Tomato root distribution, yield and fruit quality under different subsurface drip irrigation regimes and depths

Tomato rooting patterns, yield and fruit quality were evaluated in a field trial where three irrigation regimes [0.6 (DI), 0.9 (DII) and 1.2 ET_c (DIII)] and three drip irrigation depths [surface (R0), subsurface at 20 cm depth (RI) and subsurface at 40 cm depth (RII)] were imposed following a split-plot experimental design, with four replications. The behaviour of the root system in response to the irrigation treatments was evaluated using minirhizotrons installed between two plants, near the plant row. Root-length intensity (L _a)—length of the root per unit of minirhizotron surface area (cm cm⁻²)—was measured at four crop stages. For all sampling dates, none of the factors studied were found to influence L _a or rooting depth significantly or the interaction between treatments. For all treatments most of the root system was concentrated in the top 40 cm of the soil profile, where the root-length density ranged from 0.5 cm cm⁻³ to 1.4 cm cm⁻³ . The response of tomato fruits to an increase in the water applied was similar in quantitative and qualitative terms for the different drip irrigation depths. Water applied by drip irrigation had the opposite effect on commercial yield (t ha⁻¹) and soluble solids (°Brix) (r=−0.82, P<0.001), however, yield in terms of total soluble solids (t ha⁻¹) was the same for the 0.9 and 1.2 ET_c. The increase in commercial yield can be described by the equation      

不同增氧滴灌方式对蔬菜生长生理指标的影响

为了研究不同增氧方式对盆栽小白菜生长生理指标的影响,以小白菜为供试作物,采用盆栽地下滴灌的方式,以普通地下滴灌作为对照(CK),设置循环曝气(MAI)、双氧水(H₂O₂)、纯氧扩散器曝气(OC)及射流振荡器曝气(FO)4个增氧灌溉处理.结果表明,增氧地下滴灌显著提高了土壤呼吸速率,处理MAI,OC和FO较对照处理分别增大了65.87%,66.79%和111.62%.增氧地下滴灌促进了小白菜的根系生长、光合作用、蒸腾速率和气孔导度,进而提高了小白菜的物质量积累和产量.与对照相比,处理MAI的地下部鲜质量增大了42.03%,地下部干质量增大了79.85%;处理MAI,H₂O₂,OC和FO的光合速率分别增大了868.62%,794.14%,778.67%和650.19%;处理MAI,H₂O₂和OC的气孔导度较CK增大了157.14%,128.57%和85.71%,蒸腾速率增大了55.61%,32.38%和19.58%;处理MAI和H₂O₂的产量分别增大了56.36%和38.72%.综上,增氧地下滴灌可增强小白菜根区的土壤呼吸作用,改善光合作用、蒸腾速率和气孔导度,提高了产量及水分利用效率.其中,循环曝气处理的改善效果最为显著.     

不同降水年型地下滴灌追氮对玉米产量的影响

采用完全组合设计,在长期试验基础上探讨了枯、丰2种降水年型滴灌追氮对玉米产量的影响.结果表明:丰水年整体产量高于枯水年,高水高氮和高水低氮处理在丰、枯水年间产量差异不具有统计学意义.枯水年滴灌对产量影响具有统计学意义(P<0.01),水氮互作对产量影响具有统计学意义(P<0.05),追氮对产量影响不具有统计学意义.丰水年滴灌对产量影响具有统计学意义(P<0.05),追氮对产量影响具有统计学意义(P<0.01),水氮互作对产量影响不具有统计学意义.不同降水年型间产量随滴灌量的增大而增大,枯水年滴灌对产量的提高幅度大于丰水年;随追氮量的增加先增大后减小,丰水年增加追氮量对产量的影响均大于枯水年.通过分析,确定了不同降水年型适宜的水肥施用模式:播种期沟施复合肥(N∶P₂O₅∶K₂O=15∶15∶15)450 kg/hm²后,在枯水年滴灌48 mm、追氮120 kg/hm²,丰水年滴灌36 mm、追氮240 kg/hm².     

