Control of water and nutrients using a porous tube: a method for growing plants in space

A plant nutrient delivery system that uses a microporous, hydrophilic tube was developed with potential application for crop production in the microgravity of space. The tube contains a nutrient solution and delivers it to the roots. Pumps attached to the tubing create a very small suction that holds the solution within the tube. This system was used to grow wheat (Triticum aestivum cv. Yecora Rojo) for 107 days in a controlled environment at suctions of 0.40, 1.48, or 2.58 kPa. The water absorbed through the pores of the tube by baby diaper sections decreased as suction increased. Correspondingly, final plant biomass, seed number, and spikelet number also tended to decrease as suction increased. The reduced yield at higher suction suggests that the plants experienced water stress, although all suctions were below those typical of soils at field capacity.     

Split root fertigation enhances cucumber yield in both an open and a semi-closed greenhouse

We investigated the hypothesis that split root fertigation (SRF) approach could provide complementary benefits over traditional fertigation (TF) in terms of water use, vegetative growth and yield formation in the high radiation season and under two atmospheric conditions in a greenhouse. Plants of cucumber (Cucumis sativus L. cv. Cumuli) were grown in a traditional high-wire cultivation system in a peat growing medium. In the SRF method the root system of a plant was separated into two compartments over the crop cycle. One compartment received fertigation solution with low EC (1.2 dS m⁻¹) and the other compartment solution with high EC (3.5 dS m⁻¹) value. In the TF method the EC value of fertigation solution was 2.4 dS m⁻¹. The atmospheric conditions included an open (ventilated) and a semi-closed (cooled) greenhouse. The employment of cooling resulted in an enhancement of the average CO₂ in a semi-closed (810 ppm) over an open (530 ppm) greenhouse resulting in a yield improvement (37%). SRF improved water uptake in both atmospheric conditions and water use efficiency (WUE) in an open greenhouse. The water uptake in SRF was highest in the root part with the low EC values, namely 61% in the open and 66% in the semi-closed greenhouse. In both atmospheric conditions, SRF decreased flower abortion, leading to an improved fruit set with a small effect on vegetative growth. SRF increased yield by 21% in the open and 17% in the semi-closed greenhouse compared to TF in corresponding greenhouses.     

我国北方水质与无土栽培系统的选择

经过分析我国北方各地的水质，指出了北方地区配制营养液用水中的超标元素及其浓度，并比较了营养液、基质和土壤对ＰＨ变化的缓冲能力的大小。在此基础上，探讨了在北方硬水地区配制营养液应采取的措施及适宜的无土栽培系统，供无土栽培生产者参考     

新疆吐鲁番地区‘无核白’葡萄水分和矿质元素周年吸收规律研究

为探究新疆吐鲁番地区‘无核白’葡萄水分和矿质元素的周年吸收规律,以4年生‘无核白’葡萄为试材,采用密闭式营养液循环供给系统栽培,避免了水分和矿质元素的流失,并设置低、中、高浓度(0.5、1.0和1.5倍标准配方浓度)的Hoagland营养液处理。在葡萄植株的生长发育过程中持续测定营养生长(新梢长度、新梢粗度、叶片面积)和生殖生长(果粒横径、果粒纵径、单果质量、可溶性固形物、可滴定酸)指标,检测和计算了不同发育阶段葡萄植株对水分和矿质元素的吸收量,并测定葡萄叶片和果实中矿质元素的含量变化。结果表明,中浓度营养液栽培的‘无核白’葡萄长势中庸,果实品质最佳,作为吐鲁番地区葡萄水分和矿质营养吸收量的参考依据,其生理需水量为每年4 149.5m~3·hm~(-2),矿质元素每公顷的吸收量分别为N 227.9 kg,P 22.9 kg,K 325.9 kg,Ca 341.8 kg,Mg 117.8 kg,Fe 1.9 kg,Mn 460.6 g,Cu 182.3 g,Zn 198.1 g,B 728.3 g。花后47~75 d,‘无核白’葡萄植株的水分和矿质元素吸收速率最大。叶片和果实中的矿质元素含量总体呈高浓度营养液处理中浓度营养液处理低浓度营养液处理的趋势。     

