菠萝自动采摘机的结构设计

提出了对菠萝实现自动采摘的总体结构方案,主要由机架部分、采摘部分、刀具升降部分、动力传动部分、果实输送部分等组成,并对各部分结构设计作了进一步阐述。为便于进行结构上的干涉检查以及动力学特性研究,建立了基于SolidWorks的菠萝采摘机主体结构三维模型,主要研究了导果槽细部结构对采摘后菠萝运动轨迹的影响规律,优化了导果槽的结构参数。     

菠萝茎尖玻璃化法超低温保存及植株再生

以菠萝为试材,建立试管无性系,进行玻璃化法超低温保存及植株再生研究,结果表明,约2.0 ～3.0 cm的菠萝茎尖于含有0.Smol/L蔗糖的培养基上预培养l～2d,剥取含1～2片叶原基(1.0～2.5 mm长)的茎尖,室温(25℃)下用LS装载液预处理50min,再用PVS2溶液于0℃下处理40 min,换入新鲜的PVS2溶液后迅速投入液氪,保存24h后在40℃水浴中迅速化冻90 s,用1.2 mol/L的蔗糖培养液洗涤2次,每次10 min,然后转入含0.3 mol/L蔗糖的MS培养基上,暗培养48 h后转入含BA 0.5 mg/L的MS培养基上,暗培养1周后转移到正常光下,4个菠萝品种(澳大利亚卡因、夏威夷、巴厘、台农16号)的成活率分别为96.5％、95.3％、78.6％、87.7％,再生率分别为93.2％、92.6％、76.7％、87.7％.再生植株生长和分化正常,其形态上与对照一致,生根后可移栽成活.     

菠萝开花诱导及其生理与分子基础

菠萝开花分为自然开花和诱导开花两大类。由于菠萝自然开花的时间和开花率受环境因素影响较大,具有较大的不确定性,在实践中常常通过施用乙烯利或CaC2诱导菠萝开花达到调节菠萝上市时间的目的。通过合理安排种植时间与使用开花诱导技术,目前已经实现反季节生产和周年生产菠萝的目标。笔者对近年来菠萝自然开花、诱导开花及其生理、分子基础方面的研究进展进行了综述,并展望了该领域今后的研究方向。     

菠萝叶纤维制备纳米纤维素晶体的研究

菠萝叶纤维经过氢氧化钠预处理、硫酸水解制备得到纳米纤维素晶体（NCC）,再用扫描电镜（SEM）、傅立叶转换红外光谱仪（FTIR）、热重（TG）分析仪和X-射线衍射分析仪（XRD）对其结构和性能进行表征和分析。结果表明,NCC晶体颗粒尺寸为30~50 nm;红外光谱证明非纤维素部分有效去除;NCC晶型仍属于纤维素I,结晶度从75.9％提高到87.5％;比起原纤维,NCC的降解温度明显降低。     

菠萝组织培养与遗传转化研究进展

介绍了外植体种类、培养基、激素类型对菠萝组织培养的影响,概述了目前取得成功的基因枪法和农杆菌介导法,并探讨了当前研究中存在的问题及今后的研究方向。     

Evaluation of shelf-life of fresh-cut pineapple using FT-NIR and FT-IR spectroscopy

The aim of this work was to investigate the loss of freshness of fresh-cut pineapple samples stored at different temperatures using non-destructive spectroscopic methods. Three lots of fresh cut pineapples (Ananas comosus L. cv. Golden Ripe, from Costa Rica), packaged in PVC trays (250 g) were analyzed during storage at three different temperatures (5.3, 8.6 and 15.8 °C). Loss of quality of these fruit was evaluated by chemical and microbiological parameters and using NIR and MIR spectroscopy. The FT-NIR spectra were acquired in reflectance mode directly on the slice of fresh-cut pineapple, over the range 12,500–3900 cm⁻¹, while FT-IR spectra were collected over the range 4000–700 cm⁻¹ using an horizontal ATR cell. Some chemical and microbiological parameters were also measured. Principal component analysis (PCA) was applied to the second derivative of the spectra to uncover molecular modifications occurring over the storage time. A clear discrimination between “fresh” and “old” samples was obtained and a stability time corresponding to the time of the initial loss of freshness was defined at each temperature. The stability times revealed by NIR spectroscopy were in good accordance with those evaluated by MIR. At each temperature the stability times (i.e. the initial loss of freshness times) defined by spectroscopic techniques (4–5 d at 5.3 °C, 3–4 d at 8.6 °C and 1 d at 15.8 °C) were associated with a mesophilic bacteria count ranging between 10⁵ and 10⁶ CFU g⁻¹ and lower than the maximum limit for mesophilic bacteria (<5 × 10⁷ CFU g⁻¹) given by French hygienic regulations at consumption.These results show that NIR and MIR spectroscopy could support conventional techniques (chemical and microbiological analysis) in studying shelf-life of fresh-cut fruit. In particular these techniques define the initial loss of freshness time, indicating a product which rapidly will be no longer acceptable if stored beyond that time. The main advantage of using IR spectroscopic techniques is to rapidly draw a profile of the product related to its change in quality.     

