Partial Rootzone Research Articles

Physiological and growth responses of pomegranate tree (Punica granatum (L.) cv. Rabab) under partial root zone drying and deficit irrigation regimes

This study evaluated the effects of full irrigation (FI, 100% ETC), partial root zone drying and deficit irrigation with mild (75%ETC) and severe (50% ETC) water stress on the physiological and growth behavior of pomegranate trees in southern Iran in 2011 and 2012. The experiment was set up as a split plot design in completely randomized blocks design with three replications. Results showed that the stem water potential (ψstem) was directly related to the soil water deficit (SWD), and it varied from −2.07 to −3.27MPa in 2011 and −1.67 to −3.23MPa in 2012. In all times of measurements, higher values of stomatal conductance (gs), net photosynthesis (An) and leaf scale transpiration (Tr) were obtained in FI and mild water stress treatments (An: 3.15–12.64μmolm−2s−1, gs: 0.032–0.129molm2s−1 and Tr: 2.72–9.48mmolm2s−1) in comparion with those obtained in the severe water stress treatments (An: 2.11–11.81μmolm−2s−1, gs: 0.021–0.11molm2s−1 and Tr: 1.89–7.58mmolm2s−1). Results generally showed low values of gs in the Rabab cultivar in the studied arid area. Furthermore, the hydraulic signaling (ψstem) in response to the water stress and weather conditions controlled the seasonal variation of gs. Transpiration efficiency (TE) increased with increasing the degree of water stress and PRD showed higher TE (1.17–1.18μmolmmol−1) than that in DI strategies (1.06–1.07μmolmmol−1). Furthermore, the value of intrinsic water use efficiency (IWUE) in FI (85μmolmol−1) was statistically lower than that obtained in mild (PRD75, DI75) and severe (PRD50, DI50) water stress treatments (87.8–89.9μmolmol−1). Different irrigation strategies did not significantly affect the fruit growth rate, and its maximum values occurred at about 170 DAB (0.27–0.35mmd−1) in all irrigation strategies. The LAI values in FI and mild water stress strategies were significantly different compared with those in the severe water stress treatments. For all irrigation strategies, the maximum LAI values occurred at flowering stage (68 DAB), and was 6.09 and 6.15 (FI), 5.97 and 6.04 (DI75), 6.33 and 6.64 (PRD75), 4.60 and 4.82 (DI50) and 4.91 and 5.03m2m−2 (PRD50) in 2011 and 2012, respectively. In conclusion, PRD75 is the recommended, applicable water-saving strategy and good alternative with respect to FI among other irrigation managements when water resources are limited in order to increase TE and IWUE while other physiological and growth parameters are maintained at an acceptable level.

Evaluation of soil chemical properties irrigated with recycled wastewater under partial root-zone drying irrigation for sustainable tomato production

Recycling of wastewater is becoming more popular in order to augment the inadequate irrigation supplies and meet the growing water demands for agriculture in arid regions of the world. This study investigated the environmental impact of deficit irrigation regimes on soil properties with five scenarios using recycled wastewater (RW), fresh tap water (FW), and a blend of RW and stormwater (BW). The five irrigation scenarios were applied to tomato plants growing in pots and included: (i) full irrigation (FI); (ii) partial root zone drying (PRD) irrigation at 75% of FI involving irrigation of only one part of the root zone, while the other part was exposed alternately to soil drying (PRD 75); (iii) PRD irrigation at 50% of FI (PRD 50); (iv) conventional deficit irrigation (DI) at 75% of FI applied on both sides of the root zone (DI 75); and (v) DI at 50% of FI (DI 50). Among the different irrigation scenarios, the PRD 75 treatment led to the lowest level of salinity for the surface soil layer. The PRD reduced TN in the soil compared with DI, while the water source significantly increased soil TN and TC with RW by 4% and 7%, respectively, compared with FW under FI. However, the irrigation scenarios and water sources did not show significant differences in the sodium absorption ratio (SAR), but PRD could reduce SAR compared with DI when using water with a high sodium concentration, such as RW.

