M. Robiul Islam

Effects of water-saving superabsorbent polymer on antioxidant enzyme activities and lipid peroxidation in corn (Zea mays L.) under drought stress

BACKGROUND Drought stress significantly limits oat (Avena sativa L.) growth and productivity. Thus an efficient management of soil moisture and study of metabolic changes in response to drought are important for improved production of oat. The objective was to gain a better understanding of drought tolerance mechanisms and improve soil water management strategies using water-saving superabsorbent polymer (SAP) at 60 kg ha(-1) under three irrigation levels (adequate, moderate and deficit) using a new type of hydraulic pressure-controlled auto irrigator. RESULTS The results showed that the relative water content and leaf water potential (ψ(1) ) were much higher in oats treated with SAP. Although the SAP had little effect on plant biomass accumulation under adequate and moderate irrigation, it significantly increased the biomass by 52.7% under deficit irrigation. Plants treated with SAP under deficit irrigation showed a significant decrease in superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and glutathione reductase activities in leaves compared with control plants. CONCLUSION Our results suggested that drought stress leads to production of oxygen radicals, which results in increased lipid peroxidation and oxidative stress in the plant, and the application of SAP could conserve soil water, making same available to plants for increased biomass accumulation and reduced oxidative stress especially under severe water stress.

Effectiveness of a water-saving super-absorbent polymer in soil water conservation for corn (Zea mays L.) based on eco-physiological parameters

BACKGROUND The objective was to study soil water conservation and physiological growth of corn (Zea mays L.) using water-saving super-absorbent polymer (SAP) at 30 kg ha(-1). The effectiveness of SAP was studied under three irrigation levels (adequate, moderate and deficit) using a new type of negative hydraulic pressure controlled auto-irrigator in the years 2009 and 2010 in a greenhouse at Beijing, P.R. China. RESULTS Eight weeks after sowing, plant height and leaf area increased significantly by 41.6 and 79.6% under deficit irrigation for SAP treatment. The SAP had little effect on shoot dry mass under adequate and moderate irrigation but increased it significantly by 133.5% under deficit irrigation. Similarly, the efficiency of water use also increased by 97.1%. Leaf water potential under adequate and moderate irrigation differs slightly for SAP application, whereas under deficit irrigation the values were exceeded significantly by 27.8%. The superior growth and water use efficiency of corn treated with SAP under deficit irrigation was ascribed to maintenance of higher relative water contents in leaves as well as intercellular carbon dioxide concentration, net photosynthesis and transpiration rate. CONCLUSIONS Our results suggested that plant growth and different physiological activities are restricted by drought stress and the application of super-absorbent polymer could conserve soil water, making same available to plants for increased growth and biomass accumulation especially under severe water stress. Thus, application of SAP is a suitable soil management practice for the locations characterised by severe water stress.

A lysimeter study of nitrate leaching, optimum fertilisation rate and growth responses of corn (Zea mays L.) following soil amendment with water-saving super-absorbent polymer

BACKGROUND Nitrate leaching and the resulting groundwater contamination from intensive cereal production has become a major concern for long-term farmland efficiency and environmental sustainability in northern China. The aim of this study was to evaluate a water-saving super-absorbent polymer (SAP) for minimising NO(3)(-) leaching from soil and optimising corn growth and yield. Thirty-six undisturbed soil lysimeters were installed in a field lysimeter facility in drought-affected northern China to study the growth and yield characteristics of summer corn (Zea mays L.) as well as the amount of NO(3)-leaching losses under different fertiliser (standard, medium or 75% and low, or 50% of conventional fertilisation rate) and SAP (control, 0; level-1, 15 kg ha(-1) and level-2, 30 kg ha(-1)) treatments. RESULTS Corn yield fell by 19.7% under medium and 37.7% under low fertilisation; the application of SAP increased yield significantly by 44.4% on level-1 and 80.3% on level-2. Similarly, plant height, leaf area, number of grains as well as protein, soluble sugar and starch contents in the grain also increased with SAP treatment. Application of SAP at 30 kg ha(-1) plus half of conventional fertilisation can reduce maximum (64.1%) nitrate leaching losses from soil. CONCLUSIONS Application of SAP at 30 kg ha(-1) plus only half the amount of conventional fertiliser rate (150 kg urea, and 50 kg each of superphosphate and potassium sulfate) would be a more appropriate practice both for minimising nitrate leaching and sustainable corn production under the arid and semiarid conditions of northern China.

