Crop Ear Research Articles

DRIP-IRRIGATED SWEET CORN WATER USE DEPENDING ON THE DEPTH OF PLOWING, MINERAL FERTILIZATION RATES AND CROPS DENSITY

The effect of plowing depth (20-22; 28-30 cm), mineral fertilization rates (N-P: 0-0, 60-60, 120-120 kg ha-1), and crops density (35,000, 50,000, 65,000, 80,000 plants ha-1) on the yield, and water use efficiency (WUE) of drip-irrigated sweet corn were studied. The field experiment was conducted in the semi-arid climatic conditions of the South of Ukraine (Kherson oblast) at the dark-chestnut middle-loamy soil. The trials were conducted using split-plot design in four replications. Irrigation scheduling and rates were set by the field water balance method considering the amounts of available soil moisture and precipitation. Manual harvesting of the crop ears was conducted at R3 phenological stage. WUE was calculated as the ratio of the ears’ yield to the gross water use of the crop. Statistical evaluation was performed by analysis of variance (ANOVA) and regression analysis at the probability level of 95%. The studied factors and their interaction had a significant effect on sweet corn productivity and WUE. The best crop productivity along with the best WUE was provided by plowing on 20-22 cm, fertilization rates of 120-120 kg ha<sup<-1</sup<, and crops density of 65,000 plants ha<sup<-1</sup<.

Rattail fescue (Vulpia myuros) interference and seed production as affected by sowing time and crop density in winter wheat

AbstractField experiments were conducted in the growing seasons of 2017 to 2018 and 2018 to 2019 to evaluate the competitive effects of rattail fescue [Vulpia myuros (L.) C.C. Gmel.] in winter wheat (Triticum aestivum L.) and to assess whether delayed crop sowing and increased crop density influence the emergence, competitiveness, and fecundity of V. myuros. Cumulative emergence showed the potential of V. myuros to emerge rapidly and under a wide range of climatic conditions with no effect of crop density and variable effects of sowing time between the two experiments. Grain yield and yield components were negatively affected by increasing V. myuros density. The relationship between grain yield and V. myuros density was not influenced by sowing time or by crop density, but crop–weed competition was strongly influenced by growing conditions. Due to very different weather conditions, grain yield reductions were lower in the growing season of 2017 to 2018 than in 2018 to 2019, with maximum grain yield losses of 22% and 50% in the two growing seasons, respectively. The yield components, number of crop ears per square meter, and 1,000-kernel weight were affected almost equally, reflecting that V. myuros’s competition with winter wheat occurred both early and late in the growing season. Seed production of V. myuros was suppressed by delaying sowing and increasing crop density. The impacts of delayed sowing and increasing crop density on seed production of V. myuros highlight the potential of these cultural weed control tactics in the long-term management programs of this species.

Cereal Crop Ear Counting in Field Conditions Using Zenithal RGB Images

Cereal Crop Ear Counting in Field Conditions Using Zenithal RGB Images

Cereal Crop Ear Counting in Field Conditions Using Zenithal RGB Images.

Ear density, or the number of ears per square meter (ears/m2), is a central focus in many cereal crop breeding programs, such as wheat and barley, representing an important agronomic yield component for estimating grain yield. Therefore, a quick, efficient, and standardized technique for assessing ear density would aid in improving agricultural management, providing improvements in preharvest yield predictions, or could even be used as a tool for crop breeding when it has been defined as a trait of importance. Not only are the current techniques for manual ear density assessments laborious and time-consuming, but they are also without any official standardized protocol, whether by linear meter, area quadrant, or an extrapolation based on plant ear density and plant counts postharvest. An automatic ear counting algorithm is presented in detail for estimating ear density with only sunlight illumination in field conditions based on zenithal (nadir) natural color (red, green, and blue [RGB]) digital images, allowing for high-throughput standardized measurements. Different field trials of durum wheat and barley distributed geographically across Spain during the 2014/2015 and 2015/2016 crop seasons in irrigated and rainfed trials were used to provide representative results. The three-phase protocol includes crop growth stage and field condition planning, image capture guidelines, and a computer algorithm of three steps: (i) a Laplacian frequency filter to remove low- and high-frequency artifacts, (ii) a median filter to reduce high noise, and (iii) segmentation and counting using local maxima peaks for the final count. Minor adjustments to the algorithm code must be made corresponding to the camera resolution, focal length, and distance between the camera and the crop canopy. The results demonstrate a high success rate (higher than 90%) and R2 values (of 0.62-0.75) between the algorithm counts and the manual image-based ear counts for both durum wheat and barley.

