Efficiency Of Maize Research Articles

Effects of Mulching and Nitrogen on Soil Nitrate-N Distribution, Leaching and Nitrogen Use Efficiency of Maize (Zea mays L.).

Mulching and nitrogen are critical drivers of crop production for smallholders of the Loess Plateau in China. The purpose of this study was to investigate the effect of mulching and nitrogen fertilizer on the soil water content, soil nitrate-N content and vertical distribution in maize root-zone. The experiment was conducted over two consecutive years and used randomly assigned field plots with three replicates. The six treatments consisted of no fertilizer without plastic film (CK), plastic film mulching with no basal fertilizer and no top dressing (MN0), basal fertilizer with no top dressing and no mulching (BN1), plastic film mulching and basal fertilizer with no top dressing (MN1), basal fertilizer and top dressing with no mulching (BN2) and plastic film mulching with basal fertilizer and top dressing (MN2). In the top soil layers, the soil water content was a little high in the plastic film mulching than that without mulching. The mean soil water content from 0 to 40 cm without mulching were 3.35% lower than those measured in the corresponding mulching treatments in 31 days after sowing in 2012. The mulching treatment increased the soil nitrate-N content was observed in the 0–40-cm soil layers. The results indicate that high contents of soil nitrate-N were mainly distributed at 0–20-cm at 31 days after sowing in 2012, and the soil nitrate-N concentration in the MN2 treatment was 1.58 times higher than that did not receive fertilizer. The MN2 treatment greatly increased the soil nitrate-N content in the upper layer of soil (0–40-cm), and the mean soil nitrate-N content was increased nearly 50 mg kg−1 at 105 days after sowing compared with CK treatment in 2012. The soil nitrate-N leaching amount in MN1 treatment was 28.61% and 39.14% lower than BN1 treatment, and the mulch effect attained to 42.55% and 65.27% in MN2 lower than BN2 in both years. The yield increased with an increase in the basal fertilizer, top dressing and plastic film mulching, and the grain yield increase ranged from 31.41% to 83.61% in two consecutive years. The MN1 and MN2 treatment is recommended because it increased the grain yield and improved the fertilizer use efficiency, compared with the no-mulching treatment.

High-efficiency CRISPR/Cas9 multiplex gene editing using the glycine tRNA-processing system-based strategy in maize.

BackgroundCRISPR/Cas9 genome editing strategy has been applied to a variety of species and the tRNA-processing system has been used to compact multiple gRNAs into one synthetic gene for manipulating multiple genes in rice.ResultsWe optimized and introduced the multiplex gene editing strategy based on the tRNA-processing system into maize. Maize glycine-tRNA was selected to design multiple tRNA-gRNA units for the simultaneous production of numerous gRNAs under the control of one maize U6 promoter. We designed three gRNAs for simplex editing and three multiple tRNA-gRNA units for multiplex editing. The results indicate that this system not only increased the number of targeted sites but also enhanced mutagenesis efficiency in maize. Additionally, we propose an advanced sequence selection of gRNA spacers for relatively more efficient and accurate chromosomal fragment deletion, which is important for complete abolishment of gene function especially long non-coding RNAs (lncRNAs). Our results also indicated that up to four tRNA-gRNA units in one expression cassette design can still work in maize.ConclusionsThe examples reported here demonstrate the utility of the tRNA-processing system-based strategy as an efficient multiplex genome editing tool to enhance maize genetic research and breeding.Electronic supplementary materialThe online version of this article (doi:10.1186/s12896-016-0289-2) contains supplementary material, which is available to authorized users.

Effect of different furrow and plant spacing on yield and water use efficiency of maize

