Main Maize Research Articles

Maize breeding effects on grain yield genetic progress and its contribution to global yield gain in Argentina

Context or problemMaize production in Argentina has increased in recent years, following the global gain (GG) in grain yield (GY). The GG in GY depends on genetic progress (GP), which requires frequent quantification to detect potential plateaus and variations in its contribution to the GG. In this sense, hybrid adoption in Argentina shifted from double- and three-way to single cross (F1) hybrids in the 1990s, thereby increasing the level of heterosis of released hybrids. Since heterosis increase may have had a greater impact on estimates of maize GG than those based on a single cross type, GP based exclusively on F1 hybrids and its contribution to GG could be lower than that including different types of crosses. Objective or research questionThe main objectives of this work were to (i) analyze grain yield GP, (ii) dissect grain yield GP into the corresponding trends in its physiological determinants and numerical components, and (iii) estimate the relative contribution of GP to GG in the main maize producing region of Argentina for the period marked by significant changes in heterosis level (i.e. from 1960s to 1990s) and the period of massive adoption of F1 hybrids (from 1990s onwards). MethodsWe used a dataset obtained at the core of the mentioned region (INTA Pergamino; 33°56’S, 60°34’W) from era-decade experiments (ERA) including 24 hybrids released between 1965 and 2016 and grown with no abiotic or biotic restrictions. We quantified GY, its numeric components (KN: kernel number m−2, KW: individual kernel weight) and its physiological determinants (BT: total shoot biomass at maturity, HI: harvest index). ResultsA GP of 0.84 % y−1 was computed for GY from 1965 to 1993, and of 0.51 % y−1 thereafter. We also detected genetic progress for KN (0.53 % y−1) and BT (0.26 % y−1) but not for KW. A GP of 0.66 % y−1 was computed for HI up to 1993, which plateaued thereafter. A 40 % contribution of GP to GG was estimated for the Pergamino site from 1965 to 1993, predominantly driven by changes in heterosis level. The contribution dropped to 32 % from 1993 onwards, when F1 hybrids were massively adopted by the farmers. This contribution was much smaller (e.g. 19 %) in areas less representative of the target population of environments of dominant breeding programs. ConclusionsOur findings underline that the relative contribution of GP to GY improvement at the regional level varies markedly depending upon the period included in the analysis and the environment used for evaluation. The decline observed at less representative locations of the main target population of environments may guide breeders in their decision for developing new programs.

Farmers’ Perceptions of Maize Production Constraints and the Effects of Push–Pull Technology on Soil Fertility, Pest Infestation, and Maize Yield in Southwest Ethiopia

This study aimed to analyze farmers’ perceptions of maize production constraints and determine the effects of push–pull technology (PPT) on crop yield, pest control, and improving soil fertility status. Increasing fertilizer prices and pesticide prices, FAWs (fall armyworms) and stemborers, declining soil fertility, and drought are the main maize production constraints in the area. Seventy percent of the respondents indicated that an increase in input prices such as those of fertilizer and seeds is the major constraint in the area, while FAWs (55%) and stemborers (44.3%) were ranked the third and fourth major constraints. About 67% of farmers reported that stemborer damage to maize in PPT plots was either minimal or non-existent. Fifty-five percent of farmers stated that the damage caused to maize by FAWs was low or that there was no damage in PPT plots. PPT reduced stem borer infestation from 83% to 44%. The yield gained from PPT plots ranged from 18% to 31%. Soil samples taken from PPT plots showed improved soil organic carbon, organic matter, total nitrogen, and cation exchange capacity.

