茶园套种牧草对作物产量及土壤基本肥力的影响

我国关于茶园生草和低层套(间)种研究起步很晚且报道甚少,有必要深入研究适宜我国茶园推广应用的低层茶草套(间)种模式。通过3年的田间小区试验,以不套种任何牧草处理为对照,研究了3种不同牧草[百喜草(Paspalum natatu)、白三叶(Trifolium repens)、平托花生(Arachis pintoi)]套种模式对茶青和鲜草产量及其茶园土壤基本肥力的影响。结果表明:3种不同牧草套种模式比对照提高茶青产量6.48%~20.26%,并收获鲜草产量1 352~4 023 kg·hm?2·a?1;3年来逐年减少茶园表土流失厚度幅度分别为25.0%~30.6%、33.3%~38.9%和53.3%~60.0%,并提高茶园土壤pH 9.64%~11.76%、有机质8.23%~76.13%、全氮13.59%~245.63%、全磷3.41%~210.51%、全钾1.37%~9.65%、碱解氮69.63%~109.33%和速效磷11.40%~34.20%;其中,茶园套种白三叶和套种平托花生处理对提高茶叶产量和茶园土壤基本肥力的效果相对更佳,值得在生产上进一步推广应用。     

Radioactive cesium distribution in bamboo [Phyllostachys reticulata (Rupr) K. Koch] shoots after the TEPCO Fukushima Daiichi Nuclear Power Plant disaster

Abstract

Radioactivity levels of cesium (Cs)-134 and ¹³⁷Cs in bamboo [Phyllostachys reticulata (Rupr) K. Koch] sprouts grown from April to June 2011 over a wide area (including Fukushima Prefecture) were elevated (max. 3100 Bq kg^?1 fresh weight) after the Tokyo Electric Power Company, Inc. (TEPCO) Fukushima Daiichi Nuclear Power Plant disaster in March 2011. Bamboo sprouts in 2012 also contained high radioactivity levels. Radioactivity imaging analysis of bamboo sprouts harvested in 2012 showed increasing concentration gradients of radioactivity from the lower parts to the top of the sprouts. The peels were individually separated from the sprouts, and the inner edible part (trunk) was cross-sectioned at the internodal sections from the top to the lower parts. Each segmented trunk and its corresponding peel were analyzed for radioactive cesium (¹³⁴Cs and ¹³⁷Cs) and stable cesium (¹³³Cs). The concentrations of ¹³⁴Cs and ¹³⁷Cs showed significant increases from the lower part to the top, whereas ¹³³Cs showed an almost constant value in the trunk and peel except in the peel of the top node. We speculated that ¹³⁴Cs and ¹³⁷Cs in newly emerging bamboo sprouts in 2012 were translocated mainly from various plant tissues (where the fallout was layered on the bamboo tissues) in older bamboo, while ¹³³Cs was translocated from the soil through the roots of the new bamboo sprouts and was present in the roots and stems.     

盛夏覆盖对幼龄茶园土壤温湿度和杂草生长的影响

江南茶区夏季高温少雨,新建茶园易受旱热草害,从而影响茶苗成活率和生长。为了探讨不同覆盖材料在幼龄茶园中保湿、降温、抑制杂草的效果,采用单因素对比试验,设置4个覆盖处理,1个裸地对照,在杭州盛夏高温季节对各处理土壤温度和湿度变化及控草效果进行了比较研究。结果表明:夏季晴热高温季节,黑膜、无纺布和覆草处理均可显著降低土壤温度,减小温度日较差。持续晴热7天和14天时,黑膜和覆草处理土壤含水量显著高于对照组。覆盖均能极显著抑制茶行杂草的生长,其中黑膜和无纺布处理的杂草生长量极显著低于白膜和覆草处理。所有覆盖处理都能极显著降低拨草人工费,最高效的黑膜覆盖处理可以节约8 550元/hm~2,所用工时只有对照组的24.95%,扣除覆盖成本投入,每公顷可以节约6 370元。综合比较各种覆盖材料在降低土壤温度、提高土壤含水量、控制杂草生长及降低除草成本方面的效果,发现黑膜处理效果最好,其次是无纺布和覆草处理。因此,新茶园夏季覆盖材料推荐使用黑地膜、覆草和无纺布。     

The use of the 15N‐dilution technique for field measurement of symbiotic nitrogen fixation

Abstract

Quantitative distribution of ¹⁵N in artificially and naturally enriched field‐growing legume‐based pastures are presented and compared. The results are discussed in terms of the assumption of the ¹⁵N‐dilution technique as a means of measuring symbiotic nitrogen fixation under field conditions.     

