Lettuce (Lactuca sativa L.) growth,yield and quality response to nitrogen fertilization in a non-circulating hydroponic system

The objective of this study was to determine the effect of nitrogen fertilization rate on growth and quality of leafy lettuce grown during the winter season in non-circulating hydroponic system. Plants were subjected to seven nitrogen (N) concentrations, i.e. 0, 30, 60, 90, 120, 150 and 180 mg L^?1 N using ammonium nitrate. Nitrogen treatments did not have a significant effect on leaf fresh and dry mass, root fresh and dry mass, number leaves and leaf area. Leaf ascorbic acid and total phenolic content, and antioxidant capacity peaked at 100 and 120 mg L^?1 N, whereas leaf chlorophyll concentration linearly increased with increasing N application. The results indicate that a solution N concentration of 100 and 120 mg L^?1 may be sufficient to improve growth, yield and quality parameters of leafy lettuce grown in non-circulating hydroponic system.     

Responses of aerobically grown iron chlorosis tolerant and susceptible rice (Oryza sativa L.) genotypes to soil iron management in an Inceptisol

Iron deficiency is a serious nutritional disorder in aerobic rice, causing chlorosis, poor yields and reduced grain nutritional quality. The problem can be managed by complementing the use of Fe-efficient plant type with a suitable Fe management strategy. In the present paper, we report the effect of eight iron management practices to resolve the problem of iron (Fe) chlorosis through the use of an iron deficiency tolerant (IDTR) and iron deficiency susceptible (IDSR) rice genotype, i.e. Pusa 33 and ADT 39, respectively. Fe deficiency tolerance of these genotypes was related to the root release of PS which enabled a higher uptake of Fe in the IDTR than the IDSR under Fe deficiency. In general, IDTR performed better than the IDSR as evident from a significant increase in total iron, active iron, chlorophyll content and grain and straw yield. IDSR produced the highest grain and straw yield under slow iron release nano clay complex source. Grain Fe content of the IDTR and IDSR increased by 18.9 and 13.4%, respectively, under recommended dose of Fe. The results identified the most effective soil management strategies for the alleviating Fe deficiency chlorosis and improving Fe nutrition of both IDTR and IDSR genotypes.     

Macronutrients Composition of Lettuce Plants (Lactuca sativa L.) as Affected by Mineral Nutrition Level and ION Exchange Substrate Biona-312 Supplementation

The effect of ion exchange substrate Biona-312 addition (2 or 5%) on the macronutrients composition of butterhead lettuce cv. ‘Justyna’ plants under conditions of basic (1.5-times) and intensive (3-times concentrated Hoagland solution) mineral nutrition level was investigated. Both experimental doses of Biona-312 introduced into 1.5-times concentrated Hoagland nutrient solution [electrical conductivity (EC) 2.41–2.47 dS m^?1] dropped nitrogen (N) content in roots. Simultaneously statistically proven increase in foliar concentration of total sulfur (S) as well as a decrease in phosphorus (P) and potassium (K) contents in lettuce above- and underground organs were observed. The changes in calcium (Ca) and magnesium (Mg) content were insignificant. Ion exchange substrate supplementation into 3-times concentrated Hoagland nutrient solution (EC 6.85–7.30 dS m^?1), significantly elevated N and K contents in above- and underground organs, raised the foliar S content, decreased Ca and Mg contents in leaves, as well as dropped P concentration in roots and increased content in leaves.     

基于主动冠层光谱仪的莴苣生物量及氮素营养状况估测

[目的]研究冠层光谱技术在蔬菜氮素营养诊断中应用的可行性和提高其准确性的方法,为推进蔬菜氮素营养管理与施肥推荐提供快速无损检测技术.[方法]以茎菜类蔬菜—莴苣(Lactuca sativa L.)为研究对象进行田间试验.设置5个化肥年施用梯度:0、108、162、216、270kg/hm2,在莴苣幼苗期、莲座期、茎形成...     

