Tiller Density Research Articles

Changes in sward structure, plant morphology and growth of perennial ryegrass–white clover swards over winter

White clover (Trifolium repens L.) is at a disadvantage to perennial ryegrass (Lolium perenne L.; PRG) due to its limited cold tolerance and low growth rates at colder temperatures, which can affect subsequent spring herbage dry matter (DM) availability. The effect of PRG ploidy on white clover morphology and growth over winter, and its subsequent recovery in spring and the following growing season, is poorly understood. The objective of this study was to compare the effect of white clover inclusion and PRG ploidy on sward structure, plant morphology and growth of PRG–white clover swards over winter. Four swards (diploid PRG only, tetraploid PRG only, diploid PRG–white clover and tetraploid PRG–white clover) were evaluated over a full winter period (November–February) at a farmlet scale. The PRG ploidy had no effect on herbage DM production, white clover content or tissue turnover (P > 0.05) over winter. However, white clover inclusion caused a significant decrease in herbage DM production (P < 0.001; −254 kg DM/ha) and tiller density (P < 0.001; −1,953 tillers/m2) over winter. Stolon mass was not affected by PRG ploidy (P > 0.05); however, stolon length and number of leaves per stolon were affected by PRG ploidy (P < 0.05). Including white clover in PRG swards can alter winter sward dynamics, potentially causing difficulties in subsequent spring management and performance due to the reduced over-winter growth rate when compared with PRG.

An examination of the effect of autumn closing date on over-winter herbage production and spring yield

Altering autumn management affects the herbage mass available in spring. An experiment was established to determine the effect of five autumn closing dates (CDs) on herbage production, herbage quality, leaf, stem and dead proportions and tiller density over winter. In the study 50% of the herbage available in spring was accounted for by autumn CD. Each 1 d extra a sward was closed from 25 September to 9 December increased herbage mass by 16 kg DM/ha in spring. Swards closed earlier (25 September–26 October) had consistently higher herbage masses in spring (1,301 kg DM/ha) compared to swards closed later (11 November–9 December; 703 kg DM/ha). Later closed swards had greater herbage quality compared to earlier closed swards (organic matter digestibility = 852 and 825 g/kg DM, respectively) due to increased stem and dead material in the grazing horizon of earlier closed swards. There was no effect of autumn CD on sward quality in the subsequent defoliation in spring. However, following the initial spring grazing there was an effect of autumn CD on subsequent grass growth rates; swards closed in October had a lower growth rate (33 kg DM/ha per day) compared to swards closed in November and early December (49 kg DM/ha per day). Results indicate that earlier autumn closing is beneficial to meet high-feed demand in spring but can affect sward quality and growth rates in spring.

Grazing strategies for resilience of ryegrass (

Perennial ryegrass (Lolium perenne L.) is a widely sown pasture species in temperate regions. Under heat and moisture-deficit stress, its production is suppressed and tiller mortality increases, particularly when plants are simultaneously exposed to other stresses such as intense defoliation. We investigated the effects of extended grazing exclusion periods in spring and summer on herbage and soils of rotationally grazed, perennial ryegrass-dominant pastures at a summer-wet site and a summer-dry site in sheep and beef hill country in New Zealand. Treatments comprised ‘grazed’ (conventional rotational grazing), ‘early opening’ (grazing exclusion from mid-spring to mid-summer to allow perennial ryegrass to flower), and ‘deferred grazing’ (grazing exclusion from mid-spring to late summer to allow perennial ryegrass to flower and set seed). At both sites, deferred grazing increased perennial ryegrass tiller density and total vegetation cover, and reduced the abundance of broadleaf species and Pseudopithomyces chartarum spores for up to 15 months after exclusion compared with the grazed control. Herbage production was reduced during the deferred period but there was a growth surge thereafter so that herbage production over the study period was similar in the deferred and grazed treatments. Pasture nutritive values were lower in the deferred than the grazed treatment during the exclusion period but were similar in all treatments by the end of the following winter. In the autumn after deferring, seedlings contributed ~50% of the perennial ryegrass tillers present at the summer-dry site but only ~10% at the summer-wet site, where regrowth tillering of existing plants contributed a high proportion of the perennial ryegrass tillers present. Overall, early opening had few effects on the pasture, whereas deferred grazing had numerous positive effects on the pasture but only short-term effects on soil quality.