Economics of maize cultivation at selected intensive areas of Bangladesh

The study was undertaken to assess the input used pattern and profitability of maize in selected intensive maize-growing areas of Bangladesh from February to July 2019. The present study was conducted in four districts viz. Chuadanga, Jhenaidah, Meherpur and Kushtia were located at AEZ-11, an intensive maize-growing area. In this study, 160 farmers were selected, of which 40 from each district were randomly selected for data collection. The average farm size was 0.64 ha, whereas the maize cultivated area was 0.34 ha. It was observed that maize was cultivated from November to December in the study area. The average per hectare seed required was 20 kg ha-1 and the fertilizer requirement was 1532 kg ha-1. The average labor required was 275 man-days in a season due to less use of technology. Total production cost was Tk. 162047 ha-1, in which variable cost was Tk. 101066 ha-1 (62%) and the fixed cost was Tk. 60980 ha-1 (38%). The price of the main maize grain at Farmgate was Tk. 18 kg-1. The gross margin was Tk.1 91962 ha-1 and the net margin was Tk. 40515 ha-1 average. The benefit-cost ratio on a cash-cost basis was 1.90 and on a total-cost basis was 1.18, meaning maize cultivation was profitable. Land preparation, seed, organic manure, TSP, Urea, MoP, DAP, Gypsum, Zinc and Boron had a positive influence on maize production. The high price of fertilizer and seed was the main problem farmers faced and due to high demand, there were no marketing problems. Though it had some problems, maize cultivation overall was a profitable crop. Int. J. Agril. Res. Innov. Tech. 13(2): 70-78, Dec 2023

Effects of Intercropping on Maize and Soybean Yield Performance, Land Equivalent Ratio, and Maize Leaf Area in Conservation Agriculture

Maize-soybean intercropping systems as a conservation farming practice are receiving increased focus from the scientific community. This is because of the advantages of intercropping, especially nutrient benefits through cereal-legume interactions, alternative sustainable methods to manage biotic stress (pests, diseases, weeds), and crop failure risk management due to erratic weather. In addition, smallholders in developing countries commonly use intercropping to produce crops. In Uganda, 40% of smallholder farmers are practicing intercropping yet no adequate location-specific information is available to inform their practice. Farmers who adopted conservation farming practices did not mulch their maize due to drudgery associated with collecting mulch. This study evaluated the effect of two tillage methods (T1 = Conventional tillage using ox drawn mould board plough, T2 = Minimum tillage using ox drawn ripper) and five soil cover practices (SC1 = Mulched Maize, SC2 = Control no mulch, SC3 = Two rows of soybean in between one row of maize, SC4 = One row of soybean in between one row of maize, SC5 = Sole soybean) on maize and soybean yield performance. The trials were established for 4 rainy seasons on a sandy loam ferrosol at National Agricultural Research Organization Institute in Lira, Uganda. Soil cover practice had a significant effect on maize and soybean crop Yield. Mulching significantly increased maize yield and LAI. The LER for both intercropping partterns were above 1.2. Tillage methods were not significantly different in determining crop performance. The practice of minimum tillage should also be adopted because it enhances the positive effects of soil cover (intercropping). We recommend farmers to adopt the intercropping pattern of one row of soybean in between maize row spaced at 75 × 30 cm for better LER, and crop performance. This intercropping pattern maximizes on available resources to deliver better output in conservation farming. Maize crop generally performed better during first season as compared to second season. We recommend farmers to utilize the first rains as the main maize production season.

Physiological Effects of Microbial Biocontrol Agents in the Maize Phyllosphere.

In a world with constant population growth, and in the context of climate change, the need to supply the demand of safe crops has stimulated an interest in ecological products that can increase agricultural productivity. This implies the use of beneficial organisms and natural products to improve crop performance and control pests and diseases, replacing chemical compounds that can affect the environment and human health. Microbial biological control agents (MBCAs) interact with pathogens directly or by inducing a physiological state of resistance in the plant. This involves several mechanisms, like interference with phytohormone pathways and priming defensive compounds. In Argentina, one of the world's main maize exporters, yield is restricted by several limitations, including foliar diseases such as common rust and northern corn leaf blight (NCLB). Here, we discuss the impact of pathogen infection on important food crops and MBCA interactions with the plant's immune system, and its biochemical indicators such as phytohormones, reactive oxygen species, phenolic compounds and lytic enzymes, focused mainly on the maize-NCLB pathosystem. MBCA could be integrated into disease management as a mechanism to improve the plant's inducible defences against foliar diseases. However, there is still much to elucidate regarding plant responses when exposed to hemibiotrophic pathogens.

Invasions and Local Outbreaks of Four Species of Plague Locusts in South Africa: A Historical Review of Outbreak Dynamics and Patterns.

