Maize Water Use Efficiency Research Articles

Effects of biochar and inorganic fertiliser applications on growth, yield and water use efficiency of maize under deficit irrigation

The additions of biochar and inorganic fertiliser to agricultural soils have been reported to enhance soil fertility and crop production under rainfed and irrigation conditions. However, it is unclear how biochar improve the growth, yield, irrigation and crop water use efficiency of a field grown maize under deficit irrigation. The objective of this study is to determine the main and interactive effects of biochar and fertiliser on the maize growth, yield, crop water use efficiency (CWUE) and irrigation water use efficiency (IWUE) under deficit irrigation, which has been scarcely studied. Therefore, a field experiment which consisted of factorial combination of Irrigation (100% Full Irrigation (FI), 80% FI and 60% FI), biochar (0 and 20 t/ha) and fertiliser (0 and 300 Kg/ha) was conducted over two growing seasons. The 100% FI, 80% of FI and 60% of FI received 1, 0.8 and 0.6 of the estimated irrigation need required to bring the soil water to field capacity, respectively. Effect of the soil amendments were determined on the crop evapotranspiration (water use), soil hydrophysical and chemical properties. Maize growth parameters were determined weekly while the yield components were determined at harvest. Results showed that the application of the soil amendments improved the soil hydro-physical, chemical properties, and water use by maize plant which consequently resulted in increased maize growth, yield, IWUE and CWUE under all irrigation treatments. Combined addition of the soil amendments gave significant (P < 0.05) improvement on the maize grain yield, biomass yield, CWUE and IWUE compared to the unamnded plot in all irrigation treatments. Also, insignificant interaction occurred between biochar and irrigation on maize productivities. Therefore, amending soil with biochar under limited water supply might be a novel approach for enhancing maize yield and water use efficiencies by minimizing the negative impact of drought stress.

GROWTH PARAMETERS, IRRIGATION REQUIREMENTS AND PRODUCTIVITY OF MAIZE IN RELATION TO SOWING DATES UNDER NORTH-DELTA OF EGYPT CONDITIONS

Field experiments were conducted in El-Bosaily farm in the Northern Coastal of Egypt during summer seasons of 2015 and 2016 to study the response of the single Cross 10 maize (Zea mays L.) hybrid to three sowing dates (1st of May, 1st of June and 1st of July) and three levels of irrigation; 60%, 80% and 100% of irrigation requirements (IR) which applied by drip irrigation system. The experimental design was split plot with four replications where the sowing dates and the irrigation levels were located in the main plots and the sub-plots, respectively. Germination percentage, vegetative growth, indices yield and yield components and water use efficiency were compared under the various sowing dates and irrigation level treatments. The main results were as follows: Vegetative growth traits, yield and water use efficiency of maize were decreased as sowing date delayed beyond the 1st of May. Sowing maize seeds at 1st of July gave the lowest vegetative growth traits and productivity compared to the other sowing dates during both seasons. Meanwhile application of 60% (IR) decreased vegetative growth traits as well as grain yield. Nevertheless, the 100% (IR) irrigation treatments gave the highest vegetative traits and grain yield. In contrary, results showed that the 60% (IR) irrigation requirement gave the highest water use efficiency (WUE). Increasing irrigation water above 60% (IR) led to decrease the values of water use efficiency. Meanwhile, the highest water use efficiency was obtained from the first sowing date (1st May) followed by the second sowing date (1st June) while the lowest value was obtained by the third sowing date (1st July).

Modeling the impact of climate change on yield, water requirements, and water use efficiency of maize and soybean grown under moderate continental climate in the Pannonian lowland

In Central and Eastern Europe, climate changes have been predicted (Trnka et al., 2009). These changes are expected to have a great impact on field crops during the spring-summer growing season. The aim of this paper is to estimate the impact of climate change on the main field crops (maize and soybean) in the Republic of Serbia. The AquaCrop model was used as a tool to quantify climate change impact on yield and net irrigation using results from the ECHAM climate model (SRES A2 scenario for the 2041–2070 and 2071–2100 periods) and data from two experimental fields located in the southern part of the Pannonian lowland. The analyzed results for the 2041–2070 and 2071–2100 periods showed an increase in maize (1 and 1.3 t/ha) and soybean (1.9 and 2.8 t/ha) yields and a very significant increase in the net irrigation of 151.4 and 183.1 mm in maize production and 179.3 and 227.3 mm in soybean production under climate change conditions compared to the 1961–1990 period. Additionally, irrigation water use efficiency was calculated to estimate the importance of irrigation, because crop production is usually conducted under rainfed conditions. It was concluded that maize and soybean production should benefit from climate changes but with higher water quantities.

