Tall Crops Research Articles

Morphological characterization and development potential of beneng variety (Xanthosoma undipes K. Koch) Pandeglang - Banten

Beneng is a local giant taro that is easily found around the Gunung Karang areas, Pandeglang District, Indonesia. Beneng has the potential to be developed as a commercial crop due to high demand of its product (tuber and leaves). Therefore, the study aimed to characterize the morphology of Beneng, and to analyze its potential development. The research was conducted in Juhut Village, Pandeglang District, Banten Province from 2017 to 2020. Morphological characterization was observed following the guidelines on the descriptor for taro. A series of data were collected from Beneng farmers and the Beneng Association. Beneng is a unique crop with a big yellow tuber. Besides, all parts of the crop are useful and economically valuable. Beneng can grow well under, and well adapted to, low light intensity. Therefore, this crop is suitable as a secondary crop in plantation areas or intercropped with other tall crops. Additionally, Beneng is a food crop with a high carbohydrate content (78%) which is suitable as a fresh product or processed products (flour and chips). Beneng dried leave is also valuable as herbal teas and tobacco. High demand of Beneng product showed that Beneng has a comparative and competitive advantage as compared to other types of taro. Currently, Beneng is marketable for export to other countries. The demand for fresh tuber, flour, and dried leaves reached 60-80, 200, and 300 ton per month, respectively. Our study showed that Beneng plants can produce 10-15 kg fresh tuber or around 100-150 ton per ha, and can be as much as 2 kg per plant dried leaves or around 20 ton per ha, with the total plant growth duration of 8 to 12 month. In order to fill the gap between demand and supply of Beneng products, an expansion of Beneng cultivation is needed through optimizing the arable land around Gunung Karang and surrounding areas.

Trend analysis of tall crop reference evapotranspiration (ETr) for Bhilwara district

Trend analysis of tall crop reference evapotranspiration (ETr) for Bhilwara district

Shade Effects on Peanut Yield Associate with Physiological and Expressional Regulation on Photosynthesis and Sucrose Metabolism

Intercropping improves land utilization with more crops grown together; however, shorter crops in intercropping experience stress, being shaded by the taller crops. Systematic changes in phenotype, physiology, yield, and gene regulation under shade stress in peanut are largely unknown, although shade responses have been well analyzed in model plants. We exposed peanut plants to simulated 40% and 80% shade for 15 and 30 days at the seedling stage, flowering stage, and both stages. Shade caused the increased elongation growth of the main stem, internode, and leaf, and elongation was positively associated with auxin levels. Shade stress reduced peanut yield. Further comparative RNA-seq analyses revealed expressional changes in many metabolism pathways and common core sets of expressional regulations in all shade treatments. Expressional downregulation of most genes for light-harvesting and photosynthesis agreed with the observed decreased parameters of photosynthesis processes. Other major regulations included expressional downregulation of most core genes in the sucrose and starch metabolism, and growth-promoting genes in plant hormone signal pathways. Together, the results advance our understanding of physiological and molecular regulation in shade avoidance in peanut, which could guide the breeding designing in the intercropping system.

Plant architectural responses in simultaneous maize/soybean strip intercropping do not lead to a yield advantage

AbstractMaize/soybean strip intercropping is a commonly used system throughout China with high crop yields at reduced nutrient input compared to sole maize. Maize is the taller crop, and due to its dominance in light capture over soybean in the intercrop, maize is expected to outperform maize in sole cropping. Conversely, soybean is the subordinate crop and intercropped soybean plants are expected to perform worse than sole soybean. Crop plants show plastic responses in plant architecture to their growing conditions to forage for light and avoid shading. There is little knowledge on plant architectural responses to growing conditions in simultaneous (non‐relay) intercropping and their relationship to species yields. A two‐year field experiment with two simultaneous maize/soybean intercropping systems with narrow and wide strips was conducted to characterise architectural traits of maize and soybean plants grown as intercrop and sole crops. Intercropped maize plants, especially those in border rows, had substantially greater leaf area, biomass and yield than maize plants in sole crops. Intercropped soybean plants, especially those in border rows, had lower leaf area, biomass and yield than sole soybean plants. Overall intercrop performance was similar to that of sole crops, with the land equivalent ratio (LER) being only slightly greater than one (1.03–1.08). Soybean displayed typical shade avoidance responses in the intercrop, such as greater internode elongation and changes in specific leaf area, but these responses could not overcome the consequences of the competition with the taller maize plants. Therefore, in contrast to relay intercrop systems, in the studied simultaneous maize/soybean system, plastic responses did not contribute to practically relevant increases in resource capture and yield at whole system (i.e., intercrop) level.