Effect of high frequency surface and subsurface drip irrigation on root distribution of sweet corn

Summary Characterization of root growth and distribution is fundamental in explaining crop responses to irrigation and in determining appropriate management of irrigation systems, particularly with drip systems since it is widely believed that drip irrigation may limit the extent of root development. An experiment was conducted to study root distribution of sweet corn grown under high frequency surface (S) and subsurface (SS) drip irrigation, fertilized daily through drip systems at three phosphorus levels of P₀ (no injected P), P₁ (P injected at 67 kg/ha) and P₂ (P injected at 134 kg/ha). Root sampling at the end of the growing season indicated that: (1) Root extension continued at depths in excess of 2 m in both the surface and subsurface drip at all P levels. (2) The greatest differences between SS and S treatments were observed in the top 45 cm depth. Higher root length density was observed in the surface 30 cm in S plots while the sweet corn in the SS plots had greater root length density than S plots below 30 cm, and (3) the greater root length density in the SS irrigated sweet corn was not reflected in a similar increase in total above-ground dry matter.This project was partially supported by a grant from BARD Project no I-1116-86     

Bell pepper response to surface and subsurface drip irrigation under different fertigation levels

A two-year field experiment was conducted in 2007 and 2008 to investigate different bell pepper responses to subsurface drip irrigation (SDI) and surface drip irrigation (DI) under four nitrogen levels: 0, 75, 150, and 300 kg/ha N (N₀, N₇₅, N₁₅₀, and N₃₀₀, respectively). Irrigation interval was set at 4 days. Bell pepper yield under SDI was significantly higher than that under DI by 4% in 2007 (13% in 2008). Water consumption under SDI was lower than that under DI by 6.7% in 2007 (7.3% in 2008). Meanwhile, root length density under SDI was obviously higher than that under DI by 11.8% in 2007 (12.5% in 2008). The percentage of root length below 10-cm soil depth under SDI was higher than that under DI by 7%, proving that SDI promotes crop root growth and enhances downward root development. Soil N residue under SDI was lesser than that under DI. Lastly, SDI with N application of 150 kg/ha is recommended as an optimal fertigation practice in improving bell pepper yield and water-use efficiency, as well as in NO₃ ⁻-N leaching.     

Spatial root distribution of mature apple trees under drip irrigation system

The study was undertaken in order to quantify the effect of 12-year irrigation by drip emitters placed on one side of the tree trunk on the rooting pattern of Gloster apple trees (Malus domestica Borkh) grafted on M26 rootstock under the conditions of south-west Poland. The orchard was established in 1994 and since 1995 was drip irrigated under three treatments: V0 - without irrigation (control), V1 - intensive irrigation, and V2 - economical irrigation. In March 2007, after 12 years of irrigation, a profile trench observation method was used to map the number and the location of root distribution in clay loam (Luvisol) soil.The root system architecture was largely affected by irrigation. In case of the trees irrigated intensively (V1), the study showed asymmetry in the distribution of roots of diameter <1 mm and 1-3 mm. In V1, shallow root system, concentrated in the wetted zone developed on the irrigated side of the tree, where on the side of the tree trunk opposite the emitter trees developed significantly larger numbers of roots, which penetrated deeper soil layers. There were no statistically significant differences in the number of roots between both sides of the tree trunk under the treatment with economical irrigation (V2). Moreover, spatial roots distribution over the entire soil profile was found to be the most uniform compared to the other experimental treatments (V0 and V1). Finally, the study examined the relationship between root system and yield. Obtained results showed that in the 3-year period less frequent water application (V2) resulted in the highest yield.     

