"西蓝花"穴盘基质育苗的技术要点与特点

一、穴盘基质育苗的八大技术要点 1、把好种子关：可选优秀等优良品种进行种植。 2．把好穴盘关：可选用128孔黑色塑料穴盘进行育苗。 3、把好消毒关：一是把好穴盘消毒关，可采取石灰水消毒法，在土坑或水泥池灌石灰水对穴盘消毒一天即可；也可采取药剂消毒法，药剂选用0．1％高锰酸钾溶液喷雾或浸泡消毒；     

水分胁迫对荔枝幼树根系与梢生长的影响

以盆栽沙培1年生荔枝空中压条苗为试材,研究了水分胁迫对荔枝幼树根系和梢生长的影响以及二者的相互关系。3个处理为:沙体积含水量为7.5%(严重缺水),15.0%(一般缺水),22.5%(充分供水)。结果表明:水分胁迫严重抑制荔枝幼树地上部分和各级侧根的生长,使地上部枝梢生长严重受阻,叶片数量、平均叶面积、叶片厚度均显著变小;根总干重、侧根长度、根表面积显著减少。水分胁迫下促进须根的生长,须根的长度、根表面积比水分充足时显著增加。水分胁迫时叶片淀粉含量下降,而根系积累更多的淀粉。比较不同处理的根梢比发现,干旱对根系生长的抑制作用比枝梢更显著。     

The effects of cultural factors on yield and curd quality of autumn cauliflower

The effects of six cultural treatments on (a) marketable yield, (b) percentage marketable plants and (c) percentage perfect quality curds produced, were studied on representative varieties of three groups of autumn cauliflower in experiments carried out over a period of five years. The treatments included a comparison of the use of graded and ungraded seed, transplanting and direct-drilling of the crop, different transplant ages, selection for uniformity at planting or thinning time, and plant density and nitrogen levels during the early seedling stage of growth.

In general the yields and quality of drilled and transplanted crops were similar with all varieties each year and neither the use of graded seed nor the nitrogen treatments had any significant effect on yield or curd quality. Both increasing plant density in the seedbed and increasing age of transplant caused a reduction in yield on most occasions. The effects of the treatments on yield and quality are discussed in relation to their effects on the maturity characteristics of the crops.     

Comparison of sub-irrigation and overhead irrigation of tomato and lettuce seedlings

Summary

Overhead irrigation is a common irrigation practice in nurseries, yet it can be wasteful of water and nutrients. We compared the water use, fertilizer use and growth of ‘Top Gun’ lettuce (Lactuca sativa L.) and ‘Grosse Lisse’ tomato (Lycopersicon esculentum Mill.) seedlings in sub and overhead irrigation systems. Five rates of controlled release fertilizer were used – 0.625, 1.25, 2.5, 5 and 10 kg m^–3. Sub-irrigation used 86% less water than overhead irrigation. Irrigation type had a significant effect on some growth measurements by final harvest, 43 d after sowing. The sub-irrigated lettuce seedlings were significantly taller. The overhead irrigated lettuce seedlings had a higher dry weight and more leaves. The sub-irrigated tomato seedlings were taller, had longer leaves, a larger leaf area and more leaves. Increasing levels of controlled release fertilizer produced quadratic type responses over time for shoot dry weight, with 10 kg m^–3 producing tomato and lettuce transplants with a higher biomass in a shorter time than lower levels of fertilizer.     