Association of carbon isotope discrimination with leaf gas exchange and water use efficiency in maize following soil amendment with superabsorbent hydrogel

The correlation of carbon isotope discrimination (△&lt;sup&gt;13&lt;/sup&gt;C) with photosynthetic gas exchange and water use efficiency (WUE) in maize was investigated under low rainfall conditions with or without superabsorbent polymer (SAP). SAP (45 kg/ha) was mixed into the top 10 cm soil layer at sowing in lysimeters. Compared with the control plants not treated with SAP, the application of SAP increased net photosynthesis rate; stomatal conductance (g&lt;sub&gt;s&lt;/sub&gt;); transpiration rate; chlorophyll content (Chl) and intrinsic water use efficiency at leaf level (WUE&lt;sub&gt;i&lt;/sub&gt;), but decreased intercellular CO&lt;sub&gt;2&lt;/sub&gt; concentration (C&lt;sub&gt;i&lt;/sub&gt;) and leaf △&lt;sup&gt;13&lt;/sup&gt;C. In plants supplied with SAP, leaf △&lt;sup&gt;13&lt;/sup&gt;C was positively correlated with C&lt;sub&gt;i&lt;/sub&gt; (r = 0.864, P &amp;lt; 0.01) and negatively correlated with g&lt;sub&gt;s&lt;/sub&gt; and WUE&lt;sub&gt;i&lt;/sub&gt; (r = –0.860 and –0.626, P &amp;lt; 0.01, respectively). Leaf △&lt;sup&gt;13&lt;/sup&gt;C was not correlated with Chl with or without SAP. Grain △&lt;sup&gt;13&lt;/sup&gt;C significantly decreased by 12.4% and showed a significant negative correlation with grain WUE under SAP treatments (r = –0.670, P &amp;lt; 0.05). These results suggest that in the presence of SAP, maize leaf and grain △&lt;sup&gt;13&lt;/sup&gt;C could be good indicators for evaluating maize WUE during periods of low rainfall.

Effects of deficit irrigation with saline water on soil water-salt distribution and water use efficiency of maize for seed production in arid Northwest China

In order to explore the utilization of groundwater resource, field experiments were conducted in 2012 and 2013 in the Shiyang River Basin of Northwest China. Altogether nine treatments included three water levels w1, w2 and w3 (1ETc, 2/3ETc, and 1/2ETc, ETc = 555 mm) in combination with three salinity levels s1, s2 and s3 (0.71 g/L, 3 g/L and 6 g/L).Soil water content, soil salt content and yield of maize for seed production were measured for studying the effects of deficit irrigation with saline water on water-salt distribution and water use efficiency of maize for seed production. The results showed that soil water content of saline water irrigation was higher than fresh water irrigation and soil salt content increased with increase of irrigation water salinity under the same irrigation water amount. Soil water content of deficit irrigation was lower than sufficient irrigation and soil salt content increased with decrease of irrigation water amount under the same irrigation water salinity. The soil salt accumulation increased gradually with increase of irrigation water salinity and decrease of irrigation water amount under the combined effect of irrigation water amount and irrigation water salinity. Irrigation with water salinity of 3 g/L and water amount of 370 mm will not cause a substantial yield reduction and could increase water use efficiency of maize for seed production. Irrigation schedule with irrigation water amount about 370 mm and irrigation water salinity below 3 g/L is recommended in this study area. The irrigation schedule of this study can be used in the practice of agricultural production and the results show a reasonably utilization of saline water, thereby supplying theoretical guidance for water-saving irrigation development.

Foliar antitranspirant and soil superabsorbent hydrogel affect photosynthetic gas exchange and water use efficiency of maize grown under low rainfall conditions.