Effect of Frost on Triticale and Wheat Varieties at Flowering in the North Eastern Australian Cereal Belt

Spring radiation frost is a serious problem in Australia particularly at the reproductive stage, causing an annual revenue loss of more than AU$ 360 million. The focus of frost research therefore has been to identify reproductively frost resistant cereals at the both varietal and species levels that can contribute to alleviating frost damage. Seven triticale and three wheat varieties were assessed to determine relative frost tolerance under natural frost conditions. Plants were grown in pots and raised in the glasshouse. At flowering (±5 days), plants were exposed to a single overnight frost or frost maintained for a short time with varying intensities from 0.2 to −6.6 °C at crop ear height. The frost impact was assessed at maturity based on ear fertility by counting the number of developed grains. There were variable levels of tolerance between triticale varieties with Tahara being more susceptible than other varieties. At species level, triticale was more susceptible than wheat. Temperatures below −3.9 °C were economically damaging. A holistic approach of breeding and agronomic management may be needed to mitigate the frost problem in winter cereals.

A Non-Coding Genomic Duplication at the HMX1 Locus Is Associated with Crop Ears in Highland Cattle

Highland cattle with congenital crop ears have notches of variable size on the tips of both ears. In some cases, cartilage deformation can be seen and occasionally the external ears are shortened. We collected 40 cases and 80 controls across Switzerland. Pedigree data analysis confirmed a monogenic autosomal dominant mode of inheritance with variable expressivity. All affected animals could be traced back to a single common ancestor. A genome-wide association study was performed and the causative mutation was mapped to a 4 Mb interval on bovine chromosome 6. The H6 family homeobox 1 (HMX1) gene was selected as a positional and functional candidate gene. By whole genome re-sequencing of an affected Highland cattle, we detected 6 non-synonymous coding sequence variants and two variants in an ultra-conserved element at the HMX1 locus with respect to the reference genome. Of these 8 variants, only a non-coding 76 bp genomic duplication (g.106720058_106720133dup) located in the conserved region was perfectly associated with crop ears. The identified copy number variation probably results in HMX1 misregulation and possible gain-of-function. Our findings confirm the role of HMX1 during the development of the external ear. As it is sometimes difficult to phenotypically diagnose Highland cattle with slight ear notches, genetic testing can now be used to improve selection against this undesired trait.

Winter Wheat Growth and Yield Influenced by Wild Barley (Hordeum spontaneum Koch) Competition

Field experiment was conducted at Karaj, Iran to evaluate the growth and yield responses of winter wheat tovarious densities of wild barley and nitrogen (N) application rates. The experimental design was split-plot with 3replications. The main factor was four N levels of 0, 130, 260, and 390 kg Urea per ha and the sub factor was weeddensities. Results showed that in unfertilized plots, wild barley densities of 80 and 160 plants per sq. metersignificantly decreased wheat plant height, LAI and tillers. In comparison to excess N and N deficiency treatments,the optimal N rate decreased wheat LAI losses at weed densities of 80 and 160 plants per sq. m. Wild barley hadgreater plant height and the number of tillers per plant at densities of 20 and 40 plants per sq. meter. At 130 kg Nper ha, weed densities of 20, 40, and 80 plants per sq. meter did not reduce the number of crop ear compared tohand-weeded plots. On unfertilized plots with 40, 80, and 160 weed plants per sq. meter, the reduction in numberof grains per ear were 18 and 38%, respectively. Nitrogen rates of 130 and 260 kg per ha increased crop and weedGNCs, whereas their STNCs were increased by N rate up to of 390 kg per ha. Added N resulted in higher winterwheat ANUE compared to weed ANUE.