Technique of soil sample pretreatment for analysis of 15N:14N isotope ratio

Abstract

The technique of simultaneous quantitative determination of mineral N soil forms (nitrates, exchangeable and non‐exchangeable ammonium, and total amount of these compounds) and sample pretreatment for the analysis of ¹⁵N:¹⁴N ratio is suggested. The technique is based on the selective association of NH₄ ⁺‐ions into indophenol complex and subsequent ethyl‐acetate extraction of this complex from solution. The mineralization of indophenol is carried out in alkaline medium with simultaneous NH₃ distillation into H₂SO₄ titrant. The application of given technique allows us to shorten significantly the time required for analysis and to increase the accuracy of analytical determination.     

Visualization of 15O-water flow in tomato and rice in the light and dark using a positron-emitting tracer imaging system (PETIS)

Abstract

¹⁵P-water flow from the roots to the top in tomato (Lycopersicon esculentum Mill.) and rice (Oryza sativa L.) plants was visualized with time using a positron-emitting tracer imaging system (PETIS). The ¹⁵O-water flow was switched on by light and completely stopped in the dark. The flow rate in the stem of tomato and the shoot of rice at a light intensity of 500 μmol·m^?2·s^?1 was 1.9 and 0.4 cm min^?1, respectively.     

Analysis of NO3 interception of the parasitic angiosperm Orobanche spp. using a positron-emitting tracer imaging system and 13NO− 3: A new method for the visualization and quantitative analysis of the NO3 interception ratio

Abstract

The root parasitic plants Orobanche spp. (broomrapes) seriously affect agricultural production. A visualization and quantitative analytical method for the interception of nutrients was established using a positron-emitting tracer imaging system and ¹³NO^? ₃. By using this analytical method that involves volume normalization with ¹⁸F^? images, the nitrogen nutrient interception ratio of the Orobanche spp. was calculated to be 73.6 ± 3.9% in a host–parasite system of red clover (Trifolium pratense L.).     

Interactive Effect of Soil Salinity and Water Stress on Growth and Chemical Compositions of Pistachio Nut Tree

ABSTRACT

The effects of three sodium chloride (NaCl) levels (0, 1200, and 2400 mg kg^{? 1} soil) and three irrigation intervals (3, 7, and 14 d) on the growth and chemical composition of two Pistacia vera rootstocks (‘Sarakhs’ and ‘Qazvini’) were investigated under greenhouse conditions. Eight-week-old pistachio seedlings were gradually exposed to salt stress which afterward, water stress was initiated. At any irrigation interval, plant height and shoot and root dry weights of both rootstocks were reduced with increasing salinity. However, increasing irrigation intervals alleviated the adverse effects of soil salinity. A negative relationship observed between relative shoot growth and electrical conductivity of soil saturation extract (EC_e) confirmed the above findings. Under 3-d irrigation interval, the EC_e required to cause a 50% growth reduction was lower than those under 7- and/or 14-d irrigation intervals. Shoot and root chemical analyses indicated that the salinity as well as irrigation regime affected the concentration and distribution of sodium (Na⁺), potassium (K⁺), and chloride (Cl^?) in pistachio. The concentration of Na⁺, K⁺ and C1^? ions increased with a rise in NaCl level, and was generally declined with increasing irrigation interval. Based on plant height, shoot and root dry weights and the concentrations of Na⁺, K⁺, and C1^? in the plant tissues, at lowest irrigation intervals ‘Sarakhs’ shows a higher sensitivity to soil salinity than ‘Qazvini’, but with increasing irrigation interval, ‘Sarakhs’ and ‘Qazvini’ can be classified as resistant and sensitive to salinity, respectively.     

