Productivity and water use efficiency of sweet sorghum as affected by soil water deficit occurring at different vegetative growth stages

The growth and production of sweet sorghum [Sorghum bicolor (L.) Moench] crops under semi-arid conditions in the Mediterranean environment of southern Italy are constrained by water stress. The effects of temporary water stress on growth and productivity of sweet sorghum were studied during three seasons at Rutigliano (Bari, Italy). The aim of this research was to evaluate the sensitivity of phenological stages subjected to the same water deficit. In a preliminary study it was observed that stomata closed when pre-dawn leaf water potential (Ψ_b) became lower than −0.4 MPa. This criterion was used in monitoring plant water status in three different plots: one never stressed and two stressed at different phenological stages (‘leaf’ and ‘stem’) when mainly leaves or stems were growing, respectively. An evaluation of the sensitivity of phenological stages subjected to identical water stress was obtained by comparing the above-ground biomass and WUE of drought crops with those of the well-irrigated crop (up to 32.5 t ha⁻¹ of dry matter and 5.7 g kg⁻¹). The sensitivity was greatest at the early stage (‘leaf’), when a temporary soil water stress reduced the biomass production by up to 30% with respect to the control and WUE was 4.8 g kg⁻¹ (average of three seasons). These results help quantify the effects of water constraints on sweet sorghum productivity. An irrigation strategy based on phenological stage sensitivity is suggested.     

宁夏引黄灌区不同苜蓿品种主要农艺性状关联分析及干草产量比较

通过对20个苜蓿（Medicago sativa L.）品种连续4年（2015-2018年）主要农艺性状的相关性分析及草产量比较,探究苜蓿农艺性状与草产量的关系,筛选出适宜宁夏灌区种植的苜蓿高产品种。结果表明,株高与干草产量呈显著正相关（P<0.05）,相关系数为0.554;分枝数、茎粗、叶片数、节间距、叶宽、鲜干比、叶茎比与干草产量相关系数分别为0.430、0.264、0.284、-0.064、0.344、-0.110和0.153,相关性较低且不显著（P>0.05）。株高可作为苜蓿草产量预测评价指标,国外品种WL354、康赛、标靶、岩石、挑战者、大银河和WL343在4年中干草产量突出,达80 000kg/hm²以上,适宜在宁夏引黄灌区大面积推广种植。     

Effect of combined application of heat treatments and plastic packaging on keeping quality of ‘Oroblanco’ fruit (Citrus grandis L.×C. paradisi Macf.)

Combinations of various heat treatments with individual fruit sealing, packaging in polyethylene liners or waxing were tested as means to control pathological and physiological spoilage of ‘Oroblanco’ fruit (Citrus grandis L.×C. paradisi Macf.). The following heat treatments were used: curing at 36°C for 72 h, hot water dip at 52°C for 2 min or ‘hot drench brushing’ at 52, 56 or 60°C for 10 s. The standard packinghouse treatment included waxing with addition of thiabendazole (TBZ) and 2,4- isopropyl ester. The fruit was stored for 2 weeks at 1°C (simulated low-temperature quarantine treatment), followed by 12–13 weeks at 11°C (simulated sea transportation to Japan) and 1 additional week at 20°C (simulated retail shelf-life period). The lowest weight loss and the highest firmness were observed with individually sealed fruit. Polyethylene liners were usually more efficient for weight loss control than waxing. However, the liner packaging enhanced the risk of postharvest disease development, if not accompanied by appropriate decay-controlling measures. Applying TBZ, hot water dip or curing controlled the development of postharvest pathogens, especially that of Penicillium molds. In another trial, both hot drench brushing at 56 or 60°C and hot water dip reduced decay incidence. Hot drench brushing at 60°C and hot water dip slowed fruit softening and reduced buttons abscission. In addition, the hot drench brushing at 60°C significantly delayed the loss of ‘Oroblanco’ green rind color, especially at the stylar and stem ends of the fruit. The hot dip at 52°C inhibited yellowing only when combined with individual seal-packaging.     

