不同微灌方式下水分调控对猕猴桃光合特性及产量的影响

【目的】为了研究不同微灌方式下水分调控对猕猴桃叶片光合特性及产量的影响,以"翠玉"猕猴桃为研究试材。【方法】采用小管出流(X)、微喷灌(P)和滴灌(D)3种灌溉方式在猕猴桃全生育期实施85%灌水量的轻度亏水(LD)、70%灌水量的中度亏水(MD1)、55%灌水量的偏重度亏水(MD2)和40%灌水量的重度亏水(SD)处理,并设置100%灌水量的对照组(CK),研究了猕猴桃叶片胞间CO2摩尔分数(Ci)、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、羧化速率(CE)、瞬时水分利用效率(WUEi)、产量及产量水分利用效率(WUEET)在不同水分亏缺下的变化。【结果】与CK相比,D-MD1处理的日均WUEi及CE分别提高了8.5%和2.7%。P-MD1处理的日均Pn与CE较CK分别提高了10.7%和10.4%,X-MD1处理的日均Ci、Pn、CE较CK分别提高了10.9%、12.2%和11.4%。D、P和X三个处理的WUEET均较CK有不同程度的提高,但D、P和X的产量随着水分的亏缺程度的加大而下降,而滴灌各处理间无显著性差异。与CK相比D-MD1、P-MD1、X-MD1处理的产量分别提高了1.4%、1.6%、2.3%,重度亏水处理的产量显著低于其余水分处理,且其他各处理间无显著性差异。MD1处理在不降低产量的情况下,可以节约灌水同时提高WUEET,重度亏水与偏中度亏水间在WUEET无显著性差异,同时X-MD1的产量均高于其他处理。【结论】X-MD1处理是"翠玉"猕猴桃较为合适的灌溉水分亏缺模式。     

拟穴青蟹GRP78基因的克隆与应激表达

葡萄糖调节蛋白78(glucose regulated protein 78 ku,GRP78)是热休克蛋白70家族成员之一,在调节蛋白质折叠和维持内质网稳态过程中起着分子伴 侣作用。采用RT-PCR、RACE等技术,首次从拟穴青蟹获得了GRP78的cDNA全长序列。该序列全长2 284 bp,开放阅读框(ORF)为1 962 bp,编码653个氨基酸残基。 同源分析显示,该基因编码的蛋白含有HSP70家族的签名序列,C末端为内质网蛋白滞留信号KDEL,与其他物种具有很高相似性。实时荧光定量PCR结果表明,GRP78 基因在拟穴青蟹多个组织中均有表达。第一期仔蟹在不同的温度和盐度下暴露12 h后,GRP78基因表达量随环境温度升高而增加;在高盐(30)条件下GRP78表达量 较高,进而推测拟穴青蟹GRP78参与蛋白质折叠和环境胁迫的应答。     

Drying half of the root-zone from mid fruit growth to maturity in ‘Hass’ avocado (Persea americana Mill.) trees for one season reduced fruit production in two years

We tested the effect of extended drying of half the root system on fruit yield and fruit Ca concentration, an indirect measure of fruit quality, in avocado (Persea americana Mill. cv Hass). In a field experiment on a sandy soil, withholding irrigation and plastic sheeting was used to dry the root-zone beneath the whole canopy (DD) or half the canopy (WD), compared with well-watered trees (WW). The irrigation water contained added nutrients and was slightly saline. Yield, shoot growth, leaf conductance, leaf and fruit water status and mineral concentrations of leaves and fruit were studied. The responses of treated trees were assessed in the following season during which normal irrigation practices were restored. With respect to yield, the WD treatment behaved the same as the DD treatment. It reduced yield by more than half and proportionately more than the reduction in water supply thus reducing irrigation efficiency. Re-watering did not restore yield of WD or DD-trees in the next season. The WD and DD treatments had no effect on the concentration of Ca in the fruit mesocarp and so are unlikely to affect fruit quality. The main impact of reduced water supply on the trees was fruit abscission and this was linked to dry soil around the roots rather than the water status of the leaves or fruits. We conclude that extended drying of half of the root-zone in one season reduced irrigation efficiency for two seasons by promoting the abscission of developing fruit to the same extent as occurred when the whole root system was exposed to extended drying.     

Relationship between stable carbon isotope discrimination and water use efficiency under regulated deficit irrigation of pear-jujube tree

