Assessing climate change adaptations for community-scale water resources using a low-frequency weather generator

Paddy and Water Environment - Water adaptation strategies are necessary for decreasing climate change impacts on local societies. This study models a community water supply system as a distributed...     

Application of system dynamics approach for time varying water balance in aerobic paddy fields

Increasing water scarcity has necessitated the development of irrigated rice systems that require less water than the traditional flooded rice. The cultivation of aerobic rice is an effort to save water in response to growing worldwide water scarcity with the pressure to reduce water use and increase water productivity. An accurate estimation of different water balance components at the aerobic rice fields is essential to achieve effective use of limited water supplies. Some field water balance components, such as percolation, capillary rise and evapotranspiration, can not be easily measured; therefore a soil water balance model is required to develop and to test water management strategies. This paper presents results of a study to quantify time varying water balance under a critical soil water tension based irrigation criteria for the cultivation of non-ponded “aerobic rice” fields along the lower parts of the Yellow River. Based on the analysis and integration of existing field information on the hydrologic processes in an aerobic rice field, this paper outlines the general components of the water balance using a conceptual model approach. The time varying water balance is then analyzed using the feedback relations among the hydrologic processes in a commercial dynamic modeling environment, Vensim. The model simulates various water balance components such as actual evapotranspiration, deep percolation, surface runoff, and capillary rise in the aerobic rice field on a daily basis. The model parameters are validated with the observed experimental field data from the Huibei Irrigation Experiment Station, Kaifeng, China. The validated model is used to analyze irrigation application soil water tension trigger under wet, dry and average climate conditions using daily time steps. The scenario analysis show that to conserve scarce water resources during the average climate years the irrigation scheduling criteria can be set as −30 kPa average root zone soil water tension; whereas it can be set at −70 kPa during the dry years, however, the associated yields may reduce. Compared with the flooded lowland rice and other upland crops, with these two alternatives irrigation event triggers, aerobic rice cultivation can lead to significant water savings.     

Rapid one-step separation and purification of recombinant phenylalanine dehydrogenase in aqueous two-phase systems

Background: Phenylalanine dehydrogenase (PheDH; EC 1.4.1.20) is a NAD+-dependent enzyme that performs the reversible oxidative deamination of L-phenylalanine to phenylpyruvate. It plays an important role in detection and screening of phenylketonuria (PKU) diseases and production of chiral intermediates as well. The main goal of this study was to find a simple and rapid alternative method for purifying PheDH. Methods: The purification of recombinant Bacillus sphaericus PheDH was investigated in polyethylene glycol (PEG) and ammonium sulfate aqueous two-phase systems (ATPS). The influences of system parameters including PEG molecular weight and concentration, pH and (NH4)2SO4 concentration on enzyme partitioning were also studied. The purity of enzyme was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Results: A single extraction process was developed for separation and purification of recombinant PheDH from E. coli BL21 (DE3). The optimized conditions for partitioning and purification of PheDH were 9% (w/w) PEG-6,000 and 16% (w/w) (NH4)2SO4 at pH 8.0. The partition coefficient, recovery, yield, purification factor and specific activity values were achieved 58.7, 135%, 94.42%, 491.93 and 9828.88 U/mg, respectively. Also, the Km values for L-phenylalanine and NAD+ in oxidative deamination were 0.21 and 0.13 mM, respectively. Conclusion: The data presented in this paper demonstrated the potential of ATPS as a versatile and scaleable process for downstream processing of recombinant PheDH.     

Growth and photosynthesis of salt‐stressed sunflower (Helianthus annuus) plants as affected by foliar‐applied different potassium salts

In order to assess the effectiveness of foliar‐applied potassium (K⁺, 1.25%) using different salts (KCl, KOH, K₂CO₃, KNO₃, KH₂PO₄, and K₂SO₄) in ameliorating the inhibitory effect of salt stress on sunflower plants, a greenhouse experiment was conducted. Sodium chloride (150 mM) was applied through the rooting medium to 18 d–old plants and after 1 week of salt treatment; different K⁺‐containing salts were applied twice in 1‐week interval as a foliar spray. Salt stress adversely affected the growth, yield components, gas exchange, and water relations, and also caused nutrient imbalance in sunflower plants. However, foliar‐applied different sources of potassium improved shoot and root fresh and shoot dry weights, achene yield, 100‐achene weight, photosynthetic rate, transpiration rate, stomatal conductance, water‐use efficiency, relative water content, and leaf and root K⁺ concentrations of sunflower plants grown under saline conditions. Under nonsaline conditions, improvement in shoot fresh weight, achene yield, 100‐achene weight, photosynthetic and transpiration rates, and root Na⁺ concentration was observed due to foliar‐applied different K sources. Of the different salts, K₂SO₄, KH₂PO₄, KNO₃, and K₂CO₃ were more effective than KCl and KOH in improving growth and some key physiological processes of sunflower plants.     