Physiological Responses of Greenhouse-grown Drip-irrigated Chile Pepper under Partial Root Zone Drying

Water saving, productivity, and quality of the chile pepper were evaluated under three irrigation treatments. Three drip irrigation treatments used were 1) control, where water was applied at the surface using two drip emitters; 2) partial root-zone drying vertically (PRDv), where subsurface irrigation was applied at 20 cm depth from soil surface; and 3) partial root-zone drying compartment (PRDc), where roots were divided into two compartments and irrigation was applied to one of the compartments on every alternate-day cycle for 15 days. Continuous measurements of soil water content were carried out during the growing seasons of 2013 and 2014, respectively. During both growing seasons, the stomatal conductance (gS) and net photosynthetic rates (Pn) were similar among all treatments including the control. In both PRD treatments, a higher rooting depth and root length density (RLD) than the control likely compensated for the water stress in dry soil zones by taking up more water from the water available parts of the root-soil system. In PRDc and PRDv treatments, 30% less water was applied than control without significant changes to plant stress expressed by stem water potential, plant height, capsaicinoid concentration, and yield. The increased irrigation water use efficiency (IWUE) demonstrated water saving potential of both PRD techniques for chile pepper production in water-limited arid environments.

Impact of deficit irrigation strategies in a saline environment on Shiraz yield, physiology, water use and tissue ion concentration

Background and Aims This study investigated the response of field-grown Shiraz vines to saline irrigation involving water-deficit irrigation techniques. Methods and Results Drip-irrigated Shiraz vines were subjected to control (1.0–2.3 ML/ha), reduced control and partial root zone drying (both approximately 50% less than control) irrigation treatments utilising moderately saline irrigation over three seasons. Grape juice chloride (Cl−) and sodium (Na+) concentration was not affected significantly by irrigation treatment, although it did vary greatly between seasons. Seasonal influence of rainfall was shown to have more of an effect on Na+ concentration in grape juice, while irrigation applied and hence overall salt load impacted more heavily on grape juice Cl−. Partial root zone drying when compared against the controls had reduced stomatal conductance, leaf water potential, berry mass, and yield and pruning mass, while there was no significant effect on TSS (°Brix), pH and titratable acidity. Conclusion In this study, the seasonal variation of rainfall and total irrigation applied played a greater role in altering the concentration of grape juice Cl− and Na+ than the application of irrigation water with the same moderate salinity but with the differing irrigation strategies. Significance of the Study Regions, where water allocation has been reduced and which are relying on a saline irrigation source, have the ability to manage the Cl− and Na+ concentration present in grape juice by having a better understanding of the role season can play and the variability within that season, thereby making more informed decisions on when to apply irrigation.

Effect of partial root zone drying and deficit irrigation on nitrogen and phosphorus uptake in potato

Better understanding of the effects of deficit irrigation regimes on phosphorus (P) and nitrogen (N) uptake dynamics is necessary for sustainable water, P and N management. The effects of full (FI), deficit (DI) and partial root-zone drying (PRD) irrigation on potato P and N uptake with P fertilization (P1) or without (P0) were investigated in two split-root pot experiments in a soil with low plant available P. Under FI, the plants were irrigated to pot water holding capacity while under DI and PRD, 70% of the water amount of FI was applied on either both or one side of the pots, respectively. During potato growth, plant P uptake increased while P concentration decreased at P1 and was almost constant at P0. PRD and DI reduced plants P uptake to a same extent, ca. 22% compared to FI at P1, while at P0, plants P uptake was similar for the three irrigation treatments. Soil P transport to the root surface by diffusion was similar under DI and PRD. DI treatments had higher soil microbial biomass P, water soluble P, root biomass and leaf water potential than PRD treatments, while PRD treatments had higher plant N:P ratios than DI treatments and higher root secretion of acid phosphatases that may have compensated for the lower level of water soluble P. N was immobilized in soil in all the treatments. Plant N uptake under PRD was higher than DI at both P levels, which could be explained by the higher microbial biomass and N-immobilization under DI. In conclusion, when same amount of water was used, PRD was superior to DI in terms of N uptake, but not P uptake. Challenges remain how to maintain crop yield and P uptake under reduced irrigation regimes. Utilization of water and N fertilizer was low when the soil was deficient in P.