Growth survey of crisphead lettuce (Lactuca sativa L.) in fertilizer trial by low-altitude small-balloon sensing

Abstract

Both efficiency and precision of field-grown plant biomass survey are expected to be improved when aerial images of whole fields are acquired. Many such studies have been conducted in paddy rice (Oryza sativa L.), wheat (Triticum aestivum), and beans (Glycine max (L.) Merr. and Phasaeolus vulgaris), but few in vegetables. In this study, we examined whether or not aerial image analysis is useful for the biomass survey of vegetables. Aerial images of field-grown crisphead lettuce (Lactuca sativa L.) in a three-year fertilizer trial were acquired at head formation and harvesting stages in summer and autumn cropping with a compact digital camera hung under a tethered small balloon (2.2 m in length, 0.56 m³ in volume). The camera height ranged from 36 to 65 m, and the ground resolution ranged from 1.3 to 2.2 cm pixel ^?1. The horizontally projected area of the plant was measured as follows: Aerial images of the field were topographically corrected, the lettuce part was extracted based on the difference in color, the images were binarized, and the projected area was determined by image processing software. The estimation of fresh weight of one plant from the projected area was difficult because of the large data dispersion. When the averaged projected area in each plot was used, estimation was improved in some cases. Estimation of fresh weight at the harvesting stage by using the projected area at the head formation stage was difficult due to the low correlation coefficient. The results of factor analysis of fertilizer treatments by using projected area agreed well with those done using fresh weight when the correlation coefficient between the projected area and the fresh weight was high. It was concluded that the estimation of absolute lettuce fresh weight was difficult, but relative comparisons among treatments were possible until the head formation stage, using aerial images acquired by low-altitude small-balloon sensing.     

The effect of chloride and sulphate salts on the nitrate content in lettuce plants (Lactuca sativa L.)

The effect of chloride and sulphate on the nitrate accumulated in lettuce plants (Lactuca sativa L., cv. deci minor) under low light conditions was examined. The plants were grown on a complete nutrient solution for circa 45 days and then chloride was substituted for the nitrate in the nutrient solution. In another experiment, sulphate was substituted for the nitrate in the nutrient solution. Approximately 5 days later a reduction in growth occurred. The nitrate in the plants was not completely exhausted and was very slowly available for reduction both in the leaf blades and midribs. It was immaterial whether sulphate or chloride was substituted for nitrate in the nutrient solution. Chloride was taken up from the solution but sulphate was not. In plants in both treatments, sugars accumulated concomitantly with the decrease in nitrate content.

The actual nitrate reductase activity in the leaf blades decreased several days after the chloride and sulphate treatments began and was negligible on day 12. Nevertheless, the potential nitrate reductase activity of the treated plants was still 50% of the control.

It is suggested that the availability of nitrate from the storage pool is the limiting process for nitrate reductase activity, and is independent of the metabolic demand. For commercial growers it may be of advantage to use hydroponics in which the nitrate can be removed easily several days before harvest, to reduce high nitrate contents in vegetables, particularly under low light conditions.     

Effects of Low-Level Aqueous Hydrogen Sulfide and Other Sulfur Species on Lettuce (Lactuca sativa) Seed Germination

Low concentrations of aqueous hydrogen sulfide (H₂S) can stimulate growth of some crops. However, it is not clear whether H₂S provides crops with only sulfur and whether other sulfur compounds have similar beneficial effects. Therefore, impacts of solutions of sodium sulfate (Na₂SO₄), sodium sulfite (Na₂SO₃), sodium sulfide (Na₂S), ferrous sulfide (FeS), and H₂S at 0.01–1 mM were assessed on 5-day lettuce seed germination. Results showed that 0.01 mM H₂S solution significantly increased lettuce shoot elongation by 40 percent (to 43.6 mm from 31.0 mm in the control), whereas 0.1 mM increased elongation by 24 percent to 38.5 mm. Only a slight 10 percent increase was observed in 0.1 mM Na₂SO₄, suggesting that ameliorative impact of H₂S on plant growth was not a result of providing sulfur nutrient. Other sulfur solutions, however, inhibited lettuce germination and elongation to varying extents, hinting that H₂S might work as a signal molecule in regulating plant cellular activities.     

