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991.
Ryan B. Mounce Susan A. O’Shaughnessy Brock C. Blaser Paul D. Colaizzi Steven R. Evett 《Irrigation Science》2016,34(3):231-244
In the High Plains, corn (Zea mays L.) is an important commodity for livestock feed. However, limited water resources and drought conditions continue to hinder corn production. Drought-tolerant (DT) corn hybrids could help maintain high yields under water-limited conditions, though consistent response of such hybrids is unverified. In this two-year study, the effects of three irrigation treatments were investigated for a DT and conventional maize hybrid, Pioneer AQUAMax P0876HR and Pioneer 33Y75, respectively. In 2013, the drier of the 2 years, irrigation amounts and crop water use (ETc) were greater for the conventional hybrid, but grain water use efficiency (WUE) and harvest index were significantly greater for the DT hybrid. In 2014, grain yields and WUE were not significantly different between hybrids. However, irrigation amounts, ETc and biomass yields were greater for the conventional hybrid. Results from both years indicate that the DT hybrid required less water to maximize grain yield as compared to the conventional hybrid. Producing relatively high yields with reduced amounts of water may provide a means for producers to continue corn production in a semiarid environment with declining water supplies. 相似文献
992.
The use of overhead trellis systems for the production of dry-on-vine (DOV) raisins and table grapes in California is expanding. Studies were conducted from 2006 to 2009 using Thompson Seedless grapevines grown in a weighing lysimeter trained to an overhead arbor trellis and farmed as DOV raisins for the first two years and for use as table grapes thereafter. Maximum canopy coverage for the two lysimeter vines across years was in excess of 80 %. Seasonal (15 March–31 October) evapotranspiration for the lysimeter vines (ETLys) was 952 mm in 2007 (farmed as DOV raisins) and 943 and 952 mm (when farmed as table grapes). The maximum crop coefficient (K cLys) across all 4 years ranged from 1.3 to 1.4. These maximum values were similar to those estimated using the relationship where K c is a function of the amount of shaded area measured beneath the canopy at solar noon (K c = 0.017 × percent shaded area). Covering the lysimeter’s soil surface with plastic (and then removing it) numerous times during the 2009 growing season (1 June–14 September) reduced ETLys from an average of 6.4 to 5.6 mm day?1 and the K c from 1.07 to 0.93. A seasonal basal K c (K cb) was calculated for grapevines using an overhead trellis system with a 13 % reduction in the K cLys across the growing season. 相似文献
993.
José Manuel Mirás-Avalos Francisco Pérez-Sarmiento Rosalía Alcobendas Juan José Alarcón Oussama Mounzer Emilio Nicolás 《Irrigation Science》2016,34(2):161-173
Irrigation techniques that reduce water applications are increasingly applied in areas with scarce water resources. In this study, the effect of two regulated deficit irrigation (RDI) strategies on peach [Prunus persica (L.) Batsch cv. “Catherine”] performance was studied over three growing seasons. The experimental site was located in Murcia (SE Spain), a Mediterranean region. Two RDI strategies (restricting water applications at stage II of fruit development and postharvest) based on stem water potential (Ψs) thresholds (?1.5 and ?1.8 MPa during fruit growth and ?1.5 and ?2.0 MPa during postharvest) were compared to a fully irrigated control. Soil water content (θv), Ψs, gas exchange parameters, vegetative growth, crop load, yield and fruit quality were determined. RDI treatments showed significantly lower values of θv and Ψs than control trees when irrigation water was restricted, causing reductions in stomatal conductance and photosynthesis rates. Vegetative growth was reduced by RDI, as lower shoot lengths and pruning weights were observed under those treatments when compared to control. However, fruit size and yield were unaffected, and fruit quality was slightly improved by RDI. Water savings from 43 to 65 % were achieved depending on the year and the RDI strategy, and no negative carryover effect was detected during the study period. In conclusion, RDI strategies using Ψs thresholds for scheduling irrigation in mid–late maturing peach trees under Mediterranean conditions are viable options to save water without compromising yield and even improving fruit quality. 相似文献
994.
