无土栽培营养液消毒技术研究与应用

为了减少营养液排放对环境造成的污染,世界范围内的无土栽培系统正逐步由开放式向封闭式转变.封闭式无土栽培系统中根系病害的传播危险急剧增加,因此营养液消毒技术的研究和应用发展迅速.该文综述了国内外营养液消毒方法、原理、成本及应用效果,重点介绍了营养液消毒新技术-慢砂过滤.     

无土栽培营养液消毒技术研究与应用

为了减少营养液排放对环境造成的污染，世界范围内的无土栽培系统正逐步由开放式向封闭式转变。封闭式无土栽培系统中根系病害的传播危险急剧增加，因此营养液消毒技术的研究和应用发展迅速。该文综述了国内外营养液消毒方法、原理、成本及应用效果，重点介绍了营养液消毒新技术－慢砂过滤。     

Physiological,nutritional and growth responses of melon (Cucumis melo L.) to a gradual salinity built-up in recirculating nutrient solution

Minimizing salinity impacts on yield in melon crops cultivated in closed-loop hydroponic systems requires better understanding of the physiological impact of gradual salt accumulation in the recycled solution. To attain this objective, different sodium chloride (NaCl) concentrations in the irrigation water, i.e. 0.7, 2.5, and 5 mM, were applied in two cropping seasons (winter-spring;WS and spring-summer;SS). In both seasons plant biomass and yield were negatively affected only in high NaCl-treated plants, due to stomatal limitations, which restricted carbon dioxide (CO₂) diffusion into the leaf, osmotic and salt-specific effects. However, a progressive NaCl built-up to maximum concentrations in the root zone solution of 15 (WS) and 20 mM (SS), enabled plants to preserve several physiological mechanisms, thereby adjusting growth and yield without impairing fruit quality. Our results suggest that the use of irrigation water, containing up to 2.5 mM NaCl, is feasible in melon crops grown in closed-loop hydroponic systems, without yield and quality losses.     

根区温度对黄瓜生长和土壤养分利用的影响

采用盆栽试验,研究了不同土壤温度（对照不加温10?2℃、加温到18?2℃、加温到26?2℃）和不同盐分含量土壤（1#>2#>3#）对黄瓜干物质积累、矿质元素吸收与分配特征的影响,并对土壤性状、酶活性的影响进行了研究。结果表明：与对照不加温10℃相比,加温到18℃和26℃可以克服冬季土壤低温对黄瓜生长的限制作用,促进黄瓜苗的正常生长,为黄瓜开花结果提供保障。随着土壤温度升高,黄瓜果实干物重增加;加温到26℃与加温到18℃相比,三种盐分含量土壤1#、2#、3#黄瓜果实干物重分别增加了41.84%、15.49%、3.59%,同时反映了盐分含量高的土壤加温对提高黄瓜产量更明显。与对照不加温相比,土壤加温使黄瓜单株N、P、K的总摄取量增加,促进黄瓜根系吸收的养分向地上部转移,使土壤中速效养分（碱解氮、速效磷、速效钾）含量降低。土壤加温使土壤脲酶活性明显升高,对磷酸酶和过氧化氢酶影响不大。因此,冬季升高土壤温度可增加黄瓜产量,促进土壤养分转化,提高土壤养分利用率。     

Effects of mycorrhiza colonization on growth,root exudates,antioxidant activity and photosynthesis trait of cucumber grown in Johnson modified nutrient solution