Effect of different irrigation strategies on vine physiology, yield, grape composition and sensory profiles of <em>Vitis vinifera</em> L. Cabernet-Sauvignon in a cool climate area

<p style="text-align: justify;"><strong>Aim</strong>: The efficacy of partial root zone drying (PRD) and regulated deficit irrigation (RDI) on vine physiology, yield components, fruit composition and wine sensory profiles of ‘Cabernet-Sauvignon’ was investigated in a cool climate region in Ontario, Canada.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Field experiments were conducted in a Cabernet-Sauvignon block in Niagara-on-the-Lake, ON Canada between 2006 and 2008. There were five treatments : non-irrigated control, PRD, full irrigation [100 % of crop evapotranspiration (ET<sub>c</sub>)] and two levels of RDI (50 and 25 % ET<sub>c</sub>). Treatments started immediately after fruit set and continued until post-veraison. Soil and vine water status were apparently controlled not only by the amount of water but also by the irrigation strategy used. In the PRD treatments, soil moisture, leaf water potential, and transpiration rate were generally lower than in 100 % ET<sub>c</sub> but higher than non-irrigated and RDI treatments. Almost all treatments were different than in non-irrigated vines in fruit composition and wine sensory attributes. Wine sensory attributes differed considerably due to the amount of irrigation water applied in 2007. RDI strategies were more consistent than the PRD treatments in their effect on vine water status, grape composition and wine sensory profiles. Inconsistent patterns across seasons for some variables indicated that besides soil and vine water status, there were other factors that impacted vine physiology, yield components and berry composition.</p><p style="text-align: justify;"><strong>Conclusions</strong>: RDI treatments improved wine quality when compared with full or either non-irrigated treatments. Overall, use of RDI irrigation or PRD during dry and warm years can improve grape composition in cool climates.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: To the best of our knowledge, this is the first evaluation of PRD and RDI on Cabernet-Sauvignon in a cool humid climate. It suggests that although RDI strategies are more effective, PRD also has value, particularly in dry seasons.</p>

Improvement of yield and grape and wine composition in field-grown Monastrell grapevines by partial root zone irrigation, in comparison with regulated deficit irrigation

Regulated deficit irrigation (RDI) and partial root zone irrigation (PRI) were compared for four years (2009–2012), each at two different irrigation volumes (110mmyear−1 (1) and 78mmyear−1 (2)), in field-grown Monastrell grapevines grafted onto 1103P, in South Eastern Spain. The aim was to distinguish the effects of deficit irrigation per se from specific PRI effects (placement of water) on yield response and berry and wine quality. Vines grown with PRI-1 or RDI-1 received around 30% of the ETc from budburst to fruit set, 13–15% ETc from fruit set to véraison and 20% ETc from véraison to harvest. The RDI-2 and PRI-2 vines received around 20% ETc from budburst to fruit set, no irrigation from fruit set to véraison and a recovery (21-24% ETc) thereafter. In general, the PRI-2 and RDI-2 vines (the most-severely water-stressed) showed greater yield reduction and lower overall berry and wine quality (including technological and phenolic composition) than the moderately-water-stressed vines (RDI-1 and PRI-1). Compared to RDI-1, PRI-1 improved the yield response—increasing mean yield, cluster number per vine and berry weight and maintaining better bunch health at late ripening and a greater proportion of bigger bunches. In addition, PRI-1 increased the anthocyanin and amino acid concentrations of the berries and altered their composition, improving the phenolic and chromatic characteristics of the wine and enhancing the health-promoting value of the fruit. It was also the option most economically viable under the present conditions of the wine grape market, compared to RDI-1 and the rest of the treatments. In contrast, PRI-2, although it improved some technological quality attributes and phenolic and chromatic characteristics of Monastrell berries and wines compared to RDI-2, did not have a positive effect on yield (yield and cluster and berry weight decreased in some years) and its implementation was economically unviable under these soil and climatic conditions. The significant interaction between irrigation volume (high vs. low) and irrigation placement (PRI vs. RDI) indicate that the response to PRI also depended on the volume of water applied in the wet root zone and the soil total water availability.