盐胁迫对甜菜植株显微结构影响的初步研究

旨在明确盐胁迫条件下甜菜植株显微形态结构变化情况。本论文以甜菜T510为研究对象,研究280mmol/L NaCl组与空白对照组的甜菜的叶、叶柄及根的显微结构差异。结果表明：盐处理的叶片、茎及根部位的木质部和韧皮部相比空白对照组甜菜的木质部和韧皮部直径变小;盐处理叶片的气孔几乎都关闭,即使开放,开放程度也比较小;盐处理的茎的薄壁细胞所占体积增大;盐处理根的表皮细胞壁加厚,并且根的薄壁组织中出现大量通气组织。     

广西野生茶树叶片横切结构及特性分析

对广西野生茶树叶片进行解剖,从解剖学的角度对它们的抗旱、抗寒以及抗病虫害的特性进行比较分析,以期为广西茶树资源的快速鉴定与新品种选育提供依据。运用改良石蜡切片方法制片,光学显微镜观察,对广西区内7个县（区）的21个野生茶树株系的叶片进行解剖观察与比较。叶脉、叶片、上表皮角质层、海绵组织和栅栏组织等的厚度均因株系的不同而异。叶脉与叶片厚度的比值为1.62~7.06,上表皮角质层厚度为1.63~4.21 μm,上表皮细胞厚度为14.83~30.17 μm,上表皮细胞厚度与海绵组织厚度的比值为0.08~0.21,栅栏组织与海绵组织厚度的比值为0.31~1.04。综合抗性最强的是六堡01和六堡02,其次是白牛01、开山茶01和开山茶02,它们均具有较强的抗旱、抗寒和抗病虫害能力。     

水稻白条纹叶突变体wsl1的遗传分析及基因精细定位

从粳稻日本晴和籼稻R1128杂交衍生的重组自交系群体中获得一个稳定遗传的白条纹叶突变体wsl1(white stripe leaf 1),世代为F10。与亲本R1128相比,突变体wsl1表现出白条纹叶,同时叶脉呈现白化,该性状在苗期就出现并持续整个生育期;突变体的株高、每穗总粒数、剑叶长、生育期显著增加,而结实率显著下降,其他农艺性状没有显著变化。分蘖期突变体wsl1的叶绿素a、叶绿素b和胡萝卜素含量较杂交亲本R1128显著下降;透射电镜观察表明,与野生型相比,突变体的叶绿体形状异常,不规则。遗传分析表明,该突变性状由1对隐性核基因控制。精细定位后发现,目标基因WSL1位于第1染色体短臂上标记M1-54与标记M1-70之间,两者相距89.7kb。生物信息学分析表明候选区间内共有8个开放阅读框,暂未发现已报道的叶色相关基因;其中LOC_Os01g02080编码肽基脯氨酰顺反异构酶,GO(Gene Ontology)分类显示其可能与类囊体形成有关,后续将通过比较测序、qRT-PCR等分子实验来确定候选基因。     

Sodium bicarbonate reduces postharvest decay development on melons

Sodium bicarbonate (SBC) inhibited in vitro mycelial growth of A. alternata, Fusarium spp. and R. stolonifer. SBC action was fungistatic rather than fungicidal. Coating commercially harvested ‘Galia’ and ‘Ein-Dor’ melons with wax containing 2% SBC reduced decay incidence after storage and shelf life simulation by four to seven-fold, to a commercially acceptable level of 6–7%, compared to untreated or waxed-treated controls. This treatment also maintained the fresh and blemish-free appearance of the fruit at harvest. Higher concentrations of SBC (3%) were phytotoxic and significantly reduced general fruit appearance. A trial shipment by sea transport to Europe demonstrated that 2% SBC incorporated into a wax coating maintained the marketability of ‘Galia’ melon fruits compared to that of untreated fruit. SBC can be an alternative biocide to the fungicide imazalil, thus eliminating unwanted residues on melon fruits.     

