Increased Maize Yield Research Articles

Drought Stress Alleviation by ACC Deaminase Producing Achromobacter xylosoxidans and Enterobacter cloacae, with and without Timber Waste Biochar in Maize

The high consumption of water in industries, domestic areas and increasing earth temperature are major hurdles for the optimization of maize yield. Being the third most widely cultivated cereal crop, improvement in maize yield is a big challenge under the limited availability of irrigation. As the water requirement for maize cultivation is high, it is time to introduce technologies that can mitigate drought stress and are environmentally friendly. The inoculation of rhizobacteria with ‘1-aminocyclopropane-1-carboxylate deaminase’ (ACCD) can play an imperative role in that regard by decreasing stress ethylene in plants. Biochar (BC) can also alleviate drought stress. Therefore, a field study was conducted, to examine the single and combined application of drought-tolerant plant-growth-promoting rhizobacteria (PGPRs) Achromobacter xylosoxidans and Enterobacter cloacae, with 15 Mg ha−1 of timber waste biochar (TWBC) at normal irrigation = 16 irrigations, mild drought = 14 irrigations and severe drought = 12 irrigation for maize cultivation. A significant improvement in shoot dry weight (28%), 1000-grains weight (19%), grain yield (27%), concentrations of N (43%), P (92%) and K (71%) in grains, rate of photosynthesis (33%), transpiration rate (55%), stomatal conductance (104%), chlorophyll A (33%), chlorophyll B (62%) and total chlorophyll (45%) of maize was noted under drought stress where E. cloacae + TWBC was applied. Likewise, the application of A. xylosoxidans + TWBC also significantly enhanced the plant height (24%) and cob length (9%) of maize under drought stress. In conclusion, E. cloacae is more effective than A. xylosoxidans, with 15 Mg ha−1 TWBC to increase maize yield under drought stress, due to the potential of higher ‘1-aminocyclopropane-1-carboxylate’ (ACC)-deaminase synthesis, better nutrient solubilization and indole acetic acid (IAA) production.

Biochar increases maize yield by promoting root growth in the rainfed region

ABSTRACT Although biochar amendment could increase crop yield globally, it remains unclear how biochar improves grain yield. A two-year field experiment was conducted to investigate the role of plant roots in promoting crop growth under biochar amendment. The field experiment, started in 2015, was conducted in a rainfed region of North China. We hypothesized that biochar increases maize yield by promoting root growth. In the first year (2015), maize grain yield increased by 23.9% and 25.3% under biochar application rate of 20 and 40 t ha−1, respectively. Biochar increased the biomass of maize stalk and root and their potassium uptake significantly. The root morphology of maize also improved significantly following biochar amendment. Yet, the double increase in biochar application rate did not lead to any additional grain yield increase. The grain yield was positively correlated with the maize ear size, the soil organic carbon content, the biomass of maize stalk and root and their K uptake. In the second year (2016), however, biochar had no effect on the root morphology and the grain yield was not affected. Here we show that biochar increases maize yield by increasing maize ear size directly and by promoting root growth and nutrient uptake indirectly.

The effectiveness of local strains of Fusarium oxysporium f. Sp. Strigae to control Striga hermonthica on local maize in western Kenya.

Striga hermonthica weed infestation continues to persist among smallholder poor farmers in Kenya who depend on traditional maize (Zea mays L.) seeds for their livelihood. The purpose of this study was to evaluate the efficacy of five local Fusarium oxysporum f. sp. Strigae strains (FK1, FK2, FK3, FK4, and FK5) to control Striga on susceptible local maize cultivar “Rachar” in three farmer field sites in Siaya County, Kenya. A complete randomized block design was used in each site. Statistical analysis was done using SAS 9.1 software, and means for different strains were tested with Fisher's LSD. The strains differentially reduced the number of emerged Striga and infected most of the emerged Striga, which affected performance of the local maize. Striga emergence and infection rates were significantly different (p < .05) between different strains of F. oxysporum f. sp. strigae. FK1 and FK2 strains had the least pathogenicity, while FK5 strain had the highest pathogenicity on Striga. Soil and climatic factors influenced the rate of infection for the tested strains and maize performance. Improvement in yield during the short rains was attributed to the persistence of Fusarium strains in the soil. Based on Striga emergence and infection rates, and maize yield, FK5 was the most effective strain to curb Striga menace. Adoption of local F. oxysporum strains will increase maize yield in Siaya County's Striga‐infested fields from a dismal average of 0.95 t/ha to about 1.95 t/ha. The observed significant differences in the tested strains between sites for the infection and emergence rates revealed the importance of considering pathogens on a field‐to‐field basis. Further studies should be carried out to establish the relationship between soil properties and the five fungal strains.