In southern zone of Tigray, Ethiopia, there is a large competition between maize production and other horticultural crops for the limited irrigation water. Hence, there is an imminent need to improve the water use efficiency or more importantly the water productivity of the area. The objective of the study was to evaluate the effect of furrow and plant spacing and their interaction on yield and water use efficiency of maize. Experimental treatments include three levels furrow spacing (50, 70 and 90cm) and three levels of plant spacing (20, 25 and 30cm) were arranged in factorial RCBD design under three replications. Maize (BH543 variety) was used in this study in which all agronomic practices were treated equally including the amount of water applied. Maize water requirement was estimated using CROPWAT 8 software. The result revealed that there was significant difference among the treatments (p<0.05) for grain yield, biomass yield and irrigation water use efficiency (IWUE). But it was not significantly different for the yield components (plant height and number of cobs per plant). Maximum grain yield (56.26qt/ha) and IWUE (0.876kg/m3) were obtained from 50cm furrow and 30cm plant spacing interaction. But maximum biomass yield (250.6qt/ha) was obtained from 50cm furrow and 20cm plant spacing interaction. The IWUE ranges from 0.357kg/m3 to 0.876kg/m3 for the equal amount of irrigation water applied (642mm) for each treatment. This shows how much IWUE of small scale farmers can vary as their agronomic practice (plant and furrow spacing) is different from one another. Hence, it can be concluded that irrigation agronomist experts and development agents of the study area must create awareness to the small scale farmers to exercise 50cm furrow spacing with 30cm plant spacing to improve and increase the water productivity of maize.

Nitrogen use efficiency and fertiliser fate in a long-term experiment with winter cover crops

Abstract The use of winter cover crops enhances environmental benefits and, if properly managed, may supply economic and agronomic advantages. Nitrogen retained in the cover crop biomass left over the soil reduces soil N availability, which might enhance the N fertiliser use efficiency of the subsequent cash crop and the risk of depressive yield and pre-emptive competition. The main goal of this study was to determine the cover crop effect on crop yield, N use efficiency and fertiliser recovery in a 2-year study included in a long-term (10 years) maize/cover crop production system. Barley (Hordeum vulgare L.) and vetch (Vicia sativa L.), as cover crops, were compared with a fallow treatment during the maize intercropping period. All treatments were cropped following the same procedure, including 130 kg N ha−1 with 15N fertiliser. The N rate was reduced from the recommended N rate based on previous results, to enhance the cover crop effect. Crop yield and N uptake, soil N mineral and 15N fertiliser recovered in plants and the soil were determined at different times. The cover crops behaved differently: the barley covered the ground faster, while the vetch attained a larger coverage and N content before being killed. Maize yield and biomass were not affected by the treatments. Maize N uptake was larger after vetch than after barley, while fallow treatment provided intermediate results. This result can be ascribed to N mineralization of vetch residues, which results in an increased N use efficiency of maize. All treatments showed low soil N availability after the maize harvest; however, barley also reduced the N in the upper layers before maize planting, increasing the risk of pre-emptive competition. In addition to the year-long effect of residue decomposition, there was a cumulative effect on the soil’s capacity to supply N after 7 years of cover cropping, larger for the vetch than for the barley.

Effects of Mg-Al Layered Double Hydroxide on Nitrate Leaching and Nitrogen Uptake by Maize in a Calcareous Soil

ABSTRACTThe potential use of a layered double hydroxide (magnesium aluminum nitrate (Mg-Al)-LDH) to suppress the leaching of nitrate from a calcareous sandy loam soil and to enhance the nitrogen utilization efficiency of maize was assessed. The results of column studies showed that nitrate leaching efficiently decreased by 24, 46, and 76% compared to control when 2.5, 5, and 10 g LDH kg–1 soil were applied, respectively. Nitrate leaching was also reduced by use of LDH in pot experiments. The hindrance effect of LDH in using ammonium nitrate was higher than urea. Application of 2.5, 5, and 10 g LDH kg–1 soil increased mean nitrogen uptake of maize by 14, 20, and 44% over the control. The studied LDH has a potential to be used as a nitrate-selective exchanger to reduce risks of nitrate leaching. However, the use of Mg-Al-LDH (4:1) can be limited because of its relatively high solubility in soil.

Ammonia volatilization from enhanced-efficiency urea on no-till maize in brazilian cerrado with improved soil fertility

ABSTRACT High nitrogen losses by ammonia volatilization are expected when urea is used as the source of N. The use of controlled-release urea and urease inhibitors are possible strategies to reduce such losses and increase nitrogen use efficiency. This study aimed to evaluate nitrogen losses by ammonia volatilization from stabilized, slow and controlled release urea and its absorption by maize grown under no-till in an improved Cerrado soil. Four N sources were used: conventional urea, urea + N-(n-butyl) thiophosphoric triamide (NBPT), urea + Cu and B and urea coated by sulfur + polymers. These N sources were surface applied along the rows using three N doses of 100, 150 and 200 kg ha-1. No N was added to the control. Data were collected regarding N losses by volatilization, the N contents accumulated in the stubble and grains, and the yields of the stubble and grains. Stabilized urea and slow release urea were efficient for postponing the ammonia volatilization peaks. The urease inhibitors postponed the peaks for up to two days, reducing the accumulated volatilization by 18% when compared with common urea. Polymer sulfur coated urea resulted in a 37% reduction in ammonia volatilization. Increasing the N application rate to 200 kg ha-1 resulted in 16% greater yields and 37% greater N accumulation in the plants relative to the control. However, the stabilized and slow-release urea did not improve the N accumulation or yield. Consequently, the nitrogen use efficiency of maize was not improved relative to the use of conventional urea.

