The effect of drip line spacing, irrigation regimes and planting geometries of tomato on yield, irrigation water use efficiency and net return

This study was conducted in order to determine the effect of drip line spacing, irrigation regimes and planting geometries of tomato on yield, irrigation water use efficiency (IWUE) and net return. The experiments were carried out in the conditions of Eskisehir in Central Anatolian part of Turkey, between 2003 and 2005, with cv. Dual Large F1 tomatoes (Lycopercion esculentum L). The maximum yield of 121.1 t ha⁻¹ was obtained from the treatment in which both the lateral and row spacing were 1 m, and irrigated with water amount based on the percentage of canopy cover. The seasonal irrigation water amount of the treatment was 551 mm. Tomatoes yield of 109.9 t ha⁻¹ was obtained under conditions of 491 mm seasonal irrigation water applied for the 2-m lateral spacing in which two plant rows (twin rows) were planted 0.35 m on either side of the lateral with a row spacing of 0.70 m across the drip lateral and 1.30 m in the interrow between each set of twin rows. Although water saving of 60 mm and investments economy of 40% were provided from the twin-row design, the yearly return of the design including one lateral for each row was US$ 1590 ha⁻¹ higher than that the return of the twin-row design. The method of determination of irrigation water amount based on the percentage of canopy cover appeared to be the most reasonable and effective one in terms of the yield and IWUE. On the other hand, the maximum irrigation water use efficiency (22.3 kg m³) was obtained from 2-m lateral spacing and the percentage of canopy cover for calculation of the amount of irrigation water applied. Thus, canopy cover may be used successfully at any lateral design conditions.     

Irrigation rate and plant density effects on yield and water use efficiency of drip-irrigated corn

The efficient use of water by modern irrigation systems is becoming increasingly important in arid and semi-arid regions with limited water resources. This study was conducted for 2 years (2005 and 2006) to establish optimal irrigation rates and plant population densities for corn (Zea mays L.) in sandy soils using drip irrigation system. The study aimed at achieving high yield and efficient irrigation water use (IWUE) simultaneously. A field experiment was conducted using a randomized complete block split plot design with three drip irrigation rates (I₁: 1.00, I₂: 0.80, and I₃: 0.60 of the estimated evapotranspiration), and three plant population densities (D₁: 48,000, D₂: 71,000 and D₃: 95,000 plants ha⁻¹) as the main plot and split plot, respectively. Irrigation water applied at I₁, I₂ and I₃ were 5955, 4762 and 3572 m³ ha⁻¹, respectively. A 3-day irrigation interval and three-way cross 310 hybrid corn were used. Results indicated that corn yield, yield components, and IWUE increased with increasing irrigation rates and decreasing plant population densities. Significant interaction effects between irrigation rate and plant population density were detected in both seasons for yield, selected yield components, and IWUE. The highest grain yield, yield components, and IWUE were found for I₁D₁, I₁D₂, or I₂D_1, while the lowest were found for I₃D₂ or I₃D₃. Thus, a high irrigation rate with low or medium plant population densities or a medium irrigation rate with a low plant population density are recommended for drip-irrigated corn in sandy soil. Crop production functions with respect to irrigation rates, determined for grain yield and different yield components, enable the results from this study to be extrapolated to similar agro-climatic conditions.     

Different drip irrigation regimes affect cotton yield, water use efficiency and fiber quality in western Turkey