Avocado root distribution in fine and coarse-textured soils under drip and microsprinkler irrigation

A common irrigation-scheduling problem in orchards is the proper location of instruments for monitoring soil water content within the active root zone. Given the high spatial variability of soils in the field, and seasonal changes in root distribution and frequency, both within the orchard and around the trees, the accuracy and representativeness of soil water measurements can be strongly affected. Adequate soil water monitoring in orchards thus requires assessment of the variability and location of the active roots in a given location over an extended period of time. We examined the root systems of 12-year-old ‘Hass’ avocado (Persea americana Mill.) trees grafted on ‘Mexicola’ seedling rootstocks, growing in fine or coarse-textured soils, under either drip or microsprinkler irrigation systems in Central Chile. We dug 3 m long and 0.75 m deep trenches within the tree rows in spring, summer and autumn, and counted the active roots (white, diameter ≤2 mm) found on the walls. Over the three growing seasons of our study, season had the most significant effect on root distribution, as autumn root frequencies accounted for about half of the cumulative average. Also, the location of the highest concentration of roots under microsprinklers in autumn clearly differed between the fine soils, at about 200 cm from the trunk and 50–60 cm deep, and coarse soils, where they were found within 30 cm from the trunk, and within the first 25 cm of soil. Trees in fine soil had 25% more roots than those in coarse soil, and drip irrigation produced about 30% more roots than microsprinkler, although both of these figures are mainly due to the high number of roots found in the fine soil-drip irrigation combination. Overall, we found the highest root frequency within the first meter from the tree trunk, for all combinations, with some differences between irrigation types. Throughout the growing season in semi-arid regions, some changes in both the quantity of tree roots and the location of the zones of the greatest root activity should be expected, which will vary according to the seasonal soil temperatures, soil texture, and type of irrigation used.     

循环曝气地下滴灌的温室番茄生长与品质

循环曝气滴灌可以大幅度提高灌溉水掺气比例,有效改善普通地下滴灌引起的黏质型土壤根区间歇性缺氧环境,提高作物生产力.以河南省中牟县黄河淤积黄黏土为供试土壤,以温室番茄为供试对象,研究循环曝气地下滴灌对番茄生理及品质的影响.结果表明,与普通地下滴灌(对照处理)相比,相同灌溉定额条件下曝气处理番茄果实前5次产量提高了29.15%;番茄的水分利用效率提高了20.72%.曝气处理气孔导度提高了30.51%,植物的生长活力得到增强.番茄果实维生素C含量提高了13.25%,可溶性固形物含量提高了8.62%,糖酸比提高了22.05%,而总酸含量和硬度分别下降了15.50%和11.19%.曝气处理最大根长增加了16.75%,根冠质量之比提高了25.81%.综合分析表明,曝气滴灌可显著促进黄黏土中番茄的生长,促进番茄果实成熟,有效提高作物产量,改善番茄品质.     

Soil moisture distribution patterns under surface and subsurface drip irrigation systems in sandy soil using neutron scattering technique

This study was carried out at the experimental field station of the Atomic Energy Authority in Anshas, Egypt, by the aim of assessing the soil moisture status under surface and subsurface drip irrigation systems, as a function of the variation in the distance between drippers along and between laterals. Moisture measurements were carried out using neutron moisture meter technique, and water distribution uniformity was assessed by applying Surfer Model. The presented data indicated that the soil moisture distribution and its uniformity within the soil profile under surface drip was to great extent affected by the distance between drippers rather than that between laterals. Generally, the soil moisture distribution under using 30-cm dripper spacing was better than of that under 50 cm. Under subsurface drip irrigation, the allocation of the irrigation system was the factor that dominantly affected the moisture trend under the studied variables. Installing the system at 30 cm from the soil surface is the one to be recommended as it represents the active root zone for most vegetable crops, beside it leads to a better water saving in sandy soils than that allocated at 15 cm depth.     

