Increased Maize Yield Research Articles

Intercropping regulation of soil phosphorus composition and microbially-driven dynamics facilitates maize phosphorus uptake and productivity improvement

Intercropping is a powerful way that promote a more diversified plant community in croplandas. It is important to understand how this practice regulates phosphorus (P) footprint and trade-off in plant-soil system which influences crop productivity. Herein, a field-based experiment was conducted to investigate the effects of intercropping of maize with legumes (peanut and soybean) and non-legumes (gingelly and sweet potato) on maize productivity and P transformation and regulation. Compared with the monoculture, intercropping treatments increased maize yield, P use efficiency (PUE), P partial factor productivity (PFPP), and aboveground P uptake by 13.3–34.4%, 6.2–41.2%, 13.6–68.2%, and 10.3–20.1%, respectively. Intercropping treatments significantly reduced the cumulative losses of total P, dissolved P, and particulate P by 4.7–60.1%, 3.2–67.1%, and 2.7–64.7%, respectively. Maize/peanut and maize/soybean systems showed a better advantage in improving maize productivity and mitigating P runoff loss than the maize/gingelly and maize/sweet potato. Compared with the monoculture, intercropping increased the contents of soil labile-P, stable-P, solution-P, hydrolysable-P, and exchangeable-P by 3.1–7.8%, 18.7–63.2%, 8.4–35.5%, 0.2–28.3%, and 38.6–637.1%, respectively. The potential activities of soil alkaline and acid phosphatase in intercropping treatments increased respectively by 15.3–173.7% and 5.6–215.2% compared with the monoculture. Maize productivity components (crop yield, PFPP, and PUE, and plant P uptake) were positively correlated with soil P composition and bioavailability, microbial biomss P, and phosphatase activity, while negatively correlated with P runoff loss (P < 0.05). Those findings highlight the importance in understanding how soil P composition and microbially-driven P dynamics mediates plant P uptake to determine the consequences of intercropping for maize productivity. • Intercropping increased maize yield and PUE by 13–34% and 6–41%, respectively. • Intercropping decreased the runoff loss of TP, DP, and PP by 5–60%, 3–67%, and 3–65%. • Intercropping increased soil phosphatase activities by 6–215% with maize development. • Increased productivity was related to soil P composition, bioavailability, and dynamics. • Intercropping-driven plant-soil P trade-off contributed to maize productivity improvement.

Optimizing arrangement and density in maize and alfalfa intercropping and the reduced incidence of the invasive fall armyworm (Spodoptera frugiperda) in southern China

Maize and alfalfa intercropping has yield advantages and is an important cropping system. However, the row arrangement and density design of narrow-strip intercropping systems require improvement for the synergistic production of maize and alfalfa with higher yield advantages. Moreover, whether this system is adequate for pest control is unclear. In this study, a three-year field experiment was conducted at Yunnan in southwestern China. Using monocultures of maize and alfalfa as controls (CK), the experimental design comprised intercropping with three row arrangements: 2M2A (two maize rows with two alfalfa rows); 1M3A (one maize row with three alfalfa rows); and 2M3A (two maize rows with three alfalfa rows) under low density with a replacement design and high density with an additive design for the maize density. The growth and yield of maize and alfalfa were measured; the total and partial land equivalent ratio, overyielding of intercropping, and the competition ratio of crops were evaluated. Moreover, the incidence of the invasive fall armyworm ( Spodoptera frugiperda , a major agricultural pest) was investigated. Maize and alfalfa intercropping produced a yield advantage, with 1.31 being the highest land equivalent ratio. The yield was affected by planting row arrangement and maize density. The land equivalent ratio of 1M3A was significantly higher than that of 2M2A and 2M3A by 20% and 18%, respectively. A high maize density with additive design increased the land equivalent ratio by 8% compared with a low maize density with replacement design; the maize had a competitive advantage in intercropping; the row arrangement significantly affected the alfalfa yield but not the maize yield, while a high maize density with additive design slightly increased maize yield compared with a low maize density with replacement design, but had no significant effect on alfalfa yield. In addition, compared with sole maize cropping, intercropping significantly reduced the incidence of the invasive fall armyworm by 80%. These findings suggested that increasing the alfalfa row number and maize density improved the land equivalent ratio for narrow-strip intercropping, and that the 1M3A arrangement under high maize density with an additive design synergistically produced maize and alfalfa. Importantly, the results also suggest that maize and alfalfa intercropping has the potential to ecologically control the incidence of the fall armyworm for the sustainable production of maize. • Low alfalfa production should be increased in narrow-strip intercropping with maize. • Optimizing arrangement and density increased both the alfalfa and maize yield. • One high density maize with three alfalfa rows was recommended for application. • Intercropped alfalfa reduced the incidence of invasive fall armyworm on maize.

