃薯块茎需吸收N 2.9 kg、P 0.5 kg、K 4.0 kg。产量与氮磷钾养分吸收量呈显著正相关,维生素C和蛋白质含量与氮磷...     

Fertility Response of Potato to Municipal Wastewater and Inorganic Fertilizers

This study evaluated fertilizer contribution of municipal wastewater on potato (Solanum tuberosum L.) cultivation in a split-plot experiment having two factors: water quality with 5 levels and fertilizer with 2 levels. Irrigation by raw wastewater supplied 16, 13, 13, 23, 1.7, and 83% of nitrogen (N), phosphorus (P), potassium (K), sulfur (S), zinc (Zn), and boron (B) requirement of potato, respectively. Wastewater compared to freshwater, improved plant height, vigority, area coverage, leaf area index (LAI), stem per plant, number and weight of tuber per plant, above-ground dry matter (ADM), and tuber yield of potato. Averaged over 3 years, irrigation by 75 and 100% (raw) wastewater with recommended standard fertilizers produced the maximum, but identical, tuber yield. Wastewater raised N, P, and K contents in potato plants and tubers. Irrigation by wastewater could reduce the fertilizer requirement of potato by 10–15%. However, it caused high accumulation of total coliform (TC) and faecal coliform (FC) on potato skin, restricting the use of the produce.     

宁夏马铃薯氮、 磷、 钾养分的吸收累积特征

【目的】马铃薯氮、 磷、 钾养分吸收累积特点国内外已有不少报道,但在宁夏地区的生产条件下尚缺乏系统研究,马铃薯配方施肥技术推广中也缺少施肥参数,难以确定合理的施肥量。因此,针对宁夏地区马铃薯种植基地的土壤条件,系统分析马铃薯干物质累积和氮、 磷、 钾养分含量,探明其对氮、 磷、 钾养分吸收累积特点,以期为马铃薯的精准施肥提供科学依据。【方法】采用田间试验和室内测定相结合的方法。于2012年分别在宁夏西吉县、 原州区、 红寺堡和同心县马铃薯种植基地进行肥料田间试验,按照当地推荐的施肥量统一施肥量和施肥方法(农家肥、 70%氮肥、 全部磷、 钾肥基施,30%氮肥在现蕾期追施),在马铃薯不同生育期采集植株样品,测定不同器官干重和氮、 磷、 钾含量,分析不同生育期马铃薯干物质累积量、 氮、 磷、 钾含量及其吸收累积量的变化特点。【结果】1)从不同种植基地来看,红寺堡区马铃薯干物质累积量最高,其次是原州区和西吉县,同心县最低;马铃薯干物质累积量随生育期的推进而增加,符合Logistic曲线,幼苗期、 块茎形成期、 块茎膨大期和淀粉累积期的干物质累积量分别占总累积量的5%、 20%、 40%和35%。2)马铃薯植株氮含量随生育期而降低,其变异系数较大; 磷、 钾含量随生育期呈先增后减的变化态势,但变异系数较小; 氮、 磷含量叶片高于其他器官,钾含量茎秆中较高。3)马铃薯氮、 磷、 钾吸收累积量在红寺堡区最高,原州区和西吉县居中,同心县最低;苗期氮、 磷、 钾的吸收量分别占全生育期总吸收量的11%、 6%、 8%,块茎形成期占28%、 23%、 31%,块茎膨大期占36%、 39%、 41%,淀粉积累期占25%、 31%、 20%;成熟期块茎中氮和磷的累积量分别占各自总累积量的60%以上,钾的累积量占50%。【结论】供试土壤条件下,马铃薯干物质累积量及养分吸收量因种植基地、 生育期和器官不同而异。从不同种植基地来看,红寺堡区马铃薯的干物质及氮、 磷、 钾累积量较高,原州区和西吉县居中,同心县最低;干物质及氮、 磷、 钾累积量随生育期的变化符合Logistic曲线,具有明显的阶段性特点,块茎膨大期累积最多,块茎形成期和淀粉积累期次之;马铃薯根、 茎和叶中吸收累积的氮、 磷、 钾占同期总累积量的比例随生育期而降低,但块茎则相反,氮、 磷、 钾吸收累积量随生育期而增加,成熟期块茎中吸收累积的养分量占全株的一半以上。     

Effects of chromium on the nutrient element content and morphology of tomato

An hydroponic experiment was conducted to study the effects of chromium (Cr³⁺) on the distribution of nitrogen (N), phosphorus (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), and Cr in the plant, and the growth and yield of a tomato plant. Three Cr treatments were established (0, 50, and 100 mg Cr/L in a nutrient solution). In general, the nutrient element concentration in stems and branches was significantly affected by the Cr treatments. Chromium accumulated preferentially in the roots and low transport was detected to the aerial parts. Growth was diminished due to Cr presence in the nutrient solution. Total yield was not affected, however the number of fruits was diminished and the mean fresh weight of fuit increased with each increment of Cr in the nutrient solution. Chromium was not detected in the edible part (fruit) of the plant.     