Mycorrhiza can improve plant growth and increase nutrient uptake. This study was conducted as factorial experiment based on complete random design (CRD) to study effects of mycorrhiza inoculation under limited iron (Fe) condition on antioxidant activity, phenol content and photosynthesis trait of cucumber (Cucumis sativus cv. N3). Treatments were Johnson modified nutrient solution (MNS) with 25% Fe (MNS1) = 0.57 mg/L Fe, 50% (MNS2) = 1.14 mg/L Fe and 100% (MNS3) = 2.3 mg/L Fe and mycorrhiza inoculation (M+) and non-mycorrhiza inoculation (M?) with 3 replications under hydroponic conditions. The results showed that plant growth and shoot phenol content decreased in the MNS1 treatment; whereas phenol content of the root exudates and antioxidant activity significantly increased in this treatment. All photosynthesis attribute increased in the MNS3 treatment. Mycorrhiza inoculation increased plant growth, phenol content, antioxidant activity and photosynthesis trait of cucumber. Also, mycorrhiza inoculation enhanced SPAD value in the MNS2 treatment and photosynthesis rate, transpiration and mesophyll conductance in all the modified nutrient solutions. Moreover, mycorrhiza symbiosis was stimulated by the internal carbon dioxide (CO₂) content of the stomata in the MNS2 and MNS3 treatments. Furthermore, Mycorrhiza inoculation improved phenol content of the shoots and roots in all the nutrient solutions, whereas antioxidant activity was affected by mycorrhiza inoculation only in the MNS2 treatment.     

Effect of different macronutrient cation ratios on macronutrient and water uptake by melon (Cucumis melo) grown in recirculating nutrient solution

The aim of the present study was to determine uptake ratios between macronutrients and water for melon (Cucumis melo L. cv. Dikti) grown in a closed soilless cropping system. The obtained data can be used to establish standard nutrient solution compositions for melon crops grown in closed hydroponic systems under Mediterranean climatic conditions. Nutrient and water uptake by plants in the closed hydroponic system was compensated for by supplying replenishment nutrient solutions (RNS) differing either in the concentrations of K⁺, Ca²⁺, and Mg²⁺ or in their mutual ratio. The RNS, used as control treatment, had an electrical conductivity (EC) of 1.74 dS m^?1 and contained 6.5 mM K⁺, 2.8 mM Ca²⁺, and 1.0 mM Mg²⁺ (K⁺ : Ca²⁺ : Mg²⁺ = 0.63 : 0.27 : 0.10). Control RNS was compared with two other RNS, both with a high Ca²⁺ level (4.2 mM). The K⁺ and Mg²⁺ levels in these two RNSs were: (1) not altered (corresponding to a ratio of K⁺ : Ca²⁺ : Mg²⁺ = 0.55 : 0.36 : 0.09; EC = 2.0 dS m^?1) or (2) increased to maintain the same K⁺ : Ca²⁺ : Mg²⁺ ratio as in the control RNS (EC = 2.45 dS m^?1). Nutrient to water uptake ratios, commonly termed uptake concentrations (UCs), were assessed by two alternative methods, i.e., (1) estimating the ratio between nutrient and water removal from the system or (2) estimating the ratio between the mass of the nutrient that was recovered from plant biomass and the water consumption. Over the two methods, mean UCs for N, P, K, Ca and Mg were 15.4, 1.31, 5.47, 3.78, and 1.02 mmol L^?1, respectively, and tissue analysis resulted in a K : Ca : Mg molar ratio of = 0.55 : 0.34 : 0.11 in the whole plant. Moreover, the UCs tended to decrease as the crop aged although, in absolute values, the mass of nutrients absorbed increased following dry‐weight accumulation. Based on the obtained results, adapting the composition of the nutrient solution at least three times during the cropping period of melon is recommended. Further, the results revealed that the damage caused by the increase of the EC when attempting to maintain a target K⁺ : Ca²⁺ : Mg²⁺ ratio in the replenishment NS is higher than the benefits from the optimal cation ratio. Increasing K⁺ and Mg²⁺ concentration in addition to that of Ca²⁺ to maintain a standard K⁺ : Ca²⁺ : Mg²⁺ ratio raises the EC in the root zone (4.62 dS m^?1), due to increased accumulation of nutrients, thereby reducing the mean fruit weight and concomitantly the total fruit yield (20% decrease). Leaf gas exchange, chlorophyll parameters and fruit taste quality were not influenced by the differences in macronutrient cation concentrations or ratios in the RNS, whereas phenolics and antioxidant capacity in melon fruit were enhanced by the increased root‐zone EC.     