Effects of mulching on water saving, yield increase and emission reduction for maize in China

Mulching, an agricultural management measure widely used in arid and semi-arid regions of China, can effectively improve the hydrothermal environment of farmland and increase crop yield and crop water productivity (WPc). However, previous studies on the effects of mulching on water saving, yield increase and emission reduction of maize have provided inconsistent results. Therefore, a meta-analysis was used in this study to (1) evaluate the effect of mulching types [plastic film (PM), straw (SM) and degradable film (DM)] on maize yield, evapotranspiration, WPc and greenhouse gas emissions; and (2) determine the effects of mulching measures on water saving, yield increase and emission reduction in maize farmland under different climatic conditions. Compared with the no-mulching control, mulching significantly raised maize yield, WPc and carbon dioxide (CO2) and nitrous oxide (N2O) emissions. The PM, SM and DM increased maize yield by 27.31 %, 6.98 % and 16.55 % compared with no-mulching, respectively, and correspondingly WPc by 34.08 %, 11.48 % and 24.20 %. The PM and SM significantly increased CO2 emissions by 39.91 % and 16.43 %, respectively, and N2O emissions by 51.1 % and 30.12 %, but had no significant effect on methane absorption. For maize planting, in areas with altitudes < 500 and > 1000 m, average annual rainfall < 1000 mm, average annual air temperature of 5–15 °C and average annual evaporation < 1500 mm, a combination of PM and ridge–furrow planting can achieve the best effect of increasing production and saving water. In areas with an altitude of 1000–1500 m and average annual evaporation of 1500–2000 mm, the DM had the greatest effect of improving yield (by 16.17 %) and saving water, with a decrease in evapotranspiration of 8.82 % and an increase in WPc of 24.71 %. The local level of mechanization and labor costs should be considered when choosing a maize mulching pattern.

Effect of biochar application method and amount on the soil quality and maize yield in Mollisols of Northeast China

There have been many studies on soil quality and crop yield using different biochar application amounts, but few studies have focused on the combination of different methods and amounts of biochar application in moderately degraded Mollisols. In this study, the methods of mixing biochar evenly with the soil of the plough layer (0–20 cm depth) [homogeneous biochar application (HO)] and burying biochar above the soil plow pan (under 20 cm depth) (heterogeneous biochar application (HE)) were used to reveal how biochar application methods influenced soil quality, crop yield and agronomic characteristics in moderately degraded Mollisols (soil organic matter (SOM), 30.33 g kg−1). The biochar application amounts were 0 (control), 10 (level 1), 20 (level 2), and 40 (level 3) t ha−1 in both the HO and HE treatments. The results showed that, compared with control, HO3 significantly increased maize yield in the first year, and HO2, HO3, HE2 and HE3 continuously increased maize yield in the next three years but not significantly. HO1 and HE1 had the lowest maize yield. HO2 tended to delay maize leaf senescence. There was a positive linear relationship between soil quality index (SQI) and biochar application amount in HO. Compared with other treatments, the pH, EC, SOM, available phosphorus, sucrase and catalase activities were highest in HO3. However, the effects of HE on soil quality and crop productivity were limited at first but gradually increased with time. Overall, HO3 was beneficial for improving the soil quality and crop productivity in Mollisols for short-term cultivation (3-year), while HE showed an effect over time.Graphical

Sustained improvement in tolerance to water deficit accompanies maize yield increase in temperate environments