Decreasing in water availability for cotton production has forced researchers to focus on increasing water use efficiency by improving either new drought-tolerant cotton varieties or water management. A field trial was conducted to observe the effects of different drip irrigation regimes on water use efficiencies (WUE) and fiber quality parameters produced from N-84 cotton variety in the Aegean region of Turkey during 2004 and 2005. Treatments were designated as full irrigation (T₁₀₀, which received 100% of the soil water depletion) and those that received 75, 50 and 25% of the amount received by treatment T₁₀₀ on the same day (treatments T₇₅; T₅₀ and T₂₅, respectively). The average seasonal water use values ranged from 265 to 753 mm and the average seed cotton yield varied from 2550 to 5760 kg ha⁻¹. Largest average cotton yield was obtained from the full irrigation treatment (T₁₀₀). WUE ranged from 0.77 kg m⁻³ in the T₁₀₀ to 0.98 kg m⁻³ in the T₂₅ in 2004 growing season and ranged from 0.76 kg m⁻³ in the T₁₀₀ to 0.94 kg m⁻³ in the T₂₅ in 2005 growing season. The largest irrigation water use efficiency (IWUE) was observed in the T₂₅ (1.46 kg m⁻³), and the smallest IWUE was in the T₁₀₀ treatment (0.81 kg m⁻³) in the experimental years. A yield response factor (k_y) value of 0.78 was determined based on averages of two years. Leaf area index (LAI) and dry matter yields (DM) increased with increasing water use for treatments. Fiber qualities were influenced by drip irrigation levels in both years. The results revealed that well-irrigated treatments (T₁₀₀) could be used for the semi-arid climatic conditions under no water shortage. Moreover, the results also demonstrated that irrigation of cotton with drip irrigation method at 75% level (T₇₅) had significant benefits in terms of saved irrigation water and large WUE indicating a definitive advantage of deficit irrigation under limited water supply conditions. In an economic viewpoint, 25.0% saving in irrigation water (T₇₅) resulted in 34.0% reduction in the net income. However, the net income of the T₁₀₀ treatment is found to be reasonable in areas with no water shortage.     

Effects of deficit irrigation on the yield and yield components of drip irrigated cotton in a mediterranean environment

A field study on cotton (Gossypium hirsutum L., cv.) was carried out from 2005 to 2008 in the Çukurova Region, Eastern Mediterranean, Turkey. Treatments were designated as I₁₀₀ full irrigation; DI₇₀, DI₅₀ and DI₀₀ which received 70, 50, and 0% of the irrigation water amount applied in the I₁₀₀ treatment. The irrigation water amount to be applied to the plots was calculated using cumulative pan evaporation that occurred during the irrigation intervals. The effect of water deficit or water stress on crop yield and some plant growth parameters such as yield response, water use efficiencies, dry matter yield (DM), leaf area index (LAI) as well as on lint quality components was evaluated. The average seasonal evapotranspiration ranged from 287 ± 15 (DI₀₀) to 584 ± 80 mm (I₁₀₀). Deficit irrigation significantly affected crop yield and all yield components considered in this study. The average seed cotton yield varied from 1369 ± 197 (DI₀₀) to 3397 ± 508 kg ha⁻¹ (I₁₀₀). The average water use efficiency (WUE_ET) ranged from 6.0 ± 1.6 (I₁₀₀) to 4.8 ± 0.9 kg ha⁻¹ mm⁻¹ (DI₀₀), while average irrigation water use efficiency (WUE_I) was between 9.4 ± 3.0 (I₁₀₀) and 14.4 ± 4.8 kg ha⁻¹ mm⁻¹ (DI₅₀). Deficit irrigation increased the harvest index (HI) values from 0.26 ± 0.054 (I₁₀₀) to 0.32 ± 0.052 kg kg⁻¹ (DI₅₀). Yield response factor (Ky) was determined to be 0.98 based on four-year average. Leaf area index (LAI) and dry matter yields (DM) increased with increasing water use. This study demonstrated that the full irrigated treatment (I₁₀₀) should be used for semiarid conditions with no water shortage. However, DI₇₀ treatment needs to be considered as a viable alternative for the development of reduced irrigation strategies in semiarid regions where irrigation water supplies are limited.     