Salim Bounoua Séverine Tomas Jérôme Labille Bruno Molle Jacques Granier Pierre Haldenwang Surani Nuur Izzati 《Irrigation Science》2016,34(4):327-342
Dripper clogging is a major drawback of microirrigation systems that must be addressed to improve their efficiency and durability. Particle-induced clogging is first studied in situ. The experiments consist in observing in real conditions the behavior of a series of drippers fitted on an agricultural plot in the south of France. The plot is supplied from a canal with Durance River water. The latter is loaded with sediments that gradually clog drippers and filters. Water analysis reveal that physicochemical clogging prevails over biological clogging. This characterization helps in setting in-lab experiment protocol. Indeed, besides field observation of clogging, laboratory analyses of both the irrigation water and the clogging material are performed with reactive and inert clay: smectite and an illite–calcite mix. A surprising tendency is observed: Salt concentration in smectite seeded water decreases the clogging, whereas it increases agglomerate size. Computational fluid dynamic simulations are carried out to investigate the impact of particles on flow behavior. Results demonstrate that clay particles interacting with the flow govern the complex structure of the fluid velocity fields inside the dripper labyrinth channel. 相似文献
995.
A modern computer-based simulation tool (WaterMan) in the form of a game for on-farm water management was developed for application in training events for farmers, students, and irrigators. The WaterMan game utilizes an interactive framework, thereby allowing the user to develop scenarios and test alternatives in a convenient, risk-free environment. It includes a comprehensive soil water and salt balance calculation algorithm. It also employs heuristic capabilities for modeling all of the important aspects of on-farm water management, and to provide quantitative performance evaluations and practical water management advice to the trainees. Random events (both favorable and unfavorable) and different strategic decisions are included in the game for more realism and to provide an appropriate level of challenge according to player performance. Thus, the ability to anticipate the player skill level, and to reply with random events appropriate to the anticipated level, is provided by the heuristic capabilities used in the software. These heuristic features were developed based on a combination of two artificial intelligence approaches: (1) a pattern recognition approach and (2) reinforcement learning based on a Markov decision processes approach, specifically the Q-learning method. These two approaches were combined in a new way to account for the difference in the effect of actions taken by the player and action taken by the system in the game world. The reward function for the Q-learning method was modified to reflect the suggested classification of the WaterMan game as what is referred to as a partially competitive and partially cooperative game. 相似文献
996.
Stenocarpella ear rot of maize caused by Stenocarpella maydis (Berk.) Sutton is one of the most important ear rot diseases in South Africa. The objective of this study was to identify
suitable maize inbred lines and top cross hybrids with Stenocarpella ear rot resistance and high grain yield. The study was conducted using 54 inbred lines and 54 top crosses with selected standard
checks under natural and artificial disease inoculations. A split-plot design was used with three replications. There were
considerable variations among tested inbred lines and top crosses for Stenocarpella ear rot resistance and grain yield. Two promising inbred lines GCI-35 and GCI-50 were selected possessing resistance to Stenocarpella ear rot and increased grain yield. Inbred line GCI-35 had a grain yield of 6.31 and 6.27 t/ha under natural and artificial
inoculations, respectively. Line GCI-50 yielded 5.8 and 5.7 t/ha when tested under natural and artificial disease infestations,
respectively. Two top cross hybrids GCT-14 and GCT-30 were selected with greater grain yield and high level of Stenocarpella ear rot resistance. Top cross entry GCT-14 yielded 7.5 and 9.33 t/ha, respectively, whereas GCT-30 had yield of 7.65 and
9.21 t/ha, respectively. The selected inbred lines and top cross hybrids will be useful in maize improvement for Stenocarpella ear rot resistance and increased grain yield in South Africa or other similar environments. 相似文献
997.
Ram C. Sharma Alexei I. Morgounov Hans J. Braun Beyhan Akin Mesut Keser David Bedoshvili Ahmet Bagci Christopher Martius Maarten van Ginkel 《Euphytica》2010,171(1):53-64
Improved winter wheat (Triticum aestivum L.) cultivars are needed for the diverse environments in Central and West Asia to improve rural livelihoods. This study was
conducted to determine the performance of elite winter wheat breeding lines developed by the International Winter Wheat Improvement
Program (IWWIP), to analyze their stability across diverse environments, and to identify superior genotypes that could be
valuable for winter wheat improvement or varietal release. One hundred and one advanced winter wheat breeding lines and four
check cultivars were tested over a 5-year period (2004–2008). Grain yield and agronomic traits were analyzed. Stability and
genotypic superiority for grain yield were determined using genotype and genotype × environment (GGE) biplot analysis. The
experimental genotypes showed high levels of grain yield in each year, with mean values ranging from 3.9 to 6.7 t ha−1. A set of 25 experimental genotypes was identified. These were either equal or superior to the best check based on their
high mean yield and stability across environments as assessed by the GGE biplot analysis. The more stable high yielding genotypes
were ID800994.W/Falke, Agri/Nac//Attila, ID800994W/Vee//F900K/3/Pony/Opata, AU//YT542/N10B/3/II8260/4/JI/Hys/5/Yunnat Esskiy/6/KS82W409/Spn
and F130-L-1-12/MV12. The superior genotypes also had acceptable maturity, plant height and 1,000-kernel weight. Among the
superior lines, Agri/Nac//Attila and Shark/F4105W2.1 have already been proposed for release in Kyrgyzstan and Georgia, respectively.