AbstractStudies at a regional scale suggest that although maize (Zea mays L.) yield increased substantially, sensitivity to water deficit also increased concurrently with crop improvement. This study assessed changes in yield and yield stability after two decades of breeding by evaluating two cohorts of hybrids released by the AQUAmax program and comparing them to a non‐AQUAmax control. Studies were conducted in 2019 and 2020 seasons at four sites under well‐watered, moderate and severe stress conditions. Plant densities varied from 2.5 to 12.5 pl m−2. AQUAmax hybrids yielded more than non‐AQUAmax hybrids under water deficit conditions with the magnitude of the difference dependent on plant density. The sensitivity in yield across environments with a wide range of total crop evapotranspiration (350–800 mm) was lower for AQUAmax than non‐AQUAmax, so both yield and yield under stress conditions (yield stability), were enhanced for AQUAmax hybrids. The median differences between observed yields and the 80% quantile yield–evapotranspiration front were 379 for AQUAmax and 427 g m−2 for non‐AQUAmax hybrids. We conclude that deliberate selection of hybrids for yield performance under water deficit underpinned the sustained improvement in yield stability after two decades of drought breeding. Future research should focus on understanding the root causes for the suboptimal utilization of drought tolerant maize for the diversity of environments at a regional scale.

Effects of animal manure and nitrification inhibitor on N2O emissions and soil carbon stocks of a maize cropping system in Northeast China

The incorporation of animal manure (AM) in soil plays an essential role in soil carbon sequestration but might induce higher soil nitrous oxide (N2O) emissions. The use of nitrification inhibitors (NI) is an effective strategy to abate N2O emission in agro-ecosystems. However, very few studies have evaluated the effectiveness of applying NI under the combined application of organic and inorganic fertilizers for increasing soil carbon sequestration and reducing N2O emissions simultaneously in Northeast China. Here, a four-year field experiment was conducted with three treatments [inorganic fertilizer (NPK), inorganic fertilizer + manure (NPKM), and inorganic fertilizer with NI + manure (NPKI + M)], in a rainfed maize cropping system in Northeast China. Plots of different treatments were kept in the same locations for 4 years. Gas samples were collected using the static closed chamber technique, and nitrous oxide (N2O) concentration in gas samples was quantified using a gas chromatograph. Soil organic carbon sequestration rate (SOCSR) was calculated based on the changes in SOC from April 2012 to October 2015. Averaged over the four years, AM incorporation significantly increased soil N2O emissions by 25.8% (p < 0.05), compared to NPK treatment. DMPP (3,4-dimethylpyrazole phosphate) significantly decreased N2O emissions by 32.5% (p < 0.05) relative to NPKM treatment. SOC content was significantly elevated by 24.1% in the NPKI + M treatment than the NPK treatment after four years of manure application (p < 0.05). The annual topsoil SOCSR for the NPKM and NPKI + M treatments was 0.57 Mg ha−1 yr−1 and 1.02 Mg ha−1 yr−1, respectively, which were significantly higher than that of NPK treatment (− 0.61 Mg ha−1 yr−1, p < 0.05). AM addition significantly increased the aboveground biomass and crop yields of maize in the fourth year. Overall, combined application of DMPP, inorganic fertilizer and AM is strongly recommended in this rainfed maize cropping system, which can increase maize yield and SOC sequestration rate, and mitigate N2O emission.

Effect of Winter Cover Cropping on Soil Greenhouse Gas Emissions in a Dryland Spring Maize Field on the Loess Plateau of China