Grain yield and water use efficiency of maize as influenced by different irrigation regimes through sprinkler irrigation under temperate climate

In Vojvodina region, water deficit during the growing season is a major factor limiting maize production. Therefore, to achieve the ideal soil water content in this region, it is of crucial importance to optimize irrigation. The effects of different irrigation levels with sprinkler irrigation system on crop yield, yield components, water use, water (WUE) and irrigation water use (IWUE) efficiency of maize (Zea mays L.) were investigated in Vojvodina (northern Serbia), on a Calcaric Chernozem soil in temperate environment for 3 consecutive years (2006–2008). Maize was subjected to four irrigation regimes, as follows: non-limited irrigation (I100), 75% of non-limited irrigation (I75), 50% of non-limited irrigation (I50), and rainfed (non-irrigated) as the control (I0). The irrigation treatments were arranged in a complete randomized block design with 4 replicates. Results showed that maize grown in rainfed conditions had high annual variability, mainly due to amount of rainfall and its distribution during the crop-growing seasons. A significant irrigation effect was found for yield, yield components and others investigated parameters under study. Water stress had significant impact on yield response: as an average of the three years, a grain yield increase of 47.8, 32.8, and 22.9% was observed in I100, I75 and I50 treatments compared to rainfed (I0) treatment, respectively. Yield increased linearly with seasonal crop evapotranspiration and irrigation amount. Furthermore, WUE is maximized with a moderate water deficit (I50), while IWUE is the highest in I100 treatment. The deficit irrigation stress index, DISI, decreased with increasing irrigation rate. The results revealed that irrigation is necessary for maize cultivation because rainfall is insufficient to meet the crop water needs in Vojvodina. In addition, the study indicated that the irrigation regime of 25% water saving (I75) could ensure satisfactory grain yield of maize and increment of WUE.

Effect of tillage, crop rotations, residue and fertilizer management on productivity, profitability and resource use efficiency of maize (Zea maysL.)-based cropping systems in north-west Himalayas

Diversification and intensification of existing maize-wheat cropping system on small, undulating and marginal farmer's field with suitable resource conserving practices is the key answer for increasing the profitability of hill farmers. Keeping this in view, an experiment with two tillage methods viz., zero tillage and conventional tillage, three cropping systems viz., maize-wheat, baby corn+frenchbean-pea-summer squash and maize+soybean-gobhi sarson+toria, two mulch treatments viz., no mulch and crop residue mulch, and two fertilizer treatments viz., recommended dose of fertilizers and 75% RDF+25% N through FYM was conducted at Palampur during kharif 2012-rabi 2014. The results showed that conventional tillage produced significantly higher maize grain equivalent yield [MGEY (11.2%)], production efficiency (13.9%), productivity of the system (11.2%), net returns (17.3%) and B: C ratio (12.4%) over zero tillage. Replacing traditional maize-wheat with baby corn+frenchbean-pea-summer squash increased MGEY (190.8%), production efficiency (190.5%), productivity of the system (182.1%), gross returns (121.0%), net returns (176.4%), B: C ratio (64.1%) and profitability of the system (176.4%). Application of mulch significantly increased MGEY by 7.4% as compared to no mulch. Similarly, integrated nutrient management also signifcantly inceased MGEY by 4.3% over recommended dose of fertilizers.

Hybrid variation for root system efficiency in maize: potential links to drought adaptation.