Soil water distribution, uniformity and water-use efficiency under alternate furrow irrigation in arid areas

Soil water distribution, irrigation water advance and uniformity, yield production and water-use efficiency (WUE) were tested with a new irrigation method for irrigated maize in an arid area with seasonal rainfall of 77.5–88.0 mm for 2 years (1997 and 1998). Irrigation was applied through furrows in three ways: alternate furrow irrigation (AFI), fixed furrow irrigation (FFI) and conventional furrow irrigation (CFI). AFI means that one of the two neighboring furrows was alternately irrigated during consecutive watering. FFI means that irrigation was fixed to one of the two neighboring furrows. CFI was the conventional method where every furrow was irrigated during each watering. Each irrigation method was further divided into three treatments using different irrigation amounts: i.e. 45, 30, and 22.5 mm water for each watering. Results showed that the soil water contents in the two neighboring furrows of AFI remained different until the next irrigation with a higher water content in the previously irrigated furrow. Infiltration in CFI was deeper than that in AFI and FFI. The time of water advance did not differ between AFI, FFI and CFI at all distances monitored, and water advanced at a similar rate in all the treatments. The Christiansen uniformity coefficient of water content in the soil (CU_s) was used to evaluate the uniformity of irrigated water distribution and showed no decrease in AFI and FFI, although irrigation water use was smaller than in CFI. Root development was significantly enhanced by AFI treatment. Primary root numbers, total root dry weight and root density were all higher in AFI than in the FFI and CFI treatments. Less irrigation significantly reduced the total root dry weight and plant height in both the FFI and CFI treatments but this was less substantial with AFI treatments. The most surprising result was that AFI maintained high grain yield with up to a 50% reduction in irrigation amount, while the FFI and CFI treatments all showed a substantial decrease of yield with reduced irrigation. As a result, WUE for irrigated water was substantially increased. We conclude that AFI is an effective water-saving irrigation method in arid areas where maize production relies heavily on repeated irrigation. Received: 16 October 1999     

Salt distribution and the growth of cotton under different drip irrigation regimes in a saline area

A 3-year experiment was conducted in an extremely dry and saline wasteland to investigate the effects of the drip irrigation on salt distributions and the growth of cotton under different irrigation regimes in Xinjiang, Northwest China. The experiment included five treatments in which the soil matric potential (SMP) at 20 cm depth was controlled at −5, −10, −15, −20, and −25 kPa after cotton was established. The results indicated that a favorable low salinity zone existed in the root zone throughout the growing season when the SMP threshold was controlled below −25 kPa. When the SMP value decreased, the electrical conductivity of the saturation paste extract (EC_e) in the root zone after the growing season decreased as well. After the 3-year experiment, the seed-cotton yield had reached 84% of the average yield level for non-saline soil in the study region and the emergence rate was 78.1% when the SMP target value was controlled below −5 kPa. The average pH of the soil decreased slightly after 3 years of cultivation. The highest irrigation water use efficiency (IWUE) values were recorded when the SMP was around −20 kPa. After years of reclamation and utilization, the saline soil gradually changed to a moderately saline soil. The SMP of −5 kPa at a depth of 20 cm immediately under a drip emitter can be used as an indicator for cotton drip irrigation scheduling in saline areas in Xinjiang, Northwest China.     

Cotton root and shoot responses to subsurface drip irrigation and partial wetting of the upper soil profile