A temporal limit to the association between flag leaf life extension by fungicides and wheat yields

Three field experiments, each repeated over two or three seasons, on winter wheat investigated a possible limit to the association between grain yield and flag leaf life, as extended by fungicide application. The experiments involved up to six cultivars and different application rates, timings and frequencies of the strobilurin azoxystrobin and the triazole epoxiconazole. In the 2000/01 and 2001/02 seasons, the relationships between the thermal time to 37% green flag leaf area (m) and yield deviated from linearity. ‘Broken stick’ models were fitted to cultivar × experiment combinations within each season and the limit to the benefit to yield associated with extending flag leaf life was 700 °C days (S.E. = 20.7) and 725 °C days (S.E. = 9.33) after anthesis in 2000/01 and 2001/02, respectively. In 2002/03, the relationship between yield and m did not deviate significantly (P > 0.05) from linearity, but in this latter year the fungicide application failed to increase m past 700 °C days.     

喷施微肥对定位施肥烟株成熟期生理代谢的影响

为探究叶面喷施微肥对烟叶成熟的影响,提高烟叶适烤性,以‘翠碧一号’为试验材料,在连续10年纯化肥定位施肥烟田,于烟株打顶后10、20天时喷施不同中微量元素,测定其对烟叶生理代谢的影响。叶面喷施不同中微量元素后,叶绿素a、叶绿素b和叶绿素总量均有较明显上升,叶片光合速率、蒸腾速率和气孔导度明显提高,荧光参数中Fo和Fo/Fm显著下降,Fm、Fv、Fv/Fm和Fv/Fo显著上升;硝酸还原酶活性显著提升;细胞膜相对透性显著降低;过氧化氢酶和超氧化物歧化酶均能保持较高的活性,而丙二醛含量显著下降。表明在长期纯施化肥烟田的烤烟生长后期喷施中微量元素有利于提高细胞膜结构稳定性,减轻膜脂过氧化程度,维持光合结构的稳定性,减少叶绿体色素的降解,提高光能转化效率,减缓活性氧伤害。喷施微肥有利于提高烟叶光合作用能力,缓解烟株叶片伤害与衰老,提高上部烟叶的适烤性。     

Baby-leaf and multi-leaf of green and red lettuces are suitable raw materials for the fresh-cut industry

Consumer demand for softer leaves with variation in taste, shape and colours has encouraged the development of new lettuce products of baby-sized leaves. The objective of this study was the comparison of whole-head lettuce, as the most common raw material for fresh-cut, with baby-leaf and multi-leaf as the newest baby-sized lettuce leaves. Lettuces (Lactuca sativa L.) of the types Green Leaf, Red Leaf and Lollo Rosso were cultivated in the same field with different plant densities, under commercial conditions. Although baby-leaf was subjected to far less wound damage than the shredded lettuce from the whole-head, leaf age could play an important role in increasing respiration rate and determining postharvest quality. After 9-11 d of storage, minimally processed products from the three types of raw material showed good visual quality without differences among them. However, over the 12-d storage period, quality decreased to the limit of marketability mainly due to browning of the cut edge surface of the fresh-cut product from whole-heads and decay due to the soft tissue in the case of baby-leaves. Additionally, with the processing of whole-heads, the increase in cut-damage surfaces and availability of cell nutrients provided conditions that favoured the growth of lactic acid bacteria (LAB) and total coliforms compared to uncut surfaces of baby-sized leaves. The ratio between the oxidized and reduced forms of ascorbate (DHA/AA) increased 2-4 times after 9-11 d of storage. Furthermore, baby-sized leaves had higher phenolic contents than the shredded product from the whole-head which probably contributed to reaching a shelf-life of 11 d. In conclusion, the new green and red baby-sized leaves both at immature and mature stages provided high quality lettuce for the fresh-cut market, meeting specific requirements regarding visual quality, microbial load and high content of phytochemicals.     