Fertilizer use efficiency of drought-stressed oat (Avena sativa L.) following soil amendment with a water-saving superabsorbent polymer

Abstract In arid and semiarid regions of northern China, there is an increasing interest in using reduced rates of chemical fertilizer along with water-saving superabsorbent polymer for field crop production. Field experiments were conducted during the year 2009 and 2010 to study the growth performance and yield characteristics of forage oat (Avena sativa L.) as well as soil moisture and nutrient status of the experimental field under different fertilizer (standard, 300; medium, 225; and low, 150 kg ha−1) treatments with (60 kg ha−1) or without application of superabsorbent polymer. Our results show that above-ground biomass accumulation fell by 14.8% under medium and 32.6% under low fertilizer levels whereas application of superabsorbent polymer increased it significantly by 39.7%. Similarly plant height, tiller fertility rate, grain yield, relative water content in the leaves as well as quality of forage also increased for superabsorbent polymer treatment. Considering the trends of growth reduction (qualitative and quantitative) due to fertilizer reduction and progressive influence of superabsorbent polymer on those parameters, it was clear that application of superabsorbent polymer plus only half the conventional fertilizer rate (150 kg ha−1) would be a more appropriate practice for forage oat production under arid and semiarid conditions of northern China or in areas with similar ecologies.

A Lysimeter Study for Leaching Losses, Sustainable Fertilization, and Growth Responses of Corn (Zea mays L.) Following Soil Amendment with a Water-Saving Superabsorbent Polymer

Nitrate leaching and the resulting ground water contamination from intensive cereal production has become a major concern for long-term farmland efficiency and environmental sustainability in northern China. The aim of this study was to evaluate a water-saving superabsorbent polymer for minimizing nutrient leaching from soil and optimizing corn growth and yield. Twenty-four undisturbed soil lysimeters (35-cm diameter and 150-cm depth) were installed in a field lysimeter facility in drought affected northern China to study the growth and yield characteristics of summer corn (Zea mays L.) as well as soil fertility and the amount of nutrient (NO3-N, P, and K) leaching losses under different fertilizer (standard, medium, or 75% and low, or 50 % of conventional fertilization rate) treatments with (30 kg ha-1) or without the application of SAP. Corn yield fell by 19.7% under medium and 37.7% under low fertilization; the application of SAP increased it significantly by 80.3%. Similarly intercellular carbon dioxide concentration, net photosynthesis and transpiration rate, relative water contents in the leaves as well as available nutrient elements in the soil also increased with SAP treatment. Application of SAP at 30 kg ha-1 plus only half of conventional fertilization can provide the same yield at the same cost but reduce nitrate leaching significantly by 64.1% compared with conventional (excessive) fertilization. At the same time P and K leaching can be reduced significantly by 12.6% and 36.8%. Application of SAP at 30 kg ha-1 plus half the amount of conventional fertilizer rate (150-kg urea, and 50 kg each of superphosphate and potassium sulfate) would be a more appropriate practice both for minimizing nutrient leaching and sustainable corn production under the arid and semiarid conditions of northern China.

Effectiveness of Water-Saving Superabsorbent Polymer in Soil Water Conservation for Oat Based on Ecophysiological Parameters

The objective of the study was to study soil water conservation and physiological growth of oat (Avena sativa L.) using water-saving superabsorbent polymer (SAP) at 60 kg ha−1. The effectiveness of SAP was studied under three irrigation levels (adequate, moderate, and deficient) using a new type of negative hydraulic pressure–controlled auto-irrigator. Seven weeks after sowing (WAS), the number of tillers and leaves increased significantly by 33 and 40%, respectively, under deficient irrigation due to application of SAP. The SAP had little effects on shoot dry mass (SDM) and root dry mass (RDM) under adequate and moderate irrigation but increased both parameters significantly (59 and 45%) under deficient irrigation. As a result, the water-use efficiency (WUE) increased substantially (50%) under deficient irrigation. Leaf water potential (ψ1) under adequate irrigation exceeded that under moderate and deficient irrigation by 26.4 and 39.6%, respectively, and the application of SAP further increased it by 7.2%. The superior growth and WUE of oat treated with SAP under deficient irrigation was ascribed to maintenance of greater relative water content (RWC) in leaves as well as intercellular carbon dioxide concentration (Ci), net photosynthesis (PN), and transpiration rate. It is suggested that the application of SAP is a suitable soil management practice for locations characterized by severe water stress.