Effect of mepiquat chloride and nitrogen fertilizer on growth, yield, quality and lodging in basmati rice (Oryza sativa L.) cultivars in Punjab

The effect of growth regulation and nitrogen on yield, quality and lodging in two basmati rice cultivars was studied at Ludhiana and Rupnagar during summer 2018. The field experiment was laid out in a split-split plot design having basmati cultivars (Basmati 370 and CSR 30) in main plots, nitrogen levels (20 and 30 kg N ha−1) in sub plots and growth regulation treatments (untreated control, lopping, mepiquat chloride at 300, 400 and 500 ppm) in sub-sub plots. Basmati rice cv. CSR 30 recorded 6.9% higher tiller density, 11.4% higher leaf area and 10.9% higher panicles while lodging was 37.4% lower as compared to Basmati 370. Basmati 370 had 43.0, 21.5 and 31.0% higher grains per panicle, panicle length and panicle weight than CSR 30. Both cultivars gave similar grain yield, milling quality and net returns. Nitrogen application at 30 kg N ha−1 increased growth attributes, however, it had no effect on yield attributes and grain yield other than 20 kg N ha−1 level. Growth regulation treatments of lopping, or mepiquat chloride at 300 ppm significantly reduced lodging and increased grain yield by 7–10% and net returns by 14–16% over untreated control.

Does the residual effect of n-fertilization applied on corn phase maintain forage production of the following pasture phase in an integrated crop-livestock system?

Nutrient cycling represents an important nutrient source in the Integrated Crop-Livestock Systems (ICLS). In general, only the crop phase of the ICLS is fertilized, however little is known about this residual effect of nitrogen fertilization from summer crop to succeeding winter pasture. This research aimed to evaluate the forage growth dynamic and botanical composition of a mixed pasture of black oat (Avena strigosa Schreb) and ryegrass (Lolium multiflorum Lam.) affected by two canopy height managements (high and low) and nitrogen fertilization applied to either the summer crop (corn) or winter pasture phase of an ICLS. The experiment was established in 2012 in southern Brazil. Black oat and ryegrass were growing during winter season and corn (Zea mays L.) during summer season, being this paper related to the 2014 pasture period. Treatments were composed by two canopy heights (25 and 10 cm) and two N-Fertilization Times (N-Pasture or N-Corn) of 200 kg of N ha-1. Canopy height was regulated by beef steers grazing through continuous stocking with a variable stocking rate. Forage mass was lower in the 10 cm canopy height on average, however this forage mass was composed by greater proportion of ryegrass leaves and lower proportion of dead material in relation to the treatment with 25 cm canopy height. The N-fertilization applied directly on pasture phase (N-Pasture) increased forage mass, tiller population density, participation of ryegrass and ryegrass leaf proportion in the forage mass. Furthermore, when pasture was fertilized with N, the forage accumulation rate increased about 69%, highlighting that the corn N-fertilization did not present significant effect on forage productivity. The residual effect of corn N-fertilization was not enough to maintain high forage accumulation. Thus, the pasture N-fertilization is fundamental to keep high-productive crop-livestock system.

Morpho‐physiological, biochemical and isotopic response of tall wheatgrass populations to salt stress

AbstractTall wheatgrass [Elymus elongatus subsp. ponticus (Podp.) Melderis] is a C3 grass native from dry or saline habitats in SE Europe. The aim of this study was to better understand response mechanisms of populations from different origins to salinity and to provide new tools to select germoplasm with high salinity tolerance. Four populations (P3‐P4‐P5‐P9) were irrigated with five solutions of increasing salinity (Salt: 0–0.1–0.2–0.3–0.4 M NaCl) and evaluated in pots in a greenhouse. Two experiments were carried out, a short 40‐day long experiment with vegetative plants, and a longer 85‐day long one with plants that underwent vegetative‐reproductive stage. No evidence was found of an interaction between population and salt. Morpho‐physiological, biochemicals, isotopic and productive variables were differently affected by increasing salinity and were also different among populations. Proline, Na+ and Cl− consistently appeared to function as osmotic agents. P5 showed the highest biomass in the 85‐day experiment and had the highest leaf length, tiller density, water use efficiency and δ13C isotope; and the lowest Cl− concentration and evapotranspiration rate. However, P5 showed the lowest biomass in the 40‐day experiment, suggesting that duration of the stress is an important aspect to consider when selecting germoplasm for tolerance to salinity. Differences among populations in growth strategies and physiological mechanisms could be related to their origin environment.