Two lysimeter experiments with maize plants were conducted to investigate the effect of combined superabsorbent polymer (SAP) and fulvic acid (FA) application on photosynthetic gas exchange and water use efficiency (WUE) under deficit irrigation conditions. Soil SAP (45 kg hm-2 ) was applied while sowing, and FA solution (2 g L-1 ) was sprayed onto the crop canopy three times at later plant growth periods. Combining SAP and FA application significantly improved plant photosynthesis, chlorophyll contents and instantaneous WUE while maintaining optimal leaf stomatal transpiration. The effect of using the combined chemicals on photosynthesis and leaf instantaneous WUE was superior to the effects of their individual applications. Compared with plots not treated with chemicals, soil SAP significantly improved the yield by 12% and grain WUE by 10% when averaged across the two experiments, whereas foliar FA application did not affect yield and grain WUE. In contrast, the combined use of the two chemicals significantly increased the yield by 20% and grain WUE by 26%, largely attributed to the increase in grain number. Soil SAP and foliar FA use under low rainfall conditions had little influence on crop water consumption but improved plant WUE by enhancing photosynthesis and increasing kernel number. © 2018 Society of Chemical Industry.

Nitrogen Time of Application Impact on Productivity, Water Use Efficiency and Agronomic Efficiency of Maize in a Semi-arid Environment

Water is one of the most important limiting factor of rainfed continuous maize (Zea mays L.) cropping systems in northwest of China. A three continuous year field experiments were conducted to study the influence of different nitrogen time of application on grain yield and water use efficiency of maize (Zea mays L.) in the Western Loess plateau. The experiment was laid in a randomized complete block design with two treatments and three replicates. Treatments were; (one-third application of N at sowing + two-third application at pre-flowering) and (one-third application of N at sowing + one-third pre-flowering + one-third at milking) as T1 and T2 respectively. The results showed that, T1 significantly increased grain yield by 9% in 2014 and 2016; and WUE by 11% in 2016 compared to T2. T1 increased AE by 43% compared to T2. Our results indicate that ⅓ application of Nitrogen at sowing and ⅔ application of Nitrogen at pre–flowering (T1) for maize is more appropriate for sustainable maize production in terms of satisfactory grain-N recoveries and low environmental losses of N fertilizer.

Effects of plastic film mulching patterns on maize grain yield, water use efficiency, and soil water balance in the farming system with one film used two years.

The aim of this study was to develop cost-saving and efficiency-improving technologies in whole plastic mulching and double ridge-furrow maize in semi-arid region of Loess Plateau. The objective was to investigate soil water balance in farming system with one film used two years. A field experiment was conducted to investigate the effects of different mulching and tillage patterns under one film used two years conditions on the yield, economic benefits, and water use efficiency of maize. There are four treatments: Ridge-furrow planting with complete plastic film mulching, F1M; flat-planting with complete plastic film mulching, F2M; flat-planting with half plastic film mulching, F3M; and flat-planting without mulching, F4M, the control. The results showed that the F1M and F2M treatments had significant effects on the improvement of the production and efficiency compared with the control. The F1M and F2M treatments improved biomass by 32.8% and 32.9%, enhanced grain yield by 60.0% and 51.7%. Water use efficiency and rainfall use efficiency in F1M and F2M treatments were increased by 59.8%, 35.9% and 87.6%, 64.4%, respectively. Furthermore, gross output value and input-output ratio of F1M and F2M treatments under every new plastic film mulched pattern were enhanced by 51.0%, 41.2% and 15.1%, 16.2%, respectively. The production pattern on cost-saving and efficiency-increasing of the system on double ridge-furrow and flat planting with one film used two years, this pattern increased gross output value by 40.8%, 42.2%, and increased input-output ratio by 40.3%, 42.2%, respectively. Under the condition of low precipitation (606.5 mm), total water consumption of ridge-furrow and flat planting under the system of one film used within two years was 731.3 mm and 746.8 mm, the soil moisture deficit was 124.8 mm and 140.3 mm, with enhancement of 22.7% and 38.0%, respectively. The total water consumption of ridge-furrow and flat planting treatments was reduced by 28.6% and 30.0%, and the fallow efficiency was improved by 178.9% and 148.3%. In conclusion, whole plastic mulching with double ridge-furrow and flat planting farming system had positive effects on yield and water use efficiency in semi-arid region of Loess Plateau. Combined with the technology of one film used within two years, this cropping system could be cost saving and efficiency increasing. However, the water deficit under low water condition should be seriously considered in practice.