The current paper provides a detailed review of the historical outbreaks of each of the four plague locust species found in South Africa, namely the brown locust, the African migratory locust, the red locust, and the southern African desert locust. The history and dynamics of the plague infestations and the major local outbreaks are summarized. The typical patterns of the outbreaks of the different species are described, and the threat of these locusts to agriculture in South Africa is defined. The brown locust produces regular outbreaks in the semi-arid Karoo, with large-scale eruptions of plague proportions occurring about once per decade. Patterns of outbreaks often repeat themselves, but the sheer size of the plague outbreaks is almost impossible to stop, and the brown locust has the potential to threaten food security throughout southern Africa. The African migratory locust produces outbreaks in some of the main maize and wheat cropping areas where it is difficult to control. This locust has taken advantage of the man-made crop environment to produce an extra generation per year that was not previously possible in the original grasslands. The coastal area of KwaZulu Natal Province in South Africa was a prime reception and breeding area for plague invasions of the red locust in the past, and the country, therefore, relies on the successful control of outbreaks in east and central Africa to prevent the recurrence of the plague invasions. The southern African desert locust occurs in the Kalahari Desert area, and outbreaks requiring chemical control are rare.

Evaluation of downscaling seasonal climate forecasts for crop yield forecasting in Zimbabwe

Meteorology and weather forecasting are crucial for water-limited agriculture. We evaluate the added value of downscaling seven-months global deterministic seasonal forecasts from the Climate Forecast System version 2 (CFSv2) using the Weather, Research and Forecasting (WRF) model over Zimbabwe for ten growing seasons (2011–2021). Downscaling reduces the area of significant differences between forecasted and observed total seasonal rainfall. Downscaling also improves the score for droughts as measured through the standardized precipitation index and 3-class method. Yield forecasts by the WOrld FOod STudies (WOFOST) model reveal that downscaling improves the estimated growing season evolution and maize yield in all studied regions across the country. For the main maize production region Karoi, the bias, root mean square error, mean absolute error and mean absolute percentage error reduce by 33% (0.2 ton/ha), 27% (0.4 ton/ha), 31% (0.4 ton/ha) and 27% (8.3 %) respectively by downscaling. Hence we illustrate that downscaling the deterministic seasonal forecasts may assist in food security in a crucial area in southern Africa.

Multi-mycotoxins analysis in post-harvest maize (Zea mays L.) grain from major producing areas of Ethiopia

Mycotoxins are the most notorious compounds contaminating food crops in the production chains, in which cereals and nuts are primarily infected. The present study was aimed at determining multi-mycotoxins in maize grain samples collected at post-harvest stages across the main maize producing districts of Ethiopia. Then, 80 maize samples were collected from three districts (Bako, Ilu Gelan and Oda Bultum) and were analysed by LC-MS/MS. A total of 114 metabolites were withPenicillium andAspergillus metabolites being positively identified in 26.3 and 18.4% of the samples, respectively. Among the mycotoxins addressed by regulatory limits, deoxynivalenol was detected in 85% of samples with the maximum level of 2,530 μg/kg, while zearalenone was detected in 81%, with levels as high as 3,750 μg/kg. A marked difference was observed across the study locations in the study areas, in which significant difference (P<0.005) of mycotoxin contamination recorded. For instances, of the total sample, contamination was detected on 78.1% in Oda Bultum followed by Ilu Gelan which was detected on 73.7% of the total samples with less proportion of contaminated from Bako district (68.4%). Different mycotoxins of regulated, binding or masked and emerging mycotoxin were also simultaneously detected in the samples. Intervention strategies which can reduce mycotoxin contamination along the maize value chains are required to combat the mycotoxin problems. Further, multi-season studies over multiple agro-ecologies are suggested for the county.

Potential Effect of DIMBOA (2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one) on Alleviating the Autotoxic Coumarin Stress in Alfalfa (Medicago sativa) Seedlings.