Strip-tillage renovation of intermediate wheatgrass (Thinopyrum intermedium) for maintaining grain yield in mature stands

AbstractKernza® intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & Dewey], the first perennial grain crop to come to market in North America, can provide a number of ecosystem services when integrated into cropping systems that are dominated by annual grain crops. However, grain yield from Kernza is lower than comparable annual cereal crops such as wheat and oats. Also, although Kernza is a long-lived perennial that can persist for decades, grain yield tends to decline over time as Kernza stands age leading most farmers to replant or rotate to a different crop after 3–5 yrs. Increased intraspecific competition as stand density increases with age has been reported to cause grain yield declines. We investigated the effect of strip-tillage applied at two different timings, between the third and fourth grain harvests, from a Kernza stand in upstate New York. Strip-tillage applied in late fall as plants were entering dormancy increased grain yield by 61% when compared to the control treatment without strip-tillage. However, total crop biomass was not reduced resulting in a greater harvest index for the fall strip-tillage treatment. Strip-tillage applied before stem elongation the following spring reduced overall tiller density and total crop biomass but did not impact tiller fertility or grain yield compared to the control treatment without strip-tillage. Increased grain yield in the fall strip-tillage treatment was due to an increase in the percentage of tillers that produced mature seedheads. This suggests that grain yield decline over time is at least partially caused by competition between tillers in dense stands. Results support further research and development of strip-tillage and other forms of managed disturbance as tools for maintaining Kernza grain yield over time.

Population Trends of the Sugarcane Borer (Lepidoptera: Crambidae) in Louisiana Sugarcane.

The sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), is the primary pest of sugarcane, Saccharum spp., in Louisiana. Spring populations are not considered economically damaging, but quantifying infestations can provide an indication of the spatial and temporal character of the damaging summer populations. Statewide surveys quantified the density of sugarcane tillers killed by D. saccharalis (deadhearts) from sugarcane fields across the state in spring from 2003 to 2020. Deadheart density varied greatly among years with a high of 1,318/ha in 2003 to a low of 0/ha in 2018. Linear regressions of the 3-yr rolling average showed declines in spring D. saccharalis populations and the percentage of acreage treated with insecticides over 17 yr. Weather factors including minimum winter temperatures and average spring temperatures were poor predictors of D. saccharalis populations. Only total precipitation in the month of April was positively correlated with numbers of deadhearts per hectare. Results suggest overwintering mortality is not a key factor influencing populations of the first generation of D. saccharalis in Louisiana. Total precipitation in the month of July was positively associated with percentage of treated acreage. Spring deadheart density was directly related to percentage of acreage treated with insecticides during the summer. Quantifying first-generation D. saccharalis populations by recording deadheart density can aid in predicting pest pressure later in the growing season.

Influence of Nitrogen Fertilization Pattern on Productivity, Nitrogen Use Efficiencies, and Profitability in Different Rice Production Systems

The major challenge in sustainable rice production is to achieve the goals of increasing crop productivity, profitability, and resource use efficiency. Production systems (PS) and nitrogen (N) management patterns are two key agronomic practices influencing crop performance, profitability, water use efficiency (WUE), and N use efficiency (NUE). So, this study was conducted to check the influence of split application of N on rice productivity, NUE and profitability under dry direct-seeded rice (DDSR) and transplanted rice (TPR) systems. A field study was conducted in the summer season of 2017 and 2018 to investigate the influence of two PS (dry direct-seeded rice = DDSR and transplanted rice = TPR) and six N management treatments (N1 = control, N2 = 50 kg N ha−1 as basal, N3 = 100 kg N ha−1 as basal, N4 = 150 kg N ha−1 as basal, N5 = 100 kg N ha−1 in three splits and N6 = 150 kg N ha−1 in three splits) on crop productivity, profitability, and resource use efficiency. Yield-related traits, spikelet sterility, WUE, and profitability aspects were significantly influenced by PS. All aspects of crop performance, kernel quality, N uptake, and NUE (except NUE on biomass basis = NUEB) were affected by N management pattern, while no significant interaction between PS and N management was observed for any aspect. On average, DDSR improved the productive tiller density (26%), biological yield (16%), WUE (14%), and NUEB (27%) as compared with TPR. Similarly, DDSR reduced the cost of production (31–43%), while maintaining statistically similar paddy yields and reducing total water inputs (5–17%) in comparison with TPR. Among N management pattern, 100 kg N ha−1 in three splits increased paddy yields (44%), and WUE (42%) as compared with the basal application of 100 kg N ha−1. Similarly, application of N at 100 kg ha−1 in three splits improved the total N uptake (42%), agronomic NUE (146%), apparent recovery efficiency (226%) while reducing the spikelet sterility (28%) as compared with the basal application of 100 kg N ha−1. The DDSR has the potential to maintain or increase yield, WUE, NUE, and economic returns. While, split application of N at 100 kg ha−1 either in DDSR or TPR not only increased the SPAD-chlorophyll value, WUE, NUE, and economic returns but also reduced the spikelet sterility.