Meta-analysis of no-tillage effect on wheat and maize water use efficiency in China

No-tillage (NT) is a popular agricultural technique worldwide, but it remains unclear how NT affects the yield, evapotranspiration (ET), and water use efficiency (WUE) of maize and wheat. We performed a meta-analysis of the NT effects on the yield, ET and WUE for wheat and maize based on the literatures published during 1950–2018. Yield, ET, and WUE varied by species, region, and agronomic and environmental factors. Averaged across all the geographic locations NT had no effect on the yield, ET, or WUE of wheat in northwestern and northern China, and no effect on the yield or ET of maize, but significantly increased the maize WUE by 5.9%. NT increased the WUE and yield of wheat in regions with ≤400 mm of mean annual precipitation, increased the yield in regions with 400–600 mm of precipitation, and decreased the yield and ET in regions with ≥600 mm, but had no effects on maize. In the first 1–3 years of NT implementation, the wheat ET was reduced. However, a significant decrease in maize yield and ET occurred in 3–6 years of NT implementation. Meanwhile, yield and WUE in both wheat and maize were improved after >6 years. In general, NT effect on yield, ET, or WUE was not related to soil texture. However, NT increased maize WUE in a medium soil texture. Without crop rotation, NT increased wheat yield and ET but decreased maize yield. No NT effects were observed when crop residues retained and under crop rotation. Consequently, optimizing NT effects on yield, ET and WUE for wheat and maize in China was largely dependent on environmental conditions and management practices.

INFLUENCE OF MULCHING SYSTEMS ON SOIL TEMPERATURE, PRODUCTION AND WATER USE EFFICIENCY UNDER TRICKLE IRRIGATION SYSTEM

The aim of this research is to study the influence of different mulching materials on soil surface temperature, water use efficiency and production. Two field experiments were conducted at the Research Farm of Faculty of Agriculture, Suez Canal University, Ismailia, Egypt, during the summer of 2016 and the winter 2017 growing season in a sandy soil under trickle irrigation system. Six treatments transparent polyethylene sheets, rice straw, maize straw and control were investigation in the field. The results showed that there were more increases in soil temperature under plastic mulch than under others treatments. The recorded soil surface temperature was lowest under rice straw mulch during both summer and winter seasons. The field investigation revealed that, the highest grain yield and water use efficiency of maize was obtained during summer which were 9563 kg ha-1 and 1.54 kg m-3, respectively under rice straw mulch. During winter, faba bean gave the highest values of seed yield and water use efficiency 7521 kg ha-1 and 2.20 kg m-3, respectively were achieved under transparent plastic mulch followed by rice straw mulch. Mulching method can help to improve yield of crops. It was recommended that, using 8 Mg ha-1 rice straw mulch in both summer and winter conditions was the best for soil temperature. It is also more attractive option by its very cheap and ease in availability and is environmental friendly.

Effects of different tillage patterns on soil properties, maize yield and water use efficiency in Weibei Highland, China.