The allelopathic theory has garnered considerable attention in the field of agricultural production for its efficient plant protection, rapid crop yield increase, and scientific establishment of the crop rotation system. To study the effects of the main maize allelochemical DIMBOA (2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one) on the growth and development of alfalfa under autotoxic coumarin stress, we treated alfalfa seedlings with DIMBOA under coumarin stress and non-stress conditions in this study. Results show that 0.0342 mM coumarin significantly inhibited alfalfa seed germination percentage(Gp), germination potential(GP), radicle length, germ length, seeding height, and simple viability index (SVI), with decreases of 37.29%, 59.91%, 7.60%, 30.90%, 13.27%, and 45.70%, respectively. An amount of 0.6 mM DIMBOA could promote alfalfa seed Gp, GP, radicle length, germ length, seeding height, dry fresh ratio, and SVI, with increases of 12.38%, 23.91%, 48.69%, 48.65%, 48.68%, 295.12%, and 67.17%, respectively. However, the addition of DIMBOA under conditions of coumarin stress could effectively alleviate coumarin effects on alfalfa seedlings. Coumarin + DIMBOA treatment for 24 h mainly decreased reactive oxygen species (ROSs) and malondialdehyde (MDA) as well as soluble protein and soluble sugar, increasing some antioxidant enzyme activities and antioxidant content to alleviate the oxidative damage of alfalfa caused by coumarin stress. Administration of treatment for 72 h significantly promoted the morphological development of alfalfa seeding roots. Administration of treatment for 96 h significantly enhanced the photosynthetic capacity of alfalfa seedlings. The results of principal component analysis demonstrated that chlorophyll b(Chl b)and net photosynthetic rate(Pn) were the key indicators for coumarin + DIMBOA treatment to promote photosynthesis in alfalfa seedlings. Additionally, root length, mean root diameter, and root volume were the key indicators of root growth and development. Coumarin + DIMBOA treatment primarily increased catalase(CAT), peroxidase (POD), and ascorbate peroxidase (APX) activity and antioxidants(ASA) while reducing MDA and superoxide anion radical(O2•-). This study strongly suggested that DIMBOA can effectively improve the tolerance of alfalfa seedlings to coumarin stress through a combination of effects on root morphology, photosynthesis, and physiological indicators.

Predictive and estimation model of Cd, Ni, and Zn bioaccumulations in maize based on diffusive gradients in thin films

Consumption of maize contaminated with heavy metals such as cadmium, nickel, and zinc threaten human health. For situ measuring the bioavailability of heavy metals, the diffusive gradients in thin films (DGT) is superior to other traditional methods. It is also important to find a method for predicting heavy metal enrichment in maize based on the DGT method. In this study, field surveys were conducted in the main maize producing areas of Tianjin, China. Heavy metal concentrations in maize grains were predicted by coupling DGT with traditional extraction methods. The results show that coupling DGT with soil solution can significantly improve prediction accuracy (Cd-R2 = 0.908, Ni-R2 = 0.903, and Zn-R2 = 0.904). This indicated that DGT and soil solution were feasible predictors of heavy metal concentration in maize. The DGT induced fluxes in soil/sediment (DIFS) model was used to simulate the uptake process of heavy metals by DGT, and better reveal the desorption processes of heavy metals in soils. DIFS-based desorption processes were employed to characterize the resupply ability of heavy metals in soils. The coupling of DGT and DIFS parameters provided the best prediction accuracy in this study (Cd-R2 = 0.920, Ni-R2 = 0.928, and Zn-R2 = 0.908). Predictions are slightly weaker for Zn than for Cd and Ni (Cd-P < 0.01, Ni-P < 0.01, and Zn-P < 0.05). The reason is that the average resupply type of Cd and Ni in soil is partially sustained while Zn is resupplied via diffusion only. The desorption rate k−1 can excellently improve the prediction accuracy of DGT, which avoids the disadvantage that soil solution does not consider desorption. The coupling of DGT and DIFS parameters provides an accurate and reliable method for predicting heavy metal enrichment in maize.

Epicoccum spp. Causing Maize Leaf Spot in Heilongjiang Province, China.

Maize leaf spot occurs worldwide and affects maize production. Maize can be infected by several pathogens causing leaf spot, such as Bipolaris zeicola, Bipolaris maydis, Curvularia species, Alternaria species, etc. In the current study, 30 Epicoccum isolates recovered from symptomatic maize leaves were identified based on morphological characteristics, pathogenicity, and multilocus sequence analyses of nuLSU, ITS, tub2, and rpb2. These maize isolates were grouped into five Epicoccum species, including E. nigrum, E. layuense, E. sorghinum, E. latusicollum, and E. pneumoniae. Pathogenicity tests showed that all five Epicoccum species could produce small ellipse- and spindle-shaped spots on maize leaves. The lesion center was grayish yellow to dark gray and surrounded by a chlorotic area. Furthermore, the Epicoccum isolates exhibited high pathogenicity to 20 main maize varieties of Heilongjiang Province but showed different sensitivities to the commonly used fungicides carbendazim and tebuconazole. In addition, these Epicoccum isolates showed different production capacity of pectinase, cellulase, protease, amylase, laccase, and gelatinase, but all showed high lipase activity. This is the first report globally of E. layuense, E. latusicollum, and E. pneumoniae as causal agents of maize leaf spot. E. pneumoniae was first reported as a plant pathogen.

