控制性分根区交替滴灌对苹果幼树形态特征与根系水分传导的影响

采用固定滴灌(根区一侧固定供水)、控制性分根区交替滴灌(根区两侧交替供水)和常规滴灌(紧贴幼树基部供水)3种灌水方式和3种灌水定额(固定滴灌和交替滴灌均为10、20和30 mm,常规滴灌为20、30和40 mm),对比研究了控制性分根区交替滴灌对苹果幼树形态特征与根系水分传导的影响.结果表明： 交替滴灌的根区两侧土壤出现反复干湿交替过程,常规滴灌的根区两侧土壤含水率差异不显著.在灌水定额相同时,灌水侧的土壤含水率在3种灌水方式间差异不显著.与常规滴灌和固定滴灌相比,交替滴灌显著增加了苹果幼树的根冠比、壮苗指数和根系水分传导,在30 mm灌水定额处理下,交替滴灌的根冠比分别增加31.6%和47.1%,壮苗指数增加34.2%和53.6%,根系水分传导增加9.0%和11.0%.3种灌水方式下,根干质量和叶面积均与根系水分传导呈显著线性正相关.控制性分根区交替滴灌增强了苹果幼树根系水分传导的补偿效应,促进了根系对水分的吸收利用,有利于干物质向各个器官均衡分配,显著提高了根冠比和壮苗指数.     

控制性分根区交替滴灌对苹果幼树形态特征与根系水分传导的影响

采用固定滴灌(根区一侧固定供水)、控制性分根区交替滴灌(根区两侧交替供水)和常规滴灌(紧贴幼树基部供水)3种灌水方式和3种灌水定额(固定滴灌和交替滴灌均为10、20和30 mm,常规滴灌为20、30和40 mm),对比研究了控制性分根区交替滴灌对苹果幼树形态特征与根系水分传导的影响.结果表明： 交替滴灌的根区两侧土壤出现反复干湿交替过程,常规滴灌的根区两侧土壤含水率差异不显著.在灌水定额相同时,灌水侧的土壤含水率在3种灌水方式间差异不显著.与常规滴灌和固定滴灌相比,交替滴灌显著增加了苹果幼树的根冠比、壮苗指数和根系水分传导,在30 mm灌水定额处理下,交替滴灌的根冠比分别增加31.6%和47.1%,壮苗指数增加34.2%和53.6%,根系水分传导增加9.0%和11.0%.3种灌水方式下,根干质量和叶面积均与根系水分传导呈显著线性正相关.控制性分根区交替滴灌增强了苹果幼树根系水分传导的补偿效应,促进了根系对水分的吸收利用,有利于干物质向各个器官均衡分配,显著提高了根冠比和壮苗指数.     

根系分区交替滴灌对苹果幼苗生理特性和水分利用效率的影响

以矮化红富士苹果幼苗为试验材料,采用交替滴灌(ADI)、固定滴灌(FDI)和常规滴灌(CDI)3种滴灌方式和3种灌水量对苹果幼苗的生理特性和水分利用效率进行了研究,以阐明根系分区交替灌溉下苹果幼苗生理特性和节水机理.结果表明:与CDI方式相比,当灌水定额由20 mm增大到30 mm时,ADI方式提高了苹果幼苗根干重、根系导水率、叶水势和净光合速率,降低了其蒸腾速率、棵间蒸发量和蒸散量,从而使得ADI方式下的叶片水分利用效率、总水分利用效率和灌溉水分利用效率较CDI方式大大提高;3种滴灌方式的根系导水率均存在显著的季节变化,并以8月份最大,12月份最小;与CDI方式相比, ADI和FDI方式在节水达33.3%时的平均根系导水率仅分别降低了5.81%和14.7%,但水分利用效率、灌溉水利用效率分别较CDI方式高出16.31%和14.48%、40.52%和27.65%.可见,局部根区灌溉方式能促进苹果幼苗生长和光合作用,并主要通过提高根系导水率的途径来提高水分利用效率.     