The Contribution of Soil Tillage and Nitrogen Rate to the Quality of Maize Grain

A soil tillage system adjusted to the soil type and agro-ecological conditions, together with the optimal nutrient supply, is a prerequisite for high maize (Zea mays L.) yield. However, there is little knowledge about the influence of soil tillage and nitrogen (N) rates on maize grain quality. A study was initiated in 1978 in Zemun Polje, Belgrade, Serbia, on the chernozem soil type. The effects of three N rates—0, 180 and 240 kg N ha−1—within three tillage practices—no-tillage, reduced and conventional tillage—and their influence on grain yield (GY) and the content of proteins, starch, oil, total tocopherols and carotenoids, phytic phosphorus (Phy), glutathione (GSH), phenols and inorganic P (Pi) in maize grain were analysed in the period 2016–2018. Differences in maize GY were 2.57 and 3.01 t ha−1 for reduced- or no-tillage, respectively, in comparison to conventional tillage. Conventional tillage and higher N rates contributed to the increase in maize yield and the grain nutritional quality with regard to the increased level of proteins, GSH and Phy. On the other hand reduced inputs were beneficial only for grain quality, in relation to the increase in tocopherols and phenols.

Limits of conservation agriculture to overcome low crop yields in sub-Saharan Africa

Conservation agriculture (CA) has become a dominant paradigm in scientific and policy thinking about the sustainable intensification of food production in sub-Saharan Africa. Yet claims that CA leads to increasing crop yields in African smallholder farming systems remain controversial. Through a meta-analysis of 933 observations from 16 different countries in sub-Saharan African studies, we show that average yields under CA are only slightly higher than those of conventional tillage systems (3.7% for six major crop species and 4.0% for maize). Larger yield responses for maize result from mulching and crop rotations/intercropping. When CA principles are implemented concomitantly, maize yield increases by 8.4%. The largest yield benefits from CA occur in combination with low rainfall and herbicides. We conclude that although CA may bring soil conservation benefits, it is not a technology for African smallholder farmers to overcome low crop productivity and food insecurity in the short term. Principles of conservation agriculture are widely promoted for sustainable agricultural intensification, but their effects on crop yields in sub-Saharan Africa are poorly understood. A meta-analysis covering 16 countries quantifies such effects and reveals the conditions under which they are maximized.

Moisture stress induced changes in root anatomy and antioxidants level in maize (Zea mays L.)

Maize is a drought sensitive crop whose growth and yield is seriously affected by this stress. Development of drought tolerant genotypes is the need of the hour and the only alternative to increase maize yield. In the present research, some biochemical and anatomical indices have been identified which can be used to screen the tolerant genotypes from a large population pool. The results obtained from the present study revealed that tolerant genotypes (LM 16, CM 140) as well as check (PMH 2) showed higher carotenoids, chlorophylls, proline and activities of SOD and POX enzymes, whereas, accumulation of H2O2 was lower than sensitive genotypes (LM 13, LM 20). Some morphological and anatomical changes were also induced in roots due to moisture stress. The number of metaxylem elements increased in both sensitive and tolerant genotypes. Diameter of metaxylem was reduced in tolerant genotype (CM 140) while number of root hairs increased in tolerant genotype (LM 16) with drought stress. Consequently, all these modifications in the root anatomy, enzyme activities and biochemical parameters could provide a useful tool to breeders for identification of moisture tolerant genotypes.

