苹果根域交替、定位灌水对新梢生长和叶片生理的影响

以3年生盆栽嘎拉苹果（砧木为八棱海棠）为试材,研究了苹果根域交替和定位灌溉不同水量对新梢生长、叶片生理特性的影响。结果表明：交替灌水条件下,随每次灌水量增加,秋梢恢复生长时间提早,且生长量增大;灌水根域相同时,除1/4、2/4、3/4根域每次灌水500 mL和2/4根域每次灌水750 mL处理外,其余各处理新梢均有二次生长。定位灌水条件下各处理间新梢变化不明显,且新梢生长量较小。交替灌水和定位灌水对苹果叶片水势、气孔导度等生理特性指标无影响,但交替灌水叶片水势和气孔导度等指标相对于定位灌水而言变化较平稳。由此可见,灌水量是调节新梢二次生长的决定因素,而灌水根域主要影响相关生理指标;部分根域灌水,新梢可发生二次生长,灌水根域过多（3/4或4/4）和每次灌水量大于750 mL对新梢生长不利。从减少树体冗余生长和节水、保持树体生理稳定方面考虑,2/4根域每次交替灌水750 mL为最佳处理。     

短枝富士苹果不同负载和灌水量对新梢生长、产量和灌水利用效率的影响

【目的】探明黄土高原地区苹果优质高效生产的负载量与灌溉量的关系。【方法】以9年生短枝富士苹果树为研究对象，试验设3种负载量：低负载T1(2果·cm^-2主干横截面积)、中负载T2(4果·cm^-2主干横截面积)和高负载T3(6果·cm^-2主干横截面积)，及6个灌水梯度：W0(0)、W1(40%ETc)、W2(60%ETc)、W3(80%ETc)、W4(100%ETc)和W5(120%ETc)。研究负载量与灌水处理对苹果生长、叶面积指数、光合特性、品质、产量及灌水利用效率的影响。【结果】在相同负载量条件下，随着灌水量的减少，新梢生长长度和叶面积指数LAI逐渐降低，光合速率Pn、蒸腾速率Tr和气孔导度Gs的日均值均会随灌水量的增加呈现先增加后减小的趋势。在相同灌水量条件下，随着负载量的增加，新梢生长长度显著降低(p<0.05)，其他无明显变化。负载量和灌水量对苹果产量和灌溉水利用效率(简称IWUE)有极显著影响，各处理以T3W4产量最高，T1W1处理产量最低；T3W1处理的IWUE最大，T1W5处理最小。【结论】回归分析表...     

“红富士”苹果离体/活体枝叶光合作用及水分利用效率的季节变化

以25a生"红富士"苹果为试材,于生长季节对饱和水分环境的离体枝条叶片与活体叶片的水势和光合作用进行了连续观测,以探索年周期内果树生长不同发育阶段叶片水分状况对光合作用和水分利用效率的影响。结果表明:在"红富士"苹果生育期前半阶段的展叶抽梢期、开花坐果期、花芽分化期,由于尚未进入降雨季节,叶片水势不断下降,光合速率和蒸腾速率都明显小于离体枝条叶片,叶片水势的降低在一定程度上限制了蒸腾速率,但是也同样降低了光合速率,导致水分利用效率逐渐下降。因此在4~5月份抽梢展叶期和开花坐果期应当及时进行灌水补充,6月份适度的水分胁迫则有利于花芽分化。在7、8月份冠层蒸腾作用强烈,叶片的水势下降明显,此时的水分胁迫限制了蒸腾速率,提高了水分利用效率。由于此期已经进入雨季,除个别干旱年份以外,通常无需灌溉。在9月份以后进入果树生长发育后期,随着日照时数和气温逐日下降,活体叶片的光合速率和蒸腾速率与离体枝条叶片的差异变小,树体的水分利用效率提高,一般不予灌溉。     

灌水量对温室自根与嫁接黄瓜根系分布及水分利用效率的影响

 为探求黄瓜适宜的节水灌溉方式,以温室栽培的黄瓜自根苗和嫁接苗为试验材料,设定每次灌水150、300和450 m³ · hm^-2的不同灌水量,研究灌水量对黄瓜根系分布、商品瓜产量和水分利用效率的影响。结果表明,与常规灌水量对照（每次450 m³ · hm^-2）相比,适度减少灌水量,在多数情况下不会显著影响黄瓜根系生长、垂直分布与水分利用,每次150 m³· hm^-2的灌水量对自根与嫁接黄瓜的产量无显著影响,水分利用效率显著提高。每次150 m³ · hm^-2灌水量下,嫁接黄瓜的根系旺盛且粗壮,同时诱发了大量毛细根向土壤深层分布,使其产量显著高于自根黄瓜,因此在减量灌溉条件下,嫁接具有良好的促根节水丰产的效果。     