水稻黄绿叶基因Yellow-Green Leaf 6 (YGL6)的表达模式与蛋白定位

叶色突变既可作为形态标记用于杂交稻育种, 又是研究光合系统的结构和功能、叶绿素生物合成及其调控机制的理想材料。EMS (ethyl methane sulfonate)诱变籼稻恢复系“缙恢10号”获得1个稳定遗传的黄绿叶突变体, 暂命名为ygl6 (yellow-green leaf 6)。前期我们通过图位克隆筛选出候选基因Os12g23180, 通过遗传互补实验证实了黄绿叶基因YGL6为Os12g23180, BLASTp分析表明YGL6基因编码NAD(P)-结合的Rossmann折叠超家族蛋白质, 属于短链脱氢酶/还原酶家族, 推断为异黄酮还原酶、糖脱水酶或mRNA结合蛋白。利用qRT-PCR进行表达模式的分析表明YGL6基因仅在绿色组织如心叶、成熟叶、叶鞘和绿色颖壳中表达, 尤其以心叶的表达量最高, 同时YGL6基因表达还受光照的诱导。构建亚细胞定位载体, 转水稻原生质体结果表明YGL6蛋白定位于叶绿体。本研究丰富了水稻突变体库, 为YGL6基因的功能分析奠定了基础。     

核桃物候期与叶、果表型可塑性研究

大尺度范围内研究‘清香’核桃的物候期和叶、果表型可塑性,探讨气候变化对核桃物候期的影响,为核桃跨区域优质栽培和理解核桃种群分化提供参考。以中国暖温带栽培区、北亚热带栽培区和南亚热带栽培区的‘清香’核桃为研究对象,观测不同栽培区‘清香’核桃的物候期和复叶、单枝多果率和坚果果面特征等表型可塑性。不同栽培区‘清香’核桃遗传相似系数总体平均值为0.998,说明其纯度较高;从暖温带栽培区到南亚热带栽培区迁移栽培过程中,各区域‘清香’核桃物候期顺序一致,但果实发育时间从125天延长至150天;复叶小叶数从5～9片渐变为5～11片,侧叶由椭圆形叶尖锐尖渐变为长椭圆形叶尖渐尖;单枝多果率从2.22%增加至7.43%;坚果果面刻纹和刻窝逐渐增多增深。‘清香’核桃从暖温带到北亚热带再到南亚热带迁移栽培过程中,生长期延长,叶片逐渐由圆变长,叶尖变尖,单枝坐果数逐渐增多,坚果表面光滑程度减弱,物候期和叶、果均表型出了较强的表型可塑性。由其表现出的核桃向泡核桃转变的趋势推测,核桃和泡核桃2个种的分化可能是由环境因子所致。     

高山杜鹃离体叶片高效再生及其再生途径研究

为建立高效的高山杜鹃植株再生体系,以6种(‘Percy Wiseman’、‘Cunnigham’s White’、‘Halfdem Lem’、‘Madame Masson’、‘Scintillation’、‘XXL’)高山杜鹃组培苗叶片为材料,研究高山杜鹃离体叶片分化的基因型效应和外源激素效应,并通过形态学和组织细胞学研究其再生途径。结果表明,TDZ诱导6种高山杜鹃离体叶片再生的效果好于ZT,0.04~0.08 mg/L TDZ诱导离体叶片的分化率可达100%,叶片平均分化不定芽数为5.67~13个/片。6种高山杜鹃均可作为遗传转化的候选材料,其中‘Scintillation’、‘Halfdem Lem’和‘Cunnigham’s White’的再生能力更强。6种高山杜鹃离体叶片的再生途径主要为器官直接再生,其中‘Percy wiseman’和‘Madame Masson’除器官直接发生途径外,在TDZ诱导下少量叶片存在愈伤组织间接再生途径分化不定芽。试验结果可为研究高山杜鹃离体叶片再生芽机理,提高其植株再生频率和遗传转化效率提供技术支持。     

干旱胁迫对不同生态条件下蒙古扁桃叶片PAL和C_4H活性的影响

植物细胞壁在遭遇逆境后会出现增厚现象,以抵御不良环境,有研究认为这是由于细胞壁内的木质素沉积形成的.目前认为木质素的合成途径不只一条,但苯丙氨酸解氨酶(PAL)和肉桂酸4-羟基化酶(C_4H)等酶在合成中起到了十分重要的作用.因此,本试验以野生蒙古扁桃为试验材料,研究干旱胁迫对其在不同生态环境条件下体内PAL和C_4H酶活性影响的变化.结果表明:在遭受干旱胁迫时,蒙古扁桃叶内PAL和C_4H活性随干旱胁迫程度的增加而逐渐增强,且干旱地区的蒙古扁桃叶内PAL和C_4H活性要强于相对不干旱地区.PAL和C_4H活性与植物的抗旱性呈正相关关系.     