A field experiment was carried out to study the effects of winter cover cropping on soil greenhouse gas emissions in dryland maize. Four cover crop treatments, namely oat, lentil, a mixture of oat and lentil, and no cover crops (CK), were included during the winter fallow period. Greenhouse gas emission fluxes from soil were measured using the static chamber-gas chromatograph technique. The results showed that:both soil CO2 and N2O were emitted, but the soil acted as a sink for CH4. Compared with the that in CK, oat and lentil had no effect on the cumulative amount of soil CO2 emissions during the winter fallow period and increased the cumulative amount of soil CO2 emissions by 7.77% and 25.7% (P<0.05) in the spring maize growing period, respectively; the mixture increased the cumulative amount of soil CO2 emissions by 19.1% and 14.5% (P<0.05) during the winter fallow and spring maize growing periods. In the winter fallow and spring maize periods, compared with that in CK, oat declined the cumulative amount of soil N2O emissions by 11.6% and 14.7% (P<0.05), and lentil increased the cumulative amount of soil N2O emissions by 31.9% and 14.9% (P<0.05), respectively. Compared to that in the CK, the mixture declined the cumulative amount of soil N2O emissions by 19.2% (P<0.05) in the winter fallow period but had no effect in the spring maize period. Compared with the CK, oat, lentil, and their mixture resulted in a declined cumulative amount of soil CH4 uptake by 37.9%, 23.6%, and 29.6% (P<0.05) in the winter fallow period and by 19.4%, 33.5%, and 31.5% (P<0.05) in the spring maize growing period, respectively. Compared with the CK, oat had no effect on global warming potential (GWP), maize yield, and greenhouse gas intensity (GHGI). Lentil and the mixture increased GWP, and lentil showed a greater increase in GWP than that of the mixture. Compared with the CK, lentil and the mixture increased maize yield by 20.3% and 15.4% (P<0.05), respectively, and had no effect on GHGI. The findings from this study show that the lentil and oat mixture can significantly increase maize yield and decrease GHGI.

Spatial patterns and driving factor analysis of recommended nitrogen application rate for the trade-off between economy and environment for maize in China

Appropriate nitrogen (N) application increases crop yield, while its unreasonable application results in environmental problem. Determining the appropriate N application rate is the key to sustainable development. Here, the denitrification-decomposition (DNDC) model was used to analyze the effects of N fertilizer on maize yields, economic benefits, nitrate leaching, and nitrous oxide emissions in China. The N application rate for the trade-off between economy and environment at the county scale was further determined. The geodetector model was used to identify the main driving factors and their interactions of the recommended N rate in each agricultural zone. The results showed that the recommended N rate was generally high in the northwest but low in the south, consistent with the spatial patterns of yield potential. However, clay soils with clay ratios greater than 34% in southern China and sandy soils with bulk densities greater than 1.5 g cm−3 on the Huanghuaihai Plain experienced high N levels and low yields, and thus soils need to be improved. Potential grain yield was the main driving factor in most zones, yet its effects gradually weakened from north to south. The influence of soil characteristics increased from north to south. It was found that the current average N application rate of farmers in China was 249 kg N/ha, and 86.55% of counties had excessive N applications. Compared to the regional optimal N rate at a regional scale, a differentiated N application strategy at the county scale determined in this study increased maize yield and economic benefit by 10.51% and 10.85%, respectively, and reduced N2O emissions and NO3− leaching by 28.72% and 33.60%, respectively. The current research provides a scientific basis for China to formulate a win-win N management strategy for economy and environment and provides a method reference for other countries.

Optimizing Planting Density to Increase Maize Yield and Water Use Efficiency and Economic Return in the Arid Region of Northwest China

High grain yield and water use efficiency (WUE) are the key goals when producing maize (Zea mays L.) under irrigation in arid areas. Increasing the planting density and optimizing irrigation are important agronomic practices for increasing the maize grain yield and WUE. A two-year field experiment was conducted to investigate the effects of planting density and irrigation on the maize grain yield, WUE, and economic return of spring maize under a mulch drip irrigation system in Xinjiang, Northwest China. The experiment included four irrigation levels and five planting densities. The results showed that the reduction of irrigation decreased the yield and evapotranspiration (ETc) but improved the WUE. Increasing the planting density increased the ETc, but there was a quadratic curve relationship between yield and WUE and planting density. Treatment with 600 mm of water and 12 plants m−2 obtained the highest grain yield (21.0–21.2 t ha−1) and economic return (3036.0 USD ha−1) and a relatively high WUE (2.64–2.70 kg kg−1). Therefore, a reasonable increase in planting density and an appropriate reduction of irrigation combined with drip irrigation under a mulch system can simultaneously achieve high yields and economic return and high WUE in maize production.

