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.     

Effects of pre-sowing seed treatments and temperatures on tomato seed germination and seedling emergence

Sowing pre-germinated seeds with radicles 2–3 mm long reduced the time from sowing to seedling emergence to 17 days compared with 41 days in untreated seeds at soil temperatures of 10°C, and to 5 days compared with 11 days at 18°C. Sowing pre-germinated seeds also improved percentage seedling emergence and reduced the variability of times of emergence of individual seedlings. Seeds imbibed for 56 h before sowing (radicles just emerging) emerged about 3 days earlier at both 10°C and 18°C than untreated seeds. Seeds soaked in a solution containing 1.5% each of KNO₃ and K₃PO₄ for 5 days at 24°C, or in “Carbowax 20 M” for 20 days at 15°C, and then dried before sowing, gave results similar to imbibed seeds. Soaking seeds in 70% of their weight of water followed by drying for different lengths of time and for different numbers of cycles of wetting and drying did not improve germination or seedling emergence.     

Effect of cold temperature durations of onion sets in store on the incidence of bolting,bulbing and seed yield

The experiment was conducted at the experimental area of the School of Plant Sciences, University of Reading during 1996. The planting material comprised of sets (graded to 22.5 mm diameter) of two cultivars, Hygro and Delta. The sets were stored at 5 °C for nine chilling durations, between 10 and 90 days. A control treatment (sets stored at room temperature of 20 °C for days) was also included in the experiment for comparison. Sets of both cultivars treated for 90 days at 5 °C, produced nearly seven times more bolters than those treated for 20 days. Cool temperature treatment for 10 days was too short to induce bolting. Number of florets and percentage of seed bearing florets per umbel increased with lengthening cold durations and this resulted in higher seed yield per umbel. Mean bulb weight per plant was found to increase with shortening the period of low temperature treatment. For bulb crop, storage of sets at 20 °C for 90 days appears to be optimum, as it checked bolting and increased average bulb weight and bulb yields m⁻² in both cultivars.     

沼液对胡萝卜生长发育的影响研究

通过田间试验研究了沼液浸种和灌施对胡萝卜生长发育的影响。结果表明:以沼液2倍稀释液浸种和以45 t/hm2的用量灌施可显著提高胡萝卜产量,提高其可食部分胡萝卜素、粗蛋白、VC和可溶性糖等营养成分含量,降低其硝酸盐含量。     

Seeding rate and seed spacing modulate root yield and recovery of slicer and dicer carrots differently

Field experiments were conducted on carrot (Daucus carota var. sativus), involving a slicer variety, Caro choice; and a dicer variety, Red Core Chantenay (RCC), to determine the interactive effects of seeding rates (SR) and line spacings (LS), to identify optimal SR and LS and to understand the influence of various seed spacings on yield and root recovery. Caro choice and RCC were sown at various seeding rates: 18, 22, 27, 33 (slicer); 9, 12, 14, 18 (dicer) seeds 30 cm⁻¹ at three different line spacings: 2.5, 3.8 and 5.7 cm. The interaction between SR and LS on total root yield and yield of supreme quality roots (1.9–3.1 cm diameter) was not significant whereas, the interaction for recovery of root grades was significant for Caro choice. In contrast, the interaction between SR and LS was marginally significant for the total yield and for the yield of supreme quality roots (3.8–5.1 cm diameter) but not for the recovery percentage of any of the root grades in RCC. A line spacing of 3.8 cm and SR of 22 seeds 30 cm⁻¹ for Caro choice, and LS of 5.7 cm and SR of 18 seeds 30 cm⁻¹ for RCC were optimal to obtain the highest total and supreme quality root yield, respectively. Seed spacing between the range of 4.6–38 cm² exhibited a significantly negative relationship with total root yield and marginally significant positive relationship with the recovery percentage of 1.9–3.8 cm roots in Caro choice. Neither total yield nor recovery percentage of 3.8–5.1 cm roots showed any significant relationship with seed spacing in RCC, suggesting that RCC may be less sensitive to the spatial variations compared to Caro choice and would adjust physiologically and/or morphologically to equalize yield.     

不同浓度及药剂处理对萝卜陈种子发芽及田间成苗的影响

以4a生的“北京满堂红”萝卜种子为试材,用不同浓度聚乙二醇、青霉素、甲基托布津及双氧水进行浸种处理,以清水为对照,进行室内发芽和田间种植试验.结果表明:以聚乙二醇200 mg/L、青霉素200 mg/L、甲基托布津1.5g/L、双氧水浸泡10 min处理对种子,其发芽率、幼苗根系活力、叶片叶绿素含量和田间成苗效果最好,与CK差异达到显著水平.说明一定浓度和时间的药剂浸种处理促进了萝卜陈种子新陈代谢系统的修复和恢复,充分利用胚中贮存的营养物质,使幼苗达到与正常种子生长的指标.     