Effect of saline water on cucumber (Cucumis sativus L.) yield and water use under drip irrigation in North China

Saline water has been included as an important substitutable resource for fresh water in agricultural irrigation in many fresh water scarce regions. In order to make good use of saline water for agricultural irrigation in North China, a semi-humid area, a 3-year field experiment was carried out to study the possibility of using saline water for supplement irrigation of cucumber. Saline water was applied via mulched drip irrigation. The average electrical conductivity of irrigation water (EC_iw) was 1.1, 2.2, 2.9, 3.5 and 4.2 dS/m in 2003 and 2004, and 1.1, 2.2, 3.5, 4.2 and 4.9 dS/m in 2005. Throughout cucumber-growing season, the soil matric potential at 0.2 m depth immediately under drip emitter was kept higher than −20 kPa and saline water was applied after cucumber seedling stage. The experimental results revealed that cucumber fruit number per plant and yield decreased by 5.7% per unit increase in EC_iw. The maximum yield loss was around 25% for EC_iw of 4.9 dS/m, compared with 1.1 dS/m. Cucumber seasonal accumulative water use decreased linearly over the range of 1.5-6.9% per unit increase in EC_iw. As to the average root zone EC_e (electrical conductivity of saturated paste extract), cucumber yield and water use decreased by 10.8 and 10.3% for each unit of EC_e increase in the root zone (within 40 cm away from emitter and 40 cm depths), respectively. After 3 years irrigation with saline water, there was no obvious tendency for EC_e to increase in the soil profile of 0-90 cm depths. So in North China, or similar semi-humid area, when there is no enough fresh water for irrigation, saline water up to 4.9 dS/m can be used to irrigate field culture cucumbers at the expense of some yield loss.     

Effect of soil matric potential on tomato yield and water use under drip irrigation condition

Field experiment was carried out to investigate the effect of soil matric potential (SMP) on tomato yield, evapotranspiration (ET), water use efficiency (WUE) and irrigation water use efficiency (IWUE) under drip irrigation condition in North China Plain. The experiment included five treatments, which controlled SMP at 0.2 m depth immediately under drip emitter higher than −10 (S1), −20 (S2), −30 (S3), −40 (S4) and −50 kPa (S5), respectively, after tomato plant establishment. The results showed that different SMP affected irrigation amount and tomato ET. Irrigation amount decreased from 185 mm (S1) to 83.6 mm (S5) in 2004, and from 165 mm (S1) to 109 mm (S5) in 2005, respectively. The ET decreased from 270 mm (S1) to 202 mm (S5) in both years. However, it was found that SMP did not affect the tomato yield significantly, for the range of SMP investigated. Both WUE and IWUE increased as SMP decreased. The maximum WUE (253 and 217 kg/ha mm) and IWUE (620 and 406 kg/ha mm) were for S5 in 2 years, whereas the minimum WUE (178 and 155 kg/ha mm) and IWUE 261 and 259 kg/ha mm) were for S1 in 2004 and 2005. Based on the above results, therefore, it is recommended that if the tomatoes are well irrigated (SMP is higher than −20 kPa) during establishment, controlling SMP higher than −50 kPa at 0.2 m depth immediately under drip emitter can be used as an indicator for drip irrigation scheduling during following period of tomato growth in North China Plain.     

Subsurface drip irrigation of onions: Effects of drip tape emitter spacing on yield and quality

Improved irrigation water use efficiency is an important component of sustainable agricultural production. Efficient water delivery systems such as subsurface drip irrigation (SDI) can contribute immensely towards improving crop water use efficiency and conserving water. However, critical management considerations such as choice of SDI tube, emitter spacing and installation depth are necessary to attain improved irrigation efficiencies and production benefits. In this study, we evaluated the effects of subsurface drip tape emitter spacing (15, 20 and 30 cm) on yield and quality of sweet onions grown at two locations in South Texas—Weslaco and Los Ebanos. Season-long cumulative crop evapotranspiration (ETc) was 513 mm in Weslaco and 407 mm at Los Ebanos. Total crop water input (rain + irrigation) at Weslaco was roughly equal to ETc (92% ETc) whereas at Los Ebanos, water inputs exceeded ETc by about 35%. Onion yields ranged from 58.5 to 70.3 t ha⁻¹ but were not affected by drip tube emitter spacing. Onion pungency (pyruvic acid development) and soluble solids concentration were also not significantly influenced by treatments. Crop water use efficiency was slightly higher at Weslaco (13.7 kg/m³) than at Los Ebanos (11.7 kg/m³) partly because of differences in total water inputs resulting from differences in irrigation management. The absence of any significant effects of drip tape emitter spacing on onion yield may be due to the fact that irrigation was managed to provide roughly similar irrigation amounts and optimum soil moisture conditions in all treatments.     