水分处理对本溪山樱生物量的影响

采用盆栽试验,研究水分处理对本溪山樱生物量的影响。结果表明:不同灌水量对本溪山樱实生苗产生影响不同,过量(每日灌1500mL)或少量(每日灌水量≤350mL)灌水时,植株生长发育不良,表现出水分胁迫状态;每日灌水量为750mL时,植株生长发育正常。随着淹没根系体积的增加,茎叶含水量、叶片相对含水量降低;全淹处理4d时植株死亡。     

灌水量对温室自根与嫁接黄瓜产量品质的影响

为探求黄瓜适宜的节水灌溉方式,以黄瓜自根苗和嫁接苗为试验材料,试验设定667 m2每次10、20、30 m3的不同灌水量,研究灌水量对温室栽培自根与嫁接黄瓜产量和品质的影响。结果表明:每次667 m2灌水10 m3的减量灌溉不仅显著提高了植株的水分利用效率,而且能在保持产量的基础上显著提高果实的品质;嫁接栽培对提高黄瓜产量、水分利用效率和果实品质无显著影响。     

覆盖方式和灌水量对甘蓝水分利用和干物质积累的影响

以生产上的经验灌水量每次30 m3•（667 m2）-1-未覆膜（G30N）为对照,研究不同覆盖方式和灌水量对甘蓝水分利用和干物质积累的影响。结果表明：随着灌水量的增大,渗漏量、蒸发量增加,蒸腾量以G30N最大,其中膜孔灌溉处理（除蒸发量外）均大于裸地灌溉,而土壤储水量降低|裸地灌溉下增加灌水量可以提高甘蓝的外叶、叶球、根和总干物质量,0～10 cm和0～30 cm土层根质量增加,10～30 cm土层根质量则减少,膜孔灌溉下适当减少灌水量,则甘蓝的各部分干物质量相应提高,且减少灌水量能有效地增加各层根系干质量|增大灌水量,甘蓝产量增加,但水分利用效率则降低,且膜孔灌溉处理的产量和水分利用效率均大于裸地灌溉。综合甘蓝生产和节水两方面考虑,裸地灌溉每次20 m3•（667 m2）-1,或者膜孔灌溉每次10 m3•（667 m2）-1处理的效果较好,值得在生产上推广。     

红富士苹果园节水灌溉方式试验研究

对果园采用畦灌、隔行交替灌溉、交替单侧沟灌和不灌溉4种灌溉方式,分析红富士苹果树叶光合活性、新梢生长量及果实品质,从水分利用效率和灌溉水生产效率方面评价灌溉方式。试验结果表明:与不灌水和常规畦灌相比,红富士苹果生产中采用交替单侧沟灌,没有显著降低果品产量和质量,从经济产量的形成来看,显著提高了水分利用效率和灌溉水生产效率,减少了果园生产用工,节约了生产用水,提高了灌溉收益率。     

不同灌水方式对大棚番茄植株生长、产量及水分利用效率的影响

以番茄为试材,采用田间试验的方法,研究了膜下暗灌(G1)、膜下滴灌(G2)、隔沟交替灌溉(G3)和普通沟灌(G4)4种灌水方式对塑料大棚番茄植株生长、产量和水分利用效率的影响,以期筛选出适合当地番茄的灌溉方式。结果表明:G1、G3和G4 3种灌溉方式较G2灌水方式均显著提高了番茄株高和茎粗。G2灌水量最少,为1 146m~3·hm~(-2),G3次之为1 601m~3·hm~(-2),G1和G4 2种灌水方式灌水量最大,约为2 000m~3·hm~(-2)。G2、G3较G4灌水方式分别节水44.2%和22.1%。G2灌水利用效率最高为48.1kg·m~-3,G1、G4最低为27kg·m~-3。与其它灌溉方式相比,G3显著增加了番茄地上部和地下部干质量;而普通沟灌根系干质量最小,根/冠比最低。综上可见,膜下滴灌和隔沟交替灌溉在不降低产量的前提下,可显著降低灌水量,提高灌水利用效率,为塑料大棚番茄合适的灌水方式。     