IMPROVEMENT OF TOMATO WATER PRODUCTIVITY BY THE USE OF A PARTIAL ROOTZONE DRYING IRRIGATION STRATEGY

Water scarcity is becoming a major problem for agricultural development in the Mediterranean area. The Moroccan Massa region is a major supplier of tomato (Lycopersicum esculentum L.) both for export and for the domestic market. Current average water use for the tomato is 8,000 m3/ha for an 8-9 month production cycle. This research aims to develop irrigation strategies with this goal water saving with no effect on yield or fruit characteristics. The objective of the work was to assess the effects of the partial root zone drying irrigation (PRD) on leaf stomatal conductance, relative leaf water content (RWC), stem maximum daily shrinkage (MDS), root development and water use efficiency (WUE) of tomato grown in a greenhouse on a sandy substrate. Three treatments were applied: a control that received 100% of the water requirement, PRD-70 and PRD-50 in which 70% and 50% of water requirements were applied. The root system was divided in two sides with alternation of irrigation every three days. When vapor pressure deficit rises, PRD treatments showed a decrease in leaf stomatal conductance with, respectively, 17% and 26% compared to control. PRD-50 had the highest leaf water content during the experimental period. During periods of low and moderate climatic demand, MDS of all treatments showed the same trend. Whereas when vapor pressure deficit rose, PRD-50 had lower signal intensity. Compared to the control, number of root hairs increased by 120% and 190% in PRD-70 and PRD-50, respectively. Water use efficiency (WUE) was the highest (P < 0.001) for PRD-50 with 43 kg of fresh fruit per m3 of applied water.

Partial root zone drying exerts different physiological responses on field-grown grapevine (Vitis vinifera cv. Monastrell) in comparison to regulated deficit irrigation.

Regulated deficit irrigation (RDI) and partial root zone irrigation (PRI) were compared for 4 years at two irrigation volumes (110mm year-1 (1) and 78mm year-1 (2)) in field-grown grafted Monastrell grapevines (Vitis vitifera L.) to distinguish the effects of deficit irrigation from specific PRI effects. PRI-1 and RDI-1 vines received ~30% of the crop evapotranspiration (ETc) from budburst to fruit set, 13-15% from fruit set to veraison and 20% from veraison to harvest. RDI-2 and PRI-2 vines received around 20% of ETc from budburst to fruit set, no irrigation from fruit set to veraison, and recovery (21-24% ETc) thereafter. Compared with RDI-1, PRI-1 increased irrigation depth and total soil water (θv) availability in the root zone, and stimulated greater fine root growth and water uptake. Increased soil volume exploration supported greater canopy water use, vegetative development, biomass accumulation and internal water storage capacity. PRI-1 vines had higher stomatal conductance, lower leaf-level water use efficiency and increased leaf xylem sap concentration ([X-ABA]leaf) following reirrigation. Compared with RDI-2, PRI-2 decreased total θv availability, fine root growth and water uptake, gas exchange, leaf water status, [X-ABA]leaf, biomass accumulation and storage capacity. Xylem ABA decreased with total θv availability in PRI-2, probably from limited sap flow when θv in drying soil was low (≈20%). For this rootstock-scion combination, high irrigation volumes applied to the wet part of the roots (θv>30%) are critical for increasing root-to-shoot ABA signalling and growth, and improving performance under semiarid conditions.

