Maize Growth Responses to a Humic Product in Iowa Production Fields: An Extensive Approach

Field evaluations of commercial humic products have seldom involved replication across location or year. To evaluate the consistency of humic product efficacy in field conditions, we determined the effects of a humic product on maize (Zea mays L.) growth in high-yielding Midwestern (US) fields through the following two extensive approaches: (i) replicated strip plots in five site—year combinations from 2010 to 2013; and (ii) demonstration strips in 30–35 production fields annually from 2009 to 2011 that covered major areas of Iowa. Mechanized combine measurements of grain yield showed increases of 0.2–0.4 Mg ha–1 (1–4%) with humic product application for all five site—year combinations of the replicated strip plots. Six of 10 humic treatments within the fields responded positively (P < 0.07), and the positive responses of two more treatments approached significance at the benchmark of P = 0.10. In the demonstration strips, maize grain weight in hand-collected samples increased significantly (P < 0.004) with humic product application in each of the three growing seasons, and across all the three seasons by 6.5% (P < 0.001). Grain weight increased numerically for 76 of the 98 demonstration strips. Yield component analysis for both the replicated strip plots and the demonstration strips attributed the yield boosts largely to increased ear length, especially of the shorter ears. Humic product application caused significantly (P < 0.10) greater total leaf area in all eight field treatments at three site—year combinations. Humic product application did not consistently affect nutrient concentrations of the grain or stover or any measured soil property. These results represent among the widest geographic evaluations published on field efficacy of a humic product. They demonstrate the capability of a humic product to improve maize growth in high-yielding conditions.

Comparative effect of fertilization on cocoyam and component crops on Cocoyam-based intercropping systems in Uyo, Southeastern Nigeria

Field experiment was conducted at University of Uyo Teaching, research farm during the 2018 and 2019 cropping seasons to assess the effect of fertilization on cocoyam-based intercropping systems. The experiment was laid out in a randomized complete block design with three replications. Treatments were six fertilizers rates - 0kg/ha, NPK200kg/ha, NPK400kg/ha, PM2.5t/ha, PM5.0t/ha, Mixture (NPK200kg/ha + PM2.5t/ha) and six crop mixtures - Sole Cocoyam, Sole Melon, Sole Maize, Cocoyam + Maize, Cocoyam + Melon and Cocoyam + Melon + Maize). Result analysed with analysis of variance revealed PM2.5t/ha, NPK400kg/ha and Mixture (NPK200kg/ha + PM2.5t/ha) gave higher plant height, leaf area, stem girth in sole cocoyam, maize and melon respectively. PM2.5t/ha favoured leaf area, stem girths of cocoyam, maize with cocoyam + maize, cocoyam + melon and cocoyam + melon + maize crop mixtures. PM5.0t/ha gave higher values of corm, cormels, cormels weight, cormels number and cormels length in both sole cocoyam and mixtures (cocoyam + melon, cocoyam + maize, cocoyam + melon + maize) in both seasons respectively. PM2.5t/ha gave higher values of maize grain yield with cocoyam + maize, cocoyam + melon + maize crop mixtures. PM5.0t/ha and NPK400kg/ha gave higher melon seed values with cocoyam + melon and cocoyam + Melon + maize. Conclusively, it is recommended that application of organic fertilizer promotes higher yields and yield components in both sole and crop mixtures of cocoyam and maize respectively.

Transcriptomic analysis of the maize inbred line Chang7-2 and a large-grain mutant tc19

Backgrounds Grain size is a key factor in crop yield that gradually develops after pollination. However, few studies have reported gene expression patterns in maize grain development using large-grain mutants. To investigate the developmental mechanisms of grain size, we analyzed a large-grain mutant, named tc19, at the morphological and transcriptome level at five stages corresponding to days after pollination (DAP). Results After maturation, the grain length, width, and thickness in tc19 were greater than that in Chang7-2 (control) and increased by 3.57, 8.80, and 3.88%, respectively. Further analysis showed that grain width and 100-kernel weight in tc19 was lower than in Chang7-2 at 14 and 21 DAP, but greater than that in Chang7-2 at 28 DAP, indicating that 21 to 28 DAP was the critical stage for kernel width and weight development. For all five stages, the concentrations of auxin and brassinosteroids were significantly higher in tc19 than in Chang7-2. Gibberellin was higher at 7, 14, and 21 DAP, and cytokinin was higher at 21 and 35 DAP, in tc19 than in Chang7-2. Through transcriptome analysis at 14, 21, and 28 DAP, we identified 2987, 2647 and 3209 differentially expressed genes (DEGs) between tc19 and Chang7-2. By using KEGG analysis, 556, 500 and 633 DEGs at 14, 21 and 28 DAP were pathway annotated, respectively, 77 of them are related to plant hormone signal transduction pathway. ARF3, AO2, DWF4 and XTH are higher expressed in tc19 than that in Chang7-2. Conclusions We found some DEGs in maize grain development by using Chang7-2 and a large-grain mutant tc19. These DEGs have potential application value in improving maize performance.