Effects of combined nitrification inhibitors on soil nitrification, maize yield and nitrogen use efficiency in three agricultural soils

Application of nitrification inhibitors (NIs) with nitrogen (N) fertilizer is one of the most efficient ways to improve nitrogen use efficiency (NUE). To fully understand the efficiency of NIs with N fertilizer on soil nitrification, yield and NUE of maize (Zea mays L.), an outdoor pot experiment with different NIs in three soils with different pH was conducted. Five treatments were established: no fertilizer (Control); ammonium sulfate (AS); ammonium sulfate + 3, 4-dimethyl-pyrazolate phosphate (DMPP) (AD); ammonium sulfate + nitrogen protectant (N-GD) (AN); ammonium sulfate + 3, 4-dimethyl-pyrazolate phosphate + nitrogen protectant (ADN). The results showed that NIs treatments (AD, AN and ADN) significantly reduced soil nitrification in the brown and red soil, especially in AD and ADN, which decreased apparent nitrification rate by 28% - 44% (P < 0.05). All NIs treatments significantly increased yield and NUE of maize in three soils, especially ADN in the cinnamon soil and AD in the red soil were more efficiency, which significantly increased maize yield and apparent nitrogen recovery by 5.07 and 6.81 times, 4.39 and 8.16 times, respectively. No significant difference on maize yield was found in the brown soil, but AN significantly increased apparent nitrogen recovery by 70%. Given that the effect of NIs on both soil nitrification and NUE of maize, DMPP+N-GD was more efficient in the cinnamon soil, while N-GD and DMPP was the most efficiency in the brown and red soil, respectively. In addition, soil pH and soil organic matter play important role in the efficiency of NIs.

Cow Manure Compost Promotes Maize Growth and Ameliorates Soil Quality in Saline-Alkali Soil: Role of Fertilizer Addition Rate and Application Depth

Soil salinization and alkalization is a global problem restricting agricultural production. This study compared different fertilizer regimes (addition rate and application depth) on maize growth and soil quality in saline-alkali soil. Cow manure compost was applied with addition rates of 6, 12, 18 and 24 t·ha−1, and application depths of 5 and 20 cm, along with 0.6 t·ha−1 mineral fertilizer, and compared to a control treatment with only mineral fertilizer application. Results indicated that cow manure compost application could promote maize growth and ameliorate soil quality in saline-alkali soil. Increasing cow manure compost addition rate alleviated soil salinity better than alkalinity, while increasing compost application depth could reduce soil alkalinity more effectively than soil salt content. Moreover, increasing cow manure compost addition rate improved soil organic matter and soil nutrient content, thus promoting shoot growth and maize yield. However, increasing cow manure compost application depth could boost root growth, and further absorbed more nutrients to promote maize yield. Cow manure compost application increased maize yield by 6.0% to 28.4% with a maximum yield of 8.14 t·ha−1 in a treatment with compost addition rate of 24 t·ha−1 and application depth of 20 cm. Comprehensive evolution of soil quality, maize growth and maize yield, cow manure compost addition rate of 24 t·ha−1 and application depth of 20 cm along with 0.6 t·ha−1 mineral fertilizer application is suggested for use in saline-alkali soil.

Trichoderma asperellum GDFS1009 ‐mediated maize resistance against Fusarium graminearum stalk rot and mycotoxin degradation

Maize stalk rot caused by Fusarium graminearum is a major soil-borne maize disease, and biocontrol strategies are the best possible and eco-friendly solution to disease control and maize yield enhancement. In the past several years, the disease was successfully controlled with Trichoderma in China. However, little knowledge is available regarding the mechanism of the disease control and detoxification of Fusarium mycotoxin. Therefore, in the present study, we used physiological, biochemical, and microbiological methods to screen Trichoderma strains with high antagonistic activity to pathogens and studied the changes in major defence response genes, signal transduction, and mycotoxin degradation in maize through Trichoderma asperellum GDFS1009 against stalk rot diseases in both greenhouse and field conditions. T. asperellum significantly inhibited the growth of F. graminearum in the roots and stems of greenhouse and field plants. In addition, the plant height and fresh weight were also significantly increased. The expression of defence-related genes and signal transduction in maize plants showed that T. asperellum could upregulate the expression of the class III plant peroxidase (POD) gene, salicylic acid (SA) pathway-related gene pathogenesis-related protein 5(PR5), and jasmonic acid (JA)-related gene 12-oxo-phytodienoic acid reductase (OPR7) in roots, stems, and leaves of 5–6 leaf stage seedlings. During the tasseling period, Trichoderma upregulated the expression of PR5 in maize basal and middle stems and leaves, while OPR7 and allene oxide synthase (ACO) were upregulated in the basal stem segments. T. asperellum effectively reduced F. graminearum infection and degraded mycotoxins through upregulation of the UDP-glucuronosyltransferase (UGT) gene in the microbes and basal stem of maize plants, eventually increasing maize yield in both greenhouse and field trials.