To investigate the relationship between stable carbon isotope discrimination (Δ) of different organs and water use efficiency (WUE) under different water deficit levels, severe, moderate and low water deficit levels were treated at bud burst to leafing, flowering to fruit set, fruit growth and fruit maturation stages of field grown pear-jujube tree, and leaf stable carbon isotope discrimination (Δ_L) at different growth stages and fruit stable carbon isotope discrimination (Δ_F) at fruit maturation stage were measured. The results indicated that water deficit had significant effect on Δ_L at different growth stages and Δ_F at fruit maturation stage. As compared with full irrigation, the average Δ_L at different growth stages and Δ_F at fruit maturation stage were decreased by 1.23% and 2.67% for different water deficit levels, respectively. Δ_L and Δ_F among different water deficit treatments had significant difference at the same growth stage (P < 0.05). Under different water deficit conditions, significant relationships between the Δ_L and WUE_i (photosynthesis rate/transpiration rate, P_n/T_r), WUE_n (photosynthesis rate/stomatal conductance of CO_2, P_n/g_s), WUE_y (yield/crop water consumption, Y/ET_c) and yield, or between the Δ_F and WUE_y and yield were found, respectively. There were significantly negative correlations of Δ_L with WUE_i, WUE_n, WUE_y and yield (P < 0.01) at the fruit maturation stage, or Δ_L with WUE_i and WUE_n (P < 0.01) over whole growth stage, respectively. Δ_F was negatively correlated with WUE_y, WUE_n and yield (P < 0.05), but positively correlated with ET_c (P < 0.01) over the whole growth stage. Thus Δ_L or Δ_F can compare WUE_n and WUE_y, so the stable carbon isotope discrimination method can be applied to evaluate the water use efficiency of pear-jujube tree under the regulated deficit irrigation.     

Simulation of transpiration, drainage, N uptake, nitrate leaching, and N uptake concentration in tomato grown in open substrate

Free-drainage or “open” substrate system used for vegetable production in greenhouses is associated with appreciable NO₃⁻ leaching losses and drainage volumes. Simulation models of crop N uptake, N leaching, water use and drainage of crops in these systems will be useful for crop and water resource management, and environmental assessment. This work (i) modified the TOMGRO model to simulate N uptake for tomato grown in greenhouses in SE Spain, (ii) modified the PrHo model to simulate transpiration of tomato grown in substrate and (iii) developed an aggregated model combining TOMGRO and PrHo to calculate N uptake concentrations and drainage NO₃⁻ concentration. The component models simulate NO₃⁻-N leached by subtracting simulated N uptake from measured applied N, and drainage by subtracting simulated transpiration from measured irrigation. Three tomato crops grown sequentially in free-draining rock wool in a plastic greenhouse were used for calibration and validation. Measured daily transpiration was determined by the water balance method from daily measurements of irrigation and drainage. Measured N uptake was determined by N balance, using data of volumes and of concentrations of NO₃⁻ and NH₄⁺ in applied nutrient solution and drainage. Accuracy of the two modified component models and aggregated model was assessed by comparing simulated to measured values using linear regression analysis, comparison of slope and intercept values of regression equations, and root mean squared error (RMSE) values. For the three crops, the modified TOMGRO provided accurate simulations of cumulative crop N uptake, (RMSE = 6.4, 1.9 and 2.6% of total N uptake) and NO₃⁻-N leached (RMSE = 11.0, 10.3, and 6.1% of total NO₃⁻-N leached). The modified PrHo provided accurate simulation of cumulative transpiration (RMSE = 4.3, 1.7 and 2.4% of total transpiration) and cumulative drainage (RMSE = 13.8, 6.9, 7.4% of total drainage). For the four cumulative parameters, slopes and intercepts of the linear regressions were mostly not statistically significant (P < 0.05) from one and zero, respectively, and coefficient of determination (r²) values were 0.96-0.98. Simulated values of total drainage volumes for the three crops were +21, +1 and −13% of measured total drainage volumes. The aggregated TOMGRO-PrHo model generally provided accurate simulation of crop N uptake concentration after 30-40 days of transplanting, with an average RMSE of approximately 2 mmol L⁻¹. Simulated values of average NO₃⁻ concentration in drainage, obtained with the aggregated model, were −7, +18 and +31% of measured values.     

Agro-environmental evaluation of irrigation land: I. Water use in Bardenas irrigation district (Spain)

Non-point agrarian contamination makes its allocation to a specific territory difficult. This first part of the study seeks to analyze contamination resulting from water use in 54,438 ha of Bardenas irrigation district included in the Arba basin (BID-Arba). To this end, water balances were carried out in BID-Arba by means of measuring or estimating the main inputs, outputs and water storage between 1 April 2004 and 30 September 2006. Also, the spatial-temporal variability in water use was analyzed.The semester error balances were acceptable (between 11% and −6%), which permits the attribution of the mass of pollutants exported in drainage to the irrigation area evaluated, the objective of the second part of the study. Irrigation efficiency (IE) in BID-Arba was high (90%) despite the fact that Irrigation Sub-District VII (ISD-VII), with considerable flood irrigation drainage (27%), and ISD-XI with considerable losses due to evaporation and wind drift in sprinkler irrigation systems (15%), brought down the average (IE_VII = 73%; IE_XI = 83%). Irrigation management was inadequate as there was a water deficit (WD) of 9%, partly affected by the 2005 drought (WD_{Apr-05/Sep-05} = 21%) and the low irrigation doses applied in ISD-XI (WD_XI = 12%).To sum up, intense re-use of water caused a water use index (percentage of water used by the crops) of 85% which surpassed 90% in periods of drought. Nevertheless, irrigation management should be improved in order to annul the water deficit and to maximize the productivity of the agrarian system.     