Effect of brassinosteroids on drought resistance and abscisic acid concentration in tomato under water stress

The effect of brassinosteroid (BR) on relative water content (RWC), stomatal conductance (g_s), net photosynthetic rate (PN), intercellular CO₂ concentration (Ci), lipid peroxidation level, activities of antioxidant enzymes and abscisic acid concentration (ABA) in tomato (Lycopersicon esculentum) seedlings under water stress was investigated. Two tomato genotypes, Mill. cv. Ailsa Craig (AC) and its ABA-deficient mutant notabilis (not), were used. Water stress was achieved by withholding water and both the AC and not plants were treated with 1 μM 24-epibrassinolide (EBR) or distilled water as a control. The RWC, g_s, Ci and PN were significantly decreased under water stress. However, EBR treatment significantly alleviated water stress and increased the RWC and PN. EBR application also markedly increased the activities of antioxidant enzymes (catalase, ascorbate peroxidase and superoxide dismutase) while it decreased g_s, Ci and the contents of H₂O₂ and malondialdehyde (MDA). Interestingly, ABA concentration in AC and not plants was markedly elevated after EBR treatment although the increasing rate and amplitude of ABA in not plants treated by EBR was significantly lower than those in AC plants. Our study suggested that amelioration of the drought stress of tomato seedlings may be caused by EBR-induced elevation of endogenous ABA concentration and/or the activities of antioxidant enzymes.     

The effects of nutrient solution sterilization on the growth and yield of hydroponically grown lettuce

Two methods of removing bacteria from hydroponic nutrient solution [ultraviolet (UV) radiation and submicronic filter] were evaluated for efficiency and for their effects on lettuce (Lactuca sativa L.) production. Both methods were effective in removing bacteria; but, at high intensity, the ultraviolet sterilizer significantly inhibited the production of plants grown in the treated solution. Bacterial removal by lower intensity UV or a submicronic filter seemed to promote plant growth slightly, but showed no consistent, statistically significant effect.     

果梅种质枝条抗寒性鉴定

通过电导法对28份果梅种质的枝条抗寒性进行了比较分析,同时研究了枝条的可溶性蛋白、可溶性糖和丙二醛(MDA)的含量与果梅种质抗寒性的关系。结果表明:果梅种质资源的枝条抗寒性存在着很大的差异,经12h低温处理,其枝条的半致死温度为-9.3℃--20.2℃,其中丰后、高田丰后、软条红梅等种质比较抗寒,半致死温度分别为-20.2℃、-17.7℃、-19.3℃;东青、开蒂和红顶等种质抗寒性较差,半致死温度分别为-9.4℃、-9.4℃、-9.3℃;果梅枝条中可溶性蛋白和糖类与种质的抗寒性呈正相关关系,相关系数分别为0.93959和0.86709,而与丙二醛含量呈负相关关系,相关系数为-0.952122。     

The effects of irrigation on the establishment and yield of lettuce and leek transplants raised in peat blocks

The establishment and yield of lettuce and leeks were not reduced by transplanting dry (—0.06 to —0.09 MPa) as compared to saturated peat blocks (3.2 cm cube), provided irrigation was applied immediately after transplanting during the summer. When irrigation was withheld until eight days after transplanting the marketable yield of lettuce was reduced by 30% and 38% when transplanted in saturated and in dry blocks respectively. These reductions were due to reduced survival during establishment and to the more extensive trimming required to produce marketable heads rather than to a reduction in total fresh weight per plant at maturity. The marketable yield of leeks was reduced by 16% and 24% when saturated and dry blocks respectively were transplanted without irrigation, the reduction being largely due to a lower mean shoot weight. Measurements of block and soil water after transplanting suggested that even when the soil was irrigated immediately after transplanting, it was urmble to supply water directly to the blocks for more than a few days.     

Seasonal effects on the cropping-cycle of lettuce in glass-houses during the winter

Current information about the duration of the lettuce cropping-cycles in glasshouses during the winter is presented as linear functions which provide a simple model for crop planning. The data are also plotted against the date in the middle of each cropping-period, in order to show as accurately as possible the effect of growing-conditions on the duration of the cropping-cycle. Plotting the data in this way is based on the concept that the cropping-cycle depends mainly on seasonal radiation, presented by two-sided linear functions with a maximum value around the shortest day (21 December). The amount of radiation appears to be the dominant factor which determines the length of the cropping-cycle.     