果树滴灌需水量与灌溉制度试验研究

局部灌溉条件下的需水量与灌溉制度不同于全面积灌溉的情况,本文对此进行了分析论述,并通过对果树滴灌试验资料的分析得出了滴灌条件下的果树需水规律及有关灌溉参数。     

Effects of drip irrigation levels and planting methods on yield and yield components of green pepper (Capsicum annuum, L.) in Bako, Ethiopia

A field experiment was conducted to investigate the effects of different levels of drip irrigation and planting methods on yield and yield components (number of fruits per plant, number of primary and secondary branches per plant, and plant height) of green pepper (Capsicum annuum, L.) in Bako, Ethiopia. Three irrigation levels (50, 75 and 100% of ET_c) and two planting methods (normal and paired-row planting) were applied. The experiment was laid out in a split plot design, with irrigation levels as main plots and planting methods as sub-plots, in three replications. It was found that the effects of both treatments on yield, number of fruits per plant and plant height of green pepper were highly significant (p < 0.01) whereas the number of primary and secondary branches per plant was affected significantly (p < 0.05). The maximum and minimum values of the yield and yield components were recorded from treatment plots I₁₀₀P (full irrigation level with paired-row planting method) and I₅₀P (50% of ET_c irrigation level with paired-row planting method), respectively, with the exception of plant height. However, the average plant height (cm) recorded from the I₁₀₀N treatment plot was not significantly different from the I₁₀₀P treatment plot. Moreover, it was found that the effect of treatment interactions on both yield and yield components of green pepper was found to be highly significant (p < 0.01). A 50% reduction in irrigation level caused a reduction in yield of about 48.3 and 74.4% under the normal and paired-row planting methods, respectively, whereas, a 25% reduction in irrigation level caused a reduction in yield of about 22.8 and 47.7% under the same planting methods. Under both deficit irrigation levels (I₅₀ and I₇₅), the normal planting method gave higher total yield and yield components of green pepper than the paired-row planting method. Yield response factor (k_y) values of 0.96 and 1.57 were determined for the normal and paired-row planting methods, respectively, suggesting utmost precautions when using the paired-row planting in areas with limited water supply. The results revealed that full irrigation water supply under paired-row planting method (I₁₀₀P) could be used for the production of green pepper in an area with no water shortage. Moreover, it was found that the average yields recorded from the I₇₅ under the paired-row planting method is fairly greater than the national average.     

Evaluation of the influence of irrigation methods and water quality on sugar beet yield and water use efficiency

Rapid urbanization and industrialization have increased the pressure on limited existing fresh water to meet the growing needs for food production. Two immediate responses to this challenge are the efficient use of irrigation technology and the use of alternative sources of water. Drip irrigation methods may play an important role in efficient use of water but there is still limited information on their use on sugar beet crops in arid countries such as Iran. An experiment was conducted to evaluate the effects of irrigation method and water quality on sugar beet yield, percentage of sugar content and irrigation water use efficiency (IWUE). The irrigation methods investigated were subsurface drip, surface drip and furrow irrigation. The two waters used were treated municipal effluent (EC = 1.52 dS m⁻¹) and fresh water (EC = 0.509 dS m⁻¹). The experiments used a split plot design and were undertaken over two consecutive growing seasons in Southern Iran. Statistical testing indicated that the irrigation method and water quality had a significant effect (at the 1% level) on sugar beet root yield, sugar yield, and IWUE. The highest root yield (79.7 Mg ha⁻¹) was obtained using surface drip irrigation and effluent and the lowest root yield (41.4 Mg ha⁻¹) was obtained using furrow irrigation and fresh water. The highest IWUE in root yield production (9 kg m⁻³) was obtained using surface drip irrigation with effluent and the lowest value (3.8 kg m⁻³) was obtained using furrow irrigation with fresh water. The highest IWUE of 1.26 kg m⁻³ for sugar was obtained using surface drip irrigation. The corresponding efficiency using effluent was 1.14 kg m⁻³. Irrigation with effluent led to an increase in the net sugar yield due to an increase in the sugar beet root yield. However, there was a slight reduction in the percentage sugar content in the plants. This study also showed that soil water and root depth monitoring can be used in irrigation scheduling to avoid water stress. Such monitoring techniques can also save considerable volumes of irrigation water and can increase yield.     