The findings provide information on wide adaptation of the internationally important winter wheat genotypes, and demonstrate
that the IWWIP program is enriching the germplasm base in the region with superior winter wheat genotypes to the benefit of
national and international winter wheat improvement programs. 相似文献
998.
A model for optimal operation of water supply/irrigation systems of various water quality sources, with treatment plants, multiple water quality conservative factors, and dilution junctions is presented. The objective function includes water cost at the sources, water conveyance costs which account for the hydraulics of the network indirectly, water treatment cost, and yield reduction costs of irrigated crops due to irrigation with poor quality water. The model can be used for systems with supply by canals as well as pipes, which serve both drinking water demands of urban/rural consumers and field irrigation requirements. The general nonlinear optimization problem has been simplified by decomposing it to a problem with linear constraints and nonlinear objective function. This problem is solved using the projected gradient method. The method is demonstrated for a regional water supply system in southern Israel that contains 39 pipes, 37 nodes, 11 sources, 10 agricultural consumers, and 4 domestic consumers. The optimal operation solution is described by discharge and salinity values for all pipes of the network. Sensitivity of the optimal solution to changes in the parameters is examined. The solution was found to be sensitive to the upper limit on drinking water quality, with total cost being reduced by 5% as the upper limit increases from 260 to 600 mg Cl l–1. The effect of income from unit crop yield is more pronounced. An increase of income by a factor of 20 results in an increase of the total cost by a factor of 3, thus encouraging more use of fresh water as long as the marginal cost of water supply is smaller than the marginal decrease in yield loss. The effect of conveyance cost becomes more pronounced as its cost increases. An increase by a factor of 100 results in an increase of the total cost by about 14%. The network studied has a long pipe that connects two distinct parts of the network and permits the supply of fresh water from one part to the other. Increasing the maximum permitted discharge in this pipe from 0 to 200 m3 h–1 reduces the total cost by 11%. Increasing the maximum discharge at one of the sources from 90 to 300 m3 h–1 reduces the total cost by about 8%. 相似文献
999.
K. Palanisami Ruth Meinzen-Dick Mark Giordano Barbara Van Koppen C. R. Ranganathan 《Irrigation and Drainage Systems》2011,25(3):121-134
Irrigation tanks in India are common property resources. Tanks provide not only for irrigation, but also forestry, fishing,
domestic water supply, livestock, and other uses. Using empirical results from a study of tank performance from 80 tanks in
Tamil Nadu, South India in two time period: 1996-97 and 2009-10, this paper evaluates tank irrigation system performance in
terms of economic output and revenue generation forirrigation and other uses. The results indicate that irrigation and other
productive uses put together raised the total value of output at tank level by 12 % in 1996-97 and just 6 % in 2009-10. This
may suggest that tank multiple use values are small and getting smaller, and therefore not worth consideration. However, it
was also found that, while declining in absolute terms, non-irrigation uses provided the majority of tax revenues and still
more than cover government's operation and maintenance expenditure (O&M) budget. This finding provides another reason to consider
multiple use values and their linkage with overall system viability. 相似文献
1000.
This paper introduces a combined modelling approach using a simple water budget model (THC-model) and a 3D reservoir sedimentation
model (MOHID Water) to adapt reservoir operation and visualise their effects on the sediment deposition. By this, an effective
combined sediment-water management can be identified under semi-arid conditions for dry, median and wet years. Results are
presented for the reservoirs of the Tuyamuyun Hydro-Complex (THC), which is located in the lower Amu Darya River. The determination
of the actual and usable reservoir storage volume shows that siltation will significantly adversely affect the ability of
the in-stream Channel Reservoir to regulate seasonal demand for both irrigation and municipal water supply. However, modelling
scenarios results confirm the effectiveness of adapted operation rules for the THC reservoirs and show that the operation
of large dams could be modified according to a combined sediment-water management. The experience gained during this study
emphasizes the fact that the concept of a combined reservoir management of sediments as well as water can be an efficient
measure to improve the sustainable long-term use of reservoirs and to contribute towards a safe water supply in water crisis
regions. 相似文献