Measurement system of whole-canopy carbon dioxide exchange rates in grafted cucumber transplants in which scions were exposed to different water regimes using a semi-open multi-chamber

A continuous CO₂ measurement system was developed to monitor the CO₂ exchange rate of the whole canopy of grafted transplants using semi-open multiple chambers. Air heating or cooling and humidification inside a healing box were under control, if needed. To test the system, the gas exchange rate of the cucumber (Cucumis sativus L.) transplants grafted onto pumpkin (Cucurbita maxima cv. ‘New-Shintozwa’) was analysed. During the healing and acclimatisation of the grafted cucumber plants, the air temperature in the box remained constant at night but ranged above 1 °C of a set value under high humidity in daytime. The relative humidity was kept within the set point during the daytime, and it nearly reached 100% at night when not controlled. The cucumber seedlings were exposed to different water stresses before grafting, and the water potentials of each treatment were −0.579 (non-stressed), −0.814 (mildly water-stressed), and −0.870 MPa (strongly water-stressed) on grafting. At the water-stressed scions, leaf expansion was inhibited by 30.9–53.3% compared with the non-stressed scions. Therefore, the gas exchange rates of the strongly water-stressed scions based on the leaf area were decreased to 72.7% compared with the non-stressed scions. After grafting, the apparent photosynthesis of the transplants of all treatments was negative, with higher respiration in the strongly water-stressed scions during the initial period of healing. However, they turned to positive values and exceeded those of the non-stressed scions from three days after grafting. This result provides critical information that the water column is physiologically connected between the stock and scion within two days after grafting. As a result of water stress, the leaf area and dry weight of the transplants in the strongly water-stressed scions were inhibited by 67.5% and 83% compared with the non-stressed scions at the end of acclimatisation. In contrast, the relative growth rate and graft-take of the strongly water-stressed transplants were slightly increased, which suggests that the water stress prior to grafting alleviated the water demand of the scion. This system may provide useful information for diagnosis at the early stage by monitoring the whole canopy's photosynthesis over a long term.     

Vascular blockage in cut roses in a suspension of Pseudomonas fluorescens

Summary

To analyse quantitatively the relationships between cut rose (Rosa hybrida L. ‘Pascha’) vase-life, the onset of cavitation, plant water potential, and bacterial concentrations in the vase water, rose stems were placed in water containing different concentrations of Pseudomonas fluorescens 2892 tet^r rif ^r. There was a significant correlation (P = 0.0009) between cut rose vase-life and the concentration of bacteria in the vase water. As the number of bacteria in the vase water increased, the rate of senescence also increased. The water potential for roses in the bacterial suspension (at 8.50 log₁₀ CFU ml^–1) proceeded to drop constantly after 5.17 h in the vase solution, with the water potential falling to as low as -2.35 MPa by the end of the experiment (at 117 h). In contrast, the water potential of roses in deionised water dropped from -0.419 MPa at 5.17 h, to only –0.663 MPa after 117 h. When roses were stood in a bacterial suspension (at 8.5 log₁₀ CFU ml^–1) for 30 h, 63.8% of the total cumulative cavitation events were seen, while roses stood in deionised water exhibited only 26.8% of the total cavitation events. Uptake of acid fuchsin and the movement of tagged P. fluorescens 2892 in the xylem indicated that bacteria did not travel beyond the open-ended xylem vessels and were generally restricted to the first 50 mm from the cut end of the stem.     