Uptake of Uranium by Lettuce (Lactuca sativa L.) in Natural Uranium Contaminated Soils in Order to Assess Chemical Risk for Consumers

Uranium mining activity in Cunha Baixa (Portugal) village has left a legacy of polluted soils and irrigation water. A controlled field experiment was conducted with lettuce (Lactuca sativa L.) in an agricultural area nearby the abandoned mine in order to evaluate uranium uptake and distribution in roots and leaves as well as ascertain levels of uranium intake by the local inhabitants from plant consuming. Two soils with different average uranium content (38 and 106 mg/kg) were irrigated with non-contaminated and uranium contaminated water (<20 and >100 μg/l). A non-contaminated soil irrigated with local tap water (<1 μg/l uranium) was also used as a control. Uranium in lettuce tissues was positively correlated with soil uranium content, but non-significant differences were obtained from contaminated soils irrigated with different water quality. Uranium in plants (dry weight) growing in contaminated soils ranged from 0.95 to 6 mg/kg in roots and 0.32 to 2.6 mg/kg in leaves. Lettuce bioconcentration is more related to available uranium species in water than to its uranium concentration. Translocated uranium to lettuce leaves corresponds to 30% of the uranium uptake whatever the soil or irrigation water quality. A maximum uranium daily intake of 0.06 to 0.12 μg/kg bodyweight day was estimated for an adult assuming 30 to 60 g/day of lettuce is consumed. Although this value accounts for only 10% to 20% of the recommended Tolerable Daily Intake for ingested uranium, it still provides an additional source of the element in the local inhabitants’ diet.     

利用BP神经网络由特征气象要素预测土壤湿度

土壤湿度的实测数据量因地面观测网的稀疏不均和观测时间的不连续而十分有限,而其作为气象、农业、水文、环境等学科领域的重要研究内容,数据量的匮乏直接影响了研究工作的顺利进行。地面常规气象数据的观测频率较高(逐日/时),提供了丰富的大气及土壤状态信息,从地气交互作用的普遍性出发,对气象要素与土壤湿度之间的作用关系进行研究,拟借助人工神经网络良好的函数模拟能力,建立以多气象要素为网络输入、以土壤湿度为网络输出的BP神经网络。通过主成分分析筛选特征要素、选择训练函数、确定合理的隐层神经元个数等来精细化网络。以甘肃省2008年8、9月份的AB报(土壤湿度数据)和A报(气象观测数据)资料进行了实验,建立BP神经网络,最终获得了较好的土壤湿度预测结果。     

Iodine application affects nitrogen-use efficiency of lettuce plants (Lactuca sativa L.)

Abstract

The main objective of this work was to determine whether nitrogen-use efficiency was affected by the application of different forms (iodide vs iodate) and dosages (20, 40 and 80 µM) of iodine, to ascertain the influence of this trace element in a biofortification programme in lettuce plants. The parameters analysed were root and shoot biomass, nitrate concentration, and organic and total nitrogen as well as those defining nitrogen-use efficiency in plants: total nitrogen content, total nitrogen accumulation, nitrogen-uptake efficiency and nitrogen-utilization efficiency. In addition to decreasing shoot biomass, iodide treatments reduced leaf levels of nitrates, organic nitrogen, and total nitrogen content. Iodate treatments did not affect the concentration of nitrogen in its different forms. The application of iodide caused total nitrogen accumulation and nitrogen-uptake efficiency to decrease, iodate application improved the latter. Both iodide and iodate applications significantly improved nitrogen-utilization efficiency in comparison to the control. The results obtained show that iodate application rates of 40 µM or lower significantly improved all nitrogen parameters analysed, making it possible to increase lettuce productivity and quality.     