Agricultural Economic Resilience in the Context of International Food Price Fluctuation—An Empirical Analysis on the Main Grain–Producing Areas in Northeast China

In the context of international food price fluctuations, agricultural economic development is usually subject to large shocks, which also leads to clear spatial–temporal differentiation in regional agricultural economic resilience. However, there is a paucity of retrievable studies on the evolutionary process of agricultural economic resilience and its impact mechanisms. Taking the impact of and disturbance caused by international food price fluctuations on the agricultural economy from 2005 to 2021 as the research background, this paper adopts the economic resilience analysis framework and selects gross agricultural output value indicators to measure the agricultural economic resilience of 12 cities in the main grain-producing areas in Northeast China–Sanjiang Plain and Songnen Plain. At the same time, the regression model is used to further analyze the spatial and temporal changes of agricultural economic resilience and the main influencing factors. Based on the results of the research, it can be concluded that: ① international food prices exert different degrees of influence on agricultural economic resilience at different stages. From 2005 to 2013, the agricultural economic resilience of the two plains changed less, and the resilience capacity performed better in both the period of falling and rising international food prices, while from 2014 to 2021, the agricultural economic resilience of the two plains changed more due to the great impact of international food price fluctuations, with a steep decline in resilience capacity in the period of falling international food prices from 2014 to 2017, followed by a rapid rebound between 2018 and 2021. ② There are differences in the resilience capacity of the agricultural economy in the main maize- and rice-producing areas. Although it is a fact that agricultural economic development in the two major plains is faster than the national average in most periods, the comparison reveals that the main corn-producing area (Songnen Plain) is more volatile and its resilience capacity is relatively weak in both periods of falling and rising food prices, while the main rice-producing area (Sanjiang Plain) is less volatile, indicating its relatively strong agricultural economic resilience capacity. ③ Factors affecting agricultural economic resilience behave differently over the three cycles. During the period of rising international food prices, indicators reflecting agricultural production capacity have a greater impact on agricultural economic resilience, while during the period of falling international food prices, indicators reflecting agricultural input intensity and agricultural support capacity have a greater impact on agricultural economic resilience.

Impact of climate variability on grain yields of spring and summer maize

Crop yield is greatly impacted by climate change, and a systemic assessment of its impacts on crop yields is essential. Aiming to investigate the impact of climate change on spring and summer maize yields in main maize growing areas of China, the observed meteorological and maize yield data over 1988–2017 at the 121 sites (including 85 sitess for spring maize and 36 sites for summer maize) in main maize growing areas of China were collected. The first-order difference, Sen’s slopes and trend test, multi-collinearity detection, Pearson correlation, stepwise linear and nonlinear regression methods were used, and the best statistical regression models between maize yield and climate variables have been established. Of these, the Sen′s slopes quantify the trend magnitude of the related climate variables and spring/summer maize yields during maize growth period. The Pearson correlation coefficients assess the relationship between pairs of climatic variables and maize yields, while the multi-collinearity analysis determines the mutually independent climatic variables with maize yields. The stepwise multi-variate linear and nonlinear regressions were conducted to obtain the best functions of the one-order-differences of spring (summer)maize yields at the 85 (36) sites. The results indicated that: (1) Generally, the precipitation and temperature during growth seasons was rising, while relative air humidity and sunshine hours was declining. Both the yields of spring and summer maize showed increasing trends. (2) Spring maize yields were more related to relative humidity, sunshine hours and precipitation, while summer maize yields were more related to precipitation and temperature. (3) The multivariate nonlinear functions performed better than the linear relationship. Based on the coefficient of determination, climate change has explained 5.8–87.6% variability of spring maize yield and 6.6–78.5% variability of summer maize yield. (4) The contribution importance rank of climate variables to yields of spring and summer maize was precipitation > relative humidity > sunshine hours > minimum temperature > maximum temperature > average temperature. The wet-cold and wet-warm climate, especially the former, had positive effects on maize yield. In conclusion, climate variables affect spring and summer maize yields and their best relationships were site-specific in China. Our research provides new insights for maize planting management under climate change.