Aerial robot for smart farming and enhancing farmers' net benefit

The knitting of information and modern electronic technology with agricultural production system to determine, analyze and manage the critical temporal and spatial factors of farm for maximizing profitability, sustainability and environmental protection is need of hour. In this context, robot (Arial, Ground and Under-water) can play an important role. Aerial Robot is also commonly known as Unmanned Aerial Vehicle (UAV) or Drone. It may be boon for management of agricultural production as it can focus on small crop fields at lower flight altitudes than other regular aerial vehicle to perform site-specific farm management operation with higher precision. It can also address adverse crop and land prerequisites, where use of conventional machines is challenging, e.g. spraying under wet paddy field, tall crop sugarcane, pigeonpea etc. Embedding the available technologies and methods for meeting functional, operational and structural requisite, specifically for the crop and land environment with Arial Robot is of utmost importance. On the basis of system range, accuracy, resolution, and precision, sensitivity, linearity, offset, hysteresis and response time of different sensing and control technologies, e.g. optical, near infrared, thermal multi-spectral, hyper-spectral, Light Detection and Ranging, radio frequency and sonar .This paper presents an overview of research involving the development of UAV technology for agricultural production management. Technologies, systems and methods are analyzed for in situ integration under Indian farm conditions. The limitations of current Arial Robot for agricultural production management are deliberated, moreover forthcoming needs and suggestions for development and application of the technology in agricultural production management are projected.

High‐throughput measurement of peanut canopy height using digital surface models

AbstractPeanut (Arachis hypogaea L.) is an important food and oilseed crop in the United States and worldwide with high net returns. However, input costs are high (US$1,970–$2,220 ha−1), and yield in excess of 4,500 kg ha−1 is needed to offset the costs. Since yield is limited by biotic and abiotic stresses, newer cultivars with tolerance to these stresses are needed to optimize yield. Plant height and canopy architecture may affect crop water use and plant disease resistance. However, measuring canopy height is a time‐consuming process. Surface elevation models from red–green–blue (RGB) aerial images have been successfully developed to estimate genetic differences of plant height for tall crops like corn (Zea mays L.) and sorghum [Sorghum bicolor (L) Moench]; but they have not been tested for short crops like peanut with a runner growth habit and much smaller height differences among genotypes. The objective of this study was to derive canopy height of peanut from digital surface models (DSM). Images were aerially taken using a digital camera mounted on an unmanned aerial vehicle (UAV). Images were orthomosaiced to create the DSM and the digital terrain model (DTM) of the plot. Canopy height was derived by subtracting the DTM from the DSM in ArcGIS software. Results showed that the RGB derived canopy height was highly correlated to the manually measured height (R2 = .953). We propose the methods used here as fast and relatively easy selection tools for breeders and crop growth evaluators of peanut plant height.

Polychlorinated biphenyls in the soil–crop–atmosphere system in e-waste dismantling areas in Taizhou: Concentrations, congener profiles, uptake, and translocation

Samples of soil, air, and locally grown crops from around an old e-waste dismantling area (Fengjiang) and a new e-waste dismantling area (Binhai) in Taizhou were analyzed to investigate the behavior of polychlorinated biphenyls (PCBs) released during e-waste dismantling in the soil–crop–atmosphere system. The results indicated that PCB pollution is still widespread in the study area. The PCB concentrations were clearly higher in soil from FJ than in soil from BH, and the concentrations in the functional zones decreased strongly in the order industry park > residential area > farmland. Historical and current emissions during e-waste dismantling processes are probably the main sources of PCBs to soil because PCB production and use are banned. The long half-lives of PCBs have caused the target congener concentrations in soil not to decrease markedly over 10 years. The “halo effect” may have caused PCBs in soil in the heavily polluted FJ area to diffuse into the surrounding area. Soil–air exchange of PCBs in heavily contaminated FJ area may supply PCBs to air because the temperatures in Taizhou are often high. PCBs can accumulate in crops through various pathways. Less-chlorinated PCBs (mainly including Tri-PCBs) can enter crops by root uptake and translocated to the aerial tissues, and more-chlorinated PCBs (including Penta-PCBs and Hexa-PCBs) at high concentrations in soil can enter underground crop tissues through passive transport. More-chlorinated PCBs in underground tissues cannot be transferred to aboveground tissues of tall crops but may be transferred to aboveground tissues of short crops through the root-to-stem pathway and through soil dust being transferred to aboveground external surfaces.