不同水氮条件下灌溉方式对玉米干物质量和氮钾利用的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 不同水氮条件下灌溉方式对玉米干物质量和氮钾利用的影响 DOI: 10.5846/stxb201405090921 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金重点项目（U1033004）；国家863计划（2011AA100504） Effect of irrigation method on dry mass and nitrogen and potassium utilization of maize under different water and nitrogen conditions Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:由于作物需水随生育期的变化，分根区交替灌溉（AI）的节水效果也会随生育期而发生变化，探明不同生育期分根区交替灌溉对玉米生长和水分养分利用的影响，以期为分根区交替灌溉的实施和充分发挥其节水节肥效果奠定理论基础。通过盆栽试验，在2种灌水水平（正常灌水和轻度缺水）和2种有机无机氮比例（100%无机氮和70%无机氮+30%有机氮）下，以常规灌溉（CI）为对照，分别研究苗期-灌浆初期、苗期-拔节期以及拔节期-抽雄期进行AI对玉米干物质量、氮钾含量和吸收量以及土壤碱解氮和速效钾含量的影响。结果表明，在轻度缺水和有机无机氮肥配施下，与CI相比，拔节期-抽雄期分根区交替灌溉玉米地上部和总干物质量分别增加29.6%和27.4%，地上部和总N吸收量增加50.7%和50.4%。与单施无机氮肥相比，有机无机氮肥配施会在不同程度上增加地上部和总N吸收量，但是一般降低土壤碱解氮和速效钾含量，这说明在轻度缺水和有机无机N肥配施下，拔节期-抽雄期进行分根区交替灌溉提高玉米总干物质量和N吸收量。 Abstract:Crop water requirement varies with the growth stage, so water-saving effect of alternate partial root zone irrigation (AI) also varies with the growth stage. Understanding the effect of alternate partial root-zone irrigation at different growth stages on maize growth and water and nutrient utilization can provide the theoretical foundation for the implement of alternate partial root zone irrigation and fully exerting its effect of saving water and fertilizer. Taking conventional irrigation (CI) as the control, this study has investigated the effects of AI respectively at seedling- early grain filling, seedling-jointing and jointing-tasselling stages on dry mass, nitrogen and potassium contents and uptakes of maize and available N and K contents in soil using a pot experiment under two irrigation levels (normal irrigation and mild water deficit) and two ratios of inorganic to organic N (100% inorganic N and 70% inorganic N + 30% organic N). Results indicate that under mild water deficit and combined application of organic and inorganic N fertilizer condition, AI at the jointing-tasselling stage increased shoot and total dry masses by 29.6% and 27.4%, and shoot and total N uptakes by 50.7% and 50.4%, respectively, if compared to CI. Combined application of organic and inorganic N increased shoot and total N uptakes to some extent, but generally reduced soil available N and K contents when compared to only inorganic N. Thus alternate partial root-zone irrigation at the jointing-tasselling stage could increase total dry mass and N uptakes under mild water deficit and combined application of organic and inorganic N fertilizer. 参考文献 相似文献 引证文献

Effects of dynamic and static deficit and partial root zone drying irrigation strategies on yield, tuber sizes distribution, and water productivity of two field grown potato cultivars

New strategies of partial root-zone drying (PRD) and deficit irrigations (DI) were studied on potatoes in a semi-arid area of Iran. A factorial experiment was conducted as a complete randomized design in three replications. The potato cultivar treatments were Agria and Ramos. The whole growth period of both cultivars was divided into three stages based on the BBCH scale. There were five furrow irrigation treatments. The full irrigation treatment (FI) received 100% of potential evapotranspiration (ET); static deficit irrigation (SDI) received 75% of ET during the growth period; dynamic deficit irrigation (DDI) received 90% of ET in the first one-third of growth period, 75% of ET in the second one-third of growth period, and 50% of ET in the last one-third of growth period; static partial root zone drying irrigation (SPRD) received 75% of ET during the growth period; dynamic partial root zone drying irrigation (DPRD) received 90% of ET in the first one-third of growth period, 75% of ET in the second one-third of growth period, and 50% of ET in the last one-third of growth period. Analysis showed that there were significant differences between irrigation strategies as DI did outperform PRD in tuber production. The SDI, DDI, SPRD, and DPRD irrigation treatments decreased the potato tuber yield by 4%, 7%, 56%, and 52% compared to FI, respectively. SPRD and DPRD decreased potato tuber yield by 54% and 48% compared to SDI and DDI, respectively. Results also showed that there were no significant differences between cultivars. Interaction between irrigation strategies and cultivars was not significant. Furthermore, water productivities (WP) were significant among irrigation strategies. Compared to FI, the SDI and DDI increased WP by 28% and 34%, respectively, but SPRD and DPRD decreased WP by 40% and 31%, respectively. In general, the DI strategy (SDI, DDI) is recommended in the study area due to the slight fresh tuber yield reduction (4%, 7%) and considerable increase (28%, 34%) in WP relative to FI. Furthermore, the dynamic irrigation strategies led to higher WP than the static ones. It was also found that Agria outperformed the Ramos because of higher fresh tuber yield under water-saving irrigation strategies. Under non-limiting water conditions, Ramos produced higher fresh tuber yield. Furthermore, it is required to decrease the duration of wet/dry cycle under PRD strategy to guarantee efficient PRD and cope with extra water stress and hot weather in the region.