The ability of cotton roots to grow downwards through a partially-wetted soil (Calcic Haploxeralf) profile toward a water source located beneath them was investigated. Plants were grown in 60-cm-high soil columms (diameter 10 cm), the bottom 15 cm of which was kept wet by frequent drip irrigation, while the upper 45 cm was wetted three times per week up to 20, 40, 60, 80 or 100% of pot capacity. Pot capacity was defined as the water content which gave uniform distribution within the pot and was at a soil matric potential ( _m ) of –0.01 MPa. Plants were harvested 42 and 70 days after emergence (DAE). Root length density was reduced by decreased soil moisture content. At 42 DAE, density was reduced in the soil profile down to 36 cm. The density in the middle segment of the cylinder (24–36 cm) increased at the second harvest, from 0.1 to 0.35 cm · cm^–3 at 40% and from 0.2 to 0.5 cm · cm^–1 at 60% of pot capacity, respectively. A significant rise in root length density was found at all moisture contents above 20% in the two deepest soil segments. It was most marked at 40% where the rise was from 0.2 to 0.8 cm · cm^–3, due to the development of secondary roots at the wetted bottom of the column. When only 20% of pot capacity was maintained in the top 45 cm of the profile, almost no roots reached the wetted soil volume, and root length density was very low. Hydrotropism, namely root growth through dry soil layers toward a wet soil layer was thus not apparent. Root dry weight per unit length decreased with increasing depth in the column at all moisture levels. However, the only significant decrease was, found between the top and the second soil segments and was due to thicker primary roots in the top segment. There was no clear relationship between length and dry weight of roots. Total plant dry weight and transpiration were reduced significantly only at 20% of pot capacity. Dry matter production by roots was less severely inhibited than that by shoots, under decreased moisture content in the soil profile. Leaf water potential decreased when the soil moisture content of the top 45 cm of the profile was reduced below 60% of pot capacity. It was concluded that even at soil moisture content equivalent to a _m of 0.1 MPa, the rate of root growth was sufficient to reach a wetted soil layer at the bottom of the soil column, where the plant roots then proliferated. This implies that as long as the soil above the subsurface dripper is not very dry there is no real need for early surface irrigation.     

Yield and water productivity of five chickpea varieties under supplemental irrigation in contrasting years

Chickpea (Cicer arietinum L.) is one of the most important pulse crops in the world, cultivated on a wide range of environments. In Mediterranean regions, it is traditionally grown as a spring-sown rainfed crop, very dependent on rainfall. In this situation, supplemental irrigation can improve significantly the crop yield. The objective of this study was to evaluate the improvement on chickpea crop yield and water productivity (WP) of five chickpea varieties with supplemental irrigation, in the Mediterranean conditions, with both dry and wet years. Field tests were carried out over two cropping seasons, in Southern Portugal, using three kabuli-type and two desi-type chickpea varieties and four irrigation treatments, corresponding to 100, 50, 25 % of crop irrigation requirements (IR) and rainfed. The results show that all chickpea varieties responded to supplemental irrigation with the increase in grain and biomass yield. However, the magnitude of individual chickpea response depends on the year and the genotype. In 2009, a dry year, the highest WP values were attained at the 50 % IR treatment, whereas in 2010, a wet year, it was the rainfed treatment that showed the highest WP values. The Elixir variety showed the best grain yields and water productivity.     

Reliability of drip irrigation systems under different operation conditions in Poland

Present crop production in Poland depends on climatic, hydrologic, pedologic, social and economic conditions. Drip irrigation systems will play a significant role in the future by fulfilling the requirements of intensive, energy-saving agricultural production. The total area under micro-irrigation in Poland is estimated to be approximately 3000 ha. Drip irrigation is currently applied mainly in orchards, vegetable farms and greenhouses. The investigations of drip irrigation have shown a high influence of the operating conditions on the reliability and productivity effects of the irrigation system. This paper contains the results of the investigations on the reliability of drip irrigation systems under different operation conditions such as system components, crops, water quality, fertigation and irrigation technology.     