Sugar cane Canopy Spraying: A Perspective Solution with Ergonomics and Mechatronics Approach

Chemicals application is very significant for control of disease and insect infestation in sugar cane crop. The problem observed with existing practice is inefficient spraying due to inconvenience of operation as workers are prone to injuries and working above shoulder height results in postural stresses as sugar cane being a tall crop. To overcome these issues, a novel approach to develop canopy sprayer for sugar cane crop based on the application of mechatronics and ergonomics is worked out that consists of self-propelled e-powered unit, sensor-based foldable spraying system, operable conditioned system with control monitor unit. It will be equipped with variable height platform for safety and comfort of operator along with effective spraying at desired height.

Risk of dermal and inhalation exposure to chlorantraniliprole assessed by using whole-body dosimetry in Korea.

We determined the characteristics and evaluated associated risks of sprayed pesticide exposure among workers cultivating Korean cabbage. The test pesticide, a mixture of 3% chlorantraniliprole and 4% indoxacarb wettable granules diluted 2000 times, was sprayed on Korean cabbage within a 3000 m2 area in Goesan, Korea. Dermal exposures were measured using a whole-body dosimetry method. Exposure to chlorantraniliprole was observed among ten individuals, ranging from 140.4 to 4234.0µg person-1 . The legs were the most prominent exposure area (86.35%), with the face being the least exposed (0.06%). Exposure risk was assessed by calculating the margin of safety (MOS) on the exposure amount for each body part. The MOS based on dermal and inhalation exposure doses ranged from 59 to 1765. Exposure was the greatest for the legs, probably as a result of the low height of the crop and the use of a long-wand sprayer. An MOS value >1 indicates a low risk for applicators using this method of application. However, with tall crops, exposure level and MOS values can vary widely, as MOS increases or decreases based on exposure dose. Therefore, future research is needed to better understand appropriate safety precautions when working with potent pesticides. © 2018 Society of Chemical Industry.

A review on smart application of supplemental lighting in greenhouse fruiting vegetable production

Different spectra of light trigger different plant growth processes. Therefore, the optimum light spectrum for various plant physiological and growth processes may be different. For greenhouse fruiting vegetables, such as tomatoes, it is important to optimize light spectrum to promote canopy growth to increase light interception during the early stage of plant growth. Once the plants reach full canopy, the focus should be moved to optimizing vertical light distribution because most greenhouse fruiting vegetables are tall crops and the growth processes along the vertical profile are different; most of the canopy growth occurs in the top and middle canopy while fruit growth occurs in the middle and bottom canopy. Because the fruit, not the leaf, is the economic product, the optimized light spectral composition should enhance leaf carbon export and translocation to fruit to improve fruit yield and quality. Therefore, a research project was initiated in 2013 to identify proper light spectral composition and vertical distribution regimes for greenhouse fruiting vegetable production. Different overhead light sources (high-pressure sodium light with or without far-red light-emitting diode (LED) light, plasma light and different spectral compositions of LEDs) and several intra-canopy spectral compositions provided by LEDs were evaluated over four winters on tomatoes, mini-cucumbers and sweet peppers. The effects of light spectrum on whole-plant net carbon exchange and leaf carbon export using (14)C-isotype tracing were also investigated. The vertical light regimes resulted in significant differences in leaf photosynthetic rate, leaf size, fruit yield and fruit quality in greenhouse tomatoes, mini-cucumbers and sweet peppers. Proper vertical light regimes were identified for hybrid light systems (overhead high intensity discharge light + intra-canopy LEDs) and for pure LED light systems (overhead + intra-canopy LEDs). This review clearly demonstrates that optimized vertical light regimes can be developed for improving both plant growth and fruit yield and quality in year-round greenhouse fruiting vegetable production.