An eight-year field experiment of straw returning was conducted on dark loessial soil in Weibei Highland to investigate the effects of tillage patterns on soil aggregate, soil organic carbon (SOC), corn yield and soil water use efficiency (WUE). There were six tillage patterns, including conventional tillage (CT/CT), no-tillage (NT/NT), subsoiling tillage (ST/ST), no-tillage/subsoiling tillage (NT/ST), conventional tillage/no-tillage (CT/NT) and conventional tillage/subsoiling tillage (CT/ST). The results showed that compared with CT/CT, the patterns of NT/NT, ST/ST and the rotational tillage patterns (NT/ST, CT/NT and CT/ST) decreased the mean mass diameter of soil mechanical stable aggregate. The patterns of NT/NT, ST/ST and NT/ST increased the content of soil water-stable aggregate with the particle size >0.25 mm (WR0.25) and their mean mass diameter, especially in the depth of 20-50 cm. These patterns reduced the proportion of aggregate destruction (PAD). Compared with CT/CT, the patterns of NT/ST, CT/NT, NT/NT and ST/ST increased the content of SOC in 0-10 cm soil layer. The content of SOC decreased as the increases of soil depth for all tillage patterns, but the decrease in SOC of three single tillage patterns (ST/ST, NT/NT and CT/CT) was larger than that of three rotational tillage patterns. Compared with CT/CT, the other five tillage patterns increased soil water storage in 0-200 cm soil profile, crop yield and WUE in maize. The yield and WUE in NT/ST pattern were significantly increased by 15.1% and 27.5%, respectively. Both corn yield and WUE were significantly and positively correlated with soil water storage in 0-200 cm soil profile in field during the cropping and fallow periods. Moreover, soil water storage during the cropping period was positively correlated with WR0.25, but negatively correlated with PAD in 0-50 cm soil layer. Particularly, maize yield, WUE and soil water storage during the cropping period were closely related to WR0.25 in 20-50 cm soil layer and PAD. Both WUE and soil water storage during the cropping period was correlated with the SOC content in 0-10 cm soil layer. With respect to the soil properties, crop yield and WUE, the tillage pattern of NT/ST was the best stratety in dark loessial soil for spring maize growth in Weibei Highland.

Effect of biochar on physicochemical properties of a sandy soil and maize growth in a greenhouse experiment

Numerous studies have been conducted worldwide and more specifically in Brazil assessing the consequences of biochar amendments on the soil properties and on the agronomical production. The present study aimed to evaluate the effects of biochar of coffee residues on the physicochemical characteristics of an Entisol and water use efficiency of maize (Zea mays). Two types of biochar were produced with both coffee ground (CG) and coffee husk (CH) and their physicochemical properties were characterized. A greenhouse pot experiment, quantifying the growth of maize, with different rates of biochar amendments and fertilizing procedures was conducted in a completely randomized design. Treatments consisted in four replications of (i) control (native soil), (ii) synthetic fertilization and (iii) organic fertilization with cow manure, and (iv) the two types of biochar in four doses (4, 8, 12 and 16Mgha−1). Specific surface area (SSA) of CH was significantly higher than CG biochar but both types of biochar had higher SSA than soil. Nutrient and water retention properties of soil and maize growth were significantly improved with increasing biochar doses. The water use efficiency was 50% higher for the treatment with the highest dose of biochar. This is a significant found considering the potential of growing maize on a sandy soil in a dry regions of Brazil. Nutrient use efficiency as well as the C content in Entisol were largely improved by the use of biochar. Determination of SSA was a quick and robust method to anticipate the benefits of biochar on water retention of soil.

Effects of irrigation water salinity on soil salt content distribution, soil physical properties and water use efficiency of maize for seed production in arid Northwest China

In order to explore the use of groundwater resources, field experiments were conducted for three consecutive years during 2012-2014 in the Shiyang River basin of Northwest China. Irrigation was conducted using four different water salinity levels that were arranged in a split plot design. These four water salinity levels were s0, s3, s6 and s9 (0.71, 3, 6 and 9 g/L, respectively). The soil salt content, soil bulk density, soil porosity, saturated hydraulic conductivity, plant height, leaf area index and yield of maize for seed production were measured for studying the effects of saline water irrigation on soil salt content distribution, soil physical properties and water use efficiency. It was observed that higher salinity level of irrigation water and long duration of saline water irrigation resulted in more salt accumulation. Compared to initial values, the soil salt accumulation in 0-100 cm soil layer after three years of experiments for s0, s3, s6 and s9 was 0.189 mg/cm3, 0.654 mg/cm3, 0.717 mg/cm3 and 1.135 mg/cm3, respectively. Both greater salt levels in the irrigation water and frequent saline water irrigation led to greater soil bulk density, but poorer soil porosity and less saturated hydraulic conductivity. The saturated hydraulic conductivity decreased with increase in soil bulk density, but increased with improvement in soil porosity. It was noted that the maize height, leaf area index and maize yield gradually decreased with increase in water salinity. The maize yield decreased over 25% and the water use efficiency also gradually declined when irrigated with water containing 6 g/L and 9 g/L salinity levels. However, maize yield following saline water irrigation with 3 g/L decreased less than 20% and the decline in water use efficiency was not significant during the three-year experiment period. The results demonstrate that irrigation with saline water at the level of 6 g/L and 9 g/L in the study area is not suitable, while saline water irrigation with 3 g/L would be acceptable for a short duration together with salt leaching through spring irrigation before sowing. Keywords: saline water irrigation, soil salt content distribution, soil physical properties, maize for seed production, water use efficiency DOI: 10.25165/j.ijabe.20181103.3146 Citation: Yuan C F, Feng S Y, Wang J, Huo Z L, Ji Q Y. Effects of irrigation water salinity on soil salt content distribution, soil physical properties and water use efficiency of maize for seed production in arid Northwest China. Int J Agric & Biol Eng, 2018; 11(3): 137–145.