砂土1/4根域施用有机肥对苹果幼树生长的影响

以2 a生有机玻璃箱栽植的分根苹果幼树为材料,研究1/4根域施用不同水平有机肥对苹果幼树新梢和根系生长的影响。结果表明,6月中旬以后,10%和30%有机肥处理的新梢二次生长旺盛;20%有机肥处理春梢段节数、占总新梢节数比例、叶面积、比叶重和春梢生长量均显著大于10%和30%处理,10%有机肥处理秋梢长度、节数、叶面积和比叶重均显著大于20%处理,秋梢补偿生长旺盛;不同比例有机肥处理调控梢类组成,10%和30%处理的长梢比例分别占总新梢22.2%和25.0%,而20%处理的仅占11.8%;除6月份外,20%有机肥处理根系总长度在果树整个生长季节内均显著大于10%和30%处理。砂性土壤局部施用适量有机肥可以调控新梢生长和根系的发育,为果园土壤局部改良、集中营养供应等提供理论依据。     

Modelling salt accumulation by a bean crop grown in a closed hydroponic system in relation to water uptake

Four different NaCl concentrations in the irrigation water, 0.8, 3, 6 and 9 mol m⁻³, were applied as experimental treatments to beans (Phaseolus vulgaris L.) grown in completely closed hydroponic systems in a greenhouse. Initially, the Na and Cl concentrations increased rapidly in the root zone, as indicated by the values measured in the drainage water, and this resulted in corresponding increases in the Na/water and Cl/water uptake ratios. However, as these ratios approached equilibrium with the NaCl/water ratios in the irrigation water, the Na and Cl concentrations in the root zone converged to maximal levels, which depended on the treatment. The highest Na and Cl concentrations in the root zone and the corresponding NaCl concentrations in each treatment were used to establish relationships between the external NaCl concentration and the Na/water or Cl/water uptake ratios, which proved to be exponential for Na but linear for Cl. These relationships were then used in a previously established model [Savvas, D., Kotsiras, A., Meletiou, G., Margariti, S., Tsirogiannis, I., 2005a. Modeling the relationship between water uptake by cucumber and NaCl accumulation in a closed hydroponic system. HortScience 40, 802–807] to enable the prediction of the Na and Cl concentrations in the root zone in relation to the cumulative water uptake. The curves predicted by the model followed a convex pattern, with an initially rapid increase in Na and Cl concentrations in the root zone followed by a gradual levelling out as the cumulative water consumption rose. The measured Na and Cl concentrations in the drainage water were more accurately predicted at the higher NaCl concentrations in the irrigation water, although those predicted at 0.8 mol m⁻³ of NaCl were considered acceptable for use in commercial practice. Bean showed a high efficiency of Na exclusion from the upper leaves, while Cl was readily translocated to the young leaves as the external Cl concentration rose. Plant growth decreased with increasing salinity in a way similar to that reported for beans constantly exposed to comparable salinity levels.     

绒毛白蜡根区局部盐胁迫对其生长的影响

绒毛白蜡（Fraxinus velutina）是滨海盐渍区主要的植被和园林绿化乔木,其发达的根系易受土壤盐分异质性的影响。为探索局部盐胁迫对其生长的影响,采用分根培养桶对幼苗进行局部盐胁迫处理,分析幼苗的生长特征、光合特性、根系分布和离子积累。结果表明,局部低盐胁迫处理的幼苗生长量显著高于均匀盐胁迫和局部高盐胁迫处理;虽然局部高盐胁迫对叶片的水势无影响,但是显著降低了叶片的气孔导度、光合速率和蒸腾速率。局部盐胁迫处理中,无盐胁迫区的根系生物量显著高于盐胁迫区;与均匀盐胁迫相比,局部盐胁迫能够显著降低叶片中Na+的含量,增加K+/Na+。虽然绒毛白蜡的生长在局部盐胁迫条件下受到抑制,且局部盐分越高抑制越强,但生长量与均匀盐胁迫相比显著增高。在局部盐胁迫条件下,细根在无胁迫区的补偿性生长能够提供叶片所需水分,降低叶片中Na+的积累,增加K+含量,缓解了盐胁迫的不利影响。     