Home Ranges, Habitats, and Roosts of Wintering Burrowing Owls In Agricultural Landscapes In Central Mexico

Abstract The winter home ranges, foraging habitats, and roost characteristics of migrant Burrowing Owls (Athene cunicularia) have not been described in central Mexico. This information is needed to prioritize habitat conservation measures because the species is in decline across much of western North America. We used VHF telemetry to describe the foraging range, habitat use, and roost sites of 17 Burrowing Owls in two study areas: Irapuato and Zapopan, Mexico. Burrowing Owls did not forage in the daytime. Cropland and grasslands made up the majority of the owls' foraging ranges, which averaged 70 ha. Burrowing Owls responded quickly and opportunistically to changes in land uses that removed tall dense vegetation, such as the harvest of tall crops, and fires. Distances from foraging areas to roost sites averaged 514–751 m, but varied widely from 32–1981 m. Roost characteristics were highly variable between study sites. Overall, Burrowing Owls incorporated anthropogenic land uses into their winter habitat n...

Producing High‐Residue, No‐Till Fallow in the Low‐Rainfall Zone of the Pacific Northwest

Core Ideas Use of a stripper header to leave tall stubble for high‐residue no‐till. Winter triticale outperforms winter wheat in low rainfall dryland production. Tall crop residue reduces wind speeds at the soil surface. The low‐rainfall wheat production zone of eastern Washington is subject to wind erosion because of fine‐textured soils, low soil organic matter content, and tillage‐based winter wheat–summer fallow practices. Annual no‐till spring cropping systems to replace the low‐residue, erosive summer‐fallow period have not been economical. We conducted a 4‐year study at Ralston, WA to evaluate winter triticale (× Triticosecale) and non‐semi‐dwarf winter wheat (Triticum aestivum) biomass production, yield, nutrient use efficiency, and seed‐zone soil moisture during no‐till fallow and establishment of fall‐seeded canola. Treatments included winter triticale and winter wheat, both harvested with either a stripper header or conventional cutter‐bar header. Winter triticale produced more grain per pound of N fertilizer and per inch of soil water available than winter wheat, and overall yield was 30–80% greater than that of winter wheat. Full‐height cereals produced 20–90% more biomass than semi‐dwarf winter wheat. Stripper‐header triticale stubble maintained with no‐till chemical fallow (NTCF) reduced average wind speed at the soil surface to less than one‐half of the average wind speed recorded over reduced‐tillage winter wheat fallow. Soil moisture in the 0‐ to 3‐inch seed zone was greater and more uniform in stripper‐header no‐till fallow than in reduced‐tillage fallow. Maintenance of soil moisture by stripper‐header standing stubble was conducive to timely planting and establishment of fall‐seeded canola and led to greater crop establishment in no‐till fallow. Growing a high‐biomass cereal crop such as winter triticale or standard‐height winter wheat and harvesting with a stripper header produces a high‐residue, no‐till fallow that is a viable alternative to the traditional winter wheat–fallow cropping system.

Response of greenhouse tomato to different vertical spectra of LED lighting under overhead high pressure sodium and plasma lighting

Different light spectra trigger different plant growth processes. Therefore, the optimum light spectrum for various plant growth processes such as leaf and fruit growth may be different. Greenhouse mini-cucumber (Cucumis sativus L.) is a tall crop, with most leaf growth occurring in the top and middle canopy while fruit growth occurs in the middle and bottom canopy. Therefore, optimized vertical light spectral distribution profiles could be developed for improving both vegetative and fruit growth. In this study, we investigated the effects of different vertical spectra of light-emitting diodes (LED) lighting under high-pressure sodium (HPS) and plasma overhead lighting on plant growth and fruit yield of mini-cucumber. The study was conducted from October 2014 to April 2015 in a large greenhouse divided into 4 sections (50 m2 growing area in each section). Two sections were installed with plasma overhead light and the other two sections with HPS light, with both of them providing the same amount of overhead light (165 μmol m-2 s-1). Four vertical LED regimes (the top far red with bottom blue; the top blue with bottom far red; the top far red with bottom red; the top red with bottom far red) were applied to 4 plots inside each of the 4 sections. The blue or red LED each provided 10 µmol m-2 s-1, while the far red LED provided 8 µmol m-2 s-1 of light. The vertical LED treatments resulted in more than a 10% difference in fruit yield despite the small amount of light, indicating that the vertical light distribution had a large influence on plant growth. Top blue LED reduced leaf size and plant height in the early growth period which reduced total fruit yield for the plants grown under plasma light but not under HPS. Far red LED placed at the top of the canopy increased fruit yield, in comparison to bottom canopy placement, for plants grown under plasma light. This study has demonstrated that vertical light spectral distribution can have a large influence on plant growth and development, and optimized light distribution should and can be developed for year-round greenhouse vegetable production with supplemental lighting.