Effect of Integrated Management of Nitrogen Fertilizer and Cattle Manure on the Leaf Chlorophyll,Yield, and Tuber Glycoalkaloids of Agria Potato

Management of nutrients, especially nitrogen (N), is one of the most important factors in potato production. Cattle manure and mineral fertilizers are two sources of N that can affect the quality and quantity of potato yield. The effects of the use of cattle manure (5, 10, 15, and 20 ton ha^?1), N fertilizer (50, 100, and 150 kg ha^?1), and their interaction on tuber yield, chlorophyll content, and glycoalkaloid concentration were evaluated during field experiments in Iran in 2008 with a randomized complete block design with a factorial arrangement of three experimental replications. At the time of flowering, chlorophyll a, b, and total (chlorophyll) were recorded by spectrophotometry. Furthermore, at the end of the growth season, tuber yield was calculated and tuber glycoalkaloids were measured by the colorimetric method for the assessment of quantitative and qualitative characteristics of potato. Chlorophyll a, b, and total content increased linearly and very significantly in response to the application of manure and N fertilizer. The interaction between manure and N fertilizer was also significant; somehow the maximum content of total chlorophyll [1.448 mg g^?1 fresh weight (FW)] was obtained by using 150 kg N + 20 ton of manure per hectare. Cattle manure, N fertilizer, and their combination had a highly significant effect on tuber yield. Maximum tuber yield (36.8 ton ha^?1) was obtained by the utilization of 20 ton manure + 150 kg N per hectare. Total glycoalkaloid content was affected by the N application only. It showed a linear increase in the presence of increased concentration of N fertilizer.     

水氮耦合对膜下滴灌马铃薯产量、品质及水分利用的影响

该文通过田间试验,研究在西北旱区对膜下滴灌条件下水氮耦合效应及其对马铃薯产量、品质和水分利用效率的影响,从而确定马铃薯适宜的水氮用量,以求达到节水、节肥和高产优质的目的。试验设置2个土壤湿润比水平:40%(P1)和70%(P2),5个施氮水平:90(N1)、135(N2)、180(N3)、225(N4)、270kg/hm2(N5),共10个处理。试验结果表明:相同水分条件下,马铃薯块茎质量、块茎淀粉含量、块茎维生素C含量、耗水量、产量和水分利用效率都随施氮量的增加而呈抛物线趋势变化,块茎蛋白质含量随施氮量的增加呈增加趋势。相同氮肥条件下,湿润比P2处理的马铃薯块茎质量、块茎淀粉含量、块茎维生素C含量、块茎蛋白质含量均高于湿润比P1,湿润比P2处理的耗水量比湿润比处理P1高11%,湿润比P2处理的产量比湿润比处理P1高5%,但是湿润比P1处理的水分利用效率比湿润比P2处理高5.4%。其中,P2N3处理的马铃薯单株块茎质量、块茎维生素C含量表现最好,P1N5处理的马铃薯块茎蛋白质含量最高,P2N2处理的马铃薯块茎淀粉含量和产量表现最优,产量最高为54187kg/hm2,P1N2处理的水分利用效率最高为12.86kg/m3。P2N3处理的马铃薯高产优质,且水分利用效率较高,是西北旱区膜下滴灌条件下马铃薯生产中适宜的水氮组合。     