The characteristics of the chosen mycotoxins and their toxic influence on the human and animal metabolism

Mycotoxins are toxic secondary metabolites of fungi belonging mainly to the Aspergillus, Penicillium and Fusarium genera. They can be formed in various agricultural produce in specific conditions. These natural and zootoxic chemical compounds cause an array of diseases in people and animals, i.e., mycotoxicoses. Depending on the type and dose, mycotoxins may cause liver, kidney, and lung cancers, as well as damage to the immune system, pathological changes in the nervous system, and reproduction disorders. Many mycotoxins disrupt digestion process, cause vomiting, nausea, anorexia, skin irritation and dermatitis, and even haemorrhages. A significant threat to the health of animals and people can be observed in the case of major infestation of crop ears from which foodstuff or feed are then produced. The ear infestation is facilitated by a suitable humidity and temperature during the growing season or while harvesting and storing the agricultural produce, which enhances the growth of mycotoxin-producing fungi. Suitable agricultural treatment, crop rotation, proper storing of crops in the conditions of limited humidity after the harvest as well as regular chemical analyses of the content of mycotoxins minimize their consumption and, accordingly, decrease the threat caused by these substances to the human and animal health.

PM—Power and Machinery: Investigation of Mechanical Interaction between a Combine Harvester Reel and Crop Stalks

In the present study, the relationships between the deflection and deflection force acting on a bunch of crop stalks in the gathering operations of a combine harvester reel were analysed. Two mechanical crop models based on bending theory with regard to an elastic beam were applied in this analysis. In the first model, the sectional heterogeneity of a stalk is expressed as the different flexural rigidity of each internode. In the second model, the effect of a crop ear is added to the first model. The application of the mechanical models to the reel operations and the analytical methods of the deflection force were investigated using experiments involving reel operations. The results showed that the effect of both the buckling load due to the weight of the ear and the vertical force component acting on the crop stalks increased noticeably with the increment of deflection imposed by the gathering operations. The prediction of the relationships between deflection and deflection force in the second model, in which the effect of the ear weight was considered, involved a certain amount of error due to the effect of the initial posture of the crop stalk and the vertical force component, but coincided approximately with the experimental results. Thus, it was suggested that the model that took into account the effect of the crop ear was useful for investigating reel–crop interactions, and that the analytical accuracy of the deflection force would be increased by considering the effect of the vertical force component. Further, based on the above results, a posture analysis of a bunch of crop stalks during reel operations was conducted.

Utilization of waste office paper to reduce nitrate leaching into the Northern Guam aquifer

Rapid nitrate leaching losses due to current agricultural N management practices under the humid tropical environmental conditions of the Pacific island of Guam may contaminate fresh and salt water resources. Potential environmental contamination of the Northern Guam aquifer, which is overlain by shallow limestone-derived soils, is a major public concern because the aquifer is the sole underground source of fresh water for the island. The objectives of this study were to examine the use of waste office paper as a possible management alternative for reducing nitrate leaching due to N fertilizer applications in northern Guam while also providing sufficient N for crop growth. In a laboratory study, increasing rates of waste paper application reduced NO3–-N leaching up to approximately 200 days after incorporation of N fertilizer and paper treatments. Subsequent mineralization of immobilized N from paper applications was also observed, although cumulative NO3–-N leaching at the highest rate of paper addition was lower than the control after 394 days of incubation. The effect of waste paper on N availability and NO3–-N leaching after application of N fertilizer at rates up to 500 kg N ha–1 was also evaluated in two field experiments planted with sweet corn (Zea mays var. rugosa Bonaf.) during consecutive dry and wet periods. Leaching losses of NO3–-N were higher during the wet cropping season, leading to lower crop yields and crop N uptake. Combining paper with N fertilizer reduced NO3–-N leaching losses but also decreased crop ear yields up to N fertilizer application rates of 250 kg N ha–1 during the dry cropping season and up to rates of 100 kg N ha–1 during the wet period. Although combining waste paper with N fertilizer reduced NO3–-N leaching losses, no improvements in fertilizer N recovery were observed during the field experiments. This lack of crop response may be due to the importance of early season N availability for the short-season horticultural crops grown on Guam. We suggest that the application of waste paper may be a useful management practice to reduce NO3–-N leaching losses when high soil NO3–-N levels remain after cropping due either to crop failure or to over-application of N fertilizer.