EFFECT OF DEFICIT IRRIGATION ON YIELD, RELATIVE LEAF WATER CONTENT, LEAF PROLINE ACCUMULATION AND CHLOROPHYLL STABILITY INDEX OF COTTON–MAIZE CROPPING SEQUENCE

SUMMARYWater stress induces some physiological changes in plants and has cumulative effects on crop growth and yield. Field experiments were conducted to study the effect of deficit irrigation (DI) on yield and some physiological parameters in cotton and maize in a sequential cropping system. Creation of soil moisture gradient is indispensable to explore the beneficial effects of partial root zone drying (PRD) irrigation and it could be possible only through alternate deficit irrigation (ADI) practice in paired row system of drip layout that is commonly practiced in India. In the present study, PRD and DI concepts (creation of soil moisture gradient) were implemented through ADI at two levels of irrigation using drip system. Maize was sown after cotton under no till condition without disturbing the raised bed and drip layout. Relative leaf water content (RLWC) and chlorophyll stability index (CSI) of cotton and maize were reduced under water stress. A higher level of leaf proline content was observed under severe water-stressed treatments in cotton and maize. RLWC and CSI were highest and leaf proline content was lowest in mild water deficit (ADI at 100% crop evapotranspiration once in three days) irrigation in cotton and maize. The same treatments registered higher values for crop yields, net income and benefit cost ratio for both the crops.

Effect of Partial Root Zone Drying on Growth, Yield and Biomass Partitioning of a Soilless Tomato Crop

Effect of Partial Root Zone Drying on Growth, Yield and Biomass Partitioning of a Soilless Tomato Crop

Modeling and visualization of three-dimensional young apple tree root growth under different modes of drip irrigation

为研究不同滴灌方式下大田苹果幼树的根系生长行为, 提出一种用Otsu方法对根系图像进行分割后统计分析根系空间分布的方法, 利用图像处理库通过Python语言编程实现了获取空间分布统计矩阵, 以Lynch的根构型模型为结构原型, 结合功能模型建立不同滴灌方式下的大田苹果幼树根系生长行为结构 功能模型, 最后利用OpenAlea对该模型进行三维可视化模拟。以大田苹果幼树为试验对象进行验证, 同时依据形态特征的相似度以及仿真数据与实测数据的相关性两个参考指标将模拟结果与实物进行对比, 验证了所采用算法的有效性。结果表明, Otsu算法可有效分割苹果幼树根系图像数据, 结合常规功能结构参数和空间分布统计矩阵建立的大田苹果幼树根系结构 功能模型可科学地模拟不同滴灌方式对苹果幼树根系空间拓扑的影响, 大田苹果幼树根系结构 功能模型模拟可以可视化不同滴灌方式下的根系生长空间变化行为。可视化模拟结果表明, 分根区交替灌溉的苹果幼树根系在根区两侧分布比较均匀, 根密度较大, 有利于提高根系对水肥的吸收利用效率。研究结果可为分根区交替灌溉在果园的应用提供参考。

Effect of different irrigation strategies on vine physiology, yield, grape composition and sensory profile of Sauvignon Blanc (&lt;em&gt;Vitis vinifera&lt;/em&gt; L.) in a cool climate area

