Environmental burdens of groundwater extraction for irrigation over an inland river basin in Northwest China

Crop production is expected to increase by more than 50% to meet the demand of population growth in China in 2050 (FAO, 2017). Crop production in North China largely depends on irrigation, which is mainly from groundwater in Northwest China. Over-extraction of groundwater is decreasing groundwater levels, and threatening the fragile ecological systems of arid regions. How groundwater levels will change in order to meet the irrigation water requirement in Northwest China has not been extensively investigated to evaluate sustainability of agriculture and the cost to maintain groundwater levels. Here, we examine the dynamic relations between groundwater levels and the amount of irrigation water, by employing the Variable Infiltration Capacity model and an irrigation scheme, for the last three decades in Heihe River basin of China. The results show that on the average about 1.86 m decline of groundwater is attributable to the irrigation water consumption for the farmland area in Heihe River over the past three decades. In the scenario of ceasing irrigation activities, the groundwater level will be prevented to further decline about 3.06±0.4m under the future climate scenarios till 2050, but at the cost of crop production valued 64.2±8.4 billion CNY. Effective water-saving measures and strategies are expected to adopt to maintain both groundwater levels and agricultural productivity for the coming decades

Modeling of Hydrological Processes in Arid Agricultural Regions

Understanding of hydrological processes, including consideration of interactions between vegetation growth and water transfer in the root zone, underpins efficient use of water resources in arid-zone agriculture. Water transfers take place in the soil-plant-atmosphere continuum, and include groundwater dynamics, unsaturated zone flow, evaporation/transpiration from vegetated/bare soil and surface water, agricultural canal/surface water flow and seepage, and well pumping. Models can be categorized into three classes: (1) regional distributed hydrological models with various land uses, (2) groundwater-soil-plant-atmosphere continuum models that neglect lateral water fluxes, and (3) coupled models with groundwater flow and unsaturated zone water dynamics. This review highlights, in addition, future research challenges in modeling arid-zone agricultural systems, e.g., to effectively assimilate data from remote sensing, and to fully reflect climate change effects at various model scales

Alternate furrow irrigation for maize production in an arid area

Abstract A new irrigation method for maize production was designed and tested for yield and water use ef®ciency (WUE). A ®eld experiment was conducted in an arid area, with seasonal rainfall of 80 mm, over 2 years (1997 and 1998). Irrigation was applied through furrows in three ways: alternate furrow irrigation (AFI), ®xed 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 ®xed to one of the two neighboring furrows. CFI was the conventional way where every furrow was irrigated during each watering. Each irrigation method was further divided into three sub-treatments with different irrigation amounts: 45, 30 and 22.5 mm water at each application. Results showed that root development was signi®cantly enhanced by AFI treatment. Primary root numbers, total root dry weight, and root density were all higher in AFI than in FFI and CFI treatments. Less irrigation signi®cantly reduced the total root dry weight and plant height in both FFI and CFI treatments but not as substantially with AFI treatments. The most surprising result was that AFI maintained high grain yield with up to 50% reduction in irrigation amount, while FFI and CFI all showed a substantial decrease in yield with reduced irrigation. As a result, WUE for irrigated water was substantially increased. We conclude that AFI is a way to save water in arid areas where maize production relies heavily on repeated irrigation.

Interactive Regimes of Reduced Irrigation and Salt Stress Depressed Tomato Water Use Efficiency at Leaf and Plant Scales by Affecting Leaf Physiology and Stem Sap Flow

Interactive effects of reduced irrigation and salt stress on leaf physiological parameters, biomass accumulation, and water use efficiency (WUE) of tomato plants at leaf and whole plant scales were investigated in a field experiment during 2016 and a greenhouse experiment during 2017. Experiment utilized two irrigation regimes (full, 2/3 of full irrigation) and four soil salt regimes (0, 0.3, 0.6, 0.9% in 2016 season; and 0, 0.2, 0.3, 0.4% in 2017 season). Three salts, sodium chloride, magnesium sulfate, and calcium sulfate (mass ratio of 2:2:1), were homogeneously mixed with soil prior to packing into containers (0.024 m3). Li-COR 6400 was used to measure tomato leaf physiological parameters. Instantaneous water use efficiency (WUEins, μmol mmol−1) and intrinsic water use efficiency (WUEint, μmol mol−1) were determined at leaf scale, yield water use efficiency (WUEY, g L−1), and dry biomass water use efficiency (WUEDM, g L−1) were determined at whole plant scale. Plants irrigated with 2/3 of full irrigation with zero soil-salt treatment had higher dry biomass and yield per plant, resulting in the highest WUEDM and WUEY at whole plant scale. Increasing soil salinity decreased dry biomass and yield, leading to greater decreases in whole plant WUEDM and WUEY under both irrigation treatments. At full irrigation, no decreases in stomatal conductance (gs, mol m−2 s−1) and slight increase in photosynthetic rate (Pn, μmol m−2 s−1) led to higher WUEint at leaf scale during both years. Under full and reduced irrigation, increasing soil salt content decreased Pn and transpiration rate (Tr, mmol m−2 s−1) and led to reductions in WUEins at the leaf scale. However, compared to full irrigation, reduced irrigation improved WUEins with a significant decline in Tr in no salt and 0.3% soil-salt treatments during both years. For soil salt content of 0.6%, stomatal limitation due to salt stress resulted in higher WUEint, but soil salt content of 0.9% decreased WUEint due to non-stomatal limitation. Soil salt content significantly decreased sap flow, with the maximum variation of daily sap flow per plant of 7.96–31.37 g/h in 2016 and 12.52–36.02 g h−1 in 2017. Sap flow rate was linearly related to air temperature (Ta, °C), solar radiation (Rs, W m−2), and vapor pressure deficit (VPD, kPa). These results advance knowledge on tomato response to abiotic stresses and could improve management of tomato production in water- and salt-stressed areas