Pengaruh Pupuk Hayati Berbasis Hidrogel dan Pupuk P terhadap Pertumbuhan dan Hasil Jagung pada Inceptisols asal Jatinangor

Inceptisols are soils that have problems with fertility. Inorganic P fertilizer is a quick choice to restore nutrient availability for plants, but long-term use may harm soil and plants. Another alternative to this problem by using a biofertilizer. Biofertilizer contains microbes that can promote plant growth by increasing the supply of nutrients through their biological activities in the soil. Some microbes are known to have to dissolve phosphate ability through secretion of organic acids and enzymes mechanism. This experiment was conducted to examine the effect of hydrogel-based biofertilizer combined with inorganic P fertilizer (SP-36) on the growth and maize yields on Inceptisols Jatinangor. The biofertilizers were a consortium of phosphate solubilizing microbes (PSM) consisting of Bacillus subtilis, Pseudomonas mallei, Burkholderia cepacia, and Trichoderma asperellum. The pot experiment using a Randomized Block Design (RBD) consisted of 9 treatments with 3 replications. The treatments consisted of control, recommended dose of inorganic P fertilizer (100 kg Ha-1), biofertilizer dose of 50 kg Ha-1, and a combination of biofertilizer and inorganic P fertilizer. The results showed that the combination of ½ dose of hydrogel-based biofertilizer and ¾ dose of P fertilizer increased maize yield. In addition, the application of biofertilizer can reduce inorganic P fertilizer needs up to ¾ recommended dose.

Better tillage selection before ridge—furrow film mulch can facilitate root proliferation, and increase nitrogen accumulation, translocation and grain yield of maize in a semiarid area

Plastic film mulch systems are used widely in arid areas, and the associated tillage measures affect soil properties, root and crop growth, and nutrient uptake. However, much debate surrounds the most suitable tillage method for plastic film mulch systems. We conducted a two-year field experiment to explore the impact of three tillage treatments - rotary tillage before ridge–furrow plastic film mulch (MR), no-tillage before ridge–furrow plastic film mulch (MZ), and plow tillage before ridge–furrow plastic film mulch (MP) - on soil total nitrogen, available nitrogen, root stratification structure, nitrogen transfer and utilization, and maize yield. The results showed that MP had better soil quality than either MR or MZ over 2019 and 2020, with higher nitrate-nitrogen and total nitrogen in the 0–40 cm soil layer. MP improved the soil physicochemical properties more than the other treatments, producing significantly higher root numbers and root biomass for the aerial and underground nodal roots than MR and MZ. At harvest, MP had the highest root biomass density, root length density, and root surface area density in the different soil layers (0–20, 20–40, and 0–40 cm). Significant correlations occurred between root biomass and aboveground nitrogen accumulation during maize growth. During grain filling, MP had the greatest nitrogen transfer amount, significantly increasing root and aboveground nitrogen transfer by 19.63–45.82% and 11.15–24.56%, respectively, relative to the other treatments. MP significantly produced 1.36–26.73% higher grain yields and a higher grain crude protein content at harvest than MR and MZ. MP also had higher values for the nitrogen harvest index, nitrogen uptake efficiency, and partial factor productivity of nitrogen fertilizer than MR and MZ. In conclusion, plow tillage combined with a ridge–furrow plastic film mulch system facilitated maize root development and improved nitrogen utilization, thereby increasing maize yield more than the other treatments.

Enhancing maize yield in Ethiopia a meta-analysis

Accurate nitrogen (N) fertilization and optimum plant density increase crop yields. In this study, I report the effects of N fertilization rate and plant density on maize yield in a meta-analysis, by using observations from 15 studies conducted in Ethiopia since the 2000s for possible refinement of N fertilizer and plant density recommendations. I assessed the response of maize to different N rates ha−1 compared to the control using the yield response approach. Application of N fertilizer significantly increased maize yields by 31.5% - 65.9% compared to control. plant density increased maize yields by 42% - 72.4% compared to the control. The interaction effect of the N rate increased maize yields by 27.6% - 95.9%, with Plant density, 58.7% - 152% on loam soil, compared to control yield. The interaction effect of Plant density with soil type increased maize yields by 47% - 108% on loam soil. In conclusion, the grain yield of maize increased with increasing N rate and plant density up to the optimum. Therefore, it’s possible to recommend using a high N rate with both low and medium plant density (&lt; 45,000 plants ha-1) and (45,000 to 65,000plants ha-1) to harvest high grain yield.