典型黑土不同施氮量对马铃薯产量和氮素利用率的影响

  【目的】  我国马铃薯生产中养分不平衡施用问题严重，过量施氮不利于农业可持续发展和生态环境保护。在养分专家系统 (Nutrient Expert，NE) 推荐施肥量基础上，研究不同施氮量对马铃薯产量、养分吸收和氮肥利用率的影响，为马铃薯推荐施肥提供科学依据。  【方法】  于2017―2018年，分别在黑龙江克山县不同地块进行2个田间试验，在NE系统推荐施肥量 (N₁₈₀) 的基础上，设减施推荐施氮量的50% (N₉₀)、25% (N₁₃₅) 和增施25% (N₂₂₅)、50% (N₂₇₀) 4个处理，并以不施氮肥的处理作对照 (N₀)。测定马铃薯产量、养分吸收量、肥料利用率等指标。  【结果】  017和2018年马铃薯产量均以NE系统推荐的N₁₈₀处理最高，较N₀处理两年平均增产40.4%。N₉₀和N₁₃₅处理低施氮水平 (≤ 180 kg/hm2) 下，随着施氮量的增加，马铃薯产量也明显增加，当施氮量超过NE系统推荐的施肥量 (180 kg/hm2) 后，继续增施氮肥对产量增加无明显作用。与N₀处理相比，两年N₁₈₀处理的块茎、秸秆和全株氮素吸收量平均增幅分别为49.8%、58.2%和52.0%，磷素吸收量平均增幅为36.3%、52.2%和39.8%，钾素吸收量平均增幅为26.4%、46.8%和31.3%，生产1 t块茎 (鲜重) 所需要的氮、磷、钾养分分别为4.6、1.1和5.8 kg。N₁₈₀处理的产量和氮磷钾养分吸收量均为最高，氮素农学效率和回收率与N₉₀和N₁₃₅处理差异不显著。  【结论】  在不超过马铃薯氮素需求条件下，增加氮肥投入可显著增加马铃薯产量和氮素吸收量，NE系统能够指导马铃薯科学施肥，保障马铃薯产量，提高氮肥利用效率。     

Effect of humic acid multinutrient fertilizers on yield and nutrient use efficiency of potato

A field experiment was conducted to study the effect of humic acid multinutrient fertilizers like Grow Flow 45H and HA-NPK complex on crop yield, nutrient content and uptake, and nutrient use efficiency of potato. Application of Grow Flow 45H (humic acid multinutrient liquid fertilizer) at recommended dose increased the tuber yield by 9.3% as compared to chemical fertilizer. Nitrogen (N), phosphorus (P) and potassium (K) content of the Grow Flow 45H treated plants were 2.89, 0.33 and 1.58% in shoots and 1.89, 0.21 and 1.03% in tubers, respectively which were significantly higher than the other treatments. Grow Flow 45H increased the N, P and K use efficiencies by 16.4%, 9.3% and 18.3% respectively over chemical fertilizer. Though HA-NPK complex fertilizer (developed in the laboratory) was not significantly different from chemical fertilizer in respect of yield, the contents and uptake, and use efficiencies of N, P and K; however the former was found better than the latter.     

Pulp Fiber Residue and Supplemental Irrigation on Yield and Nutrient Uptake of Potato

ABSTRACT

Organic matter levels combined with drought periods during the growing season have adverse impacts on rain-fed potato production in coarse textured soils of eastern Canada. Using pulp fiber residues (PFR) may build up soil organic matter, improve crops yield and nutrient uptake, and reduce the need for supplemental irrigation in this region. A box experiment with 3 rates of PFR [0, 45, and 90 Mg ha^{? 1} dry mater carbon (C) basis] with or without supplementary drip irrigation was established in a sandy loam soil in New Brunswick, Canada. Red clover, barley, and potato were cultivated as three crops of the rotation in 1999, 2000, and 2001, respectively. The PFR only applied before red clover in fall 1998. Selected soil chemical and physical properties were measured before planting and after harvest. Crops yield and nitrogen (N), phosphorus (P), and potassium (K) accumulation were determined at harvest. Soil organic-C content, bulk density and water holding capacity were improved by PFR application. Red clover and barley biomass production were significantly increased by PFR application. This effect was promoted by supplemental irrigation. Potato tuber yield was not affected by PFR and it was higher in rain-fed compared to supplementary irrigated system. Although, there was some initial evidence of N immobilization but generally PFR application increased N, P, and K bioavailability. This research has demonstrated that PFR can successfully be used as soil amendment in coarse textured soils without any adverse effect.     

Crop Productivity and Nutrient Bioavailability in a Potato-Based Three-Year Rotation as Affected by Composted Pulp Fiber Residue Application and Supplemental Irrigation

The possibility of using composted pulp fiber residues (CPFR) in a potato rotation in eastern Canada was tested. Three rates of CPFR (0, 45, and 90 Mg C ha^?1) with or without supplementary irrigation were applied. Pea (Pisum sativum L.), corn (Zea mays L.), and potato (Solanum tuberosum L.) were cultivated in 2002, 2003, and 2004, respectively. Soil total carbon (C) and nitrogen (N), bulk density, and water-holding capacity were improved by CPFR. Pea and corn yields and total dry matter were increased using CPFR. Supplemental irrigation increased pea yield compared with the rain-fed system. Total tuber yield was increased by CPFR in the irrigated but not in the rain-fed system. The CPFR application increased plant-available phosphorus (P) and potassium (K) in all rotation crops. Nitrogen accumulation in all rotation crops except potato was increased by CPFR. The CPFR application successfully enhanced soil fertility and crop productivity without any adverse effects.     