洗涤剂处理对翠菊种子萌发及根尖的影响

研究了5种浓度和2个不同时间处理的白猫洗涤剂对翠菊种子萌发、根生长、细胞分裂和染色体畸变的影响。结果表明:4～64mL/L处理的翠菊种子和对照组的种子相比,萌发率及根长都比对照组低,且随着处理浓度和处理时间的增加,洗涤剂对翠菊种子的萌发和根长的生长抑制作用增强;根尖细胞有丝分裂指数随洗涤剂浓度的增高和处理时间的延长而递减;洗涤剂处理能引起不同程度的染色体畸变,其中32mL/L处理6h作用效果最明显。     

Nitrogen and water use efficiency of zucchini squash for a plastic mulch bed system on a sandy soil

Zucchini squash (Cucurbita pepo L.) is an economically important vegetable crop in Florida. Typically, it is intensively managed with high inputs of fertiliser and irrigation water. Our objectives were to evaluate the interaction between fertilisation rates and irrigation treatments, and to quantify nitrate leaching in a plastic mulched/drip irrigated zucchini squash production systems. Three studies were carried out. The first study evaluated different depth placement of drip and fertigation lines on plant growth and fruit yield. Treatments included SUR (both irrigation and fertigation drip lines placed on the surface); S&S (both lines buried 0.15 m deep); and SDI (irrigation line placed 0.15 m below the fertigation line on the surface). The second and third studies compared three different N-rates and different soil moisture sensor-based irrigation strategies. Nitrate-N leaching was monitored by zero tension drainage lysimeters and soil samples. N leaching increased when irrigation and N-rates increased, with values ranging from 2 to 45 kg ha⁻¹ of N. Use of SDI increased yields by 16% compared to the S&S treatment, and reduced nitrate leaching by 93% while increasing the water use efficiency by 75% compared to a fixed 2-h irrigation event per day treatment. Application of N above the standard recommended rate of 145 kg ha⁻¹ did not increase yield, although yields were reduced at the lowest N-rate. The use of soil moisture sensors for automatic irrigation control reduced irrigation application and minimized nitrogen leaching. In addition, combining the soil moisture controlled SDI system that had surface applied fertigation resulted in similar or higher yields, while reducing both water use and potential N leaching because of improved nutrient retention in the root zone.     

Effects of urea formaldehyde foam soil amendment on growth and response to transient water deficit stress of potted Flindersia schottiana saplings

Hydrocell™is a urea formaldehyde resin foam (UFRF) product used as a soil amendment. It is proposed to improve the physicochemical properties (viz. water relations and aeration) of the plant root zone. Flindersia schottiana is a tree species used in the ornamental horticulture industry. This study investigated the potential of Hydrocell™ [0–50% (v/v) incorporation rates] to promote growth of F. schottiana saplings during containerized nursery production in composted pine bark medium. The growth response of the potted saplings to transient water stress was also assessed. In addition, growth of F. schottiana saplings potted into three different soil types (sand, loam, clay) was assessed in the presence and absence of 30% (v/v) Hydrocell™. Under well-watered conditions in composted pine bark, Hydrocell™ treatments enhanced sapling leaflet numbers, with 30% (v/v) being the most beneficial treatment. However, no consistent significant differential effects of incorporation rate on either plant height or stem diameter were recorded. Extended time to wilting upon withholding irrigation was achieved, with the optimum Hydrocell™ rate being 10% (v/v). Among the three soil types compared, use of 30% (v/v) Hydrocell™ resulted in improved growth of potted F. schottiana saplings in the sand and loam soils, but not in the clay soil. These findings suggest that the UFRF, Hydrocell™, holds limited promise as a soil amendment for trees in the nursery phase. Optimum incorporation rates (v/v) would need to be determined for individual media types, specific irrigation regimes and individual taxa.     

水杨酸对石榴扦插苗的影响

以萘乙酸、清水处理为对照,在适宜浓度下用水杨酸对石榴插穗进行浸泡处理扦插繁殖,研究其对石榴扦插苗成活率、生根数量、根系生长及新梢的影响。结果表明:水杨酸、萘乙酸处理后成活情况相似,在促进石榴扦插苗生根及枝梢生长方面二者效果相同。     