Selecting plant traits for soil erosion control in grassed waterways under a changing climate: A growth room study

AbstractGrassed waterways are used to mitigate the offsite transport of sediment generated by soil erosion. This study used a novel trait‐based ranking approach as a method to screen potential candidate grass monocultures and mixes based on their theoretical performance in reducing (a) detachment via rainsplash, (b) detachment via scouring due to concentrated flow and (c) sediment transport and deposition processes. Selected grass species were grown under simulated UK summer and autumn establishment conditions under three different replicated rainfall scenarios: drought, normal rainfall and excess rainfall. The grass species used were the novel hybrid species Festulolium cv Prior (Fest_1) and Festulolium Bx511 (Fest_2) and a conventional mixture of Lolium perenne and Festuca rubra (Conv). Monocultures and mixtures of these species were studied. Plant traits pertinent to control of soil erosion by water were measured. Aboveground traits included plant height, percentage ground cover, aboveground biomass, stem diameter, stem area density and number of tillers. Belowground traits included total root length, root total surface area, belowground biomass, root diameter and % fine roots ≤0.25 mm. For summer conditions, the species treatments that had the highest overall soil erosion mitigation potential were Conv, Fest_1 + 2 + Conv and Fest_2. For autumn conditions, the best treatments were Fest_1 + 2, Fest_1 + 2 + Conv and Conv. The Fest 1 + 2 + Conv had more desirable traits for erosion control than mono Festulolium treatments for the autumn conditions. The conventional mixture had more desirable traits for erosion control than mono Festulolium treatments in both climate scenarios. The results indicate that the trait‐based ranking approach utilized in this study can be used to inform rapid screening of candidate grass species for soil erosion control.Highlights How to select the most suitable grass species for soil erosion control under changing climate conditions? A novel scoring system based on plant traits associated with soil erosion mitigation was developed. Fest_1 + 2 and Conv treatments expressed traits strongly associated with maximum soil erosion mitigation. Species selection for grassed waterways should consider the establishment growing season and expected rainfall.

Continuous grazing of mixed native warm‐season grass in the fescue belt

AbstractContinuous, season‐long (May–August) grazing is the most commonly used grazing strategy among tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] belt beef (Bos taurus) producers. However, little information is available regarding the feasibility of managing native warm‐season grass (NWSG) pastures in this region with continuous, season‐long grazing. We compared stand sustainability, beef cattle performance, and pasture production between continuous (CONT), season‐long grazing and heavy‐early (HEAVY), a modified continuous grazing strategy, on mixed‐NWSG pastures. Heavy‐early was designed to match the growth curve of NWSG, with an initial stocking target of 1.25 times the CONT density until 25 June, at which time stocking was reduced to 0.75 times the CONT density. Pastures were mixed big bluestem (Andropogon gerardii Vitman), indiangrass [Sorghastrum nutans (L.) Nash], and little bluestem [Schizachyrium scoparium (Michx.)]. The plant population (plants m−2) was similar between treatments, but years differed (P < .001), with a 35% reduction from 2017, the third and final year of grazing, to 2018. Despite the decline in plant density, overall tiller density (tillers m−2) increased 14%, indicating that the grazing strategies were likely sustainable. The grazing strategies had similar (P > .05) average daily gain (ADG; kg d−1), animal‐days ha−1, and total gain (kg ha−1). Weaned steer ADG was 0.98 kg d−1 for CONT and 0.89 kg d−1 for HEAVY. Total gain was 379 kg ha−1 for CONT and 334 kg ha−1 for HEAVY. Continuous grazing appears to be an appropriate strategy for managing NWSG pastures in the Fescue Belt.