Effects of adding wood vinegar to nutrient solution on the growth,photosynthesis, and absorption of mineral elements of hydroponic lettuce

This study was conducted to determine whether using wood vinegar instead of nitric acid to adjust the pH of nutrient solution in hydroponics had any effects on the lettuce. Photosynthesis, mineral elements, water absorption, and the growth of the lettuce were all comparable to those of lettuce in the control group, in which nitric acid was used to adjust the pH. Nitric acid was added to half a unit of Enshi formula to adjust the pH of the control group. The rates of growth, water and mineral element absorption, and photosynthesis were low in lettuce plants grown in nutrient solution with 1 ml L^?1 wood vinegar. However, the lettuce grown in solutions with 0.25 ml L^?1 wood vinegar showed no significant differences from the control group. Therefore, wood vinegar concentration of 0.25 ml L^?1 was found to be sufficient to keep the pH of the nutrient solution within the optimum range for growth.     

Responses of barley to hypoxia and salinity during seed germination,nutrient uptake,and early plant growth in solution culture

The resistance of most plants to salt can be impaired by concurrent waterlogging. However, few studies have examined this interaction during germination and early seedling growth and its implications for nutrient uptake. The aim of the study was to examine the response of germination, early growth, and nutrient uptake to salt (NaCl) and hypoxia applied to barley (Hordeum vulgare L. cv. Stirling), in solution culture. Hypoxia, induced by covering seeds with water, lowered the germination from 94% to 28% but salinity and hypoxia together lowered it further to 13% at 120 mM NaCl. While the germination was 75% at 250 mM NaCl in aerated solution, it was completely inhibited at this NaCl concentration under hypoxia. Sodium ion (Na⁺) concentrations in germinated seedlings increased with increasing salinity under both aerated and hypoxic conditions during germination, while K⁺ and Mg⁺ concentrations were decreased with increasing salinity in 6 d old seedlings. After 20 d, control seedlings had the same dry weights of the roots and shoots with and without hypoxia but at 10 mM NaCl and higher, shoot and root dry weight was depressed with hypoxia. Sodium ion increased in roots and shoots with increased NaCl under both aerated and hypoxic conditions while K⁺ was depressed when salinity and hypoxia were applied together and Ca²⁺ was mostly decreased by NaCl. In general, hypoxia had greater effects on nutrient concentrations than NaCl by decreasing N, P, S, Mg, Mn, Zn, and Fe in shoots and by increasing B concentrations. The threshold salinity levels decreased markedly for germination, uptake of a range of nutrients, and for seedling growth of barley under hypoxic compared to well‐aerated conditions.     

Boron nutrition and mobility,and its relation to the elemental composition of greenhouse grown root crops. II radish

Abstract

The elemental distribution between the leaves and roots of mature radish (Raphanus sativus cv Cherry Belle) plants grown in the greenhouse with various concentrations of nutrient solution B or Ca was determined to assess the role of phloem in the provision of nutrients to the root, and the retranslocation of B under deficient conditions. The relative composition and accumulation of elements in different parts, and the ratio of their concentrations in leaves:roots were used as a measure of their uptake, relative mobility and retranslocation. The data indicate that B, but not Ca is retranslocated in the phloem to the roots when that particular element was in short supply in the nutrient solution. B deficiency induced brown heart disorder in radish roots but the severity was dependent on the degree of deficiency below 28 μg g^‐l DM in the root. These symptoms were alleviated when the root B concentrations were enhanced by foliar applications of B. It is concluded that radish responded to B deficiency in a fashion similar to that reported previously for rutabaga and that it might serve as a time‐saving model system for examining the mechanisms responsible for brown heart in rutabaga.     