Effects of different colored plastic film mulching and planting density on dry matter accumulation and yield of spring maize.

In order to investigate the effect of different colored plastic film mulching and planting density on spring maize dry matter accumulation and yield in the rain-fed area of the Northeast China, a complete combination field experiment which was comprised by three types of mulching (non-mulching, transparent plastic film mulching and black plastic film mulching) and five densities (60000, 67500, 75000, 82500 and 90000 plants·hm-2), was conducted to analyze the water and heat effect, dry matter accumulation and yield of spring maize (Liangyu 99). The results showed that, compared with the other mulching treatments, the black plastic film mulching treatment significantly increased the maize dry matter accumulation and maize biomass by 3.2%-8.2%. In mature stage, the biomass increased firstly and then decreased with the increasing plant density. When planting density was 82500 plants·hm-2, the biomass was the highest, which was 5.2%-28.3% higher than that of other plant density treatments. The mean soil temperature in prophase of transparent plastic film mulching treatment was 0.4-2.7 ℃ higher than that of other treatments, which accelerated the maize growth process and augmented the dry matter transportation amount (T), dry matter transportation efficiency (TE) and contribution rate of dry matter transportation to the grain yield (TC) of maize stalk and leaf. The T, TE, TC of leaf and leaf-stalk under 60000 plants·hm-2 treatment were the highest. The highest T, TE, TC of stalk were observed under 75000 plants·hm-2 treatment. In heading period, the water consumption and daily water consumption intensity of maize under the treatment of black film mulching were the largest, which were 9.4%-10.6% and 10.6%-24.5% higher than that of other mulching treatments, respectively. The highest water consumption and daily water consumption intensity were both obtained under 90000 plants·hm-2 treatment, which increased by 6.8%-15.7% and 7.0%-20.0% compared with other plant density treatments. The combination of black film mulching and density of 82500 plants·hm-2 significantly improved the water use efficiency of maize, which increased by 4.6%-40.9% compared with other treatments. In addition, it increased yield by 3.0%-39.7% compared with other treatments. At heading stage, the correlation between the dry matter amount of stalk and leaf and the yield and yield components was the biggest. Decreasing 1 kg·hm-2 dry matter amount of stalk and leaf would decrease the population yield by almost 0.79 kg·hm-2. Decreasing 10% dry matter amount of stalk and leaf would decrease the yield by almost 10%. Based on increasing plant density, black film mulching was beneficial for increasing the dry matter accumulation and improving grain yield and water use efficiency of spring maize.

Integrated Effect of Mulching and Furrow Methods on Maize Yield and Water Productivity at Koka, Ethiopia

The study was conducted at Wondo Genet Agricultural Research Center, Koka research station, Ethiopia, 8°26’ N latitude, 39°02’ E longitude and 1602 m.a.s.l. based on the objective to select most effective water saving techniques and improve water productivity of irrigated maize (Zea mays L.). Three types of furrow irrigation methods (alternate, fixed and conventional furrow irrigation methods) and two mulch types and no mulch with three replications were used as two factors to evaluate the yield and yield component including water use efficiency of maize in split-plot design. Different types of irrigation method highly significantly (p<0.01) affected all the studied parameters of yield and yield components of maize at Koka both season except number of grains per cob. Moreover, maize growth, yield and yield components were highly significantly (p<0.01) influenced due to different mulch types used. However, there was no interaction effect due to the two factors studied (irrigation type and mulching type). Significantly a higher growth, yield and yield component of maize was recorded due to conventional furrow irrigation method than alternate and fixed furrow irrigation method. However, higher water use efficiency was obtained due to alternate furrow irrigation method. Moreover, higher growth, yield and yield components including water use efficiency were obtained due to plastic mulch than no mulch and straw mulch for maize at koka. Therefore, for maximizing grain yield under no water stress scenario, irrigation of maize with conventional furrow irrigation methods could be used. On the other hand, under limiting irrigation water resource condition, irrigation of maize could be done with alternate furrow irrigation method with plastic mulch application to minimize evaporation loss and maximize water productivity of maize at Koka and similar agro-ecology and soil type.