Variables related to microwave heating-toasting time and water migration assessment with kernel size approaches of specialty maize types.

Three main maize types with specialty kernels are used to make ready-to-eat maize by traditional toasting, and microwave toasting may be an innovative application. However, little is known of the toasting process of these Andean maize types. Therefore, the present study aimed to explore the behavior of a broad scope of variables in these maize types. The kernels were packed in sealed paper envelopes and subjected to six microwave heating-toasting times from 0 to 390 s. Subsequently, with actual kernel size approaches, water content (WC), water ratio (WR), and water loss (WL) were analyzed. In addition to WC, WR, and WL, the surface area (S), volume (V), and geometric mean diameter (GMD) behaved like time-related variables with a high correlation depending on the maize types and kernel dimensions. Thus, the WC, WR, and WL third-order polynomial regression curves computed with the spatial (S/V)2 and distance (GMD/2)2 approaches indicated the water variation at each microwave heating-toasting time with a clear difference among maize types a0, a1, and a2. Regarding their exchange profiles without and with the spatial (S/V)2 approach, the maximum rates showed significant differences between maize types and WC and WL. Likewise, the maximum rates displayed significant differences between the spatial (S/V)2 and distance (GMD/2)2 approaches, revealing a notable lack of consistency with the distance (GMD/2)2 approach. The kernel size approaches revealed that water migration rates depended on differences in maize types. Such basic information represents the first insight into more physical-based models of water diffusion during raw microwave maize heating-toasting. © 2022 Society of Chemical Industry.

Complex drought patterns robustly explain global yield loss for major crops

Multi-purpose crops as maize, rice, soybean, and wheat are key in the debate concerning food, land, water and energy security and sustainability. While strong evidence exists on the effects of climate variability on the production of these crops, so far multifaceted attributes of droughts—magnitude, frequency, duration, and timing—have been tackled mainly separately, for a limited part of the cropping season, or over small regions. Here, a more comprehensive assessment is provided on how droughts with their complex patterns—given by their compound attributes—are consistently related to negative impacts on crop yield on a global scale. Magnitude and frequency of both climate and yield variability are jointly analysed from 1981 to 2016 considering multiscale droughts, i.e., dry conditions occurring with different durations and timings along the whole farming season, through two analogous and standardized indicators enabling comparison among crops, countries, and years. Mainly winter wheat and then spring wheat, soybean and the main maize’s season reveal high susceptibility of yield under more complex drought patterns than previously assessed. The second maize’s season and rice present less marked and more uncertain results, respectively. Overall, southern and eastern Europe, the Americas and sub-Saharan Africa presents multi-crop susceptibility, with eastern Europe, Middle East and Central Asia appearing critical regions for the most vulnerable crop, which is wheat. Finally, yield losses for wheat and soybean clearly worsen when moving from moderate to extreme multiscale droughts.

HISTORY, DEVELOPMENT AND MARKET OF MAIZE CULTIVARS WITH LOW SEED COST IN BRAZIL

Maize is one of the cereal crops most produced on the planet. It constitutes one of the species of greatest economic interest and provides multiple products, with applications in diverse sectors, from animal feed to industrial products and even human food. More and more companies that represent this segment release genetically modified maize hybrids as a manner of ensuring return on investment, decreasing the supply of conventional (non-transgenic) cultivars available on the market. Seed is one of the main components of the cost of maize production. Thus, farmers that obtain lower yield are not able to afford to pay the relatively high costs of the high technology hybrid seeds or to improve their production system, but it is possible to obtain satisfactory results through lower seed investments. Intervarietal hybrids may represent an alternative for meeting the needs of small and medium-sized farmers, with fewer resources for investments in inputs and seeds, and for supplying varieties that meet the needs of the small maize grower. This review presents a history of conventional maize breeding in Brazil and describes the main maize cultivars with low-cost seeds developed by public R&D companies, mainly focusing on the Instituto Agronômico (IAC) as an option for small and medium-sized maize growers in Brazil.