The Concentration-Dependent Effects of Essential Oils on the Growth of Fusarium graminearum and Mycotoxins Biosynthesis in Wheat and Maize Grain

The presence of Fusarium fungi and their toxic metabolites in agricultural crops contributes to significant quantitative and qualitative losses of crops, causing a direct threat to human and animal health and life. Modern strategies for reducing the level of fungi and mycotoxins in the food chain tend to rely on natural methods, including plant substances. Essential oils (EOs), due to their complex chemical composition, show high biological activity, including fungistatic properties, which means that they exhibit high potential as a biological plant protection factor. The aim of this study was to determine the fungistatic activity of three EOs against F. graminearum, and the reduction of mycotoxin biosynthesis in corn and wheat grain. All tested EOs effectively suppressed the growth of F. graminearum in concentrations of 5% and 10%. Cinnamon and verbena EOs also effectively reduced the ergosterol (ERG) content in both grains at the concentration of 1%, while at the 0.1% EO concentration, the reduction in the ERG amount depended on the EO type as well as on the grain. The degree of zearalenone (ZEA) reduction was consistent with the inhibition of ERG biosynthesis, while the reduction in deoxynivalenol (DON) was not consistent with this parameter.

Determining nitrogen deficiencies for maize using various remote sensing indices

Determining a precise nitrogen fertilizer requirement for maize in a particular field and year has proven to be a challenge due to the complexity of the nitrogen inputs, transformations and outputs in the nitrogen cycle. Remote sensing of maize nitrogen deficiency may be one way to move nitrogen fertilizer applications closer to the specific nitrogen requirement. Six vegetation indices [normalized difference vegetation index (NDVI), green normalized difference vegetation index (GNDVI), red-edge normalized difference vegetation index (RENDVI), triangle greenness index (TGI), normalized area vegetation index (NAVI) and chlorophyll index-green (CIgreen)] were evaluated for their ability to detect nitrogen deficiency and predict grain maize grain yield. Strip trials were established at two locations in Arkansas, USA, with nitrogen rate as the primary treatment. Remote sensing data was collected weekly with an unmanned aerial system (UAS) equipped with a multispectral and thermal sensor. Relationships among index value, nitrogen fertilizer rate and maize growth stage were evaluated. Green NDVI, RENDVI and CIgreen had the strongest relationship with nitrogen fertilizer treatment. Chlorophyll Index-green and GNDVI were the best predictors of maize grain yield early in the growing season when the application of additional nitrogen was still agronomically feasible. However, the logistics of late season nitrogen application must be considered.

Effect of conservation agriculture on soil properties and maize grain yield in the semi-arid Laikipia county, Kenya.

Low and unreliable rainfall, along with poor soil health, is a main constraint to maize production in the semi-arid parts of Kenya that account for over 79% of the country's land area. In the vast county of Laikipia, farmers continue to plant maize despite the predominantly low quantities of precipitation. Participatory farmer experimentation with Conservation Agriculture (CA) was undertaken for six consecutive growing seasons between July 2013 and December 2016 to determine the effectiveness of CA as a method of improving soil properties and enhancing maize yields with the limited rainfall quantities received in these parts of Kenya. The main CA practices tested include chisel tine furrow opening (ripping) and live legume (Lablab purpureus) cover crop, as well as maize stover mulches, all implemented under varying inorganic fertilizer rates. The research was done across 12 administrative locations of Laikipia County where soils are mainly Phaeozems and Vertisols with a clay-loam texture. The research design used was researcher-designed and farmer-managed. In each of the 12 trial sites, participatory farmers' assessments and field days were carried out as a way of outreach to the bigger farming communities around the trial sites. The research findings obtained demonstrated that the use of CA impacts positively on soil properties and is a viable practice for enhancing maize yields in these moisture deficit-prone parts of the country. Soil chemical analysis assessment results showed that CA impacted positively on a number of soil mineral components including organic carbon, total nitrogen, phosphorus, potassium, calcium and pH. Midseason chlorophyll content assessment of the maize crop showed that there was good response to fertilizer application, as well as to mulching with crop residues for soil cover. Maize grain yield data also showed that the use of a CA package comprising chisel tine ripping combined with mulching by plant residues and use of mineral fertilizer resulted in a two- to threefold increase in grain yields above the farmer practice control. Mean maize grain yield in farmer practice plots was 1067 kg ha-1 compared with the CA-treated plot with mineral fertilization that yielded 2192 kg ha-1.