Effects of different mulching and drip irrigation patterns on photosynthetic characteristics of maize leaves in the Hetao Irrigation District, Inner Mongolia, China

Photosynthesis controls crop growth and yield, and differences in planting methods and soil moisture can significantly affect the photosynthetic characteristics of crops. Grain filling stage and milking stage are two important stages of maize from flowering to maturity, which are essential for maize grain formation and dry matter accumulation. The effects of different mulching and drip irrigation patterns on the photosynthetic characteristics and maize yield at grain filling and milking stages were investigated in a field experiment in the Hetao Irrigation District, Inner Mongolia. Maize leaf photosynthesis during the grain filling stage was not significantly different under the different treatments. During the milking stage, photosynthetic and transpiration rates under both partial (B2) and full (Q2) film mulching with drip irrigation level 2 (350 mm) were significantly higher than those in both the partial (B1) and full (Q1) film mulching with drip irrigation level 1 (200 mm). Photosynthetic and transpiration rates, water use efficiency and stomatal conductance under the B1 and Q1 treatments were significantly higher in the grain filling stage than in the milking stage. Diurnal variations in photosynthetic and transpiration rates, stomatal conductance and water use efficiency of maize leaves during the grain filling and milking stages were synchronous and showed an upside-down "U" pattern, but the intercellular CO2 concentration showed the opposite pattern. Stepwise regression analysis showed that photosynthetically active radiation, air temperature and relative humidity were the main environmental factors influencing photosynthetic characteristics of maize leaves under the different mulching and drip irrigation treatments. In addition, maize yield was significantly higher under the B2 and the Q2 treatments than under the B1 and Q1(increase of 29.3% and 50.9%, respectively), but no significant differences were found between the B1 and Q1 treatments, indicating that drip irrigation level affects the yield of maize and its photosynthetic capacity more than mulching mode in arid regions.

Biomass sorghum and maize have similar water-use-efficiency under non-drought conditions in the rain-fed Midwest U.S.

Biomass sorghum (Sorghum bicolor L. Moench) is a candidate bioenergy feedstock for the U.S. Midwest. Research suggests that biomass sorghum is more drought tolerant and has higher water-use-efficiency (WUE) than maize (Zea mays L.) in water-limiting environments, but most species comparisons of the seasonal evapotranspiration (total ET) and WUE have focused on irrigated systems (WUE defined as the ratio of cumulative dry biomass production (dry matter; DM) to total evapotranspiration (mm); g DM (mm H2O)−1). Since comparative data for the rain-fed Midwest are scarce, we conducted a side-by-side evaluation of the total ET and WUE of maize and biomass sorghum in central Iowa—a site within the U.S. Corn Belt. Total ET was estimated using a micrometeorological method, and aboveground plant biomass was determined using destructive hand harvests. Similar mean WUE was determined for maize (3.51±0.26g DM (mm H2O)−1) and biomass sorghum (3.47±0.22g DM (mm H2O)−1) over two non-drought growing seasons with total ET of 567±26mm and 600±20mm, respectively. Even though total ET and WUE were not statistically different between species (P>0.1), maize had significantly greater theoretical ethanol yield (EY; L ethanol m−2) and lower ethanol water requirement (EWR; L water L ethanol−1), relative to biomass sorghum (P<0.1). We observed differences in water dynamics between species and growing seasons that were related to biophysical properties and the pattern of canopy development of maize and biomass sorghum. Our two main findings suggest that these C4 grasses may not be intrinsically different in how they use water, unless prolonged water limitation induces contrasting biophysical responses to drought. However, considering that drought conditions did not occur in 2014 and 2015, our results do not capture the response of total ET and WUE to the full range of climate variability in the Midwest U.S.