The use of CPPU for efficient propagation of pineapple

The use of forchlorfenuron (N-(2-chloro-4-pyridyl)-N′-phenylurea) (CPPU) for efficient propagation of pineapples was investigated. About 85% of axillary buds can be forced to sprout by soaking defoliated stem pieces (12 cm in length) in a 2.5 or 5.0 mg l⁻¹ CPPU solution for more than 3 h. The use of old stems taken from the third or fourth ratoon plants had the advantage of less liability to fungal decay, as compared to young stems from the first crop plants. The CPPU treatment combined with the removal of shoots from stems at monthly intervals significantly increased the number of shoots per stem piece (about 15 shoots per piece at 5.0 mg l⁻¹ CPPU), and resulted in a more uniform shoot size (the percentage of shoots within a range of 5–15 cm in length was about 90% at 5.0 mg l⁻¹ CPPU). The rooting of shoots was easily promoted within 1 month by treating the basal portion of shoots with 20 mg l⁻¹ indole-3-butyric acid (IBA) for 15 min. The CPPU method required about 5 months for plantlet propagation. From these results, we found that pineapple plantlets could be efficiently propagated by the following method: (1) soaking defoliated stems in a 2.5–5.0 mg l⁻¹ CPPU solution for more than 3 h; (2) harvest of developed shoots from the stems at regular intervals; and (3) promotion of rooting on the shoots at 20 mg l⁻¹ IBA for 15 min.     

菠萝果肉颜色的形成与类胡萝卜素组分变化的关系

为了分析不同类型菠萝果实成熟过程中果肉类胡萝卜素成分的变化特点及其外观颜色差异形成的因素,以深黄色果肉的巴厘种和浅黄色果肉的卡因种菠萝为材料,应用高效液相色谱(HPLC)技术分析了菠萝果实不同发育阶段果肉类胡萝卜素成分及含量的变化。结果表明,随着果实的成熟,两菠萝品种果肉β-胡萝卜素、玉米黄质和β-阿朴-δ’-胡萝卜醛成分均呈上升趋势,尤其是β-胡萝卜素从青果期急剧增加到完熟期,而叶黄质却呈下降趋势。两品种的β-胡萝卜素含量都显著高于其他3种色素,而且在完熟期巴厘种的β-胡萝卜素含量是卡因种的2倍以上。因此,β-胡萝卜素是造成两品种菠萝果肉类胡萝卜素积累量及外观色泽差异的主要因素之一。     

菠萝叶基愈伤组织诱导体细胞胚

以菠萝[Ananascomosus(L.)Merr.]吸芽上的叶基部组织为材料,研究了2,4-D、NAA、BA、TDZ在菠萝愈伤组织诱导体细胞胚过程中的影响。结果表明,2,4-D在体细胞胚诱导过程中起着极为重要的作用,其适宜浓度为5mg/L,适当浓度(1mg/L)的BA在降低畸形胚比例和增加体细胞胚发生率方面有重要作用,但BA也会促进愈伤组织分化不定芽;低浓度的TDZ与BA效果相似,在不同生长调节物质处理组合中,MS+0.01mg/LTDZ+5mg/L2,4-D培养基的体细胞胚发生率最高(97%)。低浓度NAA(2￣5mg/L)利于非胚性愈伤组织的增殖,而高浓度的NAA虽能促进体细胞胚发生,但这种体细胞胚很难继续增殖,在萌发时只生根不发芽。成熟体细胞胚在MS+0.2%活性炭上30d时的转株率为22.7%。     

Fungal abundance and diversity in earthworm casts and in uningested soil

Earthworm casts and adjacent uningested soil from 30 different locations were compared to determine the abundance and diversity of fungal species. The casts contained larger fungal populations (g^-1 dry soil weight) and numbers of fungal species than the soil. Variations in these parameters between casts and soil were statistically significant (P=0.05). Fungal populations and the number of fungal species in casts and soil also varied significantly (P=0.05) between samples from different locations. A total of 27 fungal species were recorded from the casts and soil. Indices of dominance (0.084 casts; 0.14 soil) and general diversity (2.53 casts; 2.02 soil) demonstrated that the casts displayed more diverse fungal flora than the soil. The diversity of fungal species increased in earthworm casts after passing through the earthworm gut.