不同温度对黄瓜种子发芽的影响及耐热性比较

为了筛选出种子发芽耐热性强的黄瓜品种,将不同类型黄瓜品种的种子置于28、38和42℃条件下进行发芽试验,比较种子的发芽能力。结果表明:不同类型的黄瓜品种在不同的温度下发芽能力存在明显差异,其中西双版纳黄瓜、Poinsett97、北京截头种子发芽耐热能力明显强于HH1-8-57和二早子。     

叶面施铁对胡萝卜产量和品质的影响

为了提高胡萝卜产量和品质,以2种根色的胡萝卜为材料,研究叶面喷施不同浓度硫酸亚铁溶液对胡萝卜产量、叶绿素含量及矿质营养的影响。结果表明：施适量浓度的FeSO4·7H2O可以显著提高胡萝卜肉质根合格根率、胡萝卜产量、叶绿素含量及根部铁、锌、镁、钾的含量,其中,“齐头黄”和“红参808”以叶面喷施0.1%的FeSO4·7H2O为最适宜。     

Processing yield of the carrot cultivar Esplanada as affected by harvest time and planting density

Cenourete^® is a minimally processed carrot root similar to the American product known as ‘baby-carrot’. This product is obtained through peeling and abrasion of cylindrical carrot root segments. The cultivar Esplanada is well suited for the production of Cenourete^® due to its characteristics of long length and cylindrical root shape as well as uniform dark orange root colour. For Cenourete^® production, the root should be less than 25 mm in diameter. However, it is well known that root size is influenced by planting density and harvest time. Therefore, the adjustment of the cultural practices would be necessary to increase root yield aimed for Cenourete^® processing. The recovery of Cenourete^® from ‘Esplanada’ was studied under two between-line spacings: 20 cm (5 transversal lines/m) and 12.5 cm (8 transversal lines/m). Roots were harvested at 80, 90, 100 and 110 days after sowing. Cenourete^® yield ranged from 2.39 ± 0.37 to 10.75 ± 1.07 t/ha depending on the combination of harvesting date and between-line spacing. These values corresponded, respectively, to a percent Cenourete^® yield recovery of 3.3 ± 0.7%–28.6 ± 2.8% in relation to the total root production. It was concluded that higher yield is obtained with 12.5 cm between-line spacing than with 20 cm between-line spacing and with earlier harvest (80–90 days) than with late harvest (100–110 days).     

Effects of seed maturity,seed storage and pre-germination treatments on seed germination of cleome (Cleome gynandra L.)

The influence of seed maturity, seed storage and germination pre-treatments on seed germination of cleome (Cleome gynandra L.) were investigated. Seed maturation studies showed that capsules harvested at 18 days after anthesis possessed the highest dry weight with 19.2% moisture and 1% germination. Development of fresh-ungerminated seed was observed with increasing maturity of fruit, suggesting that cleome exhibited forms of seed dormancy. Storing mature seed at 15 °C and at room temperature for 5 months showed that seed dormancy was broken after 3 months under both storage regimes. When mature seeds were subjected to different treatments including various levels of GA₃, KNO₃, leaching, pre-chilling, soaking and pre-heating at different temperatures, it was found that pre-heating at 40 °C for period of 1–5 days was the most effective method in breaking dormancy in cleome.     

加工番茄种子发芽及苗期耐冷性差异研究

通过低温下种子发芽鉴定和苗期低温处理后生理生化指标的测定等方法,研究了9个加工番茄品种种子萌发期和幼苗期的耐冷反应。结果表明,供试材料对低温反应存在差异;种子萌发期耐冷性鉴定温度为15、20℃;低温下植株电解质渗透率、叶片细胞内可溶性糖含量均有上升;根据各品种种子发芽率、幼苗冷害指数、植株电解质渗透率、叶片可溶性糖含量综合评定,UC-82、里格尔、石番18号、红霸这4个品种抗冷性较好。     

Leaf and seed yield of jute mallow (Corchorus olitorius L.) accessions under field conditions for two consecutive growing seasons