不同供Zn量对三种小麦基因型幼苗生长和养分吸收的影响

采用溶液培养方法,研究了不同供Zn量(0、0.5、104、0.mg/L,分别用Zn0、Zn0.5、Zn10、Zn40表示)对三种亲缘关系很远的半冬性小麦基因型郑麦9023、陕512、西农979幼苗生长发育及Zn、Fe、Mn吸收的影响,以期为筛选耐高锌的小麦基因型提供理论依据。结果表明,不供Zn时小麦幼苗未出现缺Zn症状;Zn0.5对小麦的正常生长影响较小。三种基因型小麦的幼苗在过量供Zn(Zn10、Zn40)时均受到严重伤害:抑制小麦分蘖、根系及地上部生长,叶片叶绿素SPAD值显著降低,小麦植株尤其是根部的耐性指数降低;施入的Zn的转运率显著降低,却大大提高了小麦植株尤其是根部的Zn含量和吸收量,但Zn10时幼苗体内Zn含量和吸收量大于Zn40,且Zn10比Zn40更能在根部积累Zn。Zn与Fe的吸收在根部似乎表现为互助作用,而地上部表现为颉颃作用;Zn与Mn之间表现出强烈的颉颃作用。过量供Zn时以西农979耐性指数最大,Zn转运率最高,植株体内的Fe、Mn含量也高。总之,供Zn量为通常配方的51～0倍时对小麦幼苗的生长尚无明显影响;1002～00和4008～00倍时则能对小麦幼苗造成严重伤害,三种供试小麦基因型中以西农979对过量Zn毒害的耐性最强。     

Varietal tolerance to Zinc deficiency in wheat and barley grown in chelatorbuffered nutrient solution and its effect on uptake of Cu,Fe, and Mn

Tolerance to zinc (Zn) deficiency was examined for three wheat (Triticum aestivum L.) and three barley (Hordeum vulgare L.) varieties grown in chelator‐buffered nutrient solution. Four indices were chosen to characterize tolerance to Zn deficiency: (1) relative shoot weight at low compared to high Zn supply (“Zn efficiency index”), (2) relative shoot to root ratio at low compared to high Zn supply, (3) total shoot uptake of Zn under deficient conditions, and (4) shoot dry weight under deficient conditions. Barley and wheat exhibited different tolerance to Zn deficiency, with barley being consistently more tolerant than wheat as assessed by all four indices. The tolerance to Zn deficiency in the barley varieties was in the order Thule=Tyra>Kinnan, and that of wheat in the order Bastian=Avle>Vinjett. The less tolerant varieties of both species accumulated more P in the shoots than the more tolerant varieties. For all varieties, the concentrations of Mn, Fe, Cu, and P in shoot tissue were negatively correlated with Zn supply. This antagonism was more pronounced for Mn and P than for Cu and Fe. Accumulation of Cu in barley roots was extremely high under Zn‐deficient conditions, an effect not so clearly indicated in wheat.     

Optimization of irrigation and nutrient concentration based on economic returns,substrate salt accumulation and water use efficiency for tomato in greenhouse

To evaluate the effects of different irrigation and nutrient concentration strategy on growth, yield, water use efficiency (WUE), fruit quality and substrate salt accumulation, tomatoes were grown with five different levels of water (W: 50%, 75%, 100%, 125% and 150%) and nutrient concentrations (N: 0.5, 0.75, 1.0, 1.5 and 2.0 times of Hoagland strength(X)). Fruit quality index was determined by normalization of fruit quality parameters. Deficit irrigation at standard concentration of nutrients reduced yields by 17.43% and 15.52% for T₇ (W_75%-N_1.0x) and 49.54%–51.99% for T₈ (W_50%-N_1.0x) during spring-summer (SS) and fall-winter (FW) seasons, respectively. Contents of total soluble solids (TSS), titrable acidity (TA) and sugar acid ratio (SAR) were all increased in water-deficit treatments. T₈ was found to be highest in TSS, TA and SAR except SAR in FW. Over-irrigation with excessive and standard Hoagland nutrient concentration caused non-significant reduction in yield except T₆ (W_125%-N_1.0x) in SS. T₂ (W_100%-N_2.0x) and T₄ (W_100%-N_1.5x) caused more substrate salt accumulation which resulted in significant decrease in yield and WUE. Through economic analysis, over-watering along with excessive nutrients caused profit reductions. Considering water saving, yield and fruit quality through economic analysis, T₇ found to be optimal strategy.     