Determining effects of water and nitrogen input on maize (Zea mays) yield, water- and nitrogen-use efficiency: A global synthesis

A major challenge in maize (Zea mays) production is to achieve high grain yield (yield hereafter) by improving resource use efficiency. Using a dataset synthesized from 83 peer-reviewed articles, this study mainly investigated the effects of water and/or nitrogen (N) input on maize yield, water productivity (WP), and N use efficiency (NUE); and evaluated the effects caused by planting density, environmental (temperature, soil texture), and managerial factors (water and/or N input). The input of water increased maize yield, WP, and NUE only when the input was less than 314, 709, and 311 mm, respectively; input of N increased maize yield, WP, and NUE until input was greater than 250, 128, and 196 kg ha−1, respectively. Additionally, results of the mixed-effects model and random forest analysis suggested that mean annual temperature (MAT) was the most critical factor for narrowing gaps (between the actual and attainable variable, which was indicated as response ratio of the treatment relative to the control) of yield (RRY), WP (RRWP), and NUE (RRNUE), respectively. Specifically, RRY, RRWP, or RRNUE were negatively correlated to MAT when MAT was higher than 15 °C. Additionally, the structural equation model showed that water input and RRWP with the higher coefficient were more important than N input and RRNUE in improving RRY. These findings provide new insights into the causes and limitations of global maize production and offer some guidances for water and/or N managements.

Maize yield and root morphological characteristics affected by controlled-release diammonium phosphate and Paecilomyces variotii extracts

Abstract Application of conventional phosphorus (P) fertilizer poses great concern due to its low P efficiency and potential eutrophication of P in sensitive waters. A novel biostimulant, Paecilomyces variotii extract (ZNC), with functionality of improving nutrient uptakes of crops, was integrated with diammonium phosphate coated with biobased polyurethane polymer in a three-year field trial. The objectives were to explore the effects and mechanisms of the controlled-release diammonium phosphate (CRP), ZNC and their combination on P use efficiency (PUE), economic benefit, soil P supply, and root growth and yield of maize (Zea mays L., Zhengdan ‘958’). The experiment consisted of five treatments: regular diammonium phosphate (DAP); CRP with release longevity of three months (CDAP); regular diammonium phosphate combined with ZNC (DAPZ); CRP combined with ZNC (CDAPZ); and no added P fertilizer (Control), each with three replicates. The results indicated that CDAP and DAPZ treatments significantly increased average yield by 9.65 % and 3.56 %, and PUE by 7.72 % and 3.32 %, respectively, when compared with DAP treatment. Similarly, the average soil available-P of CDAP and DAPZ treatments was increased by 10.0 % and 45.9 % at 0−40 cm soil depth. Furthermore, CDAP and DAPZ treatments significantly increased maize total root length by 178.2 % and 223.6 %, and bleeding sap rate by 23.3 % and 32.5 %, respectively, at the jointing stage. However, the average maize yield and net income of combined CDAPZ treatment had no significant difference relative to CDAP and DAPZ treatments. Moreover, the total root length of CDAPZ treatment was reduced by 16.0 % and 27.8 %, compared to CDAP and DAPZ treatments. Hence the application of CRP or ZNC could increase maize yield by improving soil P supply intensity to meet maize P demand and promoting root morphological characteristics and vitality. However, the combination of CRP and ZNC did not demonstrate significant synergies on yield improvement and root growth promotion. Further research is needed for the development and application of biostimulant enhanced fertilizer as a green environmental technology.

No-tillage and subsoiling increased maize yields and soil water storage under varied rainfall distribution: A 9-year site-specific study in a semi-arid environment