Analysis of AET and yield predictions under surface and buried drip irrigation systems using the Crop Model PILOTE and Hydrus-2D

Innovative irrigation solutions have to face water scarcity problems affecting the Mediterranean countries. Generally, surface (DI) or subsurface drip irrigation systems (SDI) have the ability to increase water productivity (WP). But the question about their possible utilisation for crops such as corn would merit to be analysed using an appropriate economic tool. The latter would be necessary based on the utilisation of a modelling approach to identify the optimal irrigation strategy associating a water amount with a crop yield (Yc). In this perspective, a possible utilisation of the operative 1D crop model PILOTE for simulating actual evapotranspiration (AET) and yield under a 2D soil water transfer process characterizing DI and SDI was analysed. In this study, limited to a loamy soil cultivated with corn, the pertinence of the root water uptake model used in the numerical code Hydrus-2D for AET estimations of actual evapotranspiration (AET) under water stress conditions is discussed throughout the Yc = F(AET) relationship established by PILOTE on the basis of validated simulations. The conclusions of this work are (i): with slight adaptations, PILOTE can provide reliable WP estimations associated to irrigation strategies under DI and SDI, (ii): the current Hydrus-2D version used in this study underestimates AET, compared with PILOTE, in a range varying from 7% under moderate water stress conditions to 14% under severe ones, (iii): A lateral spacing of 1.6 m for the irrigation of corn with a SDI system is an appropriate solution on a loamy soil under a Mediterranean climate.A local Yc = F(AET) relationship associated with a Hydrus-2D version taking into account the compensating root uptake process could result in an interesting tool to help identify the optimal irrigation system design under different soil conditions.     

Withholding of drip irrigation between transplanting and flowering increases the yield of field-grown tomato under plastic mulch

Experiments were conducted in summer of 2003 and 2004 to study the effect of withholding irrigation on tomato growth and yield in a drip irrigated, plasticulture system. Irrigation treatments were initiated at tomato planting (S0), after transplant establishment (S1), at first flower (S2), at first fruit (S3), or at fruit ripening (S4). An additional treatment received only enough water to apply fertigation (FT). Withholding drip irrigation for a short period (S2–S3) increased tomato marketable yield by 8–15%, fruit number by 12–14% while reducing amount of irrigation water by 20% compared to the S0 treatment. Withholding drip irrigation also increased irrigation water use efficiency (IWUE). Similar trends were observed in 2003 and 2004 despite large differences in rainfall, heat units, and tomato yield between years. This suggests that if soil moisture is adequate at transplanting, subsequent withholding of irrigation for 1–2 weeks after tomato transplanting may increase yield while reducing the amount of irrigation water.     

MIRRIG: A decision support system for design and evaluation of microirrigation systems

The decision support system (DSS) MIRRIG has been developed to support the design of microirrigation systems and to advise farmers as a result of field evaluations. It is written in Visual Basic 6.0, runs in a Windows environment, and uses a database with information on emitters and pipes available in the market, as well as on crops, soils and the systems under design. MIRRIG is composed by design and simulation models and a multicriteria analysis model that ranks alternative design solutions based upon an integration of technical, economic and environmental criteria. User friendly windows are adopted for handling the databases and to manage the sub-models. The model allows creating and comparing a set of design alternatives relative to the pipe system and the emitters, either drip or microsprinkling emitters. For each alternative, the pipe system is sized and the irrigation system is simulated to produce performance, environmental and economic indicators. These include uniformity of water application, potential for contamination with agrochemicals due to water percolation, and installation and operation costs. Those indicators are used as attributes of the selected criteria. All alternatives are then compared and ranked through multicriteria analysis where the weights giving the relative importance of the adopted criteria are defined by the user. These procedures allow selecting the best design alternative and solving the complexities involved in the design of microirrigation systems. The model is available from the website www://ceer.isa.utl.pt/cms or by contacting cpedras@ualg.pt.     