Differential flood stress resistance of two almond cultivar* based on survival,growth and water relations as stress indicators

SUMMARY

Potted almond trees (Amygdalus communis L.) of the two cvs Ramillete and Garrigues were submitted to two treatments: non-flooded (control) and flooded for 7 d in June 1991 under field conditions. After being submerged for one week, the almond trees were removed from the water (recovery period). The effects of flooding on the growth, stomatal behaviour, leaf water potential, osmotic potential and turgor potential were examined through the experimental period. Flooding caused a reduction in root dry weight of 'Ramillete', wilting, chlorosis and necrosis of the leaves, and plant death. Epinasty occurred in treated trees, but it appeared sooner in 'Garrigues' than in 'Ramillete'. Garrigues presented the lower resistance of plant plus soil (R(p+S)) for both treatments. After the flooding period, a progressive reduction of R(p+S) values was noted in 'Garrigues'. The decrease in leaf water potential by flooding in both cultivars can be related to an increase in the resistance to water uptake. Leaf osmotic and turgor potential behaviour confirm the progressive dehydration of leaf tissues. The continous decrease in v|/" \ys and values in 'Ramillete' indicated that the severity of the damage induced by flooding stress was irreversible in this cultivar. The reduction in leaf conductance (g,) can be related to the leaf water deficit by effects of flooding, the recovery of g, for 'Garrigues' occurred 20 d after leaf water potential. The differences between the cultivars suggest that they differ in their ability to withstand flood conditions and their association is not desirable in poorly drained soils.     

干旱胁迫下水杨酸、脱落酸和海藻提取物对苹果幼苗抗旱性及养分吸收的影响

以盆栽苹果砧木M9T337矮化幼苗为试材,研究了水杨酸(SA)、脱落酸(ABA)和海藻提取物(SE)对重度干旱胁迫下苹果幼苗生长、光合色素、抗氧化酶活性、光合特性、渗透调节物质以及养分吸收的影响。结果表明:重度干旱胁迫显著抑制了苹果幼苗的营养生长,降低了叶片抗氧化酶活性、渗透调节物质含量、光合作用及植株养分含量。喷施SA、ABA和SE均促进了干旱胁迫下幼苗的生长,提高了叶片光合色素含量以及净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)和蒸腾速率(Tr),同时也提高了苹果叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性以及可溶性蛋白、脯氨酸等渗透调节物质的含量,降低了丙二醛(MDA)含量,有效缓解了干旱胁迫对植株造成的伤害。与SA和ABA相比,喷施SE在促进苹果幼苗营养生长、提高叶绿素a含量和叶片SOD和CAT活性、增加可溶性蛋白和脯氨酸含量、提高植株养分含量方面效果更显著。     

Simulated effects of climate change on the production pattern of winter cauliflower in the UK

Models of the phases of juvenility, curd induction and curd growth, driven by temperature, were developed for Roscoff, Walcheren and Roscoff×Walcheren winter cauliflower types and were linked to enable prediction of the time of curd maturity. Because some crop types in Cornwall (west of UK); Lincolnshire (east of UK) responded differently to weather, separate models were developed for each location. These models were then applied to each cauliflower type at four locations in the UK (Cornwall and Pembrokeshire (west); Kent and Lincolnshire (east)) using four climate impact emissions scenarios and three time-slices (2011–2040, 2041–2070 and 2071–2100). In all forecasts temperatures increased relative to baseline data (1961–1990). The phases of juvenility and curd growth were shortened by increased temperature, while in most cases that of curd induction was increased. The net effect was to advance maturity in all situations except for Roscoff types grown in Cornwall. Maturity was particularly advanced in Pembrokeshire because temperatures were closest to the optimum for curd induction. The effects of location were greater than those of time-slice and scenario and effects on Roscoff×Walcheren types were greater than those on Roscoff or Walcheren types.     