Yield and water-production functions of two durum wheat cultivars grown under different irrigation and nitrogen regimes

Wheat (Triticum durum L.) yields in the semi-arid regions are limited by inadequate water supply late in the cropping season. Planning suitable irrigation strategy and nitrogen fertilization with the appropriate crop phenology will produce optimum grain yields. A 3-year experiment was conducted on deep, fairly drained clay soil, at Tal Amara Research Station in the central Bekaa Valley of Lebanon to investigate the response of durum wheat to supplemental irrigation (IRR) and nitrogen rate (NR). Three water supply levels (rainfed and two treatments irrigated at half and full soil water deficit) were coupled with three N fertilization rates (100, 150 and 200 kg N ha⁻¹) and two cultivars (Waha and Haurani) under the same cropping practices (sowing date, seeding rate, row space and seeding depth). Averaged across N treatments and years, rainfed treatment yielded 3.49 Mg ha⁻¹ and it was 25% and 28% less than half and full irrigation treatments, respectively, for Waha, while for Haurani the rainfed treatment yielded 3.21 Mg ha⁻¹, and it was 18% and 22% less than half and full irrigation, respectively. On the other hand, N fertilization of 150 and 200 kg N ha⁻¹ increased grain yield in Waha by 12% and 16%, respectively, in comparison with N fertilization of 100 kg N ha⁻¹, while for cultivar Haurani the increases were 24% and 38%, respectively. Regardless of cultivar, results showed that supplemental irrigation significantly increased grain number per square meter and grain weight with respect to the rainfed treatment, while nitrogen fertilization was observed to have significant effects only on grain number per square meter. Moreover, results showed that grain yield for cultivar Haurani was less affected by supplemental irrigation and more affected by nitrogen fertilization than cultivar Waha in all years. However, cultivar effects were of lower magnitude compared with those of irrigation and nitrogen. We conclude that optimum yield was produced for both cultivars at 50% of soil water deficit as supplemental irrigation and N rate of 150 kg N ha⁻¹. However, Harvest index (HI) and water use efficiency (WUE) in both cultivars were not significantly affected neither by supplemental irrigation nor by nitrogen rate. Evapotranspiration (ET) of rainfed wheat ranged from 300 to 400 mm, while irrigated wheat had seasonal ET ranging from 450 to 650 mm. On the other hand, irrigation treatments significantly affected ET after normalizing for vapor pressure deficit (ET/VPD) during the growing season. Supplemental irrigation at 50% and 100% of soil water deficit had approximately 26 and 52 mm mbar⁻¹ more ET/VPD, respectively, than those grown under rainfed conditions.     

膜下调亏滴灌对制种玉米耗水规律及产量的影响

通过大田膜下调亏滴灌试验,测定了制种玉米叶面积指数、耗水量和产量等指标。结果表明,拔节—抽穗期缺水抑制了叶面积的生长,对产量负面影响极为显著,水分利用效率显著降低;灌浆—成熟期缺水对叶面积指数和产量影响甚微,而水分生产效率却显著提高,通过建立产量与叶面积指数以及叶面积指数与日耗水强度模型,提出了在抽穗期充分供水,苗期和成熟期减小供水、保持适度的水分亏缺的制种玉米节水高产水分调控模式。     

干旱胁迫对枣树叶片生理的影响

以盆栽2年生蒙山脆枣和沾化冬枣为试材,研究了不同干旱胁迫程度对叶片水分饱和亏、叶片保水力、游离脯氨酸含量、SOD活性、POD活性、甜菜碱含量等生理指标的影响。结果表明:尽管品种间的变化存在差异,但随着干旱胁迫程度的加重,两品种的叶片保水力呈下降趋势,水分饱和亏、Pro含量、甜菜碱含量呈增加趋势,SOD、POD活性呈先升高后下降趋势;高含量的甜菜碱有利于枣叶片保持较高的水分含量,甜菜碱、Pro含量与枣品种的抗旱性存在一定的正相关关系,可以作为枣品种抗旱性鉴定的指标。     

花后水分亏缺对冬小麦光合特性及产量的影响

为给小麦高产和生育后期抗旱栽培提供理论依据,盆栽试验条件下,选用旱地小麦品种长武134、长旱58和水地小麦品种西农9871作为试验材料,研究了花后水分亏缺对不同生态型小麦光合特性及产量的影响.结果表明,花后水分亏缺对小麦灌浆期旗叶光合速率(Pn)和荧光参数(Fv/Fo和Fv/Fm)、籽粒产量、收获指数及水分利用效率均有明显影响.与对照相比,中度水分亏缺下两个旱地小麦品种Pn除花后24 d外变化均不明显,Fv/Fo和Fv/Fm有升高趋势,产量和收获指数变化也不显著,水分利用效率明显提高;在重度水分亏缺下,Pn、Fv/Fo、Fv/Fm、产量和收获指数均降低,水分利用效率长武134依然高于对照,而长旱58明显降低.水地小麦西农9871的Pn、Fv/Fo、Fv/Fm随水分亏缺程度的加重呈下降趋势,产量和收获指数与旱地小麦变化相似,水分利用效率处理间差异较小.说明旱地小麦受花后水分亏缺的不利影响小于水地小麦,表现出较高的水分利用能力.