应用137Cs示踪技术估算土壤侵蚀的若干问题探讨

[目的]探讨用~(137)Cs示踪技术估算土壤侵蚀量方法(以下简称"~(137)Cs示踪方法")所存在的几个关键问题,促进该方法的标准化和系统化。[方法]对大量已发表的相关文献进行分析,根据作者的研究经验,归纳出~(137)Cs示踪方法在实践应用中所存在的核心问题。[结果]~(137)Cs示踪方法中关于~(137)Cs在空间是均匀分布的假设存在不合理性,不能直接用于定量估算单钻点取样的土壤侵蚀量。~(137)Cs活度的空间变化存在随机性的成分。敏感度和不确定性分析结果证明~(137)Cs活度的空间随机变化量是~(137)Cs示踪方法不确性的最大来源。[结论]可以用多钻点样本平均值来减少~(137)Cs随机变化量所引起的侵蚀估算误差。以统计学为基础的试验设计和采取独立样本的办法可以消除该误差。虽然~(137)Cs模型已被广泛应用,但由于缺乏长期观测资料诸多模型还处在理论研究阶段,没有得到严格的验证和评判。因为不同模型估算的侵蚀量差别甚大,模型验证和筛选对该方法的成功运用至关重要。     

Enrichment of natural 15N abundance in frankia-infected nodules

Abstract

The enrichment of ¹⁵N in the nodules of some N₂-fixing leguminous plants is an interesting finding (Shearer et al. 1982). The extent of ¹⁵N enrichment differed depending on the plant species (Shearer et al. 1982; Yoneyama 1987) and bacterial strains (Steele et al. 1983), and in soybeans it was apparently related to the nitrogen fixation efficiency (Shearer et al. 1984)     

The comparative plant availability of 32P myo‐inositol hexaphospha.te and KH2 32PO4 added to soils

Abstract

The comparative availability to Lolivm perenne of ³²P myo‐inositol hexaphosphate (IH³²P) and KH₂ ³²PO. added to soil could be determined unequivocally from the ³²P count of leaf material even when dry matter yields and total P content were not significantly different from the control.

IH³²P was equivalent to KH₂ ³²PO₄. in a soil with a low P retention at 200 p.p.m. P but not at 20 p.p.m. P. IH ³²P was totally unavailable in two soils with high P retention at 200 p.p.m. and 20 p.p.m. P, whereas uptake of KH₂ ³²PO₄. was observed in each instance.     

The Leaching Behaviour and Balances of Nitrogen and Other Elements under Spring Wheat in Lysimeter Experiment 1985–92

Abstract

In a lysimeter study it was found that moderate rates of ammonium nitrate increased utilization percentages in spring wheat, and the leaching was 10% or less of added N. Over-optimal rates reduced utilization percentages and increased leaching to almost 50% of the highest doses. Late split application of calcium nitrate increased the percentage of N in grain. Furthermore, leaching of N was not reduced, but occurred somewhat later in the fall and winter seasons. Leaching of Cl^? was more rapid and that of SO₄ ^2- was delayed relative to the leaching of NO₃ ^?. Rather large negative N balances were obtained, also after over-optimal application rates, and total N content of the soil was reduced. Compared with the N₀ treatment, differences in soil N residues amounted to 15–25% of added N in seven years. Gaseous losses had apparently taken place both from the added N and from soil N according to the total-N analysis.     

Effect of Soil Fertilizer,Foliar Fertilizer,and Growth Regulator Application on Milk Thistle Development,Seed Yield,and Silymarin Content

Abstract

An important consideration for milk thistle (Silybum marianum L.) cultivation is regulating development to lengthen the reproductive stage and increase seed yield with high silymarin content. The treatment of milk thistle with foliar fertilizers and growth regulators—thidiazuron (Dropp^®), 2,3,5‐triiodobenzoic acid (Tiba^®), mepiquat chloride (Pix^®), and prohexadione‐Ca (Regalis^®)—resulted in an increase in the proportion of mature flower heads. Highest seed yield was observed in plants treated with Pix^® and mineral soil fertilization, whereas in plants treated with foliar fertilizers, highest yields were observed with Pix^® and Regalis^®. The highest content of silymarin was found in plants treated with Dropp^® and foliar fertilizer. Generally, treatment of milk thistle with plant‐growth regulators in combination with soil or foliar mineral fertilizers increased the total amount of silymarin by increasing seed yield per hectare.     