The effect of strip orientation and width on radiation interception in maize–soybean strip intercropping systems

AbstractMaize–soybean intercropping systems are widely used in developing countries, but few studies have been performed to optimize such systems. The effects of strip width and orientation on photosynthetically active radiation (PAR) distribution characteristics were therefore determined to gain a better understanding of crop productivity in maize–soybean intercropping systems. A series of intercropping experiments incorporating different strip orientations and widths were conducted. In addition, an improved radiation transmission model was used to simulate PAR interception by the maize and soybean crops. We found that more PAR was intercepted by the soybean plants than by the maize plants when the strip orientation angle increased from 0° to 90° in the maize–soybean intercropping systems. This result was obtained in most of the main maize production areas, including those with different latitudes. The effect of strip widths within the intercropping systems also had a significant effect on PAR interception. The relative fraction of PAR intercepted ranged from 39.4% to 86% for soybean and 105.8% to 169.3% for maize. The effect of soybean strip width on leaf PAR interception was greater than that of maize strip width. These results are not only of fundamental biological importance but they also have important implications for agriculture in terms of the optimization of production in intercropping systems.

Biodiversity and Distribution of &amp;lt;i&amp;gt;Aspergillus&amp;lt;/i&amp;gt; and Their Toxins in Maize from Western and Eastern Regions of South Africa

Aspergillus species and aflatoxins production are more prevalent during times of high heat and drought. In South Africa, there is frequent occurrence of drought as a result of climate change. The aim of this study was to investigate the biodiversity and distribution of Aspergillus species with their corresponding toxins in maize from main maize producing regions of South Africa; [Western Regions (WR) and Eastern Regions (ER)]. One hundred and twenty-three (64 from WR and 59 from ER) maize samples from the two agro-climatic regions in South Africa were analyzed using cultural, molecular and analytical methods. Across agro-climatic regions, Aspergillus species contaminated about 62% of the maize samples, while Aspergillus flavus was the most prevalent (47.15%) followed by Aspergillus fumigatus (4.69%) while the least was Aspergillus parasiticus (0.81%). The Western Regions showed a higher distribution of varieties of Aspergillus species compared to the Eastern Regions. Aflatoxins contaminated only 27.64% of the maize samples with a mean total aflatoxin concentration of 2.40 μg/kg which is below the South Africa’s set standard for total aflatoxin in food (5 μg/kg). About 10.57% of the samples produce aflatoxins above the 5 μg/kg permissible limit for total aflatoxin in foods. The ratio of toxigenic to atoxigenic strains of Aspergillus flavus was generally low in all the regions of South Africa. This study could aid policy makers to make informed decisions in developing remediation strategies for Aspergillus mycotoxins.