Water availability can limit maize (Zea mays L.) yields, and root traits may enhance drought adaptation if they can moderate temporal patterns of soil water extraction to favour grain filling. Root system efficiency (RSE), defined as transpiration per unit leaf area per unit of root mass, represents the functional mass allocation to roots to support water capture relative to the allocation to aerial mass that determines water demand. The aims of this study were to identify the presence of hybrid variation for RSE in maize, determine plant attributes that drive these differences and illustrate possible links of RSE to drought adaptation via associations with water extraction patterns. Individual plants for a range of maize hybrids were grown in large containers in shadehouses in Queensland, Australia. Leaf area, shoot and root mass, transpiration, root distribution and soil water were measured in all or selected experiments. Significant hybrid differences in RSE existed. High RSE was associated with reduced dry mass allocation to roots and more efficient water capture per unit of root mass. It was also weakly negatively associated with total plant dry mass, reducing preanthesis water use. This could increase grain yield under drought. RSE provides a conceptual physiological framework to identify traits for high-throughput phenotyping in breeding programs.

Determination of Optimal Irrigation Scheduling for Maize (Zea Mays) at Teppi, Southwest of Ethiopia

Appropriate irrigation practice is relevant for increased crop productivity and conservation of water resources. No or little concern has been given to the necessity and extension of existing irrigation technologies while the impacts of climate change are visible throughout Ethiopia. A field study was carried out for determining optimal irrigation scheduling for maize production at Teppi, South west Ethiopia for three successive years. The objectives of the study were to evaluate the effect of different irrigation regime (different soil moisture depletion levels) on yield and water use efficiency of hybrid maize (BH-140). The treatments were set based on the recommended soil moisture depletion levels for maize (MAD=0.55). Then five levels of soil moisture depletion were selected for evaluation of optimum irrigation scheduling namely SMD1 (60%), SMD2 (80%), SMD3 (100%), SMD4 (120%), and SMD5 (140% of the recommended value, 0.55). The result indicated that SMD4 has significantly (P<0.05) increased the grain yield and water use efficiency of maize crop on a clay loam textured soil. In addition the total crop water requirement was 535.60 mm. However, the reduced soil moisture depletion level below the recommended values (SMD1 and SMD2) has resulted lower both grain yield and crop water use efficiency. This study also revealed that the appropriate irrigation interval at each crop growth stage should be identified for ease of work to the users.

Partial Rootzone Drying Irrigation Increase Root Surface Area, Root Hydraulic Conductivity and Water Use Efficiency in Maize

Partial root-zone drying (PRD) is an effective water-saving irrigation method and the heterogeneous soil moisture distribution induced by the method may affect root activities, crop water use efficiency and participation of different part of organ. The effects of deficit irrigation (DI) and PRD on leaf and root surface areas, root hydraulic conductivity (KR), and gas exchange and water use efficiency, were studied in maize (Zea mays L. cv., a local variety) grown in pots in the field for two months in the arid climate of Gansu Province, northwest of China in 2009. The PRD treatment was applied in two modes as PRD1 and PRD2, and they were obtained by the soil water content of the dry compartment had decreased to 18% (vol.) and 11% (vol.) (approximate 60% and 30% of the pot holding capacity) before shifting side of irrigation, respectively. DI2 was irrigated with the same irrigation amount with PRD2, while water was equally separated to two compartments. The full irrigation (FI), PRD1, PRD2 and DI2 received 10.75, 8.70, 8.45 and 8.45 liters of water during the treatment period, respectively. The evapo-transpiration water use efficiency (WUEET) was significantly higher in the PRD2 than in the DI2. PRD1 and PRD2 significantly (P<0.05) increased the root surface areas compared to DI2 by 17.8% and 14.6%, respectively, and that resulted in ratio of root surface area to leaf area of PRD2 significantly higher than that of DI2. Further, compared to DI2 and FI, PRD2 significantly (P<0.05) increased KR by 15% and 34%, respectively. The intrinsic WUE, the net photosynthesis (A) and gs relationship (A/gs), were the highest in the PRD2 treatment as compared with the other treatments on 4 f 5 occasions. On 3 out of 5 occasions, the A/gs values of PRD2 plants were significantly higher than those of FI plants. Our results indicate that PRD2 increased root-shoot surface ratio and the root hydraulic conductivity and those might play a major role in enhancing WUEET.