Abstract The application of conservation tillage with less soil disturbance appears to serve as an effective strategy to conserve water for crops. A site-specific field study was carried out in accordance with rainfall conditions to evaluate the influence of tillage methods on soil water regime, crop yield and water use efficiency for a semiarid region of the Loess Plateau in China. Three tillage methods including no-tillage, subsoiling, and plow tillage were tested from 2008−2016. Our results showed that the three tillage methods offer varying degrees of efficiency in conserving soil water and producing spring maize according to rainfall distributions. Compared to plow tillage methods, refraining from no-tillage increased soil water storage levels within the 0−200 cm layer by 7.1, 5.4, and 9.6% on an average in dry, normal and in wet years, respectively, subsoiling increased soil water storage levels by 5.1, 9.4, and 6.6% in dry, normal, and wet years, respectively. Improved soil water regimes secured by no-tillage and subsoiling respectively increased matter accumulation by 12.3% and 13.8% in dry years, by 12.3% and 18.6% in normal years, and by 13.9% and 9.2% in wet years. No-tillage and subsoiling respectively increased grain yields by 18.7% and 12.3% in dry years, by 2.9% and 8.8% in normal years, and by 9.1% and 7.9% in wet years relative to plow tillage. Consequently, water use efficiency levels achieved under the no-tillage and subsoiling methods were respectively increased on an average by 17.2% and 11.7% in dry years, by 3.1% and 8.5% in normal years, and by 9.3% and 6.0% in wet years. Hence, both the no-tillage and subsoiling methods could effectively improve soil water storage, thus significantly increasing yields and water use efficiency levels. With an increment of 10 mm of soil water storage, grain yield was increased up to 76.6 kg ha−1. The proposed method could have important applications in semiarid areas.

Evaluating the Effects of In situ Rainwater Harvesting Techniques on Maize Production in Moisture Stress Areas, Humbo Woreda, Wolaita Zone, Southern Ethiopia

This study was conducted to investigate the effect of some In-situ water harvesting techniques on production of maize with respect to soil moisture content, yield and yield components. It also aimed to assess farmers' perception of water conservation techniques. To achieve these objectives of the study, data were collected through house hold survey and field experiment. The experiment was conducted in Wolaita Zone Humbo Woreda at Abela Sippa kebele, which has an irregular rain fall distribution and has a prolonged dry season which leads to low soil moisture during critical crop growth stages. The study was conducted over a period of one growing season (2017/18) using maize as indicator crop at the farmers training center of the Abela Sippa kebele. The experiment was made in a randomized complete block design, with three replications and four treatments. The four treatments used in the study were; Control, Targa, Tieridge and Zai pits . Findings from this study revealed that maize grain yield and yield components, such as, grain yield, dry matter biomass, and cob length were significantly high (p&lt;0.05) at Targa treatments, but plant height was not significantly different. Soil-moisture content over the crop growing season at dry spell periods was significantly higher at Targa and Tie ridges than the control. Targa treatments increased maize yield to (7.15 t/ha), Tie ridge also significantly increased maize production to (6.19t/ha). Similarly, Zai pits yielded (4.5t/ha) and Control treatment yielded (4.9 t/ha). Targa and Tie ridge treatments recorded higher net returns (29712, and 25164 ha-1) than the Control (20370ha-1) and Zai (14350 ha-1) treatments. The results revealed that the rainwater harvesting technology by the community members was a good initiative in improving agricultural practices in periods of water scarcity. However, the utilization of the technology is affected by various constraints. The major constraints include: labor cost, lack of knowledge and types of crops planted on bunds. The findings suggest that Targa structure improved water availability during the growing season, thereby protecting crops from dry periods and it needs minimum cost, less labor power, and easily constructed by local farmers (not require complicated knowledge).

Simulating medium-term effects of cropping system diversification on soil fertility and crop productivity in southern Africa

Diversification of cropping is perceived as a strategy to simultaneously achieve high productivity and maintain environmental sustainability. In southern Africa, however, due to a lack of medium to long-term field trials, there is missing quantitative information. Utilising the capability of agro-ecosystem models to quantify the interactions of crop productivity with management and environmental variables, the APSIM model was evaluated against six and an eight-year field trial datasets comprised of different crop rotations and fertiliser rates under two contrasting agro-ecological conditions in South Africa (clay soil with a mean rainfall of 871 mm versus a sandy soil with a 570 mm rainfall). Model output was compared to observed grain yield, aboveground dry matter, soil organic carbon (SOC), and mineral nitrogen (Nmin) dynamics. APSIM was able to reproduce the observed grain yield dynamics fairly well as indicated by a Wilmott index of agreement of 0.90. Prediction accuracy, as indicated by the absolute model error across all crops, however, only reached 39%. Simulated Nmin and SOC dynamics showed similar patterns to the observations. Subsequently, the model was applied in a ten-year simulation experiment with rotation treatments (14 rotations, respectively intercropping systems, including a maize monoculture control), fertiliser levels (zero and 70 kg N ha−1), and residue management (retained and removed) for the two sites. For low input systems, such as smallholder farms, residue management and legume integration are of the utmost importance to maintain SOC and more pronounced Nmin levels, which, for the sandy soil, resulted in an average maize yield increase of up to 1000 kg ha−1. Maize monoculture treatments with residues removed reduced SOC moderately by 0.04–0.08 %, while yields declined strongly (>1000 kg ha−1) over the simulated period of ten years. In commercial, fertilised cropping systems, allocating land to cultivate crops other than maize reduced the simulated total yield performance. This diversification disadvantage has to be considered against the benefits of increased SOC and yields in the medium-term, i.e. a period of ten years. For the commercial systems, maize intercropped with delayed sown oats or cowpea appeared promising.