Improving Maize Shelling Operation Using Motorized Mobile Shellers: A Step towards Reducing Postharvest Losses in Low Developing Countries

Maize shelling is still a challenge in low developing countries with more efforts required to advance this operation. In Uganda, motorized immobile maize shellers have been fabricated locally to enhance the shelling operation. However, their performance has not elated the farmers. The unsatisfactory performance is a result of these shellers being fabricated by local artisan with finite understanding of the maize grain characteristics and operation factors to optimize maize shelling. In addition, farmers in these countries have a deficiency of power to operate the motorized maize shellers available. Transportation of these motorized maize shellers is also still a challenge and it imposes an extra cost to the farmers hence reducing their profits from maize growing. In this chapter, we reviewed maize shelling process in low developing countries particularly the categories of maize shelling, maize sheller design requirements, use of equations to design sheller parts, modification of the motorized maize shellers and case studies on the mobile maize shellers, comparing them with immobile maize shellers. The study concluded that on addition to other sheller performance attributes, motorized mobile maize shellers can solve transportation challenges associated with motorized immobile maize shellers.

Conservation Agriculture Based Integrated Crop Management Sustains the Maize–Wheat Rotation of North-Western India: Five Years’ Impacts on Crops and Water Productivity, Economic Profitability, Sustainable Yield Index and Soil Properties

We have evaluated eight different integrated crop management (ICM) modules for five years in a maize-wheat rotation (MWR); wherein, ICM1&2- ˈbusiness-as-usualˈ (conventional flatbed maize and wheat, ICM3&4- conventional raised bed (CTRB) maize and wheat without residues, ICM5&6- conservation agriculture (CA)-based zero till (ZT) flatbed maize and wheat with the residues, and ICM7&8- CA-based ZT raised bed maize and wheat with the residues. Results indicated that the ICM7&8 produced significantly (p<0.05) the highest maize grain yield (5 years av.) which was 7.8-21.3% greater than the ICM1-6. However, across years, the ICM5-8 gave statistically similar wheat grain yield, and was 8.4-11.5% greater than the ICM1-4. Similarly, the CA-based residue retained ICM5-8 modules had given 9.5-14.3% (5 years av.) greater system yields in terms of maize grain equivalents (MGEY) over the residue removed CT-based ICM1&4. System water productivity (SWP) was the highest with ICM5-8, being 10.3-17.8% higher than the ICM1-4. Nevertheless, the highest water use (TWU) was recorded in the CT flatbed (ICM1&2), ~7% more than the raised bed and ZT planted crops with or without the residues (ICM4-8). Furthermore, the ICM1-4 had produced 9.54% greater variable production costs compared to the ICM5-8, whereas, the ICM5-8 gave 24.3-27.4% additional returns than the ICM1-4. Also, different ICM modules caused significant (p<0.05) impacts on the soil properties, such as, organic carbon (SOC), microbial biomass carbon (SMBC), dehydrogenase (SDH), alkaline phosphatase (SAP) and urease (URE) activities. In 0.0-0.15 m soil profile, residue retained CA-based (ICM5-8) modules registered a 7.1-14.3% greater SOC and 10.2-17.3% SMBC than the ICM1-4. The sustainable yield index (SYI) of MWR was 13.4-18.6% greater under the ICM7&8 compared to the ICM1-4. Hence, this study conclude that the adoption of the CA-based residue retained ICMs in the MWR could sustain the crop yields, enhance farm profits, save water and improve soil properties of the north-western plan zones of India.