草燕1号燕麦新品种选育及品种特性评价

草燕1号燕麦（Avena sative‘Caoyan No.1’）是针对甘肃高寒地区及二阴地区旱作栽培条件下选育的高产、抗倒伏的燕麦新品种。该品种是以和政乡土燕麦为原始材料,采用单株混合选择法,经过近10年的选育而成。以青海444和青引1号为对照,在和政、定西、庆阳、天祝和夏河5个地点进行了品种比较试验、区域试验和生产试验。结果表明,草燕1号燕麦适宜在海拔1500~3000m的青藏高寒区和二阴冷凉区推广种植,其生育期比对照品种晚2~6d,牧草产量与对照无明显差异,但种子产量显著高于2个对照品种（P<0.05）,饲用品质优于青海444,且差异显著（P<0.05）,但与青引1号无显著差异。     

紫色叶用莴苣色泽参数及花色苷含量的相关研究

为获得目前紫色叶用莴苣的叶色相关数据,建立分级标准,利用色差仪及高效液相色谱仪对40个品种的叶用莴苣叶片颜色及花色苷含量进行测定,对数据进行相关分析,并建立分级系统。结果表明,根据色泽参数和花色苷的含量可将紫色叶用莴苣的分成绿色、浅紫色、中紫色、深紫色和特紫色5 个等级。据此建立了一个叶色分级标准,根据紫色部分在叶片分布特征可将紫色叶用莴苣分成裙边紫、渐变紫、全叶紫、花斑紫4 类。试验结果提供测量、评价叶片颜色性状的科学方法,有助于培育、筛选出外观品质优良的新品种。     

梨树叶片营养状况的诊断与评价

研究湖北省利川市‘长十郎’梨树叶片营养状况,为科学施肥提供依据。采用叶片营养诊断和主成分分析的方法,2017—2018年对利川市‘长十郎’梨9个梨园的叶片营养状况进行营养诊断和评价。结果表明,‘长十郎’梨树叶片的Ca、K、Cu、Zn含量基本适宜,Mg、B、P含量偏低,Mn含量高;部分梨园叶片Fe含量缺乏,2017年梨园叶片整体N含量偏低。土壤酸化是造成利川市梨园叶片营养失衡的主要原因。在生产中应通过施用酸性土壤调理剂如生石灰、硼泥类等碱性肥料提高土壤pH,增施有机肥提高土壤有机质含量,并重视补充Mg、B、Fe等中微量元素,实现‘长十郎’梨的提质增效。主成分分析可将10个叶片营养指标简化为4个主成分,代表了82.512%的原始信息量。基于主成分分析建立了‘长十郎’梨叶片营养综合评价模型Z=0.278N+0.030P+0.250K-0.042Ca-0.133Mg+0.193Fe+0.193Mn+0.174Cu+0.177Zn-0.106B,可较好地应用于梨树叶片营养的综合评价。     

Climacteric or non-climacteric behavior in melon fruit: 1. Aroma volatiles

A near-isogenic line (NIL) SC3-5 and a further nine NILs of melon contained introgressions of an exotic non-climacteric accession of Cucumis melo ‘Shongwan Charmi’ [SC (PI 161375), Conomon Group)] into the non-climacteric Spanish Inodorus type of melon cultivar ‘Piel de Sapo’ (PS). The NILs exhibited different climacteric behavior and aroma. Fruit from SC3-5 and seven NILs showed a climacteric pattern, while fruit from one NIL, both parentals and the cultivar ‘Nicolás’, were non-climacteric. The NILs were compared with the reference aromatic cultivars ‘Fado’ and ‘Védrantais’, which show climacteric behavior with high levels of respiration and ethylene production. The twenty-eight aromatic compounds common to the cultivars and NILs studied defined the aroma profile, which was composed of fifteen esters, six aldehydes, two alcohols, three derived sulfur compounds (methyldisulfanylmethane; methanethiolate; methyl 2-sulfanylacetate) and other three compounds (1,7,7-trimethylnorbornan-2-one; acetone; 2-ethylfuran). On the basis of the total ion count peak area, three compounds (isobutyl acetate; benzyl acetate; pentanal) allowed the climacteric to be distinguished from the non-climacteric NILs according to univariate analysis. Multivariate analysis of the aroma data on the basis of total ion count peak area separated the aromatic attributes of the climacteric ‘Védrantais’ and ‘Fado’ melons from the NILs that were closer to their inbred parentals when analyzed by partial least squares regression plus discriminant analysis. In the climacteric reference cultivars or NILs, esters were the predominant volatiles while aldehydes predominated in non-climacteric ones. These results support the hypothesis that at least one QTL in linkage group III boosts a series of maturation signals that are characteristic of climacteric fruit, including a different aroma profile.     