Effects of Vermicompost on Soil Physicochemical Properties and Lettuce (Lactuca sativa Var. Crispa) Yield in Greenhouse under Different Soil Water Regimes

ABSTRACT

This study mainly focused on the impacts of vermicompost (VC) treatments on physicochemical characteristics of sandy-clay-loam soil and lettuce (Lactuca sativa var. crispa) yield in a greenhouse under different soil moisture regimes. Pot experiments were conducted with different VC treatment doses (0%, 2.5%, and 5% w/w) and three soil water regimes (100%, 50%, and 25%?_f, ?_f is field capacity). Following the harvest, soil samples were taken and analyzed for physicochemical properties. The highest organic matter content (2.19%) was observed in 5% VC treatment of the full irrigation level (100%?_f) irrigation treatment and the lowest organic matter content (0.19%) was obtained from the control treatment of the lowest irrigation level (25%?_f). Soil physical properties were positively influenced by VC treatments under different irrigation regimes. The highest lettuce yield (178.7 g plant^?1) was observed in 5% VC treatment of the full irrigation level (100%?_f) irrigation treatment and the lowest lettuce yield (94.0 g plant^?1) was obtained from the control treatment of the lowest irrigation level (25%?_f). Present findings revealed that vermicompost treatments under different irrigation regimes could reliably be used to enhance soil physicochemical properties and lettuce yield.     

用遗传算法训练的多层前馈神经网络对番茄成熟度进行自动检测的研究

建立了计算机视觉系统获取番茄的图像，并将RGB值转换成HIS值，通过H值提取番茄表面颜色特征。采用遗传算法训练的多层前馈神经网络实现番茄成熟度的自动判别。实验表明：该方法准确率达到94%。     

Effect of phosphorus‐enriched biochar and poultry manure on growth and mineral composition of lettuce (Lactuca sativa L. cv.) grown in alkaline soil

The use of pyrolysis products of manures gives positive effects on soil fertility, crop productivity and soil carbon sequestration. However, effects depend on soil characteristics, plant species and the raw material from which the biochar is derived, and some negative effects of biochar have been reported. The objective of this study was to evaluate the effectiveness of poultry manure (PM)‐derived biochar on the growth, and P, N, K, Ca, Mg, Fe, Zn, Cu and Mn concentration of lettuce (Lactuca sativa L.) plant. The treatments as follows: control, 20 g/kg poultry manure (PM), 20 g/kg phosphorus‐enriched poultry manure (PM+P), 10 g/kg Biochar (B), 10 g/kg Biochar+P (B+P). Application of biochar and PM significantly increased lettuce growth, and P‐enriched forms of PM and biochar gave the higher growth. PM has no significant effect on the N concentrations but biochar and, P‐enriched PM and biochar treatments significantly increased N concentrations. Phosphorus concentration of the lettuce leaves significantly increased by PM and biochar treatments. Plant K concentrations were also increased by PM and biochar, and their P‐enriched forms. Leaf Ca and Mg concentrations were lower in Biochar and B+P treatments than that of PM and PM+P treatments. Compared to control and PM treatments, biochar applications reduced Fe, Zn, Mn and Cu concentrations of the lettuce plants. The results of this study indicated that application of biochar to alkaline soil is beneficial for crop growth and N, P and K nutrition, but it certainly reduced Fe, Cu, Zn and Mn nutrition of lettuce.     

用基于人工神经网络的数据融合法测量水流泥沙含量

在采用电容传感器测量泥沙含量的过程中，电容传感器的输出值受环境温度的影响较大，为消除温度对测量数据的影响，提出了采用人工神经网络法对传感器进行数据融合处理的方法，该方法以传感器的泥沙含量值与温度值作为网络的输入，通过对网络的训练达到消除非目标参量——温度的影响。试验结果表明该方法收敛速度快，输出稳定性可显著提高，能够有效地消除温度带来的影响。     

Utilization of some organic wastes as growing media for lettuce (Lactuca sativa L.) plants