Accumulation and distribution of Zn and Mn in soybean seeds after nutrient seed priming and its contribution to plant growth under Zn- and Mn-deficient conditions

Nutrient seed priming is a strategy to increase the seed reserves of mineral nutrients as primary source for mineral nutrition during seedling development and early growth. The present study investigates the effects of zinc (Zn) and manganese (Mn) seed priming on growth and nutritional status of soybean under conditions of Zn and Mn limitation. Nutrient seed priming increased the natural seed reserves for Zn by, approximately, sixfold and by fivefold for Mn; however, 40–60% of the primed nutrients were adsorbed to the seed coat. Zinc seed priming was able to maintain plant growth for 5 weeks in the same way as Zn supply via the nutrient solution. It is concluded that nutrient seed priming offers perspectives to improve seed quality of soybean for early seedling development under limited nutrient supply or availability and needs further investigation on performance under various stress conditions.     

Protective role of proline against salt stress is partially related to the improvement of water status and peroxidase enzyme activity in cucumber

Abstract

A salt-sensitive cucumber cultivar “Jinchun No. 2” (Cucumis sativus L.) was used to investigate the role of proline in alleviating salt stress in cucumber. Proline was applied twice (day 0 and day 4 after salt treatment) as a foliar spray, with a volume of 25?mL per plant at each time. Plant dry weight, leaf relative water content, proline, malondialdehyde (MDA), Na⁺, K⁺ and Cl^? contents, as well as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) activities in the plants were determined at day 8 after salt treatment. The results showed that 100?mmol?L^–1 NaCl stress significantly decreased plant dry weight, leaf relative water and K⁺ contents, and increased leaf MDA, Na⁺ and Cl^? contents and SOD, POD, CAT and APX activities. However, leaf proline accumulation was not affected by salinity. The exogenous application of proline significantly alleviated the growth inhibition of plants induced by NaCl, and was accompanied by higher leaf relative water content and POD activity, higher proline and Cl^? contents, and lower MDA content and SOD activity. However, there was no significant difference in Na⁺ and K⁺ contents or in CAT and APX activities between proline-treated and untreated plants under salt stress. Taken together, these results suggested that the foliar application of proline was an effective way to improve the salt tolerance of cucumber. The enhanced salt tolerance could be partially attributed to the improved water status and peroxidase enzyme activity in the leaf.     

Protective role of proline against salt stress is partially related to the improvement of water status and peroxidase enzyme activity in cucumber

A salt-sensitive cucumber cultivar "Jinchun No. 2" ( Cucumis sativus L.) was used to investigate the role of proline in alleviating salt stress in cucumber. Proline was applied twice (day 0 and day 4 after salt treatment) as a foliar spray, with a volume of 25 mL per plant at each time. Plant dry weight, leaf relative water content, proline, malondialdehyde (MDA), Na⁺, K⁺ and Cl⁻ contents, as well as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) activities in the plants were determined at day 8 after salt treatment. The results showed that 100 mmol L^–1 NaCl stress significantly decreased plant dry weight, leaf relative water and K⁺ contents, and increased leaf MDA, Na⁺ and Cl⁻ contents and SOD, POD, CAT and APX activities. However, leaf proline accumulation was not affected by salinity. The exogenous application of proline significantly alleviated the growth inhibition of plants induced by NaCl, and was accompanied by higher leaf relative water content and POD activity, higher proline and Cl⁻ contents, and lower MDA content and SOD activity. However, there was no significant difference in Na⁺ and K⁺ contents or in CAT and APX activities between proline-treated and untreated plants under salt stress. Taken together, these results suggested that the foliar application of proline was an effective way to improve the salt tolerance of cucumber. The enhanced salt tolerance could be partially attributed to the improved water status and peroxidase enzyme activity in the leaf.     

Sites and processes of nutrient accumulation in the subsoil through water percolation from the plow layer in a submerged paddy soil microcosm

The leaching of nutrients from the plow layer by water percolation and their accumulation in the subsoil observed in a Japanese paddy field (Katoh et al. 2004: Soil Sci. Plant Nutr., 50, 721-729) were determined semi-quantitatively in a soil column experiment. Ca²⁺, Mg²⁺, K⁺, Mn²⁺, Fe²⁺, and phosphate in percolating water from the plow layer soil column were retained in the subsoil columns that were connected to the plow layer soil column. Fe²⁺, K⁺, and phosphate accumulated in the uppermost part of the subsoil. Accumulation of Fe²⁺ in the uppermost part of the subsoil was presmnably due to the cation exchange process with concomitant desorption of Ca²⁺. In contrast, Ca²⁺ and Mg²⁺ in percolating water from the plow layer soil colmnn accumulated once in the subsoil, and translocated downwards slowly with successive water percolation. Considerable amounts of inorganic carbon (IC) and dissolved organic carbon (DOC) in percolating water from the plow layer soil column were also retained in the subsoil columns. IC did not accumulate a gaseous form.     