Compensating effect of fulvic acid and super-absorbent polymer on leaf gas exchange and water use efficiency of maize under moderate water deficit conditions

A field-based pot experiment with maize plants was conducted to examine the effect of combined fulvic acid (FA) and super-absorbent polymer (SAP) on leaf gas exchange, water use efficiency, and grain yield under soil water deficit. SAP (45 kg hm−2) was applied to the topsoil at sowing. Plants were well-watered (80% field capacity), but subjected to water deficit (50% field capacity) from tassel stage to grain-fill. FA solution (2 g L−1) was sprayed onto plant leaves at 2 and 9 days after imposing water deficit. Under water deficit, SAP and FA application did not affect evapotranspiration, but increased leaf abscisic acid and decreased leaf transpiration rate with a little change in photosynthesis, thus improving instantaneous water use efficiency. Applying SAP and FA under water deficit also increased grain yield by 19% and grain water use efficiency by 24%, largely attributed to an increase in kernel number. In contrast, under well-watered condition the two chemicals increased stomatal conductance, leaf transpiration, photosynthesis and chlorophyll content, but did not change kernel number and were relatively less effective in respect to water use efficiency compared to water-stressed condition. This study showed that application of foliar FA and soil SAP had little effect on evapotranspiration but maintained high photosynthesis and kernel number, and improved water use efficiency under soil water deficit.

Yield-phenology relations and water use efficiency of maize (Zea mays L.) in ridge-furrow mulching system in semiarid east African Plateau

Yield-phenology relation is a critical issue affecting rainfed maize field productivity in semiarid east African Plateau (EAP). We first introduced Chinese ridge-furrow mulching (RFM) system to EAP, using three maize cultivars with early-, mid- and late-maturing traits as test materials. A two-year field experiment was conducted in a semiarid farm of Kenya from 2012 to 2013. Three treatments were designed: alternative ridge and furrow with transparent plastic mulching (FT), with black plastic mulching (FB) and without mulching (CK). We found that FT and FB significantly increased soil moisture and accelerated crop maturity across two growing seasons. Leaf area and shoot biomass were increased by 30.2% and 67.5% in FT, 35.2% and 73.5% in FB, respectively, compared with CK. Grain yield, water use efficiency and economic output were increased by 55.6%, 57.5% and 26.7% in FT, and 50.8%, 53.3% and 19.8% in FB, respectively. Optimal yield and economic benefit were observed in late-maturing cultivar due to increased topsoil temperature in FT in 2012 (cool), and in early-maturing cultivar owing to cooling effect in FB in 2013 (warm). Our study suggested RFM system, combined with crop phenology selection, be a promising strategy to boost maize productivity and profitability in semiarid EAP.

Yield and Input Use Efficiency of Maize (Zea mays L.) as Influenced by Crop Residue Mulch, Irrigation and Nitrogen Management

Field experiments were conducted in a sandy loam soil at the research farm of the Indian Agricultural Research Institute (IARI), New Delhi during the kharif season of 2012 and 2013 with the objective to study the effect of crop residue mulch, irrigation and nitrogen (N) on soil water dynamics, growth, yield, water and N use efficiency of maize. Maize (cv. HQPM 1) was grown in a split-split plot design with two levels of irrigation, two levels of mulch and three levels of N. The grain yield of maize increased significantly by 31 per cent under irrigated condition than that of rainfed condition in the year 2012. Application of crop residue mulch increased the grain yield of maize significantly by 11.5 and 28.4 per cent compared to nomulch treatment in 2012 and 2013, respectively. Application of N significantly increased the grain yield of maize over the control. However, there was no significant difference between 75 kg and 150 kg N ha−1 with respect to grain and biomass yield of maize. The water use efficiency of maize increased significantly by 12.6 and 36 per cent in 2012 and 2013, respectively due to crop residue mulch. The apparent N recovery and agronomic N use efficiency increased significantly but physiological N use efficiency decreased under mulching. So, maize may be grown with 75 kg N ha−1 and wheat residue mulch @ 10 t ha−1 to achieve higher yield, water use efficiency and N use efficiency in Upper-Indo-Gangetic Plain region.