Role of Residual Organic Materials on Productivity of Zea mays L. for Sustainable Soil Fertility Restoration in the Guinea Savannah Zone, Ghana

A field experiment was conducted at Nyankpala, near Tamale, Ghana, during the 2014 cropping season and continued during 2015, to investigate one year residual effects of indigenous organic materials (biochar, groundnut shell, rice husk and rice straw) on the growth and yield of maize. It was a 4×3×3 factorial experiment consisting of 4 organic materials at 3 levels (2.5, 5 and 7.5 t ha-1 on dry matter basis) and 3 nitrogen (N) levels (0, 45 and 90 kg/ha N) laid out in a Randomized Complete Block Design with four replications. The study revealed that integrated management of one year residuals of the organic materials with inorganic N supported increased plant height and grain yield, and moderated time of flowering to promote production of maize variety “Wang Dataa”. Application of 7.5 t/ha biochar + 45 kg/ha N, similarly 5 t/ha biochar + 90 kg/ha N supported tallest crop of 200 cm, whilst early flowering ranged 47 to 50 days with 2.5 t/ha biochar + 90 kg N/ha, 5 t/ha biochar + 45 kg N/ha, 7.5 t/ha biochar+ 90 kg N/ha, 2.5 t/ha groundnut shell + 90 kg N/ha and 7.5 t/ha rice straw + 45 kg N/ha. Grain yield was maximised with 7.5 t/ha biochar + 90 kg N/ha, 5 t/ha groundnut shell + 45 kg N/ha, 7.5 t/ha groundnut shell + 90 kg N/ha and 7.5 t/ha rice husk + 90 kg N/ha in the range of 3000 - 3600 kg/ha. The results also showed strongly that either residual nutrients and other plant growth conditions obtained from the organic materials or application N determined LAI, height of cob attachment, cob length, cob weight, 100 seed weight and stover biomass. Residual conditions provided by 7.5 t/ha of biochar gave the highest LAI. The more increased height of cob attachment ranged from 90 to 100 cm, provided by as low as 2.5 t/ha of biochar. Best cob length of 15 to 17 cm was obtained from 2.5 t/ha biochar and 5 t/ha groundnut shell. Cob weight under residual organic materials was in the range of 125 to 165 g/cob with 5 t/ha biochar or groundnut shell and 7.5 t/ha rice straw adequate to maximize the trait. Residual organic materials impacted on 100 seed weight with 5 t/ha of biochar and 7.5 t/ha groundnut shell impacted largest grain size of 25.5g. Stover weight was both highly significantly determined by residual effects of organic materials and N. Application of 5 t/ha biochar or 5 t/ha groundnut shell or 7.5 t/ha rice husk was adequate for highest stover weight. In this study, application of 45 kg N/ha was overwhelmingly sufficient to optimize leaf area index, height of cob attachment, cob length, cob weight, 100 seed weight and stover weight. Pearson correlation coefficients of grain yield with other traits exhibited robust relationships signifying strong impact of integrated soil fertility management of one year residual organic materials and N on maize production in the Guinea savannah. Grain yield prediction indicated treatments were best fitted in polynomials with 7.5 t/ha biochar + 90 kg N/ha for optimum grain yield.

Comparison of ground cover estimates from experiment plots in cotton, sorghum and sugarcane based on images and ortho-mosaics captured by UAV.