Growth, yield and water productivity of dry direct seeded rice and transplanted aromatic rice under different irrigation management regimes

Sustainability of traditionally cultivated rice in the rice-wheat cropping zone (RWCZ) of Pakistan is dwindling due to the high cost of production, declining water resources and escalating labour availability. Thus, farmers and researchers are compelled to find promising alternatives to traditional transplanted rice (TPR). A field study was conducted in Punjab, Pakistan, in 2017 and 2018 to explore the trade-offs between water saving and paddy yield, water productivity and economics of two aromatic rice varieties under dry direct seeded rice (DDSR) and TPR. The experiment was comprised of three irrigation regimes on the basis of soil moisture tension (SMT) viz., continuous flooded (>−10 kPa SMT), alternate wetting and drying (AWD) (−20 kPa SMT) and aerobic rice (−40 kPa SMT), maintained under TPR and DDSR systems. Two aromatic rice verities: Basmati-515 and Chenab Basmati-2016 were used during both years of study. In both years, DDSR produced higher yields (13–18%) and reduced the total water inputs (8–12%) in comparison to TPR. In comparison to traditional continuous flooded (CF), AWD under DDSR reduced total water input by 27–29% and improved the leaf area index (LAI), tillering, yield (7–9%), and water productivity (44–50%). The performance of AWD with regard to water savings and increased productivity was much higher in DDSR system as compared to AWD in TPR system. Cultivation of DDSR with aerobic irrigation improved water savings (49–55%) and water productivity (22–30%) at the expense of paddy yield reduction (36–39%) and spikelet sterility. With regard to variety, the highest paddy yield (6.6 and 6.7 t ha−1) was recorded in DDSR using Chenab Basmati-2016 under AWD irrigation threshold that attributed to high tiller density and LAI. The economic analysis showed DDSR as more beneficial rice establishment method than TPR with a high benefit-cost ratio (BCR) when the crop was irrigated with AWD irrigation threshold. Our results highlighted that with the use of short duration varieties, DDSR cultivation in conjunction with AWD irrigation can be more beneficial for higher productivity and crop yield.

Maximizing fodder yield of teosinte (Euchlaena mexicana) through sowing dates and mixed fodder cropping management

Teosinte (Euchlaena mexicana) is one of the most popular summer growing cereal fodder, rich in energy, dry matter (DM) and other nutrients, yet productivity of this fodder in Nepal has not been achieved as expected due to several important factors including cultivation management and sowing dates. An experiment was done during April to August 2018 at Directorate of Agricultural Research, NARC, Province-5, Khajura, Banke by using Split Plot design with the objective to identify the appropriate sowing dates in relation to possible combination of local fodder legumes with teosinte. It was expected that best possible combination of fodder legumes with teosinte would increase both herbage mass as well as quality aspects through increased productivity. Accordingly main plot treatments were sowing dates (April 18, May 3, and May 18) and sub-plot treatments were set as combination of fodder cowpea, lablab bean, and rice bean, each with teosinte, and sowing of teosinte as sole crop. Findings revealed that plant height, leaf length, tiller density of teosinte, and number of branches and trifoliate leaves of fodder legumes had contributed significantly to the cumulative herbage mass. Significantly highest green herbage and dry herbage mass (p<0.001) was obtained if these fodder species were sown in April 18 as compared to other dates of sowing. The combination of teosinte and cowpea had yielded significantly higher herbage mass (p<0.001) compared to others fodder species combinations. Preliminary findings of this research thus indicate the possibility of promoting mixed cultivation of teosinte with fodder cowpea in order to increase both herbage mass and quality.

Genome-wide small RNA profiling reveals tiller development in tall fescue (Festuca arundinacea Schreb)