Zinc exposure has differential effects on uptake and metabolism of sulfur and nitrogen in Chinese cabbage

Zinc (Zn) is a plant nutrient; however, at elevated levels it rapidly becomes phytotoxic. In order to obtain insight into the physiological background of its toxicity, the impact of elevated Zn²⁺ concentrations (1 to 10 μM) in the root environment on physiological functioning of Chinese cabbage was studied. Exposure of Chinese cabbage (Brassica pekinensis) to elevated Zn²⁺ concentrations (≥ 5 μM) in the root environment resulted in leaf chlorosis and decreased biomass production. The Zn concentrations of the root and shoot increased with the Zn²⁺ concentration up to 68‐fold and 14‐fold, respectively, at 10 μM compared to the control. The concentrations of the other mineral nutrients of the shoot were hardly affected by elevated Zn²⁺ exposure, although in the root both the Cu and Fe concentrations were increased at ≥ 5 µM, whereas the Mn concentration was decreased and the Ca concentration strongly decreased at 10 µM Zn²⁺. The uptake and metabolism of sulfur and nitrogen were differentially affected at ≥ 5 µM Zn²⁺. Zn²⁺ exposure resulted in an increase of sulfate uptake and the activity of the sulfate transporters in the root, and in enhanced total sulfur concentration of the shoot, which could be ascribed partially to an accumulation of sulfate. Moreover, Zn²⁺ exposure resulted in an up to 6.5‐fold increase in water‐soluble non‐protein thiol (and cysteine) concentration of the root. However, nitrate uptake by the root and the nitrate and total nitrogen concentrations of the shoot were decreased upon Zn²⁺ exposure, demonstrating the absence of a mutual regulation of the uptake and metabolism of sulfur and nitrogen at toxic Zn levels. Evidently, elevated Zn²⁺ concentrations in the root environment did not only disturb the uptake, distribution and assimilation of sulfate, it also affected the uptake and metabolism of nitrate in Chinese cabbage.     

Water management and crop production for food security in China: A review

Food security is a high priority issue on the Chinese political agenda. China’s food security is challenged by several anthropogenic, sociopolitical and policy factors, including: population growth; urbanization and industrialization; land use changes and water scarcity; income growth and nutritional transition; and turbulence in global energy and food markets. Sustained growth in agricultural productivity and stable relations with global food suppliers are the twin anchors of food security. Shortfalls in domestic food production can take their toll on international food markets. Turbulence in global energy markets can affect food prices and supply costs, affecting food security and poverty. Policy safeguards are needed to shield food supply against such forces. China must make unremitting policy responses to address the loss of its fertile land for true progress towards the goal of national food security, by investing in infrastructure such as irrigation, drainage, storage, transport, and agricultural research and institutional reforms such as tenure security and land market liberalization. The links between water and other development-related sectors such as population, energy, food, and environment, and the interactions among them require reckoning, as they together will determine future food security and poverty reduction in China. Climate change is creating a new level of uncertainty in water governance, requiring accelerated research to avoid water-related stresses.     

Competence of Aedes albopictus and Culex quinquefasciatus as vector of Dirofilaria immitis after blood meal with different microfilarial density

Aedes albopictus and Culex quinquefasciatus were fed canine blood with different microfilarial density of Dirofilaria immitis ranging from 2500 to 25,000 mff/ml. Larval development in these two mosquito species did not differ significantly. Although C. quinquefasciatus ingested more microfilariae, the number of larvae which developed in A. albopictus was invariably greater than in C. quinquefasciatus. Mortality of the engorged A. albopictus was significantly greater than that of C. quinquefasciatus, and higher microfilarial density raised the mortality in both species. The vector efficiency index of A. albopictus was greater than C. quinquefasciatus at all microfilarial densities, but its survival time was much reduced. Thus, dogs with low microfilarial density are implicated as the main source for the transmission of D. immitis from dogs to mosquitoes.     

Dormancy induction in container-grown Abies seedlings: Effects of environmental cues and seedling age

Twelve-week-old container-grown seedlings of noble fir (Abies procera Rehd.) and Shasta red fir (A. magnifica A. Murr. var. shastensis Lemm.), both high-elevation species, were grown under controlled environments in a study of induction of terminal-bud dormancy. Eight treatment combinations of long (15 h) or short (11 h) photoperiods, warm (25°/20°C) or cool (18°/12°C) thermoperiods, and dry (–1.2 MPa) or wet (–0.6 MPa) moisture regimes were imposed upon seedlings for 12 weeks. Treatment factors significantly affecting the induction of dormancy in terminal buds of seedlings were identified over time. The results suggest that seedlings responded dynamically to dormancy cues. The warm/dry and cool/wet combinations induced dormancy in the first 2 weeks in noble fir and in the first week in Shasta red fir. Short-day/warm and long-day/cool combinations enhanced dormancy induction in weeks 3 to 4 in noble fir and in weeks 1 to 7 in Shasta red fir. Short days and cool thermoperiods independently hastened dormancy induction in noble fir in weeks 5 through 12.     

Wheat Seed Presoaking for Improved Germination

Seed presoaking improves wheat germination under marginal moisture conditions. The duration of seed presoaking was studied at The University of Arid Agriculture, Rawalpindi, using 10 wheat varieties. Seed presoaking beyond 12 h does not improve germination further, and beyond 21 h, germination rate is drastically reduced.