Chlorophyll concentration of potatoes grown under elevated carbon dioxide and/or ozone concentrations

Potato cv. Bintje was grown in open-top-chambers and free-air-CO₂-enrichment systems at 7 sites across Europe for 2 years (1998–99). The effect of different treatments (CO₂ enrichment and O₃ fumigation) on the chlorophyll content of fully expanded upper and lower canopy leaves was investigated collecting Minolta SPAD-502 meter readings. In both CO₂ treated and O₃ fumigated plants, leaves had lower chlorophyll content than those in ambient air controls; season-long chlorophyll averages were 9.3% lower in the ‘CO₂’ treatments, 9.1% lower in ‘O₃’ treatments and 12.3% lower in ‘CO₂+O₃’ treatments. The analysis of chlorophyll content in three different growth phases (Emergence–Tuber Initiation; Tuber Initiation–Maximum Leaf Area; Maximum Leaf Area–Harvest) showed that in the early growth period, i.e. before tuber initiation there was a slight indication for an higher chlorophyll content at elevated CO₂ (+3.8%) or O₃ (+1.7%). However, from tuber initiation onwards the leaves of plants grown under elevated CO₂ or O₃ showed a progressively lower chlorophyll content (−4.8% for CO₂ treatments and −2.6% for O₃ treatments) indicating a faster senescence of leaves that increased during the late growth period (−12.8% for CO₂ treatments and −12.7% for O₃ treatments) and that was enhanced by CO₂–O₃ interaction (−17.8%).     

Role of commercial sanitizers and washing systems on epiphytic microorganisms and sensory quality of fresh-cut escarole and lettuce

Increasing concerns about the possible formation of carcinogenic compounds and the emergence of new, more tolerant pathogens, have raised questions on the use of chlorine in fresh-cut produce. There is a growing need to investigate the efficacy of new commercial sanitizing and other alternative technologies. In the present study, the effectiveness of chlorine and other commercial sanitizer agents (Sanova, Sanoxol 20, Tsunami 100, Purac FCC 80, Citrox 14W and Catallix) was evaluated on epiphytic microorganisms and their influence on the sensory quality of fresh-cut escarole and lettuce. Different sanitizer concentrations (manufacturer's recommended dose and half of this dose) and application systems (submersion and spray) were also compared. The antimicrobial efficacy of the treatments was evaluated, initially after washing, and after 8 days of storage simulating a commercial shelf-life (3 days at 4 °C + 5 days at 8 °C). All the tested washing solutions were more effective in reducing the microbial load than water washes, particularly in fresh-cut escarole. However, the microbial load of fresh-cut escarole and lettuce after 8 days of storage was very similar for most of the treatments despite the different application systems and concentrations of the sanitizers. Clearly epiphytic microorganisms of fresh-cut escarole and lettuce were able to grow rapidly during storage under low temperature, reaching similar or higher values than the unwashed fresh-cut produce at the day of production. The overall visual quality of fresh-cut salad leaves was scored as good or very good (≥6) after 8 days of storage, except for the product washed with Purac. Thus, despite the high number of mesophilic bacteria present in the product, between 6 and 8 log cfu g⁻¹, it was not associated with a detrimental quality. Therefore, the determination of the initial epiphytic reductions of fresh-cut products after washing with different sanitizing agents provides little information about the microbial or sensory quality of the product at the time of consumption.