玻璃化法超低温保存柑桔茎尖及植株再生

 采用玻璃化法对柑桔茎尖的离体超低温保存进行了研究。约10 mm 长的柑桔茎尖于含5 %二甲基亚砜(DMSO) 的培养基上预培养3 d , 切取2～2. 5 mm 长的茎尖, 室温下60 %玻璃化溶液2 (PVS2) 装载20～30 min , 然后用PVS2 于0 ℃处理50～60 min , 换入新鲜的PVS2 , 迅速投入液氮中, 24 h 后在40 ℃水浴中迅速化冻, 再用1. 2 mol/L 蔗糖培养基洗涤2次, 接种于含BA 1. 0 mg/L 的MT培养基上, 26 ℃暗培养1 周后转于正常光下培养。枳壳茎尖超低温保存后用氯化三苯基四氮唑(TTC) 法检测, 成活率为100 % , 培养再生率达到90 % ,再生后的苗能正常生根, 与对照没有形态上的变异, 移栽可成活。     

Nutrient-flow wick culture system for potted plant production: System characteristics and plant growth

To compliment the current subirrigation systems used for production of potted plants, a nutrient-flow wick culture (NFW) system was developed and compared with other subirrigation systems, such as an ebb and flow culture (EBB) system and a nutrient-stagnant wick culture (NSW) system in relation to their system characteristics and plant growth. Kalanchoe (Kalanchoe blossfeldiana cv. New Alter) was cultivated in a 6 cm pot for 10 weeks in each subirrigation system. The water-absorption pattern of the medium, water content of the medium, water loss, algal growth, salt-buildup and plant growth under various culture systems were observed. The water contents of medium under the NFW and EBB systems showed fluctuations from 30 to 40% and from 50 to 60% (by volume), respectively, whereas the water content under the NSW system gradually increased to over 40% without fluctuation. Relative to other systems, the water loss in the NFW system was 50–70% due to the reduction in the evaporation from the surfaces of the trough and medium. Algae appeared in the NSW system because the nutrient solution was always stagnant in the trough, while it was not observed under the NFW system. The dissolved oxygen in the nutrient solution was the highest during the irrigation period and the salinity in the medium was the lowest in the NFW system. With regard to system characteristics, the NFW system was simple, water-saving and efficient. In addition, the growth of kalanchoes in the NFW system was similar to those in the NSW and EBB systems at an irrigation frequency of five times a day.     

Calcium-Boron Addition Promotes Pollen Germination and Fruit Set of Mango

Different concentrations of calcium and boron were investigated for their effects on pollen germination and fruit set in mango cv. Mahachanok grown for off-season production. A randomized complete block design utilizing five treatments (1.0, 2.0, 3.0, and 4.0 mL/L 40% calcium (Ca) and 0.3% boron (B) with water as a control) with six replicates per treatment was used. The solution was sprayed onto trees at three stages, i.e., bud swell, floral development (also termed the “asparagus” stage), and before flower opening. Foliar application of Ca-B at a concentration of 3.0 mL/L exerted a significant stimulatory effect on pollen germination and pollen tube growth (P ≤ 0.05). This concentration also increased inflorescence length and the number of hermaphroditic inflorescences, and enhanced fruit set of mango cv. Mahachanok (P ≤ 0.05). Foliar application of the Ca-B solution at a concentration of 3.0 mL/L, therefore, generated positive effects with the trees producing more fruit and having greater productivity.     

Impact of grafting and rootstock on nutrient-to-water uptake ratios during the first month after planting of hydroponically grown tomato

Tomato plants (cv. Primadonna F₁), non-grafted, self-grafted, or grafted onto the commercial rootstocks ‘He-man’ and ‘Maxifort’, were grown in recirculating nutrient solution. The uptake concentrations (UCs), i.e. mean nutrient-to-water uptake ratios of N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, and B, were estimated based either on depletion from the nutrient solution or on accumulation in the plant biomass. Grafting onto both commercial rootstocks increased the total plant biomass. Hetero-grafting also increased the leaf N, Ca, and Cu concentrations but decreased those of Mg and Fe in comparison with self- and non-grafted plants. The mean UCs of N, Ca, and Cu were higher in plants grafted onto both commercial rootstocks in comparison with self- and non-grafted plants. However, hetero-grafting also raised the UCs of P, Fe, Mn, and B, because of an increased deposition of these nutrients to the roots in comparison with self-rooted plants. The method used to estimate the UCs, i.e. nutrient removal from the recirculating nutrient solution vs. nutrient recovery from plant biomass per volume unit of transpired water, resulted in similar values for N, Ca, Zn, and Cu, but had a significant impact on those of P, K, Mg, Fe, Mn, and B.     