Control of European corn borer in sweet corn by Trichogramma brassicae Bezd. (Hym., Trichogrammatidae)

AbstractThe biological control effectiveness of the indigenous egg parasitoid Trichogramma brassicae Bezd, reared continuously on Ostrinia nubilalis (Hb.) (ECB) eggs, was tested against ECB in sweet corn in 1991 (2 ha release plot) and 1992 (3.5 ha release plot). T. brassicae was reared for three‐four generations on the factidious host Ephestia kuehniella Zell. and then released on the crop; a 0.5 ha plot situated at 300–400m from the test plots was used as control in both years. Four releases, each totalling 250–300 000 individuals, were made the first year and three at the same rate per ha the second. ECB adult emergence was monitored using traps baited with sex pheromone and phenylacetaldehyde food attractant. The parasitoid activity was monitored via sentinel egg masses following each release. The parasitization rates of the sentinel egg masses was always higher in the release plot vs. control. The parasitization of natural egg masses sampled in both years before harvest was: 12.5 and 10.86% in control as against 87.5 and 68.58% in T. brassicae plots in the respective years. ECB damage was calculated on crop ear samples. The rate (%) of sentinel egg mass predation by wild predators showed no significant difference between control and release plots for both years. The low level of ECB damage to crop ears evinced the good search capacity, parasitization and control effectiveness of T. brassicae.

A study of pre-harvest infestation of maize by Sitophilus zeamais Motsch. (Coleoptera, Curculionidae) in the Kenya highlands

The incidence of attack by Sitophilus zeamais Motsch in maize ears in the growing crop and in cribs during storage has been studied in the Kitale district of Kenya. There was no evidence that wild plants or cultivated wheat varieties supported high populations of this insect, the principal source of field infestation being stocks of stored maize. Ears from the previous crop ploughed in at time of cultivation and sowing rarely support S. zeamais long enough to allow cross-infestation of susceptible new crop ears. In a growing crop of the variety ‘Kitale synthetic’, 50–60 per cent of the ears were tightly enclosed by the sheath. The remainder had loose or open sheaths. In the same crop the numbers of infested grains and infested ears present immediately before harvest were estimated by placing ears in separate polythene bags just after harvest and recording daily the emergence of adults over a 5 week period. As a result it was estimated that 42 per cent of the tightly sheathed ears were infested, compared with 51 and 84 per cent respectively in the loosely and open sheathed ears. Assuming one insect per infested grain the number of infested grains for infested ears from all three categories combined was 10 per cent. The overall level for infested grains in all ears from the crop as a whole was 6 per cent. These data compare well with a field experiment in which two different pre-harvest infestation levels were measured, e.g. where the kernel damage shortly after harvest was less than 1 per cent it took 16 weeks to reach a level of 7 per cent, compared with an initial level of 3 per cent which reached 16 per cent after only 8 weeks. In a comparison of the susceptibility of six white dent maize varieties to pre-harvest infestation, Hybrid 622 proved far superior to the others in three important aspects. It had a low incidence of ears with open tips (27·5 per cent), a lower level of insect attack even when compared to another variety with a similar level of open tipped ears and a much lower moisture content at harvest. Field experiments indicated that S. zeamais would not develop in the kernel before harvest until the moisture content fell to below 60 per cent, which in Kitale district would be mid-September i.e. 3 months before harvest. As was appreciated many years ago, the most practical method of reducing pre-harvest attack is by preventing insect development in harvested grain. Lindane admixed with harvested ears from which the sheaths had been removed, killed emerging adults and achieved this. Unfortunately there are signs of resistance developing to this insecticide and alternative treatments are required. The admixture of an effective contact insecticide to prevent breeding after harvest, combined with careful cleaning and spraying of empty stores not later than pollination of the next field crop, and selection of maize varieties resistant to attack before and after harvest, appear to be the most effective way of reducing pre-harvest infestation.