The morphological development of cauliflower and broccoli cultivars depending on temperature

In growth chambers the effect of temperature (12–27°C) on the growth and development of cauliflower cultivars of temperate and tropical climates, as well as of broccoli cultivars, was tested. No difference was found between the cultivars as regards dry matter production and curd growth, but a difference was found in the time of curd initiation. The early cauliflower ‘Aristokrat’ does not form lateral shoots or floral buds before elongation of the inflorescence at any temperature level. This always occurs in broccoli cultivars. The tropical cauliflowers have an intermediate position. At low temperatures (12–17°C) only 12–14 leaves are formed. Many lateral shoots are initiated and a broccoli-like curd with fertile flowers is developed. At high temperatures (22–27°C) the same cultivars produce a considerably higher leaf weight, less lateral shoots are initiated, and a cauliflower-like curd without floral buds is formed.     

The effect of boron on tipburn and auxin activity in lettuce

Lettuce plants (Lactuca sativa L.) grown in a boron deficient nutrient medium developed tipburn. Their leaves showed no overall increased auxin activity compared with those of control plants until they were 66 days old, when boron deficient plants showed a relative increase in the activity of one auxin. It is postulated that tipburn in lettuce may be caused by interacting factors including calcium and boron deficiences, and the ontogenetic age of the plant. Environmental and cultivar effects on the incidence of tipburn indicate that agronomic or genetic control measures may become feasible, if the mechanism controlling its expression can be further elucidated.     

The effects of pre-sowing seed treatments on the germination and emergence of lettuce seeds at high salt concentrations

Radicle emergence in lettuce seeds cultivar ‘Hilde’ was reduced by NH₄NO₃ above 8×10^?2M, while radicle extension was inhibited by 8×10^?2M NH₄NO₃ and no seedlings emerged. Inhibition of radicle emergence by 8 and 16×10^?2M NH₄NO₃ was prevented by soaking seeds for 4 h before sowing in a mixture of $\text{GA}{}_{\mathrm{<mtext>4</mtext><mtext>7</mtext>}}$ and kinetin+phosphate buffer, and was partially prevented by soaking them for 4 h before sowing in phosphate buffer. These treatments did not prevent inhibition of radicle emergence by 32×10^?2M NH₄NO₃, but seeds soaked in growth regulators or phosphate buffer before sowing and taken from this NH₄NO₃ solution after 7 days and washed to remove excess salt gave 45–52% germination compared with 12 % for untreated seeds. Pre-treatment of the seeds did not prevent the inhibitory effect of NH₄NO₃ on radicle extension. In field experiments seeds treated with growth regulators + phosphate buffer or phosphate buffer alone gave a higher final percentage emergence from soils given 125 kg N/ha than did untreated seeds.     

Amelioration of chilling stress by paclobutrazol in watermelon seedlings

Paclobutrazol (PBZ) is a member of the triazole plant-growth inhibitor group that is responsible for inducing tolerance to number of biotic and abiotic stresses. An experiment was, therefore, conducted to test whether PBZ application at various concentrations (0, 25, 50 and 75 mg L⁻¹) through seed soaking or foliar spray would protect watermelon (Citrullus lanatus) seedlings, subjected to chilling stress. Thirty-five-day old plants were exposed to chilling 5 h/day at 4 °C for 5 days. PBZ improved growth rate of watermelon seedling subjected to chilling stress and increased relative leaf chlorophyll content (RLCC) and chlorophyll fluorescence ratio (Fv/Fm) compared with the control at the end of chilling stress. PBZ ameliorated the injury caused by chilling stress by inhibiting increases in proline and leaf electrolyte leakage, which suggested that PBZ ameliorated the negative effect of chilling stress. PBZ was most effective in increased chilling tolerance of watermelon seedling when applied using the seed soak method than as a foliar spray. The best protection appeared to be obtained from seedlings seed soaked with PBZ at 50 and 75 mg L⁻¹.     