MONOPOTASSIUM PHOSPHATE AS AN IN-SEASON FERTIGATION OPTION FOR POTATO

Monopotassium phosphate (MKP) is a potential option for fertigating phosphorus (P) in potato (Solanum tuberosum L.) when petioles are low in P and high in nitrogen (N); which is a situation where using ammonium polyphosphate (APP) could potentially result in excessive N application. Fertilizer trials were conducted in 2004–2006 with 0 or 56 kg P₂O₅ ha^?1 fertigated as either APP or MKP as a supplement to the pre-plant P (112 or 224 kg P₂O₅ ha^?1) broadcast applied to all plots. Supplemental P fertigation increased petiole P concentration, US No. 1 yield, and total yield over the control not receiving any in-season P fertilizer regardless of source. In addition, MKP increased tuber specific gravity. These results support previous studies showing that fertigated P can be used to increase potato yields when petiole P concentrations are low and that MKP is a viable substitute for APP fertilizer when fertigation is necessary.     

Tuber formation as influenced by the C : N ratio in potato plants

Increasing the tuber number per plant and promoting tuber formation are important goals for potato production. Thus, it is of significance to understand how environmental factors affect tuber formation, which relates to the development of agronomical practices. The objective of this research was to test whether changing the CO₂ or N supply level could alter the C : N ratio in potatoes, and whether a change of the C : N ratio in potatoes closely correlates with tuber formation in potato plants. Potato plantlets were grown in greenhouse with varied CO₂ or N levels. The C and N concentrations of plants were measured, and the tuber number and tuber weight were recorded after different growth times. The results show that the C : N ratios in the potato plants increased with increasing CO₂ concentration and that potato plants treated with higher CO₂ concentrations form tubers earlier. A decrease in the N supply also resulted in a higher C : N ratio and earlier tuber formation. Therefore the hypothesis proposed previously is supported by the present work. In addition, the results that C concentration in plants remained stable under different CO₂ or N levels imply that the variation of C : N ratio in the potato plants is mainly due to a change of N concentrations which decreased as the environmental CO₂ concentration increased, while increased as the N supply level increased.     

氮磷减量施肥对琯溪蜜柚果实产量和品质的影响

【目的】 针对当前福建省平和县琯溪蜜柚施肥过量问题,研究分析了氮磷减量施肥对琯溪蜜柚果实产量和品质的影响,对提高琯溪蜜柚果实产量和品质,促进当地琯溪蜜柚产业绿色高效发展具有重要意义。 【方法】 采用田间试验方法, 以酸柚砧木白肉琯溪蜜柚为试验材料,以前期问卷调查结果为依据设置氮磷最高施肥量:N 1.60 kg/(plant·a),P₂O₅ 1.30 kg/(plant·a),结合当地土壤养分状况和琯溪蜜柚需肥特性,以30%梯度递减氮肥用量,分别为高氮 (N1)、中氮 (N2) 和低氮 (N3),以35%梯度递减磷肥用量,分别为高磷 (P1)、中磷 (P2) 和低磷 (P3),采用双因素交互设计设置N1P1、N1P2、N1P3、N2P1、N2P2、N2P3、N3P1、N3P2、N3P3共9个处理。分别于促花期 (3月上中旬)、稳果期 (5月中旬)、壮果期 (7月下旬或8月上旬) 和越冬期 (11月中下旬) 将氮磷钾肥以不同配比施入土壤,于3月上中旬在树冠滴水线范围内撒施钙镁肥。 【结果】 减少氮磷肥用量不仅没有引起琯溪蜜柚产量的显著降低,反而使其有不同程度的增产,且氮肥减量的增产幅度大于磷肥减量。氮磷减量施肥可以提高果实可食率、可溶性固形物、固酸比和维生素C含量,并降低纵横比、单果重、果皮厚和可滴定酸含量,尤其以中氮中磷 (N2P2) 处理的果实品质整体较好。随着施氮水平的降低,果皮厚和可滴定酸含量表现出持续减少趋势,中氮水平 (N2) 的可食率、可溶性固形物和维生素C含量与高氮水平 (N1) 相比均显著增加;随着施磷水平的降低,中磷水平 (P2) 的果实纵横比和维生素C含量较高磷水平 (P1) 显著减少,低磷水平 (P3) 的可食率较高磷水平 (P1) 显著增加。氮磷交互作用对单果重、可溶性固形物有极显著影响,对果皮厚、出汁率、可食率和维生素C含量有显著影响。主成分分析和聚类分析结果表明,中氮中磷 (N2P2) 处理果实主成分综合得分最高,达2.20分,高出第二名中氮低磷 (N2P3) 处理167.06%,其果实内外品质整体较好。 【结论】 在当前的氮磷施肥量下,减少氮磷用量不会导致琯溪蜜柚减产,反而具有增产和明显改善果实品质的效果。其中以氮肥减量30%,磷肥减量35%,即施纯N 1.12 kg/(plant·a),P₂O₅ 0.85 kg/(plant·a) 时产量、品质俱佳。      