Tropical Bacillus Strains Inoculation Enhances Maize Root Surface Area, Dry Weight, Nutrient Uptake and Grain Yield

The rising demand for agricultural commodities in developing countries has put increasing pressure on land resources for higher yields, with associated growth in the demand for phosphate fertilizers. However, there are a number of adverse environmental impacts associated with the use of inorganic P fertilizers that is pushing global fertilizer prices up. In this context, phosphate solubilizing microorganisms, such as Bacillus, are the most eco-friendly and inexpensive option for enhancing P availability for plants, once they are capable of transforming insoluble P into soluble (plant accessible) forms and are regarded as plant growth-promoting microorganisms. This work aimed to understand the effect of tropical Bacillus strains on maize root morphology and growth using a hydroponic system and to evaluate their performance under two phosphorus fertilization conditions in the field. Maize root was inoculated separately with six Bacillus strains and grown in nutrient solution. Several root traits, dry weight and nutrient content were measured in maize seedlings. Moreover, we measured bacterial IAA-like molecules in vitro production and evaluated inoculated maize performance under field conditions with no P added (P0) and triple superphosphate (TSP) soil fertilization. All the Bacillus strains increased shoot and total dry weight and strains B2084, B119 and B32 had the greatest performance, producing the highest biomass, shoot nutrient content and root surface area compared to other strains in hydroponics. All strains that produced IAA-like molecules demonstrated a positive effect on plant growth by stimulating root elongation. In the field experiments, strain B116 inoculation increased maize yield and P grain accumulation by around 36% and 58%, respectively, and B119 increased P grain in 21% in soils with no P added. Even in soils fertilized with TSP, maize yield increase and P grain accumulation was around 20% after inoculation with these two strains comparing to non-inoculated control. Our results indicated that maize plants inoculated with Bacillus strains capable of producing IAA-like molecules and solubilizing phosphate, presented enhanced root system, dry matter and nutrient accumulation in hydroponics and higher yield and grain P content with and without addition of phosphate fertilizer under field conditions.

Can Innovation Platforms (IPs) Improve Rural Women Participation in Maize Value Chain? Evidence from the Eastern DR Congo

This study explored the potential of the Innovation Platform approach, in improving the participation of rural female farmers in Maize value chain. It intends to identify the peculiarities, in terms of challenges and opportunities related to its application to the rural women realities. The study collected data from 120 small scale maize producers in South Kivu province of the Democratic Republic of Congo (DRC) from 2015 to 2017, using individual interview and focus group discussion (FGD) for data confirmation. Data was analyzed using the Average Effect of Treatment of treated (ATT) and the propensity matching score to assess the effect of IP approach on rural women, who were randomly selected to participate in an innovation platform composed solely of women (100%) against those participating in a mixed innovation platform, made of 70% of men. The results show that the Innovation platform approach allowed women to address their basic challenges and improve their participation in the maize value chain. Average individual income from participation to the Innovation Platform increased from $ 100 to $ 300 per cropping season and the average earning of a women in a platform made of women solely was $552.6 higher than that of women participating in mixed platform $432.4. We hypothesized that the main benefits from the female IP would be increased maize yields. However, the analysis shows that although yield increased, the main effect was due to improved market access provided by the IP." The implementation of the innovation platform process encountered several challenges, in particular: building a consensus when the interests of the groups in place have proven to be divergent, the barrier of social consideration (social stereotype), inability of smallholder’s farmers to learn quickly and fully play expected role, the traditional culture of learning, visioning the process. Despite these challenges, IPs offered small-scale maize producers many technical, organizational and material opportunities, including income generation, access to inputs and to lucrative markets, acquisition of diversified knowledge and skills, ability to work in a commercial environment, benefiting from the services of experts, accessing new sources of financing, they could not benefit otherwise. These findings imply that to be effective for rural women, an innovation platform should include individuals with no wide social disparity and diversify the sources of income, including livestock and others off farm activities