Ground cover is an important physiological trait affecting crop radiation capture, water-use efficiency and grain yield. It is challenging to efficiently measure ground cover with reasonable precision for large numbers of plots, especially in tall crop species. Here we combined two image-based methods to estimate plot-level ground cover for three species, from either an ortho-mosaic or undistorted (i.e. corrected for lens and camera effects) images captured by cameras using a low-altitude unmanned aerial vehicle (UAV). Reconstructed point clouds and ortho-mosaics for the whole field were created and a customised image processing workflow was developed to (1) segment the 'whole-field' datasets into individual plots, and (2) 'reverse-calculate' each plot from each undistorted image. Ground cover for individual plots was calculated by an efficient vegetation segmentation algorithm. For 79% of plots, estimated ground cover was greater from the ortho-mosaic than from images, particularly when plants were small, or when older/taller in large plots. While there was a good agreement between the ground cover estimates from ortho-mosaic and images when the target plot was positioned at a near-nadir view near the centre of image (cotton: R2=0.97, sorghum: R2=0.98, sugarcane: R2=0.84), ortho-mosaic estimates were 5% greater than estimates from these near-nadir images. Because each plot appeared in multiple images, there were multiple estimates of the ground cover, some of which should be excluded, e.g. when the plot is near edge within an image. Considering only the images with near-nadir view, the reverse calculation provides a more precise estimate of ground cover compared with the ortho-mosaic. The methodology is suitable for high throughput phenotyping for applications in agronomy, physiology and breeding for different crop species and can be extended to provide pixel-level data from other types of cameras including thermal and multi-spectral models.

Влияние морфологических признаков на урожайность сортов ярового ячменя в условиях степи Оренбургского Предуралья

Terms of plant water availability during the growing season of barley promote the wide variability in the size of plant organs of modern barley varieties of Orenburg breeding. In favorable conditions, the spring barley varieties form tall crops, long stems and large ears. Tall crops are typical to Armilid, Orenburgskiy 11, Orenburgskiy 17, Pervotselinnik and T 12 varieties. In dry conditions, there is a noticeable decrease in the value of the morphological features of the barley plants. The greatest advantage over the standard one according to the length of stem and ear in drought conditions was observed in Pervotselinnik varity. Mathematical analysis revealed a close relationship between the productivity of spring barley varieties on morphological characters sizes. Analysis of the graphs showed, that with an increase in plant height, stem length and ear length, an increase of the productivity is observed in the range of parameters studied morphological traits of modern spring barley varieties. The optimal parameters for the plant height of spring barley make up 82-88 cm; ear length - 8,5-9,7 cm; stem length - 75-80 cm; stem length ration to ear - 10,00-10,50 units. These values of morphological characters allow to obtain a high yield in the steppes of Orenburg Ural region. The optimal combination of plant organs parameters is observed in Armilid, Myar 2 and Pervotselinnik varities.

Responses to shade and subsequent recovery of soya bean in maize-soya bean relay strip intercropping

In relay intercropping systems, late-planted crops often grow under the shade of the canopy of early-planted tall crops and then transfer to full sunlight after the harvest of the early-planted crops. In order to know the effects of recovery growth of the late-planted soya bean in maize–soya bean relay intercropping, a field experiment was carried out to observe architectural, morphological, physiological and anatomical traits of soya bean plants related to shade and subsequent removal in intercropping before and after maize harvest, respectively. During shade period, soya bean biomass was severely reduced, and stem elongation was stimulated. Typical features of shade grown leaves were found, such as lower LMA (leaf mass per unit area), thinner thickness, higher chlorophyll content, lower chlorophyll a:b ratio. Whole-plant leaf area analysis found that soya bean increased leaf area ratio by adjusting leaf morphology rather than by dry mass allocation. After maize harvest, leaf area and leaf mass increased rapidly, contributing to compensation growth in intercropped soya bean. Meanwhile, physiological and anatomical traits of leaf went back to similar levels as grown in sole cropping. However, stem morphological traits were irreversible after removal of shade. Finally, no difference on seed weight per plant of soya bean was observed between relay intercropping and sole cropping. Based on these findings, we speculated the recovery growth might be the direct determining factor on pod formation in soya bean, and improvement on the capacity of recovery growth could increase yield of relay intercropped soya bean.