CaCl_2缓解酸枣幼苗NaCl胁迫的主成分分析

【目的】筛选出影响CaCl_2缓解酸枣幼苗NaCl胁迫的主要指标。【方法】以酸枣水培幼苗为试验材料,研究了0mmol·L-1NaCl(对照)、NaCl处理、NaCl+CaCl_2处理对酸枣幼苗地上和地下部分自由水/束缚水、细胞膜透性、SOD、POD、CAT、MDA的影响,并采用主成分分析法对CaCl_2缓解NaCl胁迫的生理指标进行筛选。【结果】与对照相比,NaCl胁迫下酸枣幼苗地上和地下部分自由水/束缚水降低,细胞膜透性、SOD、POD、CAT、MDA升高。与NaCl胁迫相比,营养液中加入CaCl_2后,酸枣幼苗地上和地下部分自由水/束缚水、SOD、POD、CAT升高,细胞膜透性、MDA含量降低。【结论】通过主成分分析法得出细胞膜透性、MDA、POD、CAT可作为CaCl_2缓解酸枣幼苗地上部分NaCl胁迫的评价指标;细胞膜透性、MDA、SOD可作为CaCl_2缓解酸枣幼苗地下部分NaCl胁迫的评价指标。     

碳量子点对甜瓜幼苗镉胁迫的缓解作用

为探究碳量子点对植物镉胁迫的缓解作用,在含Cd2+的水培系统中加入不同浓度的碳量子点研究其对甜瓜生长发育的影响。结果表明,碳量子点能降低甜瓜幼苗根和叶中的Cd2+含量(11.4%～82%),缓解Cd2+对甜瓜生长的抑制作用。另外,碳量子点能提高叶绿素含量(8.5%～10.7%),降低根系活力、花青素、MDA含量(12.5%～14.4%)和POD活性,减弱Cd2+对叶绿素合成的阻碍,并通过调节根中代谢使可溶性蛋白含量增加抵御镉胁迫,提高根中CAT和叶中APX等酶的防御功能。综上所述,75 mg·L-1碳量子点对50 mg·L-1以下Cd2+造成的镉毒害修复作用最佳,为碳量子点作为一种新型重金属毒害修复剂在农业上的应用提供了参考。     

臭氧水对菠菜幼苗生理特性及营养成分的影响

以大田菠菜为试验材料,采用1.0 mg·L~(-1)臭氧水土壤浇灌和0.6 mg·L~(-1)臭氧水叶片喷施处理,测定菠菜幼苗相关生理指标和营养成分。结果表明,臭氧水浇灌和喷施处理显著增加菠菜幼苗鲜质量,分别比对照增加了80.07%和14.49%,明显促进菠菜幼苗生长;显著降低菠菜叶片质膜透性,分别比对照降低了53.85%和46.15%,提高了菠菜幼苗的抗逆能力;显著增加菠菜叶片氮素含量、SPAD值和叶绿素含量,浇灌处理分别比对照增加了30.74%,54.17%和125.32%,喷施处理分别比对照增加了12.45%,26.28%和89.87%,明显提高了菠菜幼苗的光合能力;显著增加菠菜叶片Fe、B和Mn含量及维生素C和可溶性糖含量,浇灌处理分别比对照增加了62.69%,30.08%,70.48%,22.58%和100.69%,喷施处理分别比对照增加了52.24%,21.59%,20.75%,9.68%和29.95%,明显改善了菠菜幼苗生理特性,提高了产量和品质。与叶片喷施处理相比,臭氧水浇灌处理的效果更好。     

板栗冰冻灾害修复技术及其效果

2008年年初,我国南方大范围持续低温、降雪和冻雨等灾害性天气,造成遂昌县大面积板栗树出现枝干断裂、树体冻伤和植株死亡。采取及时清园修剪、回缩更新、高接换种、抹芽、早摘心、多次摘心剪叶等措施,经过1年的精心管理．受灾树体得到初步恢复,预计2009年株产可达3-4kg,达到受灾前40％～50％产量