根区不同灌溉方式对苹果幼苗水流阻力的影响

研究了滴灌条件下根区不同灌溉方式（交替滴灌ADI、固定滴灌FDI和常规滴灌CDI）和灌水量对苹果幼苗及各组成部分水流阻力、气孔导度和叶面积的影响.结果表明：根区灌溉方式和灌水量对苹果幼苗水流阻力（R）的影响显著; 在相同的根区灌溉方式下,苹果幼苗根系阻力（R_r）随着灌水量的减少而增大,冠层阻力（R_s）随着灌水量的减少而减小.在相同灌水量下,与常规滴灌相比,交替滴灌和固定滴灌均提高了苹果幼苗叶片和叶柄阻力（R_l+p）,降低了幼苗全株阻力（R_t）、R_r、R_s以及侧枝和主杆阻力（R_lb+mr）.在20 mm和30 mm灌水定额下,交替滴灌的R_l+p分别比常规滴灌高1.06%和0.63%.在平均节水达33%的前提下,交替滴灌和固定滴灌的平均R_l+p分别比常规滴灌高19.65%和24.34%,但交替滴灌和固定滴灌的平均R_lb+mr分别降低了4.83%和14.97%.交替滴灌和固定滴灌等局部根区不同灌溉方式通过有效减小苹果气孔导度和叶面积,提高了R_l+p,从而减少了叶片的蒸腾失水,提高了苹果幼苗的水分利用效率,通过降低R_r和R_lb+mr提高了苹果幼苗调控水分的能力和抗干旱能力.     

交替根区滴灌下不同施氮量对葡萄干物质积累、分配和产量的影响

本试验采用盆栽的方法,在避雨栽培条件下,研究不同的灌溉方式和供氮水平对葡萄干物质积累与分配、产量和水氮生产效率的影响,以探讨北方鲜食葡萄生产最佳的水氮耦合管理模式。灌溉方式包括常规灌溉100%灌溉量(CDI)、单侧固定根区灌溉50%灌溉量(FDI)和双侧根区交替灌溉50%灌溉量(ADI);土壤施氮浓度设置0.4(N₁)、0.8(N₂)、1.2 g·kg^-1(N₃) 3个水平。结果表明: 与CDI模式相比,ADI和FDI总修剪量降低了34.8%和11.2%;随着施氮量的增加,生长冗余增加;CDIN₃处理葡萄树体冗余生长最高。ADI干物质积累量最高,分别比CDI、FDI提高5.1%和12.8%;N₂和N₃处理的树体总干物质量显著高于N₁处理。与其他灌溉模式相比,ADI模式下叶果比显著降低,收获指数显著提高;施氮量对各项指标影响不显著。所有组合中,ADIN₂处理冗余生长量与当年生物量比值最低。葡萄产量表现为ADI分别比CDI和FDI平均提高6.0%和10.4%,同一灌溉模式下,产量随着施氮量的增加而增加,以ADIN₂、ADIN₃耦合处理葡萄产量最高。与其他灌溉模式相比,ADI模式显著提高了葡萄水分利用效率,以ADI与N₂、N₃水平的耦合处理水分利用效率较高;不同施氮水平下,氮素利用效率表现为ADI＞CDI＞FDI,并随施氮水平的增加而降低。综合分析认为,ADIN₂处理能够减少葡萄冗余生长,有利于干物质向果实积累,产量较高,水氮生产效率较高,是较适宜北方葡萄生产的水氮组合模式。     

硒肥对豆科牧草圆叶决明生长和植株养分含量及其固氮能力的影响

通过田间小区试验,研究了施用不同量硒肥对种植于南方红壤的圆叶决明植株生长、牧草品质和根瘤固氮能力的影响.结果表明,1hm²施用硒肥75g(S₁)、150g(S₂)、225g(S₃)、300g(S₄)处理的圆叶决明植株株高、分枝数、根干重和茎叶干重分别比不施硒肥的对照(S₀)处理提高0.3%～6.2%、65.1%～79.5%、155%～252%和23.5%～70.6%,其中以S₂处理最佳.施用4种水平硒肥处理(S₁～S₄)的植株全氮、全磷和全钾吸收量分别比对照(S₀)处理提高21.79%～41.46%、20.74%～34.67%和34.3%～62.4%;而圆叶决明植株粗蛋白、粗脂肪、粗纤维和氨基酸含量则分别比对照(S₀)处理提高了21.79%～41.46%、1.4%～89.6%、34.1%～56.6%和6.33%～63.24%,其中以S₂处理对提高圆叶决明植株营养成分含量的效果最为明显.S₄处理的圆叶决明植株体硒含量最高,达0.695mg·kg^-1,比不施硒肥的S₀处理提高了0.658mg·kg^-1.在S₂处理中,圆叶决明的根瘤重、根瘤数和根瘤固氮酶活性均呈现为最大值,分别比对照(S₀)提高了131.7%、114.3%和1417.9%.     