设施砂壤土容重对番茄幼苗生长和根系构型的影响

土壤紧实是设施蔬菜生产的土壤障碍因子之一。在塑料大棚砂壤土条件下,用人工土柱栽培法研究了土壤容重分别为1.20、1.35和1.58 g ? cm-3的土壤对番茄幼苗生长和根系构型的影响。结果表明,随容重增大,叶片伸长速度、株高、植株含水量、鲜质量、干质量、根冠比、根表面积、根长密度和根体积密度等都显著降低。随容重增大,根系干质量、根表面积、根长密度和根体积密度在垂直面上的分布显著降低,容重1.58 g ? cm-3处理的根系全部分布在0 ~ 6 cm土层内。高容重土壤使根毛区皮层产生形变,即细胞变长,皮层下陷,根表面凹凸不平,根圆度变差,偏心率增大,降低根毛区的吸收能力。     

发酵果树枝碎屑对苹果幼树根系特征及叶片光合蒸腾的影响

以2年生盆栽红富士苹果[Malus × domestica Borkh.‘Red Fuji’/Malus hupehensis Rehd.]幼树为试材,将苹果枝干碎屑发酵后施入盆土,定期调查苹果叶片光合与蒸腾速率、干周生长量、根系活力以及根系构型等指标。结果表明,向土壤施入质量比为2%和4%的发酵果树枝碎屑可以提高苹果幼树叶片净光合速率和根系活力,增加干周增长量,对叶片蒸腾速率和水分利用效率的影响不明显;2%的处理还能够增加新根数量,提高新根表面积和体积,促进新根加粗和加长生长,增大根系分形维数,促使根系结构复杂化,而施入4%的发酵果树枝碎屑则降低新根数量、体积和长度。综合分析表明,施用2%的发酵果树枝碎屑促进幼树根系和树干生长的整体效果好于4%的处理。     

苹果幼苗部分根系水分胁迫对光合作用主要参数的影响

以1年生苹果组培苗为试材,用改良的Hoagland营养液加20%PEG-6000进行半根渗透胁迫(HS)处理,与仅加营养液的正常水分条件的对照(CK)和加20%PEG-6000进行全根胁迫处理(TS)进行比较,研究了根系不均匀供水条件下植株的叶片水势和光合作用主要参数的反应特点。结果表明,HS与CK之间叶片的日出前水势不存在显著差异,且显著高于TS,但日水势变化动态在大部分情况下HS显著低于CK;和CK相比较,HS处理的叶片气孔导度、蒸腾速率和净光合效率显著降低,但在处理的早期显著高于TS。HS还导致叶片温度较对照显著增高。另外,试验体系中HS处理部分根系处于水分胁迫状态,而另外的根系处于良好的水分供应条件下,可用于模拟定位灌溉和分根区交替灌溉根系不均匀供水条件,对于开展相关果树生理反应及生长发育调控机制的研究提供了良好的试验体系。     

Soil water stress at young urban street-tree sites in response to meteorology and site parameters

Growth conditions at urban street-tree sites are unfavorable and tree vitality is increasingly threatened by water scarcity due to changing climate. Developing adaption and management strategies to ensure early stage and long-term tree- and root growth requires thorough knowledge about root zone soil-water dynamics at young urban street-tree sites. Therefore, we established a soil water potential (SWP) monitoring at 17 young urban street-tree sites in the city of Hamburg, Germany. Over four years (2016–2019) we measured and quantified critical soil water availability in the root ball, planting pit, and surrounding urban soil using a threshold value (SWP < −1200 hPa) and assessed the tree sites sensitivity towards meteorological variables, tree- and site characteristics using a data driven random forest model. During 2018 and 2019, average critical soil water availability in the root ball and planting pit occurred between three to five months per year, and the trees were exposed to prolonged periods of critical soil-water availability for two consecutive years. After planting, critical soil water availability increasingly shifted year wise from the root ball into the entire planting pit as a consequence of root development and increasing water demand of the trees. Considering less usable water within the surrounding sandy soils, soil water in the planting pit may be depleted earlier and more rapidly with tree aging. The random forest model successfully predicted critical soil water availability and identified tree age as an important predictor. Long-term (10-day) rainfall was the most important variable predicting the occurrence of critical soil water availability, suggesting a further extension of periods with critical soil water availability as rainy summer days are projected to decrease with climate change. Additionally we identified soil temperature as a more important predictor than air temperature as it reflects site specific characteristics affecting water- an energy balance. This study underlines the urgency to adapt the growing conditions of young urban street-trees in terms of sufficient water storage, and provides an approach for future application in tree site soil water management, to maintain their vitality under urbanization pressure and climate change.