Negative correlation between the ratio of K+ to Na+ and proline accumulation in tobacco suspension cells

Abstract

The concentrations of K⁺, Na⁺, and proline and the ratio of K⁺ to Na⁺ (K⁺ / Na⁺) were analyzed in NaCl-unadapted and NaCl-adapted tobacco (Nicotiana tabacum) cells in suspension culture. At 3 to 5 d after inoculation, the NaCl-unadapted cells cultured in 100 mmol L^?1 NaCl saline culture medium (Na100 medium) accumulated 28.7 mmol L^?1 proline with a low ratio of K⁺ to Na⁺ (= 2.8) and the NaCl-adapted cells cultured in the Na100 medium contained 6.28 mmol L^?1 proline with a high K⁺ / Na⁺ ratio (≧ 7.5). The contents of amino acids for the NaCl-adapted cells in the Na100 medium were similar to those for the NaCl-unadapted cells in a modified LS medium (standard medium). At 14 d after inoculation, the NaCl-unadapted cells in the Na100 medium contained 4.77 mmol L^?1 proline and restored the K⁺ / Na⁺ ratio from 2.8 to 6.2. These results indicate the presence of a negative correlation between the K⁺ / Na⁺ ratio and proline accumulation and suggest that a balance between the K⁺ / Na⁺ ratio and proline accumulation may be the factor involved in determining the salt tolerance of plant cells.     

茶园—土壤系统铝和氟的生物地球化学循环及其对土壤酸化的影响

黄棕壤植茶以后,土壤pH下降,土壤酸度随植茶年限的增长而增大,且上层土壤pH的减幅大于下层土壤。茶园土壤的酸化是与茶树对铝和氟的生物积聚、土壤交换性铝与铝络合物的增加以及土壤盐基的淋溶有关。茶树落叶中铝和氟的含量分别高达5836—6136 ppm和469—520ppm;茶树透冠水和土壤渗漏液中均有相当多的Al和F,茶园土壤系统中铝和氟的循环,不仅导致土壤Al³⁺及F^-的增多,还使表土的有机络合态铝以及土壤交换性复合体和土壤溶液中的氟铝络合物积聚。因此,土壤中铝和氟的积累、转化及其生物地球化学循环是茶园土壤酸化的主要原因。     

The difference in N metabolism between NAD(P)H-specific NR-deficient mutant and wild-type barley (Hordeum vulgare L.)

Abstract

Barley (Hordeum vulgare L.) is an important crop for cereal research. In this study, two barley genotypes the wild-type (Steptoe) and the mutant (Az12) were used. An experiment was conducted using ¹⁵N-tracing method to NADH-specific nitrate reductase (NR)-deficient mutant seedling of barley. The N-depleted seedlings were exposed to a nutrient solution containing nitrate and nitrite, and were labeled with ¹⁵N for 38?h under (14?L/10D) cycles. The two genotypes utilized ¹⁵NO₃^? and accumulated it as reduced ¹⁵N, predominately in the shoots. However, nitrate reduction in the Az12 shoots was 9% lower than that in the Steptoe shoots at 38?h. As a result, in the Az12, nitrate accumulation in shoots was 78% higher than that in the Steptoe. Accumulation of reduced ¹⁵N in the Az12 roots was nearly similar to that of the Steptoe roots, but 8% lower in the Az12 shoots than in the Steptoe shoots at the end of the experiment. Also for both genotypes, root contribution increased during L/D cycles and decreased during the subsequent light cycle. Upward transport of reduced ¹⁵N via the xylem in the Az12 was nearly two times higher than that in Steptoe during the second light period (24–38?h). In both genotypes, xylem transport of reduced ¹⁵N was far exceeded the downward phloem transport. Abbreviations Anl accumulation of reduced ¹⁵N from ¹⁵NO₃^? in non-labeled roots of split roots

Ar accumulation in roots of reduced ¹⁵N from ¹⁵NO₃^?

As accumulation in shoots of reduced ¹⁵N from ¹⁵NO₃^?

Rr ¹⁵NO₃^? reduction in roots

Rs ¹⁵NO₃^? reduction in shoots

Tp translocation to root of shoot reduced ¹⁵N from ¹⁵NO₃^? in phloem

Tx translocation to shoot of root-reduced ¹⁵N from ¹⁵NO₃^? in xylem

FW fresh weight

     

Distribution of 14C in Pulse-Labelled Spring Barley. Effect of Light Intensity and Length of Photoperiod Before Labelling

Abstract

The distribution of photoassimilated C in spring barley plants was determined at different times after the onset of light and at different light intensities during assimilation. The plants were grown in pots in a greenhouse, and at late tillering and late elongation, ¹⁴CO₂ pulse-labellings of 2 h duration were carried out 1.5, 4 or 8.5 h after the onset of light. At the labelling started after a 4 h photoperiod, two light intensities was included (80 and 170 W m^?2).