滴灌频率和灌水量对榆林沙土马铃薯产量、品质和水分利用效率的影响

针对陕北榆林沙土马铃薯农田灌溉不合理的问题,采用滴灌水肥一体化技术,设置4 d(D₁)、8 d(D₂)和10 d(D₃)3个滴灌频率及60%ET_c(W₁,ET_c为作物需水量)、80%ET_c(W₂)和100%ET_c(W₃) 3个灌水量水平,共9个处理,在生育期内对马铃薯生长、产量和品质等指标进行观测,分析马铃薯各指标对不同灌水处理的响应规律.结果表明: 同一滴灌频率下,W₃处理的株高、叶面积指数、干物质、产量和经济效益高于W₁和W₂处理;W₁处理的灌溉水利用效率(IWUE)最高,而水分利用效率受灌水量的影响不显著;W₃处理下产量达43442 kg·hm^-2,比W₁和W₂处理分别高23.3%和11.6%;W₃处理下纯收益达23492元·hm^-2,比W₁和W₂分别高40.4%和18.7%;W₃处理的块茎淀粉和维生素C含量最大,还原糖含量最小,分别为14.4%、18.54 mg·(100 g)^-1 FW和0.7%.相同灌水量下,低、中灌水水平下D₁处理的产量、IWUE、淀粉和维生素C含量最高,还原糖含量最低;高灌水水平下D₂处理的产量、IWUE、纯收益、淀粉和维生素C含量最高,还原糖含量最低,分别为46572 kg·hm^-2、23.04 kg·m^-3、26622元·hm^-2、14.6%、19.53 mg·(100 g)^-1 FW和0.7%.从滴灌频率和灌水量的交互作用来看,D₂W₃的产量和品质均达到最高;主成分分析法得出D₂W₃处理得分最高.因此,D₂W₃(8 d,100%ET_c)处理高产优质,且水分利用效率较高,为最佳滴灌频率和灌水量.研究结果可为陕北榆林沙土马铃薯高产高效优质生产中灌溉制度的制定提供依据.     

水分对苜蓿叶片光合特性的影响

采用田间试验, 对每茬灌水3次(W₃)、2次(W₂)、1次(W₁)和不灌水(W₀)四种条件下的土壤水分, 苜蓿(Medicago sativa)叶片的叶绿素荧光参数、气孔导度(G_s)、净光合速率(P_n)和蒸腾速率(T_r)进行测定。结果表明, 灌水提高了苜蓿叶片的原初光能转换效率(F_v/F_m)、P_n和T_r, 并随着灌水量的增加而增加。苜蓿叶片的F_v/F_m、P_n和T_r的日均值与土壤含水量均呈极显著正相关关系。苜蓿叶片的P_n与F_v/F_m和光合有效辐射(PAR)的乘积呈正相关关系。灌水还改变了苜蓿叶片P_n的日变化格局。灌水较多的处理(W₃和W₂), 苜蓿叶片没有出现光合“午休”现象,P_n的日变化趋势呈现“单峰”型。而灌水较少和不灌水的处理(W₁和W₀), 苜蓿叶片出现了明显的光合“午休”现象, 其P_n的日变化进程呈现“双峰”型。在相同的水分条件下, 初花期苜蓿叶片的P_n高于再生期的, T_r则相反。     

棉花苞叶光呼吸和PSII热耗散对土壤水分的响应

在新疆气候生态条件下, 采用膜下滴灌植棉技术, 设置不同滴灌水分处理, 研究了不同滴灌量条件下棉花(Gossypium hirsutum)苞叶和叶片碳同化、光呼吸作用、光系统II (PSII)热耗散作用及其光破坏防御机制的差异, 以揭示滴灌节水条件下棉花苞叶缓解光抑制的机理及与棉花抗旱特性的关系。结果表明: 棉花开花后苞叶及叶片在高温强光下实际光化学效率(Φ_PSII)显著降低, 发生明显的光抑制现象, 但苞叶的光抑制程度较叶片轻; 与正常滴灌量处理相比, 节水滴灌条件下棉花水分亏缺, 叶片净光合速率(P_n)、Φ_PSII、光呼吸(P_r)、光化学猝灭系数(q_P)降低, 非光化学猝灭系数(NPQ)升高, 叶片光抑制程度加重, 而苞叶P_n、Φ_PSII、P_r、q_P、NPQ变化不大, 与正常滴灌量处理相比, 光抑制程度无显著差异。苞叶光呼吸速率与光合速率的比值(P_r/P_n)显著高于叶片; 滴灌节水条件下棉花适度水分亏缺对苞叶光呼吸及P_r/P_n无显著影响。高温强光下, 棉花节水滴灌对叶片PSII量子产量的转化与分配影响显著, 但对苞叶的影响不显著; 苞叶非调节性能量耗散的量子产量(Y(NPQ))高于叶片, 因此能有效地将PSII的过剩光能以热的形式耗散。综上所述, 与叶片相比, 苞叶对轻度水分亏缺不敏感, 是棉花适应干旱逆境较强的器官, 苞叶光呼吸和热耗散作用对光破坏防御具有重要意义。     