The high tolerance of different pomegranate cultivars to the excess of boron in irrigation water is due to their capacity to limit boron transport from the root to the leaves

Background : Presently, irrigation waters often have a high concentration of boron (B), and the fruit trees in the Mediterranean areas, in general, are exposed to a high risk of B toxicity. Aims : To test the hypothesis that pomegranate trees are very tolerant to the presence of B in the irrigation water, to elucidate the physiological mechanisms behind this tolerance, and to assess differences between different varieties. Methods : In this study, the physiological and nutritional behavior of three pomegranate cultivars (‘Mollar de Elche', ‘Valenciana', and ‘Wonderful'), treated with five B concentrations (0.25, 1.25, 2.5, 5.0, 10.0 mg L^?1), were studied. At day 30 and 60 after the start of the treatments, growth measurements, gas exchange parameters and organic solutes were recorded. Results : Almost no significant differences were observed between the B treatments for any of the cultivars. Increasing the B concentration in the nutrient solution increased B concentrations in the leaves, but they never exceed 40 mg kg^?1 of B. In the roots, however, B concentrations were very high, up to 400 mg kg^?1. Conclusion : Pomegranate trees are very tolerant to B excess due to their ability to accumulate B in great quantities in the root, without causing toxicity to this part of the plant, thus limiting its transport to the shoots.     

无膜棉花产量及其根区温湿盐对灌溉量的响应

为揭示无膜棉花产量及其根区温湿盐对深层、夜间灌溉量的响应机制,在等行距密植(26株/m2)条件下,以早熟品种'新陆早74号'为试材,设置5个灌水量处理(W1,2649 m3/hm2;W2,2925 m3/hm2;W3,3201 m3/hm2;W4,3477 m3/hm2;W5,3753 m3/hm2),研究了棉花产量形...     

铜、镉毒害对番茄生长和膜功能蛋白酶活性的影响及外源NO的缓解效应

为探讨外源NO（SNP为供体）对50 mol/L铜、镉毒害的缓解效应,采用营养液培养方法,研究了不同程度的铜、镉毒害（5 mol/L和50 mol/L）对番茄幼苗生物量、根系活力、硝酸还原酶、光合特性及生物膜ATPase、H+-PPase等功能蛋白酶活性的影响。结果表明,铜、镉胁迫显著抑制番茄生长。随处理浓度增加,番茄根系活力、硝酸还原酶活性显著降低,番茄长势越差; 铜、镉胁迫对根系离子吸收的影响远远大于叶片,尤其是铜胁迫,50 mol/L铜胁迫使番茄根系铜含量增加了12倍。铜浓度的增加对镉含量无影响,镉浓度的增加降低了铜的吸收。铜、镉胁迫使番茄净光合速率（Pn）、气孔导度（Gs）和蒸腾速率（Tr）显著降低,胞间CO2浓度（Ci）显著增加,表现为非气孔限制。50 mol/L 铜、镉处理显著降低叶片、根系质膜H+-ATPase、Ca2+-ATPase和根系液泡膜H+-ATPase、Ca2+-ATPase和H+-PPase活性; 提高了5和50 mol/L部分处理叶片液泡膜H+-ATPase、Ca2+-ATPase和H+-PPase的活性。表明生物膜功能蛋白对不同程度铜、镉胁迫的响应时间和部位存在差异。铜毒害对细胞质膜ATPase的影响较大,而镉毒害对液泡膜伤害的程度较大。100 mol/L SNP可以显著缓解铜、镉胁迫导致的番茄生长受抑,铜、镉总吸收量显著高于胁迫处理。