Alternate furrow irrigation can maintain grain yield and nutrient content, and increase crop water productivity in dry season maize in sub-tropical climate of South Asia

Water scarcity is becoming a major constraint for maize cultivation and increasing maize yield globally. Water-saving irrigation methods are required to increase crop water productivity (CWP) without reducing grain yield and nutrient uptake. We evaluated the effects of different methods and levels of irrigation on crop dry matter, grain yield, nutrient uptake and CWP of maize (cv. ‘BARI Hybrid Bhutta-9′) in field condition in a sub-tropical environment in Bangladesh. The experiment was laid out in a nested plot design with three replications during 2014−15 and 2015−16. The treatments were three irrigation levels (I1: 100 % field capacity, FC; I2: 80 % FC; I3: 60 % FC) and three irrigation methods (AFI: alternate furrow irrigation; SFFI: skip-fixed furrow irrigation; and TFI: traditional furrow irrigation). Results indicate that both the irrigation method and level had significant effects on dry matter, grain yield, nutrient uptake, and CWP. The AFI technique maintained similar grain yield (8.1 t ha−1) to TFI but reduced irrigation water by 37 % for irrigation applied at 100 % of FC. Both AFI and TFI had significantly higher (p ≤ 0.05) grain yield compared to SFFI at the irrigation level of I2. The interactive effect of irrigation level and method also had a significant effect (p ≤ 0.05) on maize yield. The uptakes of macronutrients (N, P, K, S, Ca, and Mg) and micronutrients (B, Zn, Fe, and Mn) by maize grain were not significantly different between AFI and TFI under I1. Irrigation level was the main driver for determining the patterns in grain yield but irrigation method controlled the patterns in CWP. The AFI technique resulted in higher CWP compared to TFI or SFFI. Results demonstrate that AFI is an effective water-saving technique, which can increase the CWP without a significant reduction in grain yield and nutrients uptake by maize grain. The AFI method in conjunction with a reduced amount of irrigation water can be adapted in the sub-tropical climates of South Asia where maize production in the dry season is heavily dependent on repeated irrigation with limited water supplies.

Plastic Film Mulching Sustains High Maize (Zea mays L.) Grain Yield and Maintains Soil Water Balance in Semiarid Environment

Ridge–furrow cultivation with plastic film mulching has been widely used for many years to increase crop yields in semiarid regions. The long-term effects of plastic mulching on crop yield and soil water balance need to be seriously considered to assess the sustainability of this widely used field management technique. A seven-year maize field experiment was conducted during 2012–2018 to estimate the yield sustainability and soil water balance with two treatments—mulching (yes; no) and nitrogen fertilization (yes; no). This resulted in the following four groups—no film mulching, no N application (M0N0); film mulching, no N application (M1N0); no film mulching, N application (M0N1); film mulching and N application (M1N1). Our results show that plastic mulching significantly increased maize yield. A combination of mulching and nitrogen application had the highest sustainability yield index (SYI) of 0.75, which was higher than the other three treatments, with SYI values of 0.31, 0.33, and 0.39, respectively. Plastic film mulching increased soil water content and water storage in both the sowing and harvesting periods and did not cause the formation of dry soil layers. Precipitation storage efficiency (PSE) in the nongrowing season played a key role in maintaining the soil water balance and it was positively affected by plastic film mulching. Our research indicates that plastic mulching and N application could maintain maize yield sustainability and the soil water balance of agriculture in semiarid regions. In addition, we highlight the importance of nongrowing season precipitation, and thus, we suggest that mulching the field land with plastic film throughout the whole year should be adopted by farmers to store more precipitation, which is important to crop growth.