石羊河流域干旱荒漠绿洲区不同滴灌模式下葡萄茎液流变化及其与环境因子的关系

研究了石羊河流域干旱荒漠绿洲区交替滴灌（ADI）、固定滴灌（FDI）和常规滴灌（CDI）模式下葡萄茎液流的变化规律及其与气象因子和土壤含水率的相关关系.结果表明：研究区葡萄茎液流表现出与太阳辐射同步的昼夜变化节律;新梢生长期和开花期CDI处理的茎液流量显著大于其它两个处理;影响瞬时茎液流的主要气象因子是太阳辐射和气温,日茎液流量与平均气温和风速具有线性相关关系;不同灌溉方式下葡萄茎液流与气象因素的相关程度依次为：CDI>ADI>FDI;葡萄日茎液流量与参考作物蒸发蒸腾量（ET₀）呈显著线性相关关系.与CDI相比,ADI节省50%水量,而茎液流总量仅降低6.56%,且其葡萄茎液流和水分传导具有明显的补偿效应.     

Influence of summer rainfall on root and shoot growth of a cold-winter desert shrub,Atriplex confertifolia

Summary The influence of irrigation and nitrogen fertilization in early summer on root and shoot growth of Atriplex confertifolia, a C₄ shrub species, was examined in a cold-winter desert community in northern Utah. Soil water and xylem pressure potentials were monitored during the summer period.At the time of watering the surface soil (0–30 cm) was dry but there were turgid fine roots in this horizon. Watering of the soil reduced plant water stress from-30 to-15 bars (dawn values) indicating that roots near the surface were capable of absorbing water, and induced root growth in the 0–30 cm zone. The addition of N to the water treatment did not further increase root production. However, watering and watering +N fertilizer failed to stimulate shoot elongation or any dry weight increase of shoots. This shoot dormancy during summer is not typical of C₄ plants and is probably associated with adaptation to the cool arid environment.This work was carried out while the senior author was on study leave from CSIRO     

Growth dynamics of root and shoot hydraulic conductance in seedlings of five neotropical tree species: scaling to show possible adaptation to differing light regimes

The dynamics of growth (shoot and root dry weights, surface areas, hydraulic conductances, and root length) were measured in seedlings of five neotropical tree species aged 4–16 months. The species studied included two light-demanding pioneers (Miconia argentea and Apeiba membranacea) and three shade-tolerant young- or old-forest species (Pouteria reticulata, Gustavia superba, and Trichilia tuberculata). Growth analysis revealed that shoot and root dry weights and hydraulic conductances and leaf area all increased exponentially with time. Alternative methods of scaling measured parameters to reveal differences that might explain adaptations to microsites are discussed. Scaling root conductance to root surface area or root length revealed a few species differences but nothing that correlated with adaptation to light regimes. Scaling of root surface area or root length to root dry weight revealed that pioneers produced significantly more root area and length per gram dry weight investment than shade-tolerant species. Scaling of root and shoot hydraulic conductances to leaf area and scaling of root conductance to root dry weight and shoot conductance to shoot dry weight also revealed that pioneers were significantly more conductive to water than shade-tolerant species. The advantages of scaling hydraulic parameters to leaf surface area are discussed in terms of the Ohm's law analogue of water flow in plants. Received: 24 March 1997 / Accepted: 17 November 1997     