黄河水滴灌对葡萄生长发育及产量品质的影响

为了探究引黄滴灌对大田葡萄生长发育以及产量品质的影响,以3 a生克伦生葡萄为供试材料,开展全生育期黄河水和地下水滴灌的大田对比试验,监测全生育期内2种水质滴灌处理条件下葡萄的各项指标,分析黄河水滴灌对葡萄生长、产量和品质的影响.结果发现：黄河水能显著影响克伦生葡萄生长发育、浆果外观品质以及果实营养物质含量,能促进新梢枝条生长发育、促进果实膨大、提高果形指数C和硬度P,葡萄可溶性固形物含量TSS和浆果可溶性糖含量WSS分别较地下水处理提高了21.26%和13.59%,Ta含量降低了15.79%.综合分析表明,黄河水滴灌对促进克伦生葡萄新梢枝条生长发育、提高葡萄产量和改善浆果营养品质具有积极意义.试验可为葡萄引黄滴灌发展提供科学依据和理论参考.     

不同施氮量对滴灌加工番茄根系构型的影响

为了探讨施氮量对加工番茄根系构型及产量品质的响应机制,基于临界氮浓度模型的施肥方案,设置不施氮(N0)、施氮200 kg/hm²(N1)、施氮300 kg/hm²(N2)和施氮400 kg/hm²(N3)4个处理,结果表明:0-60 cm土层中的加工番茄根系总干质量、总长度、总表面积和总体积都随生育期的推进呈先增加后降低的趋势,根系干质量和长度的增长速率均呈“缓慢增加-快速增加-缓慢增加-缓慢下降”的变化趋势.在定植至开花阶段,加工番茄根系干质量和根系长度在各土层中差异不具有统计学意义,开花后,处理N2促进了根系总干质量、总长度、总表面积和总体积的增加,主要体现在开花后0-20 cm土层中根系干质量和拉秧期20-40 cm土层中根系长度的增加.N2相比其他处理可以显著提高加工番茄的产量,且具有较高的可溶性糖和番茄红素.在基于临界氮浓度模型的施氮比例下,加工番茄定植至开花阶段可减氮施肥按处理N1施44 kg/hm²,在坐果期、红熟期、拉秧期施氮按处理N2施234 kg/hm²便可保证根系的最佳生长状态.     

Determination of optimum irrigation water amount for drip-irrigated muskmelon (Cucumis melo L.) in plastic greenhouse

This study was conducted to determine the optimum irrigation water amounts for muskmelon (Cucumis melo L.) in plastic greenhouse. The irrigation water amounts were determined based on the percentage of field water capacity. On the same basis of irrigation start-point of 60% (the percent to comparing to the field water capacity), there were four different irrigation water levels 100% (T100), 90% (T90), 80% (T80) and 70% (T70) as the four different treatments. The results showed that plant growth, fruit production and quality were significantly affected under different irrigation water amounts. Plant height and stem diameter decreased as well as fruit yield from treatment T100 to T70. Fruit quality was the best in the T90 treatment. The irrigation water use efficiency (IWUE) values found in this experiment showed that the lower the amount of irrigation water applied, the higher the irrigation water use efficiency obtained.Hence, based on the quality and quantity of muskmelon yield, the regime for 90% of field water capacity is the suitable soil irrigation treatment (T90) which can save irrigation water and improve the quality of fruit. Combined the crop yield, quality and pan evaporation inside greenhouse, obtained Kcp = 1.00 values can be recommended for the most appropriate irrigation scheduling, irrigation water amount is better between T100 and T90. Therefore, applying water by drip irrigation in relation to the amount of water evaporated from a standard 0.2 m diameter pan is a convenient, simple, easy, and low cost method inside a plastic greenhouse.     