果实膨大生长和吸水与气候变化之间的关系

田间和遮雨生长棚下，甜橙和荔枝果实在台风雨期间出现突发性猛长现象，而受胁迫果实的反响更加强烈。发现在果实猛长同时，果实的呼吸强度也上升。这些现象与大气的水蒸汽压亏的明显下跌有关。乙烯利溶液浸果试验证明，果实吸水的增多与乙烯利促进呼吸作用有关。果实的膨大生长主要依赖于水分的进入，果实的吸水包括被动和主动两种方式，呼吸为后乾提供能量，果实的吸水也与其本身的生长潜势有关。     

无纺布挂式立体栽培普通白菜研究

以无纺布作栽培基质,设计了一套适用于小型叶菜栽培的水肥一体化轻简栽培系统。以普通白菜品种扬州青1号和高梗白为试材,采用裂区试验设计,研究该栽培模式下不同营养液浓度对普通白菜生长指标和生理指标的影响。结果表明,营养液浓度对普通白菜地上部鲜质量、可溶性糖含量、叶片叶绿素SPAD值均有极显著影响;随着营养液浓度的增加,两个普通白菜品种的地上部鲜质量、可溶性糖含量和叶绿素SPAD值均呈现先增加后降低的趋势,根系丙二醛含量则呈现先降低后升高的趋势;125%全价营养液处理有利于提高普通白菜地上部鲜质量、可溶性糖含量和叶片叶绿素SPAD值,并保持根系较低的丙二醛含量。     

大蒜茎尖玻璃化法超低温保存技术研究

 用山东‘苍山大蒜’进行了茎尖玻璃化法超低温保存技术的研究。5～8 mm大蒜茎尖在MS +0.7 mol/L蔗糖的固体培养基上预培养7 d, 切取3.0～3.5 mm的茎尖, 在20℃下经60% PVS2 处理60 min,再于0℃下用PVS2 处理5～60 min后, 换适量新鲜PVS2 , 浸入液氮。保存2 d或1个月后取出, 在37℃水浴中解冻2 min, 用MS + 1.2 mol/L蔗糖液体培养基洗涤2次, 每次10 min, 经过恢复培养, 茎尖成活率最高可达到100%。     

Biocontrol of mildew with Bacillus subtilis in bitter gourd (Momordica charantia L.) seeds during germination

The bitter gourd seed has a thick, hard seed coat. Mildew often occurs during germination and causes uneven and low rates of seed germination. However, the problems caused by mildew can be overcome by treating seeds with hot water, by soaking in water, or by using microorganisms. Seeds of the ‘Ching Pi’ bitter gourd were treated in a water bath at 60 °C for 10 min and then soaked in tap water at 25 °C for 24 h. The resulting germination percentage was 86.7%, and the resulting percentage of mildewed seeds was 10%. The biocontrol potential of three commercially available Bacillus subtilis solutions was examined. For seeds primed with Huodijun B. subtilis solution, the germination percentage was 73.3% and the mildewed percentage 6%. In dual cultures, the antibiotic content in the Huodijun B. subtilis solution was significantly greater than in Yunghsing and Huolibao, the other B. subtilis solutions examined. B. subtilis effectively inhibited the growth of Rhizoctonia solani mycelium and caused abnormal mycelial growth.     

Growth,gas exchange,and nutrient status in pepper (Capsicum annuum L.) grown in recirculating nutrient solution as affected by salinity imposed to half of the root system