Jute mallow is a nutritious leafy vegetable used by many people in Africa. The purpose of this study was to select accessions with high leaf yield and seed yield. We investigated seven agronomic traits that are related to leaf yield and seed yield and how they correlate with each other. The results indicated significant differences among the accessions in all traits. Leaf fresh weight ranged from 18.3 to 121.3 g/plant in accessions TOT 6747 and TOT 8532, respectively. The highest variability between the accessions was also observed in seed yield. It ranged from 1.0 g/plant in accession TOT 7980 to 35.5 g/plant in TOT 7866. Eight other accessions had a seed yield of 1.0 g/plant. Significant and positive correlations were observed between leaf fresh weight and leaf dry weight (r = 0.84), leaf area (r = 0.33), and number of leaves (r = 0.40). A significant correlation was observed in seed yield and weight of pods per plant (r = 0.83). The evaluation of these agronomic traits for leaf and seed yield in this germplasm has revealed useful information for breeders in their efforts to improve the yield as well as selection of accessions with good agronomic traits.     

胡萝卜主要产量性状杂种优势及配合力分析

以３个不育系为母本，４个自交系为父本，按不完全双列杂交法配制１２个组合，进行杂种优势和配合力分析。结果表明，小区产量、单根重、根长和根粗均表现了明显的正向杂种优势，以小区产量和单根重的杂种优势较高；亲本一般配合力效应比组合特殊配合力效应更为重要，其中父本的作用大于不育系的作用；３０株系（Ｂ_３）小区产量、单根重、根长和根粗的一般配合力具有较大的正向效应值，丹富士分离株系（Ａ_２）心柱比例具有较大的负向效应值。从根形、根色及整齐度来看以丹富士分离株系（Ａ_１、Ａ_２）作母本，Ｂ_３为父本更为理想。     

PEG预处理对文冠果种子萌发和幼苗生长的影响

PEG是高分子渗透调节物质,可通过调节植物细胞内的水势变化影响种子萌发。本研究以文冠果种子为试验材料,利用不同质量浓度(15%、20%、25%、30%、35%)聚乙二醇(PEG)对文冠果种子预处理,研究不同浓度PEG种子预处理对文冠果种子萌发及幼苗生长的影响。结果表明：(1)PEG浓度为15%～25%时,可以提高种子的发芽率、发芽势及发芽指数,当浓度超过25%,发芽受到抑制。(2)幼苗的苗高和地径生长量随PEG浓度升高呈现先增加后降低的趋势,在20%PEG预处理时达到最高值。(3)幼苗叶片可溶性糖含量、脯氨酸含量、SOD和POD活性均随PEG浓度升高而增加;可溶性蛋白、CAT活性、叶绿素呈先增加后降低的趋势,在25%PEG预处理时达到峰值。(4)随PEG浓度升高,相对电导率和丙二醛(MDA)呈现先降低后升高趋势,2项指标分别在20%、25%PEG浓度时达到最低值。综合研究表明：低浓度PEG预处理(15%～25%)可促进文冠果种子萌发和幼苗生长,而高浓度PEG预处理(>25%)对其产生抑制作用。     

干旱和盐分胁迫对两种金鸡菊种子萌发特性的影响

研究了沙漠金鸡菊和鬃毛金鸡菊在不同浓度盐溶液(NaCl)和干旱胁迫(PEC-6000)下的萌发特性.结果 显示,随着溶液浓度的增加,2种植物种子的发芽率、发芽势等指标整体呈下降趋势.在PEG-6000浓度小于15％时,沙漠金鸡菊和鬃毛金鸡菊的发芽率都在80％以上,而在PEG-6000溶液浓度为25％时,2种金鸡菊的发芽率分别为10.7％、50％,均与对照组差异显著;在NaCl溶液处理中,对照组的发芽率、发芽势等指标显著高于其他组,当NaCl溶液浓度小于6 g/L时,2种金鸡菊的发芽率均高于70％,当NaCl溶液高于8 g/L时,2种金鸡菊的各项指标显著降低,且幼苗无法正常生长.综上所述,2种金鸡菊均具有较好的耐盐碱性和抗旱性,在干旱或盐碱土地的园林应用方面具有很高的开发潜力.     