Abstract

The environmental impact of crop wastes and the high cost of peat moss (PM) force scientists to find alternative growing media. In a pot experiment, peanut shell (PS) and corn wastes (CWs) were evaluated as growing media in comparison with PM in three different mixing ratios with washed sand. The mixing ratio were M₁?=?1:1 raw material to sand, M₂?=?1:2 raw material to sand, and M₃?=?1:3 raw material to sand. The tested plant was lettuce (Lactuca sativa L.). The obtained results showed that PS medium contained available nitrogen (N) and phosphorus (P) higher by 121% and 38% above the PM medium. Availability of potassium (K) in CW medium was higher by 167% than PM. The EC, pH, OC, and C/N ratio of PM were higher by 227%, 4%, 128%, and 99% above the CW and by 1,473%, 9%, 74%, and193% above the PS, respectively. The highest significant values of growth parameters were recorded in PM medium. The highest total cost and lowest net profit were recorded with the use of PMM₁, whereas the lowest cost and the highest net profit were obtained with PSM₂. Physiochemical characteristics of peanut shell suggested that it can be economical alternative growing media for PM.     

Effects of Ammonium Nitrate and Monosodium Glutamate in Waste Water on the Growth,Antioxidant Activity,and Nitrogen Assimilation of Lettuce (Lactuca sativa L.)

It has been hypothesized that the uptake of organic as opposed to inorganic nitrogen compounds found in wastewater can be properly substituted for plant nutrients. The objective of this study was to compare effects of applying monosodium glutamate wastewater (MGW) and ammonium nitrate (NH₄NO₃) (AN) on nitrogen metabolism and growth of lettuce. The results showed that while NH₄NO₃ (AN), NO₃^-, nitrite content and NR activity increased the protein content of lettuce. Applying MGW with a high concentration of 17 amino acids and macro- and microelements improved the fresh weights of shoot and root as well as the protein content of lettuce. Antioxidant activities were not affected by AN and MGW, and their interaction effects only increased POD after 8 weeks. In conclusion, substituting a portion of the chemical fertilizers with MGW improved lettuce growth, but did not increase NO₃^- accumulation in leaves.     

人工神经网络在棉花烂铃病流行趋势预报中的应用

本文运用人工神经网络的一典型模型--“反向传播”模型，根据射阳县1980--1987年棉花烂铃病流行趋势资料，建立了烂铃病控制预报模型，经1980--1989年回报和1990--1991年预报，结果令人满意。     

Application of biosolids to soil affects Cu and Zn accumulation and antioxidant activity of lettuce (Lactuca sativa L.)

The application of biosolids to agricultural fields is becoming increasingly common. The effect of biosolids on the behavior of metals in different plants has been reported to be variable and ambiguous. A greenhouse experiment was conducted on a soil spiked with four rates of copper (Cu) (0, 50, 100, and 150 mg kg^?1) and zinc (Zn) (0, 150, 300, and 450 mg kg^?1) in lettuce culture. When Cu and Zn were spiked to anaerobically-digested biosolids, their availability in lettuce increased. Root and shoot fresh weight decreased due to a decrease in photosynthetic rate. superoxide dismutase (SOD) and peroxidases (POD) activity increased after the application of Cu and Zn. The bioavailability of Zn in lettuce was greater than that of Cu because of a higher transfer factor in plants and due to a higher endogenous Zn concentration.These results will allow for better fertilization management when biosolids are applied to tomato culture.     

应用人工神经网络预测马尾松毛虫的有虫面积

运用人工神经网络的原理和方法，选取与马尾松毛虫发生量相关关系密切的8个气象因子作为样本的输入特征，建立马尾松毛虫有虫面积与气象因子的BP网络模型，结果表明：所建立的BP模型，具有令人满意的拟合精度和预测精度。当隐含层神经元个数为15个，输入因子数为8个时，18组有虫面积的平均拟合精度为100％，相关系数为1．0000，2组预留有虫面积的平均预测精度为96．85％，预测准确率为100％。