&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Aim&lt;/strong&gt;: The impacts of partial root zone drying (PRD) and regulated deficit irrigation (RDI) on soil moisture, vine water status, yield components, fruit composition and wine sensory profile of Sauvignon blanc were studied in a cool climate region.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Methods and results&lt;/strong&gt;: Field experiments were conducted in a commercial Sauvignon blanc block in Ontario, Canada between 2006 and 2008. Treatments were: non-irrigated control, PRD, full irrigation [100% of crop evapotranspiration (ET&lt;sub&gt;c&lt;/sub&gt;)] and one level of RDI (25% ET&lt;sub&gt;c&lt;/sub&gt;). Treatments began immediately after fruit set and continued until the beginning of September. Reference evapotranspiration (ET&lt;sub&gt;o&lt;/sub&gt;) was calculated using the Penman–Monteith equation. Soil moisture and vine water status (leaf water potential and transpiration rate) in the PRD treatments were generally less than in 100% ET&lt;sub&gt;c&lt;/sub&gt; but higher than in non-irrigated and 25% ET&lt;sub&gt;c&lt;/sub&gt; treatments. Almost all treatments were different than non-irrigated vines in fruit composition and wine sensory attributes. RDI strategies were more consistent across vintages than the PRD treatments in their effect on vine water status, grape composition and sensory profiles.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Conclusions&lt;/strong&gt;: Use of RDI or PRD in cool climates during dry and warm years can improve grape composition. In very dry and hot seasons, like that of 2007, irrigation improved grape composition and wine aroma typicity. RDI enhanced fruity aroma attributes, which suggests that this could be a viable strategy to improve grape and wine quality in cool areas. However, due to high climatic variation over the period studied, no consistent pattern of irrigation effects was found for berry composition, suggesting that plant water status was not the only factor that controlled fruit and wine quality.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Significance and impact of the study&lt;/strong&gt;: To the best of our knowledge, this study is the first evaluation of PRD in a cool, humid climate, and highlights the potential value of both RDI and PRD irrigation techniques in cool climate regions, particularly during dry growing seasons.&lt;/p&gt;

Effects of Partial Root Zone Irrigation on Leaf Photosynthetic Curves and Chlorophyll Fluorescence Parameters in Naked Oat

The objective of this study was to provide experimental evidence for photosynthetic mechanism under drought stress and practical technique of water-saving irrigation in naked oat(Avena nuda L.).In a pot experiment with instrument to control root zone irrigation and water amount,the effects on relative chlorophyll content(SPAD),photosynthetic curves,and chlorophyll fluorescence parameters were compared among irrigation models of alternative partial root zone irrigation(APRI),fixed partial root zone irrigation(FPRI),and conventional total root zone irrigation(CTRI).Compared to CTRI,partial root zone irrigation,including APRI and FPRI treatments,decreased leaf SPAD,net photosynthetic rate(Pn),and carboxylation efficiency(CE);however,APRI had no obvious effects on reducing initial quantum efficiency(α),maximum photochemical efficiency(Fv/Fm),actual photochemical efficiency of PSII(ФPSII),apparent electron transport rate(ETR),and photochemical quenching coefficient(qP).The leaf SPAD of APRI was significantly enhanced compared to that of FPRI(P0.05),and the maximum net photosynthetic rate(Pmax),α,light saturation point(LSP),light use efficiency(LUE),Ci/Ca,CE,CO2 saturation point(Ci,sat),Fo,Fm,ФPSII,ETR,qP,and NPQ were all higher in APRI than in FPRI.The reduction of Pn in partial root zone irrigation treatments resulted from stomatal factors,and structural damage of photosynthetic system II(PSII) was found in FPRI treatment.Clearly,partial root zone irrigation can improve the tolerance ability of naked oat against drought stress;particularly,APRI has the effect to maintain higher Pn than FPRI.

Influence of deficit irrigation on growth, yield and yield parameters of cotton–maize cropping sequence

Field experiments were conducted at Agricultural College and Research Institute, Coimbatore, India during 2007–2009 to study the effect of deficit irrigation practices implemented through drip irrigation system on cotton–maize cropping sequence. Creation of soil moisture gradient is essential to explore the beneficial effects of partial root zone drying (PRD) irrigation; and it could be possible through ADI (alternate deficit irrigation) practice in paired row system of drip layout, commonly practiced in India. In the present study, PRD and deficit irrigation (DI) concepts (creation of soil moisture gradient) were implemented through ADI at two levels of irrigation using drip irrigation system. Experimental treatments comprised of seven irrigation levels (full and deficit) through drip system with surface irrigation for comparison. Maize was sown after cotton under no till condition without disturbing the raised bed and drip layout. Response of the crops to water stress indicated growth, yield parameters and crop yield were highest in mild water deficit (ADI at 100% ETc once in three days) among different deficit irrigation treatments. Alternate deficit irrigation (ADI100-50 and ADI80-40) resulted in higher values in plant height, LAI (leaf area index) and DMP (dry matter production). Among the deficit irrigation practices, mild deficit (ADI at 100% ETc once in three days) registered higher values for seed cotton yield (3670–3760kgha−1), grain yield of maize (7420–7590kgha−1). The same treatment registered higher values for net income and benefit cost ratio (BCR) in both the crops. Number of bolls per plant and sympodial branches per plant were the highly correlated parameters to seed cotton yield. In the case of maize, the number of grain per cob and cob weight were the highly correlated parameters to grain yield.