Both uniconazole and 5-aminolevulinic acid increase maize (Zea mays L.) yield by changing its ear morphology and increasing photosynthetic efficiency and antioxidants in saline-alkali land

Saline-alkaline stress is one of the most detrimental abiotic stresses that restrict the yield and physiological activity of maize (Zea mays L.). In the present study, maize was planted on saline-alkali land, while 25 mg L-1 uniconazole (S3307) and 40 mg L-1 5-aminolevulinic acid (ALA) were sprayed at the stage of nine expanded leaves. Our results showed that both S3307 and ALA applications significantly increased all ear width, volume, and mass in the maturity stage. Both applications also upregulated photosynthetic efficiency via increasing the chlorophyll content, net photosynthetic rate, transpiration rate, and stomatal conductance, as well as reduced the intercellular CO2 concentration after the silking stage. In addition, both applications upregulated further the antioxidant system via enhancing the activity of antioxidants and contents of soluble protein and sugar, as well as reducing the malondialdehyde content after the silking stage. Thus, both S3307 and ALA applications can improve maize yield in saline-alkali land via enhancing ear morphology and increasing photosynthetic efficiency and antioxidants.

Different soil particle size changes the 15N retention in soil and 15N utilization by maize

Improving soil structure is key to improving soil quality and nitrogen utilization efficiency (NUE) in global cropping systems. Soil sieving is a direct means of dividing soil activity into components with different practical functional significance. In order to have a more intuitive understanding of nutrient turnover and NUE under different soil particle sizes, we identified the key soil particle sizes that affect N cycling in cropping systems. An in-situ field experiment was conducted in Mollisol for three years using the 15N isotope tracer technique to examine the effect of soil structure on maize growth, nutrient uptake, and 15NUE. We artificially destructed the soil structure by sieving it into four particle size classes: (i) unsieved soil (CK), (ii) <0.5 mm size (A), (iii) 0.5–2 mm size (B), and (iv) 2–5 mm size (C). Then each year, the physical properties of the soil, 15N loss and retention rate (15NRR), the 15NUE, 15N absorption, and distribution, as well as maize growth and yield, were measured. The results showed that the 0.5–2 mm size (B) and 2–5 mm size (C) improved soil physical properties and increased the uptake of 15N by maize (especially in the leaves and grains), thereby increasing maize yield. The B and C particle sizes had lower soil 15NRR and higher alkaline hydrolysable N content than the other treatments in the depth. We concluded that the B sieving treatment is the key aggregate fraction to increasing maize 15NUE and yield and minimizing the negative effects on soil N retention capacity. Furthermore, the B treatment is key to affecting crop nutrient absorption and utilization.

Quantifying contributions of leaf area and longevity to leaf area duration under increased planting density and nitrogen input regimens during maize yield improvement

Leaf area and its longevity are the key factors driving dry matter accumulation and yield formation in maize (Zea mays. L). Both factors are influenced by cultivation management measures. The objective of this study was to utilize a quantitative framework to better understand the contribution of leaf area and longevity to leaf area duration (LAD) and yield in maize plants at varying plant densities and nitrogen application rates. A two-year field experiment was conducted using a factorial combination of two plant densities and four nitrogen levels. Leaf area and longevity were measured at each leaf position in two different maize cultivars. We calculated the LAD at the single-leaf, individual-plant, and whole-population scales and quantitatively analyzed the contribution of leaf area and longevity to LAD. The results showed that in the upper leaves, leaf area had a larger proportional contribution to LAD (54.1–95.7%), whereas in the lower leaves, leaf longevity contributed more to LAD (51.8–74.1%). Both were greatly affected by variations in plant density and nitrogen application. At the individual-plant scale, the proportional contribution of leaf area to LAD (57.3%) was similar to that of leaf longevity (57.2%); at the whole-population scale, leaf area accounted for a larger contribution to LAD (87.0%). The increase in LAD (which integrating increases in leaf area and longevity) was positively associated with an increase in dry matter at maturity and grain yield. Yield gain was achieved by reasonable increases in density and nitrogen fertilizer application to promote LAD. The quantitative evaluation of leaf area and longevity described in this study provides a theoretical basis for increasing maize yield under increased plant density and nitrogen input conditions.