Alternate partial root-zone irrigation reduces bundle-sheath cell leakage to CO2 and enhances photosynthetic capacity in maize leaves

The physiological basis for the advantage of alternate partial root-zone irrigation (PRI) over common deficit irrigation (DI) in improving crop water use efficiency (WUE) remains largely elusive. Here leaf gas exchange characteristics and photosynthetic CO2–response and light–response curves for maize (Zea mays L.) leaves exposed to PRI and DI were analysed under three N-fertilization rates, namely 75, 150, and 300 mg N kg−1 soil. Measurements of net photosynthetic rate (An) and stomatal conductance (gs) showed that, across the three N-fertilization rates, the intrinsic WUE was significantly higher in PRI than in DI leaves. Analysis of the CO2–response curve revealed that both carboxylation efficiency (CE) and the CO2-saturated photosynthetic rate (Asat) were significantly higher in PRI than in DI leaves across the three N-fertilization rates; whereas the N-fertilization rates did not influence the shape of the curves. The enhanced CE and Asat in the PRI leaves was accompanied by significant decreases in carbon isotope discrimination (Δ13C) and bundle-sheath cell leakiness to CO2 (Φ). Analysis of the light–response curve indicated that, across the three N-fertilization rates, the quantum yield (α) and light-saturated gross photosynthetic rate (Amax) were identical for the two irrigation treatments; whilst the convexity (κ) of the curve was significantly greater in PRI than in DI leaves, which coincided with the greater CE and Asat derived from the CO2–response curve at a photosynthetic photon flux density of 1500 μmol m−2 s−1. Collectively, the results suggest that, in comparison with the DI treatment, PRI improves photosynthetic capacity parameters CE, Asat, and κ of maize leaves and that contributes to the greater intrinsic WUE in those plants

FGFR3 Activates RSK2 to Mediate Hematopoietic Transformation through Tyrosine Phosphorylation of RSK2 and Activation of the MEK/ERK Pathway

SummaryTo better understand the signaling properties of oncogenic FGFR3, we performed phospho-proteomics studies to identify potential downstream signaling effectors that are tyrosine phosphorylated in hematopoietic cells expressing constitutively activated leukemogenic FGFR3 mutants. We found that FGFR3 directly tyrosine phosphorylates the serine/threonine kinase p90RSK2 at Y529, which consequently regulates RSK2 activation by facilitating inactive ERK binding to RSK2 that is required for ERK-dependent phosphorylation and activation of RSK2. Moreover, inhibition of RSK2 by siRNA or a specific RSK inhibitor fmk effectively induced apoptosis in FGFR3-expressing human t(4;14)-positive myeloma cells. Our findings suggest that FGFR3 mediates hematopoietic transformation by activating RSK2 in a two-step fashion, promoting both the ERK-RSK2 interaction and subsequent phosphorylation of RSK2 by ERK

Spatial Variability of Grapevine Bud Burst Percentage and Its Association with Soil Properties at Field Scale.

There is a growing interest in precision viticulture with the development of global positioning system and geographical information system technologies. Limited information is available on spatial variation of bud behavior and its possible association with soil properties. The objective of this study was to investigate spatial variability of bud burst percentage and its association with soil properties based on 2-year experiments at a vineyard of arid northwest China. Geostatistical approach was used to describe the spatial variation in bud burst percentage within the vineyard. Partial least square regressions (PLSRs) of bud burst percentage with soil properties were used to evaluate the contribution of soil properties to overall spatial variability in bud burst percentage for the high, medium and low bud burst percentage groups. Within the vineyard, the coefficient of variation (CV) of bud burst percentage was 20% and 15% for 2012 and 2013 respectively. Bud burst percentage within the vineyard showed moderate spatial variability, and the overall spatial pattern of bud burst percentage was similar between the two years. Soil properties alone explained 31% and 37% of the total spatial variation respectively for the low group of 2012 and 2013, and 16% and 24% for the high group of 2012 and 2013 respectively. For the low group, the fraction of variations explained by soil properties was found similar between the two years, while there was substantial difference for the high group. The findings are expected to lay a good foundation for developing remedy measures in the areas with low bud burst percentage, thus in turn improving the overall grape yield and quality