Effects of Whole-root and Half-root Water Stress on Gas Exchange and Chlorophyll Fluorescence Parameters in Apple Trees

The responses of photosynthesis, chlorophyll fluorescence, and de-epoxidation state of the xanthophyll cycle pigments (DEPS) of micropropagated apple trees (Malus ×domestica) were investigated under whole-root water stress (WRS) and half-root water stress (HRS) induced by polyethylene glycol 6000 to simulate whole and partial root zone drying. Compared with control plants without water stress, plants under WRS and HRS exhibited reduced leaf net photosynthetic rate (Pn) and stomatal conductance (gS) with a greater reduction in WRS than in HRS plants. However, intercellular CO2 concentration (Ci) increased under WRS as water stress was prolonged, signifying a non-stomatal limitation of Pn. Regarding HRS, decreased Pn was mainly the result of a stomatal limitation explained by a relatively low Ci. Changes in photosynthesis and chlorophyll parameters indicate that severe and slight damage occurred to the photosynthetic apparatus of WRS and HRS leaves, respectively, starting at Day 3 after initiating water stress. This damage was not evident on the donor side but was expressed as a reduced capacity of the acceptor side of the photosystem II reaction centers. To prevent damage from excess light, the DEPS of WRS leaf increased. Decreased gS could explain reduced water use under an irrigation strategy of partial root zone drying in fruit trees.

Effect of New Irrigation Technology on the Physiology and Water Use Efficiency of Potato by Reclaimed Water Irrigation

Agriculture is a big consumer of fresh water in competition with other sectors of the society. The agricultural sector continues to have a negative impact on the ecological status of the environment. The worlds interest in high quality food is increasing. Field experiments were conducted to investigate the effect of subsurface drip irrigation on physiological responses, yield and water use efficiency, Soil nitrogen, Root weight density of potato in the semi-humid region of middle China using subsurface drip irrigation. The experiment used second-stage treated wastewater with and without addition of chloride, and both subsurface drip and furrow irrigations were investigated. Results indicated that the alternate partial root-zone irrigation is a practicable water-saving strategy for potato. The drip with chlorinated and non-chlorinated water improved water use efficiency by 21.48% and 39.1%, respectively, and 44.1% in the furrow irrigation. Partial root zone drying irrigation stimulates potato root growth and enhances root density. The content of the heavy metal in the potato tubers is no more than the National Food Requirements, and it is consistent with National Food Hygiene Stands.

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF OLIVE (Olea europaeaL.): A REVIEW

SUMMARYThe results of research on the water relations and irrigation needs of olive are collated and summarised in an attempt to link fundamental studies on crop physiology to irrigation practices. Background information on the ecology of the olive (it is native to the coastal areas of the eastern Mediterranean) and on crop development processes are presented, followed by reviews of the influence of water stress on gas exchange (stomatal conductance, photosynthesis and transpiration), crop water requirements, water productivities and irrigation systems. The olive has many attributes that help to protect it against drought, including the morphology of the leaf, and the capacity to conserve water under conditions of high evaporative demand through stomatal closure, osmotic regulation and resistance to cavitation. The concept of ‘deficit irrigation’ has been the subject of much research. Although vegetative growth is restricted, there is no convincing evidence that ‘sustained deficit irrigation’ or ‘regulated deficit irrigation’ or ‘partial root zone drying’ offer any advantages over conventional practices. Water productivities are very variable and difficult to reconcile due, in part, to biennial bearing, tree-to-tree variability and differences in tree population densities. Similarly, no clear consensus has emerged on how best to exploit the sensitivity of trunk expansion to water availability in irrigation scheduling. As production methods for this historical crop are intensified (high-density hedgerows, irrigated and mechanized orchards), so will the need to understand the role that water plays in the production processes become ever more critical.