干旱区膜下滴灌条件下土壤深层水对棉花根系生长、分布及产量的影响

在土柱栽培条件下研究膜下滴灌土壤深层水对棉花根系生长的影响及与植株地上部生长的关系,设置土壤(60～120 cm)有深层水和无深层水2个处理,每处理设2个生育期间灌溉处理,分别为田间持水量70%和55%.结果表明：棉花总根质量密度、40～120 cm土层根长密度、根系活力等与地上部干质量间均具有显著的相关关系.生育期间耕层70%田间持水量条件下,土壤有深层水处理的总根质量密度与无深层水处理无明显差异,但40～120 cm土层的根长密度增加,根系活力增强,提高了土壤贮备水消耗量,增加了地上部干质量,最终获得较高的经济产量及水分利用效率.土壤有深层水条件下,生育期间耕层55%田间持水量处理的根冠比较大,40～120 cm土层根长密度和80～120 cm土层根系活力相对较高,土壤贮备水消耗量大幅提高,但仍无法弥补生育期间水分亏缺对根系及地上部生物量造成的负面影响,导致经济产量显著低于70%田间持水量处理.综上,充足的土壤深层水配合生育期间耕层65%～75%田间持水量,可促进棉花根系向下生长,有利于实现膜下滴灌棉花节水高产高效生产.     

The growth characteristics and yield potential of rice (Oryza sativa) under non‐flooded irrigation in arid region

The objectives of this field experiment were to study the growth characteristics and yield potential of rice plants under non‐flooded irrigation in arid area. Non‐flooded treatments included drip irrigation with plastic mulching treatments (DIs), furrow irrigation with plastic mulching treatment (FIM) and furrow irrigation with non‐mulching treatment (FIN). Conventional flooded cultivation (F) was check treatment (CK). The four drip irrigation treatments differed in the amount of water applied before and after panicle initiation. Root length density, leaf dry weight, shoot dry weight and root activity were generally higher in the non‐flood‐irrigated treatments (especially the drip‐irrigated treatments) than in the flood‐irrigated treatment at mid‐tillering. However, the growth and development of rice plants were limited after jointing in the non‐flooded irrigation treatments. Increasing the root/shoot ratio and root length density in the 20–40 cm depth and decreasing specific root length at 0–20 cm soil layer were important mechanisms for helping the rice plants to adapt to the non‐flooded environmental stresses. Finally, the grain yield in the non‐flooded irrigation treatments was lower than that in the F treatment. These low yields were mainly attributed to the low root length density at 0–20 cm depth and root activity. Generally speaking, the restricted degrees in the DIs were smaller than that in the FIM and FIN treatments. Among the DIs, both the highest grain yield (8223–8900 kg ha^?1) and the highest water use efficiency (WUE) (0.63) were observed when the soil water content was kept at ?30 kPa before panicle initiation and at ?15 kPa after panicle initiation (referred to as the DI2 treatment). The yield in the DI2 treatment was not significantly different than that in the flood‐irrigated treatment. However, WUE was 2.5 times higher in the DI2 treatment than in the F treatment. These results suggest that drip irrigation technology can be considered as a better water‐saving cultivation of rice plants in arid region.     

NaCl胁迫对滨梅扦插苗生物量和水分积累的影响

以1年生滨梅(Prunus maritima Marshall)扦插苗为实验材料,在盆栽条件下用质量浓度为0.15%、0.29%、0.58%、0.88%、1.17%、1.46%的NaCl溶液进行盐胁迫处理,测定胁迫后根、茎、叶Na+、K+含量以及全叶、一年生茎、二年生茎和根系生物量、含水率、根系活力变化,探讨滨梅的抗盐胁迫机制。结果显示:(1)盐胁迫80d后,随着盐胁迫强度提高,滨梅植株根、茎、叶Na+含量显著提高,而其根、茎K+含量显著降低,根、茎、叶K+/Na+值显著降低;根Na+含量在低于0.58%NaCl胁迫下显著高于茎、叶,而在高于0.58%NaCl胁迫下却表现为叶Na+含量显著高于根、茎。(2)滨梅根、茎、叶生物量均随盐胁迫强度的提高呈先增加后减少的趋势;随着盐胁迫时间的延长,茎、叶生物量在低于0.58%NaCl胁迫下均呈积累趋势,且茎生物量在0.58%NaCl胁迫下显著提高,而根、一年生茎、叶生物量在高于0.58%NaCl胁迫下均显著下降。(3)滨梅茎、叶含水率均随盐胁迫强度的增加呈先增加后减少的趋势,而随着胁迫时间的延长呈逐渐减少趋势;根系活力及根含水率均随盐胁迫强度的提高而增加,但根含水率随着胁迫时间的延长变化不明显。由此可见,滨梅能通过根系稀释并蓄积Na+,保护地上部分正常生长,当进入根系的Na+量超过吸收阈值时,Na+迅速在叶中积累储存,且叶中较高含量的K+对Na+形成了有效的缓冲。