辽宁省玉米旱灾时空分布特征及综合风险评价

PDF HTML阅读 XML下载 导出引用 引用提醒 辽宁省玉米旱灾时空分布特征及综合风险评价 DOI: 10.5846/stxb202011112912 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（52079060）；辽宁省兴辽英才项目资助；辽宁省教育厅自然科学项目（LQ2020026）；2021年大连市科技之星项目（2021RQ101） Spatio-temporal distribution characteristics and comprehensive risk assessment of maize drought disaster in Liaoning Province Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以辽宁省气象数据、空间数据和田间管理数据集为基础，首先，依据自然灾害风险形成理论，从危险性、脆弱性、暴露性和防灾减灾能力四因子入手，选择10个副指标，构建辽宁省玉米旱灾综合风险评价指标体系，并利用组合加权法和GIS空间分析方法，确定其权重及区域化。利用自然灾害风险指数法和加权综合评价方法，建立辽宁省玉米旱灾综合风险评价模型，并进行了辽宁省玉米旱灾时空分布特征分析及综合风险评价研究。结果表明：（1）自1960年以来，研究区干旱频率总体呈上升趋势，尤其2010年以后有明显增加态势。其中1970-1979年间干旱发生频率较低，2010-2019年间干旱频率最高。不管是月尺度、季节尺度、生长季尺度还是年际尺度，辽宁省西北部干旱频率普遍较高，而东南部干旱频率较低。干旱强度呈现从辽宁省中部地区向东西地区两个方向递减的趋势，高值出现在辽宁省中部的阜新、锦州、铁岭、辽阳、盘锦、鞍山、营口和大连等地。干旱历时从辽宁省东部向西部区域递减的趋势，其中高值出现在铁岭北部、盘锦、鞍山、营口和丹东南部等地，低值分布在朝阳西南部、葫芦岛西北部、本溪西部和丹东等地。（2）从4个因子角度来说，辽宁省朝阳西部和葫芦岛西北部玉米旱灾危险性指数较低以外其他区域玉米旱灾危险性指数均较高。然而，辽宁省西北玉米主产区玉米旱灾脆弱性指数和暴露性指数均较高，且防灾减灾能力较低。当4个因子加权综合评价时，辽宁省西北部玉米旱灾综合风险呈现较高的现象。研究结果可为保障辽宁省粮食安全及制定防灾减灾政策提供理论依据和科学指导。 Abstract:First, according to the theory of natural disaster risk formation, starting with the four factors of hazard, vulnerability, exposure and emergency response & recover capability, 10 sub-index were selected to establish the comprehensive risk evaluation index system of maize drought in Liaoning Province, based on meteorological data, spatial data and field management data. Second, the combined weighting method was used to determine the weight of each index in the evaluation index system, and each index was spatially processed according to the GIS space analysis methods. Finally, the natural disaster risk index method and weighted comprehensive evaluation method were used to establish the comprehensive risk evaluation model of maize drought in Liaoning Province. At the same time, based on the evaluation model, this paper analyzed the temporal and spatial distribution characteristics of maize drought in Liaoning Province, and further studied the comprehensive risk evaluation of maize in Liaoning Province. The results showed that:(1) The drought frequency in the study area has been increasing since 1960, especially after 2010. Among them, the frequency of drought in Liaoning Province was low from 1970 to 1979, but reached the highest from 2010 to 2019. No matter what the research scale (monthly scale, seasonal scale, growing season scale or inter annual scale) it was,the drought frequency was higher in the northwest of Liaoning Province, but lower in the southeast. The drought intensity of Liaoning Province had a decreasing trend from the middle to the East and West, and areas with high drought intensity were mainly concentrated in the middle of Liaoning Province (eg.Fuxin, Jinzhou, Tieling, Liaoyang, Panjin, Anshan, Yingkou and Dalian). The duration of drought in Liaoning province gradually decreased from east to west, and areas with high drought duration mainly appeared in the north of Tieling, Panjin, Anshan, Yingkou and the south of Dandong, while areas with low drought duration mainly appeared in the southwest of Chaoyang, the northwest of Huludao, the west of Benxi and Dandong. (2) From the perspective of four factors of drought disaster hazard, vulnerability, exposure and emergency response & recover capability, except that the drought hazard indexes of maize in the west of Chaoyang and the northwest of Huludao were low, the drought hazard indexes of maize in other regions were high in Liaoning Province. However, as the main maize producing area in Liaoning Province, the northwest of Liaoning Province had high vulnerability index and exposure index of drought disaster, but its emergency response & recover capability was relatively low. Therefore, under the weighted comprehensive evaluation of four factors, there was a high risk of drought disaster in the northwest of Liaoning Province. The research results can provide theoretical basis and scientific guidance for the formulation of policy on agricultural disaster prevention and mitigation in Liaoning Province. 参考文献 相似文献 引证文献

Nanoparticles in inhibiting Pantoea ananatis and to control maize white spot

ABSTRACT: Maize white spot (MWS) caused by Pantoea ananatis is one main maize leaf diseases, and nanoparticles (NPs) are an innovative approach for bacterial disease control. This research evaluated the toxicity of pure NPs and doped NPs with different elements in inhibiting bacterial growth and to control MWS. Pure NPs and ZnO NPs doped with silver (Ag), gold (Au), copper (Cu), iron (Fe), manganese (Mn), and nickel (Ni) at different concentrations were used to determine the toxicity for P. ananatis in vitro, evaluating the bacterial growth inhibition zone. To assess the control of MWS, in the preventive application, maize plants were sprayed with NPs of ZnO:0.1Cu, ZnO:0.05Fe, ZnO:0.2Mn and ZnO:0.7Ni at 10, 5 or 2.5 mg mL-1, and after 3 days, the plants were inoculated with bacterial suspension. To assess the curative application, plants were inoculated with the bacteria, and 3 days later sprayed with the NPs. The disease severity was assessed and the area under the disease-progress curve (AUDPC) was calculated. The doped ZnO NPs with different elements, and at different concentrations inhibited bacterial growth in vitro. NPs of ZnO:0.1Cu and ZnO:0.2Mn at 5 or 2.5 mg mL-1, in both applications reduced the severity of MWS, showing potential for use in the disease management.