BackgroundTall fescue (Festuca arundinacea Schreb.) is a major cool-season forage and turfgrass species. The low tiller density and size dramatically limits its turf performance and forage yield. MicroRNAs (miRNA)-genes modules play critical roles in tiller development in plants. In this study, a genome-wide small RNA profiling was carried out in two tall fescue genotypes contrasting for tillering production (‘Ch-3’, high tiller production rate and ‘Ch-5’, low tiller production rate) and two types of tissue samples at different tillering development stage (Pre-tillering, grass before tillering; Tillering, grass after tillering). ‘Ch-3’, ‘Ch-5’, Pre-tillering, and Tillering samples were analyzed using high-throughput RNA sequencing.ResultsA total of 222 million high-quality clean reads were generated and 208 miRNAs were discovered, including 148 known miRNAs belonging to 70 families and 60 novel ones. Furthermore, 18 miRNAs were involved in tall fescue tiller development process. Among them, 14 miRNAs displayed increased abundance in both Ch-3 and Tillering plants compared with that in Ch-5 and Pre-tillering plants and were positive with tillering, while another four miRNAs were negative with tiller development. Out of the three miRNAs osa-miR156a, zma-miR528a-3p and osa-miR444b.2, the rest of 15 miRNAs were newfound and associated with tiller development in plants. Based on our previous full-length transcriptome analysis in tall fescue, 28,927 potential target genes were discovered for all identified miRNAs. Most of the 212 target genes of the 18 miRNAs were dominantly enriched into “ubiquitin-mediated proteolysis”, “phagosome”, “fatty acid biosynthesis”, “oxidative phosphorylation”, and “biosynthesis of unsaturated fatty acids” KEGG pathways. In addition, bdi-miR167e-3p targets two kinase proteins EIF2AK4 and IRAK4, and osa-miR397a targets auxin response factor 5, which may be the significant miRNA-genes controllers in tillering development.ConclusionsThis is the first genome-wide miRNA profiles analysis to identify regulators involved in tiller development in cool-season turfgrass. Tillering related 18 miRNAs and their 212 target genes provide novel information for the understanding of the molecular mechanisms of miRNA-genes mediated tiller development in cool-season turfgrass.

Forage Mass, Tillering, Nutritive Value and Root System of Ruzigrass Inoculated with Plant Growth Promoting Bacteria Associated with Doses of N-Fertilizer

The aim of this study was evaluating the effect of the inoculation of plant growth promoting bacteria (PGPB) in forage mass, tillering, nutritive value and root system of ruzigrass (Urochloa ruziziensis (R. Germ. & Evrard) Crins (syn. of Brachiaria ruziziensis) associated with doses of N-fertilizer. The bacteria inoculated were Azospirillum brasilense Ab-V5, Pseudomonas fluorescens CCTB03 and Pantoea ananatis AMG 521, plus the control treatment (non-inoculated), associated with doses of N-fertilizer (0, 50 and 100 kg N ha-1). The experiment was performed in a randomized block design, in a 4x3 factorial scheme, with four replicates, totaling 48 plots (12 m2). There were no effects of the PGPB and the use of N-fertilizer on the leaf blade, stem+sheath, forage mass, daily and yearly accumulation of forage mass. The PGPB did not have influence on the density of tillers. The doses of 50 and 100 kg of N ha-1 increased the amount of tillers. The AMG 521 strain associated with N-fertilizer provided heavier tillers. There was no effect of the PGPB on crude protein (CP), neutral detergent fiber (NDF), as well as acid detergent fiber (ADF), and in vitro digestibility of the dry matter (IVDDM). The use of 100 kg of N ha-1 contributed to an increase in CP and a decrease in NDF. The AMG 521 strain contributed to a smaller diameter of the root. Strains CCTB03 and AMG 521 demonstrated a smaller area, length and root density when associated with the dose of 50kg of N ha-1. In general, the PGPB were not efficient in promoting productive increments in ruzigrass.

An automatic method for counting wheat tiller number in the field with terrestrial LiDAR

BackgroundThe tiller number per unit area is one of the main agronomic components in determining yield. A real-time assessment of this trait could contribute to monitoring the growth of wheat populations or as a primary phenotyping indicator for the screening of cultivars for crop breeding. However, determining tiller number has been conventionally dependent on tedious and labor-intensive manual counting. In this study, an automatic tiller-counting algorithm was developed to estimate the tiller density under field conditions based on terrestrial laser scanning (TLS) data. The novel algorithm, which is named ALHC, involves two steps: (1) the use of an adaptive layering (AL) algorithm for cluster segmentation and (2) the use of a hierarchical clustering (HC) algorithm for tiller detection among the clusters. Three field trials during the 2016–2018 wheat seasons were conducted to validate the algorithm with twenty different wheat cultivars, three nitrogen levels, and two planting densities at two ecological sites (Rugao & Xuzhou) in Jiangsu Province, China.ResultThe results demonstrated that the algorithm was promising across different cultivars, years, growth stages, planting densities, and ecological sites. The tests from Rugao and Xuzhou in 2016–2017 and Rugao in 2017–2018 showed that the algorithm estimated the tiller number of the wheat with regression coefficient (R2) values of 0.61, 0.56 and 0.65, respectively. In short, tiller counting with the ALHC generally underestimated the tiller number and performed better for the data with lower plant densities, compact plant types and the jointing stage, which were associated with overlap and noise between plants and inside the dense canopy.ConclusionsDiffering from the previous methods, the ALHC proposed in this paper made full use of 3D crop information and developed an automatic tiller counting method that is suitable for the field environment.