Effect of Water pH on Yield and Nutritional Status of Greenhouse Cucumber Grown in Recirculating Hydroponics

ABSTRACT

Cucumbers are produced in integrated hydroponic and aquaculture systems (aquaponics). Aquaponics balances pH for plants, fish, and nitrifying bacteria. Nitrification prevents buildup of toxic waste ammonia by conversion to nitrate (NO₃ ^?)- nitrogen (N). The pH for hydroponic cucumbers (5.5–6.0) and nitrification (7.5–9.0) requires reconciliation to improve systems integration. Cucumbers were grown at pH of 5.0, 6.0, 7.0, and 8.0 with additional foliar sprays at pH 7.0 and 8.0. Plant shoot dry weight, length, N, and phosphorus (P) content at 14 DAT were similar from pH 5.0 to 7.0, but reduced at pH 8.0. Nutrient solution and shoot dry matter Mn and Fe decreased as pH increased. Foliar sprays had no effect on cucumber fruit yield. Early yield was higher at pH 5.0 compared to pH 8.0 but total yield was unaffected by pH. Cucumbers in recirculating culture may be maintained at pH levels more optimum for nitrification (7.5–8.0) except during production for early season markets.     

Changes in Soil Properties in Response to Irrigation of Potato by Urban Wastewater

This study evaluated the physicochemical changes in the soil of potato field that was irrigated by fresh water, differentially diluted wastewater and undiluted wastewater (hereafter called wastewater). The potato crop was cultivated for consecutive three seasons under fertilized and unfertilized conditions. The wastewater contained higher concentrations of organic carbon (C), nitrogen (N), phosphorus (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), sulfur (S), zinc (Zn) and boron (B) and lower concentrations of heavy metals. In this study, properties of wastewater-irrigated soil were compared with fresh water-irrigated soil. The application of wastewater reduced the bulk density of the surface soil by 2.83% and augmented the porosity by 6.02%. The unsaturated hydraulic conductivity and water retention capacity of the soil were improved under wastewater irrigation. Soil pH increased due to wastewater application but decreased, to a smaller extent, due to fertilizer application. Soil EC increased both with wastewater and fertilizer application; both parameters changed significantly in the top 0–15 cm soil layer. But, at the deeper layers, they were not affected by wastewater application. The organic C, total N, available P and S of the soils increased significantly (p = 0.05) when potato field was irrigated with raw wastewater. The organic C increased by 23.80% under wastewater irrigation in the top soil layer. The N content of the soil showed similarities with the organic C contents. Exchangeable Na, K, Ca, Mg; Zn and B of the soil also increased significantly with wastewater application. So, irrigation with urban wastewater is suggested to improve soil fertility as well as to ease pressure on the fresh water in the area of water scarcity.     

氮肥用量对膜下滴灌冬马铃薯产量和经济效益的影响

通过田间试验研究不同氮肥用量对膜下滴灌冬马铃薯生长、产量和经济效益的影响,通过分析马铃薯产量、经济与农学效益随氮肥用量的变化趋势提出冬马铃薯生产上适宜的氮肥用量范围。结果表明,膜下滴灌条件下,马铃薯生育期随氮肥用量的增加逐渐延长,马铃薯叶面积指数、单株结薯数、单株薯重和块茎产量随氮肥用量的增加呈先增加后降低的趋势,均在345 kg/hm²施氮量时最高,且株高和大薯重高于其他处理。施氮量在0～420 kg/hm²时对马铃薯出苗率影响不大,而施氮量达495 kg/hm²时出苗率和块茎产量显著降低;施氮效益、施氮纯收入、氮肥产投比和农学效率在施氮量195～345 kg/hm²时均随氮肥用量的增加而增加,超过345 kg/hm²施氮量时逐渐下降,施氮量为495 kg/hm²时显著降低。马铃薯产量对氮肥用量的反应通过二次多项式模型分析得出,马铃薯最高产量施氮量和经济最佳施氮量分别为341.7、327.1 kg/hm²,而最高产量与经济最佳产量二...