Pepper plants grown in recirculating nutrient solution were exposed to NaCl-salinity (60 mM NaCl, 8 dS m⁻¹) imposed either to the entire or to half of the root system and compared to plants supplied with a standard nutrient solution (1.9 dS m⁻¹). The saline solution was obtained by adding NaCl to the standard nutrient solution. In the split-root treatment, the root compartment not exposed to salinity was supplied with raw water (0.38 dS m⁻¹). Both the stem and the root dry weights were markedly restricted by salinity, irrespective of salinizing half or the entire root system. In the split-root treatment, the dry weight of the root compartment receiving raw water did not differ significantly from that exposed to salinity. The net photosynthesis and the leaf chlorophyll content were restricted by both salinity treatments, but the decrease was more marked when the entire root system was exposed to salinity. In contrast, the stomatal conductance and the transpiration rate were equally reduced, regardless of salinizing the entire or part of the root system. The leaf Na and Cl concentrations were raised by the NaCl-salinity, but only in one sampling date the increase was significantly higher when the entire root zone was exposed to salinity, as compared with salinization of half of the root system. Salinity reduced significantly the leaf K, Ca, and Mg uptake but not to levels that could cause nutrient deficiencies. These results indicate that pepper is susceptible to high salinity, predominantly due to reduced stomatal conductance. However, after long-term exposure to salinity the growth may be suppressed due also to inhibition of photosynthesis at chloroplast level. The adverse effects of high NaCl-salinity are hardly mitigated when only a part of the root system is salinized, which indicates that the response is governed by root exposure to high NaCl concentrations and not by inefficiency of the roots to take up water.     

The influence of drip irrigation or subirrigation on tomato grown in closed-loop substrate culture with saline water

In closed-loop soilless culture, one of the most relevant problems may be the accumulation in the recirculating nutrient solution of ions contained in irrigation water that are not or scarcely absorbed by the plants (e.g. Na, Cl) In order to verify the possibility to reduce the rate of recirculating water salinisation by means of subirrigation, an experiment was carried out in the spring of 2002 and 2004, with tomato plants (cv. Jama) grown in glasshouse and watered by conventional drip irrigation (D) or by subirrigation (trough bench system; S). The plants were cultivated in pots filled with a peat-perlite substrate for approximately 3 months and fed with complete nutrient solution, which was prepared with fresh water containing 10 mol m⁻³ NaCl; the nutrient solution in the collecting tank was replaced when the value of electrical conductivity (EC) exceeded 6.0 dS m⁻¹. Water and nutrient crop use, salt accumulation in the substrate, and fruit yield were monitored. In S culture, the composition and EC of the recirculating nutrient solution changed slightly, while in D treatment there was a fast water salinisation that made it necessary to flushed out the nutrient solution in six different occasions, with consequent loss of water and fertilisers. In S culture, the upward water movement in the substrate, coupled with selective mineral uptake by the roots, caused salinity build-up in the upper region of the substrate, which was associated with Na⁺ accumulation. No significant influence of irrigation methods on fruit yield and quality was observed. These findings suggest that subirrigation can be a tool to reduce the water consumption and nutrient runoff in closed-loop substrate culture of tomato conducted with saline water.     

Poor aeration in NFT and a means for its improvement

Because water can restrict rapid diffusive exchange of gases we have examined how far the nutrient solution is adequately aerated in NFT systems used for glasshouse tomato production. Measurements were at various places of: the concentrations of dissolved O₂ and dinitrogen oxide (nitrous oxide), the maximum rate of O₂ flow to an O₂-consuming sink (O₂ flux density), and the electrochemical (redox) potential. Whalehide pots containing peat-based or peat-sand based composts used to stand the plants in the NFT solution were found waterlogged and poorly aerated. Dissolved O₂ in solution drawn from the pots rarely exceeded 1-2 mg l^-1. This small amount of O₂ was associated with accumulations of dinitrogen oxide, a gaseous product of anaerobic microbial respiration. Oxygen flux density was also small but redox potentials remained above 300 mV which was too high to favour the formation of Phytotoxins such as Mn(II), Fe(II) or H₂S. Replacing the composts with more open structured inorganic media such as Perlite, Rockwool or Capogro almost completely eliminated the symptoms of poor aeration observed in the composts. On one occasion the O₂ dissolved in the flowing nutrient solution was found to be depleted by c. 50%. Thus the whole system can sometimes be subject to considerable O₂ deficits.     