Performance of different filter combinations with surface and subsurface drip irrigation systems for utilizing municipal wastewater

Large volumes of wastewater (WW) are being generated worldwide as a consequence of rapid urbanization and growth of industries. The reuse of WW finds increased application in irrigation but the presence of toxic elements and microorganisms limits its use for irrigation purpose. To reduce the contamination of WW for irrigation, drip system is seen as an appropriate choice due to restricted quantity of water application. Emitter clogging is viewed as the main problem associated with drip system for its large-scale use with WW. Physical and chemical characteristics of WW were determined and compared with groundwater (GW). Higher EC, pH, Mg, and CO₃ were observed in the GW but higher turbidity, total solids, HCO₃, and Ca were observed in the WW. The population of total coliforms (2.72 × 10⁴ to 5.2 × 10⁷) and E. coli (1.8 × 10³ to 2.64 × 10⁶) were detected in WW. The hydraulic performance of drip emitters was studied for 2 years with WW and GW using sand media filter (F1), disk filter (F2), and combination of both filters (F3). Higher removal efficiency for turbidity, total solids, Ca, Mg, CO₃ total coliforms, and E. coli was observed with combination filter. Emitter discharge exponent was also close to 0.5 with combination filter. Emitter flow rate decreased (in the sequence of F1 > F2 > F3) with increase in time of operation. After 2 years of operation under F3, coefficient of variation was less than 4 % with both WW and GW. Thus, it showed good performance in surface placed emitters but it was 7.2 % with WW and 9.5 % with GW under subsurface (15 cm) placed emitters. Clogging of emitters was controlled by flushing. Flushed emitters placed at 30 cm depth resulted in 3.7 % reduction in discharge as compared to 8.7 % reduction in the absence of flushing, under filter F1. Emitters with F2 produced least improvement in discharge.     

Time-dependent drainage from root zone and drainage coefficient under different irrigation management levels for subsurface drainage design in Egypt

Drainage water from the lower boundary of the root zone is an important factor in the irrigated agricultural lands for prediction of the water table behavior and understanding and modeling of water and chemical movement in the soil profile. The drainage coefficient is an important parameter for the design of subsurface drainage. On a 33,138 ha of the Nile Delta in Egypt, this study is conducted using 90 irrigation periods over a 3-year crop rotation to estimate the time-dependent drainage from the root zone and the design subsurface drainage coefficient with different cropping seasons and irrigation management levels.The results showed that the cropping seasons and the irrigation management levels as indicated by different irrigation efficiency are significantly affected the drainage rate from the root zone and the design value of subsurface drainage coefficient. Drainage rates from the root zone of 1.72 mm/d and 0.82 mm/d were estimated for summer and winter seasons, respectively. These rates significantly decreased in a range of 46% to 92% during summer season and 60% to 98% during winter season when the irrigation efficiency is increased in a range of 5% to 15%. The subsurface drainage coefficient was estimated to be 1.09 mm/d whereas the design drain pipe capacity was estimated to be 2.2 mm/d, based on the peak discharge of the most critical crop (maize), rather than 4.0 mm/d which is currently used. A significant decrease of the drainage coefficient and the drain pipe capacity ranges from 18% to 45% was found with the increase of irrigation efficiency in a range of 5% to 15%. The leaching requirement for each crop was also estimated.     

温室番茄循环曝气地下滴灌土壤水分动态及耗水特性

为探求循环曝气地下滴灌对温室番茄土壤水分及耗水特性的影响规律,采用正交试验,研究了不同滴灌带埋深、曝气水平及灌水量对温室番茄土壤含水率、耗水量、产量及水分利用效率的影响.整个生育期内番茄耗水量呈先增大后减小的趋势,曝气处理番茄耗水量显著高于不曝气处理.相比于不曝气处理,曝气滴灌处理番茄产量提高10%.15 cm滴灌带埋深、溶氧值30 mg/L以及K_P为0.75灌水量处理的番茄产量和水分利用效率达到最大值,分别为64 951.3 kg/hm²和23.26 kg/(hm²·mm).结果表明,曝气处理对番茄产量、水分利用效率的影响具有统计学意义(P<0.05).曝气对于土壤含水率有一定影响,且曝气处理有助于番茄对水分的吸收.滴灌带埋深和灌水量交互作用对番茄产量的影响具有统计学意义(P<0.05),滴灌带埋深和曝气量交互作用对番茄产量的影响具有统计学意义(P<0.01),灌水量与滴灌带埋深、灌水量与曝气水平交互作用分别对番茄水分利用效率的影响具有统计学意义(P<0.01).     