QTL mapping of seedling root traits associated with nitrogen and water use efficiency in maize

The dramatically increased use of nitrogen fertilizers and global warming raise concerns about environmental pollutions, crop production and future food security. The urgent need for new crops with higher nitrogen and water use efficiency in agricultural practices has been recognized. Root architecture is crucial for acquisition of water and nutrients from the soil; and the selection for specific root traits might be advantageous. In this study seedlings of seven maize inbred lines from a Southern-European breeding genepool were analysed for root morphological characteristics and response to nitrate. As all the lines revealed a similar adaptive reaction to altered nitrate concentrations, we focused our efforts on analysis of two lines, NUEC2 and NUEC4, with the most contrasting differences in constitutive root traits. Investigation of early plant growth under greenhouse conditions revealed inter-genotype differences in NUE and response to drought that might be associated with divergent root architecture of the two lines. We performed a quantitative trait locus mapping of seedling root traits in the populations of 60 double haploid lines derived from the cross NUEC2 × NUEC4. Thirty QTL were detected for seven root traits. Some of the QTL were clustered together, and, in total, 8 loci in the maize genome were found to influence multiple root traits. Interestingly, the positions of QTL for root traits located on chromosomes 3 and 8 overlap with the QTL for grain yield identified in the same population. Further research is needed to validate the QTL and examine their possible causal relationships with corn yield.

Nitrogen uptake efficiency of maize in monoculture and intercropped with Brachiaria humidicola and Panicum maximum in a dystrophic Red-Yellow Latosol of the Brazilian Cerrado

No-tillage systems associated with intercropping practices of grains and forages as cover crops are increasing in the Cerrado agricultural areas. The aim of this study was to quantify the nitrogen (N) uptake efficiency of maize (Zea mays L.) grown as monoculture and intercropped with tropical forages under a no-tillage system by using the 15N isotope tracer in conjunction with measurements of soil microbial biomass N and available soil N. The experiment was conducted in the 2010–11 growing season, in a Dystrophic Red-Yellow Latosol (Typic Haplustox) in the Cerrado. The experiment was established in a complete randomised block design with three replicates with the following treatments: maize monoculture; maize intercropped with Panicum maximum Jacq. cv. Aruana; and maize intercropped with Brachiaria humidicola (Rendle) Schweick. Nitrogen was applied as ammonium sulfate at a rate of 100 kg ha–1 (30 kg N ha–1 was applied at planting and 70 kg N ha–1 as a side-dressing). The N-fertiliser uptake efficiency in maize and grain yield was not affected by the presence of the intercropped forages. The intercropped B. humidicola and P. maximum recovered 2.08% and 3.71% of the N fertiliser applied, respectively. The soil was the main N source for maize. Maize intercropped with P. maximum showed higher values of microbial biomass N and available N in the soil.

Overexpression of GA20-OXIDASE1 impacts plant height, biomass allocation and saccharification efficiency in maize.

SummaryIncreased biomass yield and quality are of great importance for the improvement of feedstock for the biorefinery. For the production of bioethanol, both stem biomass yield and the conversion efficiency of the polysaccharides in the cell wall to fermentable sugars are of relevance. Increasing the endogenous levels of gibberellic acid (GA) by ectopic expression of GA20‐OXIDASE1 (GA20‐OX1), the rate‐limiting step in GA biosynthesis, is known to affect cell division and cell expansion, resulting in larger plants and organs in several plant species. In this study, we examined biomass yield and quality traits of maize plants overexpressing GA20‐OX1 (GA20‐OX1). GA20‐OX1 plants accumulated more vegetative biomass than control plants in greenhouse experiments, but not consistently over two years of field trials. The stems of these plants were longer but also more slender. Investigation of GA20‐OX1 biomass quality using biochemical analyses showed the presence of more cellulose, lignin and cell wall residue. Cell wall analysis as well as expression analysis of lignin biosynthetic genes in developing stems revealed that cellulose and lignin were deposited earlier in development. Pretreatment of GA20‐OX1 biomass with NaOH resulted in a higher saccharification efficiency per unit of dry weight, in agreement with the higher cellulose content. On the other hand, the cellulose‐to‐glucose conversion was slower upon HCl or hot‐water pretreatment, presumably due to the higher lignin content. This study showed that biomass yield and quality traits can be interconnected, which is important for the development of future breeding strategies to improve lignocellulosic feedstock for bioethanol production.