灌水模式及下限对滴灌棉花产量和品质的影响

为探索滴灌条件下棉花优质高效灌溉指标,在新疆石河子研究了地下滴灌(SSDI)和膜下滴灌(SDI)条件下不同灌水控制下限对棉花耗水量、品质以及水分利用率的影响.结果表明,相同滴灌模式,棉花蕾期耗水量随灌水控制下限的提高而增加,花铃期水分胁迫处理的棉花阶段耗水量普遍低于对照处理;蕾期适度水分胁迫(灌水控制下限为60% FC)花铃期充分供水(灌水控制下限为75% FC)处理(SDI-7和SSDI-7)有利于籽棉产量的提高,与对照处理相比,籽棉产量提高了14.48%(SDI-7)和11.60%(SSDI-7);水分处理对棉花衣分、棉纤维整齐度的影响不明显,蕾期和花铃期水分胁迫对棉纤维上半部平均长度的影响随水分胁迫程度的加重而加剧,蕾期适度水分胁迫(灌水控制下限为60% FC)有利于棉纤维断裂比强度的提高.相同水分处理,地下滴灌棉花产量和灌溉水利用率均高于膜下滴灌棉花.与对照处理相比,蕾期和花铃期灌水控制下限分别为60% FC和75% FC,灌水定额为30 mm处理在节约灌溉水的同时提高了籽棉产量并改善了棉纤维品质,可作为石河子垦区滴灌棉花适宜的灌水指标.     

绿洲灌区膜下滴灌调亏对辣椒品质及产量的影响

为揭示滴灌水分亏缺对辣椒营养品质及产量的影响,以"陇椒6号"为对象,在辣椒苗期分别施加轻度(65％～75％田间持水量)、中度(55％～65％田间持水量)和重度水分调亏(45％～55％田间持水量),在盛果期和后果期分别施加轻度水分亏缺,以全生育期充分供水(75％～85％田间持水量)为对照,分别测定各水分处理辣椒青果营养品...     

膜下滴灌水氮耦合效应对玉米干物质与产量的影响

通过大田试验研究膜下滴灌水氮耦合效应对玉米干物质与产量的影响,设置3个水分水平,按土壤含水率占田间持水率百分比的上下限不同设低、中、高水:低水 W1(拔节前60%~80%,拔节后55%~80%)、中水W2(拔节前65%~85%,拔节后60%~85%)、高水W3(拔节前75%~95%,拔节后70%~95%).施氮梯度按224,270,330 kg/hm²设低、中、高氮3个施氮水平.寻求适宜于科尔沁左翼中旗的玉米膜下滴灌适宜水氮用量,为玉米膜下滴灌达到高产、高效目标提供理论依据.研究结果表明:生育期中等施氮水平270 kg/hm²与高灌溉水平组合下可获得较高的全株干物质总量,但收获指数低于中水中氮的组合,中水中氮耦合用量下可获得较高的收获指数,能较好地调节光合产物在籽粒与营养器官间的分配;在当地典型地域及气候条件下,玉米采用膜下滴灌种植方式,增加水和氮的投入均能增产,并对产量有报酬递减效应,单因素施用水平的变动引起产量的改变是水分作用大于施氮作用.     

滴灌加工番茄叶面积、干物质生产与积累模拟模型

以生理发育时间为时间尺度,建立了基于生理发育时间(PDT)的加工番茄叶面积指数(LAI)、比叶面积(SLA)模拟模型,并将叶面积指数模型与基于生理生态过程的光合作用和干物质生产模型相结合,构建了滴灌加工番茄干物质生产与积累的模拟模型。结果表明:PDT法对加工番茄叶面积指数(LAI)与1∶1直线间的决定系数R2、根均方差(RMSE)和模型效率指数(ME)分别为0.926 5、12.87%、0.972 4;SLA法模拟叶面积指数的预测结果与1∶1直线间的R2、RMSE和ME分别为0.675 8、42.24%、0.712 4。本模型对加工番茄地上部干物质量的预测结果与1∶1直线间的R2、RMSE和ME分别为0.990 3、11.91%、0.990 1;而SLA法对加工番茄地上部干物质量的预测结果与1∶1直线间的R2、RMSE和ME分别为0.895 6、31.29%、0.750 4。与SLA法相比,PDT法在改善加工番茄叶面积指数预测精度的同时亦提高了干物质量的预测精度。