Degradability of biodegradable plastic films and its mulching effects on soil temperature and maize yield in northeastern China

Plastic film is an important resource in agricultural production, but it takes hundreds of years to degrade completely in natural environment. The large-scale use of plastic film will inevitably lead to serious environmental pollution. One way to solve the problem is to develop a substitutable mulching film, such as a biodegradable film that can ultimately be decomposed to water, carbon dioxide, and soil organic matter by micro-organisms. In this study, a 2-year experiment was conducted to determine the degradation properties of a biodegradable plastic film, including degradation rate, surface microstructure, tensile strength and elongation at break, and the effects of different mulching treatments on soil temperature and maize yield. The mulching experiment was conducted with three different biodegradable plastic films with different degradation rates, using a common plastic film and a non-mulched treatment as control. With the addition of the additives for degradation in the biodegradable plastic films, the degradation rates increased significantly, which were 7.2%-17.8% in 2017 and 18.1%-35.2% in 2018 after maize harvesting. However, the degradation occurred mainly on the ridge side. The decrease in tensile strength and elongation was proportional to the degradation rate of the degradable film. The SEM results indicated that the surface microstructures of the biodegradable films were loose and heterogeneous after maize harvesting. Biodegradable plastic film mulching increased the soil temperature at soil depths of 5 cm, 15 cm, and 25 cm, over the maize’s entire growth period, by 3.1°C-3.2°C in 2017 and 1.2°C-2.1°C in 2018 compared with the non-mulched treatment. The biodegradable plastic film increased the maize yield by 10.4%-14.3% in 2017 and 11.6%-24.7% in 2018. The soil temperature and maize yield increases were statistically significant; however, with respect to maize qualities, there were no statistically significant increases among the five treatments. This study shows that biodegradable plastic film can be used as a substitute for common plastic film. However, the ingredients in biodegradable plastic films should be improved further to ensure that they can be degraded completely after crop harvest. Keywords: biodegradable plastic film, film mulching, degradation properties, soil temperature, maize yield DOI: 10.25165/j.ijabe.20201302.5360 Citation: Zhang W W, Wang L H, Zhou J Q, Zhu K L, Sun S J. Degradability of biodegradable plastic films and its mulching effects on soil temperature and maize yield in northeastern China. Int J Agric & Biol Eng, 2020; 13(2): 146–153.

The Efficacy of Alternative, Environmentally Friendly Plant Protection Measures for Control of Fall Armyworm, Spodoptera Frugiperda, in Maize.

The invasive fall armyworm (FAW) is threatening maize production and the livelihoods of millions of smallholder farmers in the newly invaded areas in Africa and Asia. To control this new key pest and to overcome health, environmental, and resistance problems related to the indiscriminate use of insecticides, effective and sustainable alternative pest control approaches are needed. Here, we report on field trials that tested maltodextrin, neem-based products, ash, and soil, as well as the locally produced alata samina soap, in the Upper West and Greater Accra regions, Ghana. Significant reductions of larval numbers and crop damage, together with increased yields, were mostly achieved by applying the insecticide emamectin benzoate, which was considered the positive control in this set of trials. However, high efficiency and cost–benefit ratios were also achieved with two neem-based products. Maltodextrin was only efficient at one of the two sites, with a clear dose-dependent effect, while the higher dosage was nearly as effective as emamectin benzoate. Due to its relatively high product cost, maltodextrin is generally less cost-efficient. Ash and soil, as well as alata samina soap treatments, did not efficiently reduce FAW larval numbers or crop damage at the dosages tested; thus, they also did not significantly increase maize yields.

Evaluation of Popcorn Hybrids for Nitrogen Use Efficiency and Responsiveness

The global boom in agricultural production has been associated with the exponential increase of nitrogen (N) fertilizer application. This heavy use of nitrogen in agriculture has caused negative impacts on the environment. Therefore, new alternatives are needed to maintain or increase maize yield but reduce the environmental impact. For this purpose, one possibility is to plant N-use efficient (NUE) cultivars. In this context, the objective of this study was to identify popcorn hybrid cultivars that are highly NUE and N-responsive, bred from crosses between inbred lines with contrasting levels of N-use efficiency. For this purpose, 90 hybrids were evaluated in a 10 × 10 triple lattice design at two sites and two levels of N availability (low and ideal availability). The results indicated that for the environment with low nitrogen availability, the lack of nitrogen reduced the chlorophyll content, extended the interval between male and female flowering, and affected the performance of the tested hybrids. However, we observed the existence of hybrids with greater efficiency than the responsiveness to nitrogen and with high productivity. These can even be used on farms where the level of production inputs is low, thus contributing to ensure food security.