To analyse samples low in ¹⁴C, a ¹⁴CO₂-trapping system interfaced with a Leco high-temperature induction furnace was developed. The ¹⁴CO₂ was trapped directly in the scintillation vial in 5 mL of liquid Carbosorb, enabling subsequent liquid ¹⁴C-scintillation counting to take place without subsampling.

The proportion of photosynthate translocated below ground tended to be higher early in the morning than later in the day. Labelling 1.5 h after the onset of light, 19.8 and 7.6% was translocated below ground at late tillering and late elongation, respectively. Corresponding values found at later labellings were 15.4–16.0 and 6.0–6.4%.

Higher proportions tended to be translocated below ground when plants were exposed to low light intensity. Exposing plants to low light intensity caused below ground translocation to be 15.4 and 6.0% of the ¹⁴C recovered at late tillering and late elongation, respectively, compared with 12.1 and 5.2% after exposure to a higher light intensity. Further experiments are needed to substantiate the observations of this study. The results suggest that the distribution of photoassimilates varies during the daytime and light intensity during the labelling.     

Growth,Nitrate Accumulation,and Macronutrient Concentration of Pakchoi as Affected By External Nitrate-N: Amino Acid-N Ratio

ABSTRACT

A study was carried out to determine the influence of nitrogen (N) sources on the growth, nitrate (NO₃ ^?) accumulation, and macronutrient concentrations of pakchoi (Brassica chinensis L.) in hydroponics. Plants were supplied with NO₃ ^? and two amino acids (AA), glutamic acid (Glu), and glutamine (Gln), at six NO₃ ^?-N/AA-N molar ratios: (1) 100:0, (2) 80:20, (3) 60:40, (4) 40:60, (5) 20:80, (6) 0:100. The total N concentration was 12.5 mmol/L for all treatments in nutrient solutions. Both AAs reduced plant growth with decreasing NO₃ ^?-N/AA-N ratios, but the reduction was for Gln than for Glu. At 80:20 NO₃ ^?-N: Gln-N ratio, the Gln had no significant effect on pakchoi fresh weights. Decreasing NO₃ ^?-N/AA-N ratios reduced NO₃ ^? concentrations in the plant, regardless of AA sources. Adding an appropriate portion of AA-N to nutrient solutions for hydroponic culture increased concentrations of N, phosphorus (P), and potassium (K) in pakchoi shoots. Substituting 20% or less of NO₃ ^?-N with Gln-N in hydroponic culture will increase the pakchoi quality by reducing NO₃ ^? concentration and increasing mineral nutrient concentrations in shoots without significant reduction of crop yields.     

Evaluation of the 15Nitrogen Isotope Dilution Technique for Estimating Crop Nitrogen Uptake from Organic Residues

Abstract

A field experiment was conducted to test the new approach for estimating crop nitrogen (N) uptake from organic inputs. The soil was prelabeled with ¹⁵N by applying ¹⁵N fertilizer to sunflower crop (Helianthus annuus L. var. Viki). The ¹⁴N plots, which received unlabelled fertilizer, were also set up. At harvest, ¹⁵N labeled residues were added to the unlabeled soils at a rate of 73 kg N ha^?1 (direct technique) and unlabeled residues were added to the ¹⁵N‐labeled soils at the same rate (indirect technique). Control plots without residues were also established. All plots were sown with the wheat (Triticum aestivum L. var merchouch)–fababean (Vicia faba L.)–wheat (Triticum aestivum L. var merchouch) cropping sequence.

In the cropping sequence, the first, second and third crop derived respectively 12.01, 2.4, and 1.93 kg N ha^?1 from crop residues estimated by the direct method and 14.77, 3.3, and 1.85 kg N ha^?1 estimated by the indirect method. The results showed no significant difference between the two techniques, which suggests that the new soil prelabeling technique compares well with the direct technique.     

The determination of ‘L’ values by discrete and integrated sampling procedures

Abstract

A discrete and an integrated sampling procedure were used to determine ‘ L ‘ values for maize plants grown in a soil. In the discrete procedure a plant was grown in a sand culture labelled with ³³P solution and then transferred in a soil which was labelled with ³²P. In the integrated sampling procedure plants were grown entirely in a P label led soil.

The discrete procedure permits point of time observation so that changes in the equilibrium between solution and surface P and mineralization rates can be monitored.