Rate and Timing Effects of Growth Regulating Herbicides Applications on Grain Sorghum (Sorghum bicolor) Growth and Yield

Dicamba and 2,4-D are among the most common and inexpensive herbicides used to control broadleaf weeds. However, different studies have pointed the risk of crop injury and grain sorghum yield reduction with postemergence applications of 2,4-D. No research data on grain sorghum response to 2,4-D or dicamba exists in the Southeastern United States. Consequently, a study was conducted to investigate crop growth and yield response to 2,4-D (100, 220, and 330 g acid equivalent ha−1) and dicamba (280 g acid equivalent ha−1) applied on 20 to 65 cm tall sorghum. Greater stunting resulted from 2,4-D applied at 330 g acid equivalent ha−1or below 45 cm tall sorghum whereas lodging prevailed with 2,4-D at 330 g acid equivalent ha−1and dicamba applied beyond 35 cm tall crop. Regardless of local environmental conditions, 2,4-D applied up to 35 cm tall did not negatively impact grain yield. There was a trend for yields to be somewhat lower when 2,4-D was applied on 45 or 55 cm tall sorghum whereas application on 65 cm tall sorghum systematically decreased yields. More caution should be taken with dicamba since yield reduction has been reported as early as applications made on 35 cm tall sorghum for a potentially dicamba sensitive cultivar.

Tolerance vs. avoidance: two strategies of soybean (Glycine max) seedlings in response to shade in intercropping

Intercropping is a sustainable agricultural practice used worldwide for highly efficient utilization of resources. However, short crops often grow under the shade of the canopy of tall crops in intercropping systems. Plants evolved two main strategies to deal with shade: avoidance and tolerance. Soybean (Glycine max), a legume crop, is often planted in intercropping. But little is known about a strategy that soybean may employ to deal with shade at seedling stage. Therefore, we determined morphological and physiological traits related to shade tolerance and shade avoidance in seedlings of two varieties. Generally, both varieties showed similar shade tolerance traits, such as increased specific leaf area and chlorophyll (Chl) content, and reduced photosynthetic capacity and the Chl a/b ratio. The light-limiting environment eliminated the benefits of shade tolerance traits for the carbon gain, which led to similar real-time photosynthesis and biomass in intercropping. By contrast, two varieties expressed different changes in shade avoidance traits. The variety Guixia 3 exhibited clear preference of shade avoidance that resulted in a high main stem, hypocotyl elongation, and biomass allocation towards the stem. The variety Gongxuan 1 showed those traits less. We suggested that the genetic variation occurs within soybean, thus the shade avoidance related traits might be important for variety selection for intercropping. Hence, the evaluation of performance should focus on shade avoidance in soybean genotypes in future experiments.

Carrier Volume is More Likely to Impact Trifluralin Efficiency than Crop Residue

PRE herbicides are generally less effective in conservation farming systems because of high levels of crop residue. However, performance can be improved if the herbicides are applied with a high carrier volume. This research investigated the interaction of carrier volume and row spacing or height of crop residue on the control of rigid ryegrass with trifluralin, at Cunderdin and Wongan Hills Western Australia. To create plots with varying residue row spacing in 2011, wheat was seeded in 2010 using a narrow row spacing (25 or 22 cm at Cunderdin and Wongan Hills), wide spacing (50 or 44 cm), or not planted to wheat. Narrow or wide row spacing or no crop plots had an average residue biomass of 4480, 3560, and 2430 kg ha−1at Cunderdin and 1690, 1910, and 1030 kg ha−1at Wongan Hills. To vary residue height, the wheat was harvested to produce tall, medium, or short crop residue (22, 13, and 5 cm at Cunderdin and 27, 22, and 17 cm at Wongan Hills). Rigid ryegrass seeds were broadcast onto each site in 2011 and trifluralin was sprayed using 50, 75, or 100 L ha−1carrier volume (directly prior to seeding). Increased carrier volume increased spray coverage at both sites (average cover of 9, 15, and 26% at 50, 75, and 100 L ha−1), leading to improved control of rigid ryegrass (68, 75, and 82% control at Cunderdin and 23, 41, and 68% control at Wongan Hills). Reduced crop residue height or increased row spacing led to reduced rigid ryegrass density at Cunderdin but had no impact at Wongan Hills. Therefore, carrier volume has a more consistent impact on the performance of trifluralin than crop residue row spacing or height.