Modified fertilization management of summer maize (Zea mays L.) in northern China improves grain yield and efficiency of nitrogen use

Improving the yield of maize grain per unit area is needed to meet the growing demand for it in China, where the availability of fertile land is very limited. Modified fertilization management and planting density are efficient methods for increasing crop yield. Field experiments were designed to investigate the influence of modified fertilization management and planting density on grain yield and nitrogen use efficiency of the popular maize variety Zhengdan 958, in four treatments including local farmer's practice (FP), high-yielding and high efficiency cultivation (HH), super high-yielding cultivation (SH), and the control (CK). Trials were conducted in three locations of the Huang-Huai-Hai Plain in northern China. Compared with FP, SH was clearly able to promote N absorption and dry matter accumulation in post-anthesis, and achieve high yield and N use efficiency by increasing planting density and postponing the supplementary application of fertilizers. However, with an increase in planting density, the demand of N increased along with grain yield. Due to the input of too much N fertilizer, the efficiency of N use in SH was low. Applying less total N, ameliorating cultivation and cropping management practices should be considered as priority strategies to augment production potential and finally achieve synchronization between high yield and high N efficiency in fertile soils. However, in situations where soil fertility is low, achieving high yield and high N use efficiency in maize will likely depend on increased planting density and appropriate application of supplementary fertilizers postpone to the grain-filling stage.

Multiple interval QTL mapping and searching for PSTOL1 homologs associated with root morphology, biomass accumulation and phosphorus content in maize seedlings under low-P.

BackgroundModifications in root morphology are important strategies to maximize soil exploitation under phosphorus starvation in plants. Here, we used two multiple interval models to map QTLs related to root traits, biomass accumulation and P content in a maize RIL population cultivated in nutrient solution. In addition, we searched for putative maize homologs to PSTOL1, a gene responsible to enhance early root growth, P uptake and grain yield in rice and sorghum.ResultsBased on path analysis, root surface area was the root morphology component that most strongly contributed to total dry weight and to P content in maize seedling under low-P availability. Multiple interval mapping models for single (MIM) and multiple traits (MT-MIM) were combined and revealed 13 genomic regions significantly associated with the target traits in a complementary way. The phenotypic variances explained by all QTLs and their epistatic interactions using MT-MIM (23.4 to 35.5 %) were higher than in previous studies, and presented superior statistical power. Some of these QTLs were coincident with QTLs for root morphology traits and grain yield previously mapped, whereas others harbored ZmPSTOL candidate genes, which shared more than 55 % of amino acid sequence identity and a conserved serine/threonine kinase domain with OsPSTOL1. Additionally, four ZmPSTOL candidate genes co-localized with QTLs for root morphology, biomass accumulation and/or P content were preferentially expressed in roots of the parental lines that contributed the alleles enhancing the respective phenotypes.ConclusionsQTL mapping strategies adopted in this study revealed complementary results for single and multiple traits with high accuracy. Some QTLs, mainly the ones that were also associated with yield performance in other studies, can be good targets for marker-assisted selection to improve P-use efficiency in maize. Based on the co-localization with QTLs, the protein domain conservation and the coincidence of gene expression, we selected novel maize genes as putative homologs to PSTOL1 that will require further validation studies.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0561-y) contains supplementary material, which is available to authorized users.

Metabolite Profiling of Low-P Tolerant and Low-P Sensitive Maize Genotypes under Phosphorus Starvation and Restoration Conditions.

BackgroundMaize (Zea mays L.) is one of the most widely cultivated crop plants. Unavoidable economic and environmental problems associated with the excessive use of phosphatic fertilizers demands its better management. The solution lies in improving the phosphorus (P) use efficiency to sustain productivity even at low P levels. Untargeted metabolomic profiling of contrasting genotypes provides a snap shot of whole metabolome which differs under specific conditions. This information provides an understanding of the mechanisms underlying tolerance to P stress and the approach for increasing P-use-efficiency.Methodology/Principal FindingsA comparative metabolite-profiling approach based on gas chromatography-mass spectrometry (GC/MS) was applied to investigate the effect of P starvation and its restoration in low-P sensitive (HM-4) and low-P tolerant (PEHM-2) maize genotypes. A comparison of the metabolite profiles of contrasting genotypes in response to P-deficiency revealed distinct differences among low-P sensitive and tolerant genotypes. Another set of these genotypes were grown under P-restoration condition and sampled at different time intervals (3, 5 and 10 days) to investigate if the changes in metabolite profile under P-deficiency was restored. Significant variations in the metabolite pools of these genotypes were observed under P-deficiency which were genotype specific. Out of 180 distinct analytes, 91 were identified. Phosphorus-starvation resulted in accumulation of di- and trisaccharides and metabolites of ammonium metabolism, specifically in leaves, but decreased the levels of phosphate-containing metabolites and organic acids. A sharp increase in the concentrations of glutamine, asparagine, serine and glycine was observed in both shoots and roots under low-P condition.ConclusionThe new insights generated on the maize metabolome in resposne to P-starvation and restoration would be useful towards improvement of the P-use efficiency in maize.