地下滴灌中毛管水力计算的数学模型与试验

为了研究地下滴灌毛管水力特性与水力计算方法,用较短毛管并通过毛管末端泄流的方式,在室内利用地下滴灌毛管水力要素试验测试系统,分别测试了2种滴灌管在轻黏土中毛管上每个滴头的流量和毛管首末两端的压力水头．结果表明：在灌水持续2min之后,地下滴灌毛管上各滴头流量均趋于恒定值;在稳定的压力水头差下,滴头流量沿程依次减少．根据毛管沿程压力变化规律,结合考虑土壤质地、土壤体积质量和初始含水率的地下滴灌滴头流量计算公式,提出了毛管水力计算数学模型．利用该模型计算的滴头流量值与其实测值之间的相对误差在1．0％左右;并计算出考虑毛管局部水头损失的加大系数约为1．20．将该模型推广应用于一般情况下的地下滴灌毛管水力计算,可求解均匀坡、均质土、均匀管径与滴头等间距时的地下滴灌毛管水力特征值．     

Effects of transient subsurface waterlogging on root growth, plant biomass and yield of chickpea

Root growth and proliferation are important for achieving the yield potential of chickpea in soils prone to waterlogging. Root growth characteristics and seed yield of the desi cultivar Rupali and the kabuli cultivar Almaz that differ in seed size and early vigour were investigated under well-drained and transiently-waterlogged conditions in glass-walled root boxes in a controlled-temperature glasshouse. Rooting parameters and detailed measurements of root growth and proliferation were made at 2-day intervals using a root mapping technique and by sampling the roots from the soil 14 days after the transient waterlogging ended. Although the roots of the kabuli cultivar Almaz had greater dry matter and length than the desi cultivar Rupali, the subsurface waterlogging promptly stopped the root growth of both genotypes. Root dry matter in both types of chickpea was reduced by two-thirds, 14 days after the cessation of the 12-day waterlogging treatment. The reduction resulted from an inhibition in root growth and proliferation, which led to a lower root length density down the soil profile, particularly in the top 0.6 m of the waterlogged plants. While root length and root dry matter was higher in the kabuli cultivar Almaz than in the desi cultivar Rupali after waterlogging, they were not associated with a greater above-ground dry matter or seed yield at maturity. The transient waterlogging reduced the seed yield by 54% in the kabuli cultivar Almaz and by 44% in the desi cultivar Rupali. The reduction in seed yield in the kabuli cultivar Almaz resulted from 50% decline in the number of seeds per pod while in the desi cultivar Rupali it was a consequence of less pods and seeds per pod. Subsurface waterlogging changed the rooting pattern in chickpea, inhibiting root branching and the growth of the tap root and severely reducing the growth of root branches. The release from the waterlogging induced the production of new roots rather than regrowth of existing roots.     

间接地下滴灌下灌水量对枣树生理特征及果实品质的影响

通过小区试验,以地表滴灌为对照,探究红枣间接地下滴灌模式下水分的分布特征及不同灌水量对枣树生理生态指标、产量、品质的影响。间接地下滴灌下,最大的含水率出现在15~30cm土层处;而地表滴灌下,最大的含水率出现0~10cm土层处。枣树各生理生态指标,随灌水次数的增加,各处理性状差异逐渐增大,间接滴灌下中供水和高等供水枣树长势较好,低供水处理下红枣的糖分含量高,中供水处理下红枣的有机酸和VC含量高;地表滴灌处理枣树的平均单株产量高,但水分利用率最低,中供水处理不明显降低红枣单果质量和平均单株产量的前提下可以提高水分利用率;综合考虑枣树长势、产量、果实品质及水分利用率,中供水是间接地下滴灌下最佳的灌水量。