SA对盐胁迫下萝卜种子萌发和幼苗生长的影响

为了探讨外源水杨酸(SA)对盐胁迫下3种萝卜(‘花樱萝卜’‘西春伏萝卜3号’‘水萝卜’)种子萌发和幼苗生长的影响,采用不同浓度SA处理150 mmol·L^-1NaCl胁迫下的萝卜种子,测量种子萌发、幼苗生长及生理指标。结果表明:(1)NaCl胁迫显著抑制了萝卜种子的萌发和幼苗的生长;(2)不同浓度SA处理下,1.5 mmol·L^-1的SA处理(T3组)对盐胁迫下萝卜种子萌发和幼苗生长缓解效果最好,‘西春伏萝卜3号’在该处理下比其他处理的发芽率高6.67-14.45个百分点,‘花樱萝卜’T3组发芽率高于其他组7.78-26.67个百分点,‘水萝卜’T3组发芽率最高,但与其他处理相差不大。研究发现,外源SA在一定程度上能缓解盐胁迫对萝卜种子萌发和幼苗生长抑制作用,其中以1.5 mmol·L^-1的SA处理缓解效应最好,且缓解效应在不同萝卜品种间存在差异。     

Effects of different mowing treatments and stubble heights on the compensatory growth and quality of lettuce (Lactuca sativa L.)

This study were investigated the effect of mowing method on growth and quality of lettuce. The seedlings after a 24-day incubation in the growth chamber underwent one of six mowing treatments with different stubble heights (i.e. 0.5, 1.0, or 1.5 cm). One mowing treatment group consisted of plants that retained the 2–3 new leaves in the centre (RBL), while the other group consisted of plants in which the new leaves were removed (RBN). Seedlings that were not mowed served as the controls. The results showed that, after seedlings continued to be incubated for 10 days under red and blue light in a growth chamber, the fresh mass of plants and dry mass of shoots were higher for the RBL1.0- and RBL1.5-treated plants than those of the RBN-treated plants. With increasing stubble height, the shoot fresh mass of plants in both mowing groups gradually increased. Mowing decreased chlorophyll (a + b) contents, but did not affect carotenoid levels. Mowing treatments promoted photosynthesis, and did not decrease soluble sugar, sucrose, soluble protein, Vitamin C and anthocyanin contents. Our results implied that mowing treatments promote the compensatory growth of lettuce, and mowing plants to a height of 1.5 cm produces the greatest yield benefit.     

诱抗剂处理对甜瓜叶部病害和果实品质的影响

以抗病品种银帝和感病品种卡拉克赛为材料,在露地条件下研究了几种植物提取液和苯并噻二唑(BTH)处理对甜瓜主要叶部病害及果实大小和品质的影响。结果表明,BTH、中草药提取液和侧柏提取液对甜瓜叶部各种主要病害的发生都有明显的抑制效果,尤其对白粉病的抑制效果最好,平均防效达75%。4种诱导剂中,BTH对各种病害的防效都较稳定,平均达51.44%,且在幼果期和伸蔓期+幼果期的预防效果均较植物提取液好。采前诱抗处理能明显提高两品种甜瓜果实品质及抗病品种(银帝)的产量,但对感病品种卡拉克赛产量影响不显著;初花期BTH处理可增加果肉厚度、提高可溶性固形物含量,并能改善果实经济性状。     

Levels of physiological dormancy and methods for improving seed germination of four rose species

Low seed germination is a major problem in commercial rose propagation and breeding and is species-dependent. The present work selected four rose species previously un-examined to explore effective methods for improving seed germination and the relevant dormancy mechanism and its levels in seven experiments. The results showed that both pulp and achenes from the four rose shrubs had chemical substances that significantly inhibited seed germination with the inhibitory effect was more pronounced in pulp extract than of achenes. Single treatments of H₂SO₄ scarification, short-term cold stratification (<16 weeks) or warm stratification were less effective in breaking dormancy as indicated by lower germination index than their combinations. Comprehensive comparisons showed that among the six treatments the most effective for breaking dormancy was H₂SO₄ scarification followed by warm plus cold stratification, then H₂SO₄ scarification followed by cold stratification and finally warm plus cold stratification. Scarification with H₂SO₄ for 2–4 h ordinal followed by warm stratification at 20 °C for 4 weeks and cold stratification at 5 °C for 8 weeks was the best pretreatment for increasing seed germination percentage for Rosa multibracteata (81.4 ± 2.9%), Rosa hugonis (13.1 ± 6.0%), and Rosa filipes (62.7 ± 5.7%); and H₂SO₄ scarification for 4 h followed by cold stratification at 5 °C for 12 weeks was the best pretreatment for Rosa sericea (46.7 ± 8.7%). Our results suggest that these four species have only physiological dormancy caused by integrative roles of pulp, pericarp and embryo. The level of physiological dormancy was ranked as R. hugonis > R. sericea > R. filipes > R. multibracteata.