Effect of Coated Diammonium Phosphate Combined with Paecilomyces variotii Extracts on Soil Available Nutrients, Photosynthesis-Related Enzyme Activities, Endogenous Hormones, and Maize Yield

Coated diammonium phosphate (CDAP) is intended to release nutrients steadily in response to the demand of crop growth. A novel biostimulant extracted from Paecilomyces variotii has been shown to regulate gene expression in nutrient transport, enhance nitrogen (N) and phosphorus (P) uptake, and improve nutrient use efficiency. The application of CDAP combined with the Paecilomyces variotii extracts (ZNC) in maize is an efficient approach for reducing waste of resources, improving nutrient supply, and maintaining production stability. The effects of CDAP combined with ZNC on photosynthesis, enzyme activities, endogenous hormone content, maize yield, and P use efficiency (PUE) were investigated in this study. In a pot experiment, CDAP and diammonium phosphate (DAP) were tested together with P levels (1.80, 1.44 g pot–1, P2O5) and two ZNC application rates (0, 4.4 μg pot–1), which included the control treatment that had no P fertilizer added. Results showed that the key influencing elements of maize growth and yield were the soil available-P content, endogenous hormone content, and plant photosynthesis in this study. The combination of DAP and ZNC increased the soil available-P content and the auxin content in leaves at the key stage and hence increased the yield and PUE of maize, compared with DAP. The net photosynthetic rate of CDAP combined with ZNC was higher by 23.1% than that of CDAP alone, as well as by 32.0% than that of DAP combined with ZNC. Moreover, the combination of CDAP and ZNC increased the yield and PUE by 8.2% and 15.6 percentage points compared with DAP combined with ZNC while increasing the yield and PUE compared with CDAP. In conclusion, combining CDAP with ZNC as an environmentally friendly fertilizer could improve photosynthesis-related enzyme activity and enhance the net photosynthetic rate, resulting in an increase in maize yield and PUE significantly.

Nitrogen and Chemical Control Management Improve Yield and Quality in High-Density Planting of Maize by Promoting Root-Bleeding Sap and Nutrient Absorption.

High-density planting aggravates competition among plants and has a negative impact on plant growth and productivity. Nitrogen application and chemical control can improve plant growth and increase grain yield in high-density planting. Our experiment explored the effects of nitrogen fertilizer and plant growth regulators on maize root-bleeding sap, phosphorus (P) and potassium (K) accumulation and translocation, and grain yield and quality in high-density planting. We established a field study during the 2017 and 2018 growing seasons, with three nitrogen levels of N100 (100 kg ha−1), N200 (200 kg ha−1), and N300 (300 kg ha−1) at high-density planting (90,000 plants ha−1), and applied Yuhuangjin (a plant growth regulator mixture of 3% DTA-6 and 27% ethephon) at the 7th leaf. Our results showed that N200 application combined with chemical control could regulate amino acid and mineral nutrient concentration delivery rates in root-bleeding sap and improve its sap rate. Also, the treated plant exhibited higher P and K uptake and translocation ability. Furthermore, chemical control and N200 treatment maintained a high level of ribulose-1,5-bisphosphate carboxylase (RuBPCase), phosphoenolpyruvate carboxylase (PEPCase), nitrate reductase (NR), and glutamine synthetase (GS) enzymatic activities in leaves. In addition, plant growth regulator and nitrogen application improved the enzymatic activities of GS, glutamate dehydrogenase (GDH), and glutamic pyruvic transaminase (GPT) and the contents of crude protein, lysine, sucrose, and soluble sugar in grain and ultimately increased maize yield. This study suggests that N200 application in combination with chemical control promotes root vitality and nutrient accumulation and could improve grain yield and quality in high-density planting.