Genetic control of traits related to phosphorus use efficiency in tropical maize

Knowing the inheritance of traits is essential to establish selection strategies in breeding programs. The aim of this study was to determine the genetic control of traits related to the phosphorus use efficiency in maize. A total of 280 progenies were developed according to design III, which were evaluated in the field under high and low phosphorus (P) availability. The genetic variance components were estimated for the agronomic traits and indices that define P use efficiency. The results indicated that the additive and dominance effects were important in explaining the genetic variability for the flowering time, grain yield and P efficiency indices. However, dominance effects prevailed, indicating that breeding efforts should be made to develop hybrids exploiting the heterosis for traits related to P use efficiency.

Wheat improves nitrogen use efficiency of maize and soybean-based cropping systems

Integrated nitrogen (N) management strategies could make significant contributions to improving the efficiency of N use in the northern Corn Belt, particularly for maize, which has high N requirements. Using legume cover crops has been shown to increase both the soil's capacity to supply N and nitrogen use efficiency (NUE), through the reduction in the amount of N fertilizer that must be applied to the following crops. However, the impact of non-legume crops such as winter wheat (Triticum aestivum L.) on the diminishing return function between crop yield and N supply and its influence on N fertilizer use remains unclear. We hypothesized that maintaining wheat in short maize and soybean- based rotations is instrumental to improve cropping system performance and increase N fertilizer use efficiency while decreasing N requirements for maize. Seven maize and soybean rotations with different frequency of winter wheat with or without underseeded red clover (Trifolium pratense L.) were grown in two tillage systems (conventional and zone-tillage) and four long-term N regimes in Ridgetown, ON, Canada (2009–2013). Wheat in the rotation increased maize and soybean yields, negated crop yield lags due to zone-tillage, and decreased maximum economic rates of fertilizer N (MERN). The benefits of wheat in the rotation on maize yield were negated by high N rates; however, similar yields were obtained with lower N levels in rotationally grown maize, resulting in a 17% (conventional till) to 21% (zone-till) increase in partial factor productivity for N fertilizer at MERN (PFPMERN). While N benefits to crops following wheat alone may be attributed to a higher indigenous plant available soil N, underseeding red clover further increased the agronomic efficiency (AE) of N fertilizer (AEMERN) up to 32%. Maize yields were also less limited by N supply and less responsive to N fertilization when grown in rotation with wheat, especially in the zone-till system. These results highlight the value of wheat as a system component of dominant maize/soybean short rotations of Ontario and its potential to increase both maize and soybean productivity using less N input.

Effects of ridge and furrow rainwater harvesting system combined with irrigation on improving water use efficiency of maize (Zea mays L.) in semi-humid area of China

The ridge and furrow rainfall harvesting (RFRH) system collecting runoff by the plastic mulched ridges is a useful method to improve crop productivity in northwest China. We performed a field study where the RFRH system was combined with irrigation (RI) to reduce water irrigation use and to increase the crop water use efficiency (WUE) in a semi-humid climate. The amount of irrigation using RI was reduced by half compared with traditional furrow irrigation (FI) and border irrigation (BI) due to its rainwater harvesting effects. Our results showed that the RI treatment effectively alleviated drought stress during key periods of crop growth. At the jointing stage, the soil water storage in the 0–200cm soil layer was increased by 2.82–8.02% and 2.25–8.40% compared with FI and BI, respectively, and the soil water consumption by maize below 60cm was significantly decreased at the tasselling stage. With RI, the harvest biomass, grain yield, and WUE were significantly increased by 14.59–19.93%, 5.33–7.01%, and 12.21–18.01% compared with FI, respectively, and compared with BI, these values were significantly increased by 24.48–27.25%, 8.83–11.23%, and 14.99–22.91%, respectively. The irrigation amount was reduced by 1500m3hm−2, and the irrigation WUE with RI was 2.1 and 2.2 times higher than that using FI and BI. The irrigation water productivity was improved by 1.71 and 5.70 times compared with FI and BI, respectively in 2011. These results suggest that combining the RFRH system with irrigation is suitable for reducing irrigation water use by enhancing the efficient utilization of local rainfall, which could have very important applications in irrigated fields in semi-humid or semi-arid areas.