An empirical model to simulate sodium absorption in roses growing in a hydroponic system

Modelling nutrient absorption can contribute to the management of hi-tech cultivation systems in greenhouse horticultural production. Nevertheless, previous studies to understand the kinetics of nutrient absorption, rarely take into consideration the accumulation of salt ions in the nutrient solution. In this project we develop and validate an empirical model for sodium uptake concentration in hydroponic rose (Rosa spp. cv. Kardinal) production. Model development and validation was conducted using a series of experiments in both greenhouse and growth chamber conditions. The model framework takes into account plant developmental stage and external sodium concentration. While model calibration data were collected at levels of sodium up to 40 mol m³ NaCl as root environment salt concentration, model validation was carried out at lower ranges.The proposed model not only shows a high predictive capability, but also provides useful output parameters such as electrical conductivity, which is the main parameter currently monitored for managing nutrient solution in greenhouse cultivation. Incorporated as part of a larger DSS, our model can be used to improve nutrient solution management in production regions that do not have economically valid alternatives other than the use of poor quality (saline) irrigation water.     

The oxygen content of flowing nutrient solutions used for cucumber and tomato culture

The oxygen (O₂) content of flowing nutrient solutions was monitored periodically at various points along and across the gullies of a nutrient-film culture system (NFT). The O₂ content of solution in which mature cucumber plants were growing was more depleted than that of those in which tomatoes were growing. In good weather there was a marked depletion of O₂ in the nutrient solution as it flowed from the inlet to the lower end of gullies containing cucumber plants, which was not found in gullies with tomato plants. On sunny days, the O₂ content of the solutions in which cucumbers were growing varied through the day at all points in the gullies and was lowest in the afternoons.A cucumber crop was grown from the seedling stage to maturity in 3 NFT gullies containing nutrient solutions with O₂ contents controlled at different levels. Day-to-day variations in O₂ content of the nutrient solutions were recorded throughout the duration of the experiment and the effects of these on the growth, development and yield of the plants was measured. Growth rates, root mass, root appearance, leaf area, water consumption and yield were reduced by low O₂ levels in the nutrient solutions.     

Localized dry spots on golf greens in a moderately continental climate,and its prevention and control

There are clear and commonly accepted design criteria for the construction of golf greens. Accordingly, top layers contain at least 90% sand, which often becomes water repellent. Drought is therefore common on golf greens and it may manifest itself as spots of wilted or dead turfgrass, known as localized dry spots (LDSs).The aims of the current paper are to review soil water repellency and localized dry spots on golf greens; and to study the turfgrass appearance regarding dependence of water repellency under the moderately continental climate in the Moscow region. The study was conducted during the growing seasons of 2007 and 2008 by Moscow State Forest University, Russia, in collaboration with Wageningen University, the Netherlands.Green 4 of the Moscow golf course was intensively studied. The texture of the top layer met the USGA, German and British specifications for golf greens. The organic matter content was also as desired. The low soil water content (down to 0.80%) in top 5–10 cm layer, high reference evapotranspiration and low amount of applied water in May and June of 2007 (2.52 against 1.20 mm/day) and of 2008 (2.41 against 1.73 mm/day), resulted in drought and LDS occurrence. Severe water repellency as determined by water drop penetration time (WDPT) test was found in the 5–10 cm depth (up to 1536 s). It decreased with depth (at depth 5–10 cm 33.3% of samples were strongly and 66.7% severely water repellent; at depth 20–25 cm 41.6% of samples were strongly and 41.6% slightly water repellent, and 16.8% were wettable). However, samples from the same depth from good areas (GAs) of the turf were also water repellent – at depth 5–10 cm all samples were slightly or strongly water repellent; at depth 20–25 cm 66.7% were non-repellent.In this study, the poorest turfgrass condition was found in plots with LDSs (the scores of turfgrass quality and living ground cover were lower than 5). A negative correlation was found between WDPT and turfgrass parameters (shoot density, living ground cover and turfgrass quality). A positive correlation between water content and shoot density was found. LDSs exhibited low shoot density (which did not exceed 20 per cm² whereas in GA it exceeded 32 per cm²) and low water content (in the range 0.8–6.75% whereas in GA it was in the range 7.8–14.47%). This means that the reason of unacceptable turfgrass condition is related to water deficit and severity of water repellency.