Interacting leaf dynamics and environment to optimize maize sowing date in North China Plain

Leaf growth and its interaction with the growing environment critically affect leaf area, distribution, and function, and ultimately affects grain yield of maize (Zea mays L.). To detect the effects of leaf area dynamics, growth periods, and the environment on maize grain yield, a three-year field experiment was conducted using two maize varieties, medium plant-size variety Zhengdan 958 (ZD958) and large plant-size variety Zhongnongda 4 (ZND4), and three to five sowing dates. The sowing date significantly affected maize yield as a result of changes in leaf area, growth stage, and growing environment. Prior to the 12th leaf stage, significant correlations between leaf area dynamics, environment, and yield were seldom detected. The expansion of leaf area from 12th leaf stage to silking stage was significantly positively correlated with growing degree days (GDD), solar radiation, and grain yield, indicating the importance of leaf area dynamics during this period. After silking, solar radiation played a more important role in inducing leaf senescence than GDD, particularly in the 2nd half of the grain filling stage. Accelerated leaf senescence in late growth period can increase maize yield. The environment affected leaf area dynamics and yield of the large plant-size variety (ZND4) more easily than the medium plant-size variety (ZD958) at the optimum plant density, reflecting the difference in varietal capacity to adapt to the growing environment. This study indicates that optimizing the interaction among leaf area dynamics, growth periods, and environment is a sound strategy to increase maize yield. Favorable interactions are useful to determine the optimal sowing date of a given variety.

May conservation tillage enhance soil C and N accumulation without decreasing yield in intensive irrigated croplands? Results from an eight-year maize monoculture

Intensive management of agroecosystems has been widely indicated as major responsible for soil degradation, thus negatively impacting on relationships between agriculture and climate change. Conservation tillage (i.e. no-till and minimum tillage) has been recommended for enhancing soil organic carbon (SOC) and total nitrogen (STN) stocks while having a positive impact on food security, biodiversity, water quality and the environment. Nevertheless, positive responses were mainly reported in hot and semiarid climates, with rainfed crops and low N fertilization rates.Therefore, the main objective of this study was to test the adoption of conservation tillage in intensive maize cropping systems under temperate soil, with high N fertilization rate (> 200 kg N ha−1 yr−1) and organic matter input (i.e. manure distribution and high biomass return), and with permanent optimum water moisture due to irrigation. We conducted an 8-year field experiment on a maize (Zea mays L.) monoculture to assess: (i) the effect of no-till (NT) and minimum tillage (MT), on grain yield and biomass return as compared with conventional tillage (CT); (ii) how tillage systems affect the evolution of SOC and STN levels over time under these conditions; (iii) soil aggregation processes and mechanisms leading to SOC and STN changes in the long-term. Results showed that MT increased maize grain yield (+7 %) and total biomass (+10 %) compared with CT. Conversely, NT reduced maize grain and biomass production during the initial 5-year transition, but afterwards increased maize yield up to that of CT.At the end of the experiment, SOC sequestration was increased under NT and MT by 1.45 and 1.52 Mg C ha−1 yr−1 compared with CT, respectively. Also, STN accumulation was higher under NT and MT than under CT (+0.15 and +0.17 Mg N ha−1 yr−1, respectively). Most of such a SOC and STN increase was located into C- and N-rich macroaggregates. Within those macroaggregates (large macroaggregates, LM; small macroaggregates, sM), we found that C and N pools associated to mM accounted for between 41 and 65 % of total C and N content in NT and MT systems across the different soil layers, which is beneficial for long-term C and N stabilization in soils. Thus, introducing conservation tillage within intensive agricultural context devoted to maize monoculture as that of the Po Valley should be recommended to: (i) maintain (or even increase) maize yield, and (ii) enhance SOC and STN accumulation and stabilization.