What is the productive potential of digit grass in response to nitrogen fertilization?

The digit grass is a highly cultivated species in Northeast Brazil, especially in Sergipe and Alagoas. However, research related to the management of fertilization of this specie is incipient. This experiment was carried out to examine the productive potential of digit grass and its morphological changes in response to nitrogen fertilization. The experimental period was from August 2014 to July 2015. Treatments consisted of five levels of nitrogen fertilization (0, 50, 100, 300 and 600 kg ha-1) arranged in a randomized-block design with four replicates. Urea was used as a source of nitrogen. Height, light interception (LI), leaf area index (LAI), total tiller density (TTD), basal tiller density (BTD) and total (TDM), leaf (LDM) and stem dry matter (SDM) accumulations were influenced (P<0.05) by the nitrogen doses, fitting a positive quadratic equation. Nitrogen fertilization did not influence (P>0.05) dead material accumulation rate or aerial tiller density. Overall, the increasing nitrogen doses culminated in increased canopy height, LI and LAI as a result of the increase in TTD and BTD, which in turn elevated TDM, LDM and SDM. The herbage yield potential of digit grass can be increased with the application of 478 kg N ha-1, enabling its use as an alternative in intensive animal production systems.

Optimum harvest time for Kikuyu grass (Cenchrus clandestinus) according to the number of leaves per tiller and nitrogen fertilization

To determine the optimum harvest time of kikuyu grass (Cenchrus clandestinus (Hochst. ex Chiov.) Morrone), according to the number of leaves per tiller and nitrogen fertilization level, an experiment was carried out under greenhouse conditions using a 4×4 factorial design. The factors were the number of leaves per tiller (3, 4, 5, 6 leaves) and level of nitrogen (N) fertilization (0, 50, 100,150 kg of Nitrogen ha-1 year-1). Dry matter (DM) yield and nutritional quality were determined. Additionally, the independent effect of nitrogen fertilization on undisturbed height, tiller density, and the phyllochron were evaluated. When the number of leaves per tiller increased (3 to 6), the leaf yield and dead forage also increased (P<0.05). The leaf-stem ratio (L:S) remained constant (P>0.05) among the number of leaves. Green forage-dead forage ratio (GF:DF) decreased (P<0.05) with a higher number of leaves per tiller. The concentration of crude protein (CP) decreased while the concentration of neutral detergent fiber (NDF) increased with an increment of the number of leaves per tiller (P<0.05). Nitrogen fertilization increased the undisturbed height, the density of tillers, DM yield from leaves, stems and green forage, GF:DF, and CP (P<0.05) while NDF decreased (P<0.05). The phyllochron was higher without N fertilization. The effects of the number of leaves per tiller and N fertilization on the most variables measured were independent of each other. However, due to an increment in DM yield caused by N fertilization, the pasture can be defoliated with fewer leaves per tiller, increasing defoliation frequency and improving forage quality

Overseeding cool‐season annual grasses into dormant lowland switchgrass stands

AbstractImproved use of the land resource used to grow switchgrass (SG; Panicum virgatum L.), whether for biomass or forage production, could be achieved by dormant‐season overseeding with cool‐season annual grasses (CAGs). Cereal rye (Secale cereale L.), ryegrass (Lolium multiflorum Lam.), and wheat (Triticum aestivum L.) were overseeded into an established, mature stand of lowland (‘Alamo’) SG for two consecutive years (2010–2011) at a study site located near Greeneville, TN. Three harvest timings were imposed on CAG (15 April, 1 May, and 15 May). Yield of CAG differed (p = 0.001) by year, species (rye = 6.8, ryegrass = 5.0, wheat = 5.1 Mg ha−1), and harvest time (15 April = 2.7, 1 May = 6.5, 15 May = 7.7 Mg ha−1), but these factors did not interact. Switchgrass yield the summer following establishment of CAGs differed (p = .001) by year (11.1 and 14.7 Mg ha−1, in 2011 and 2012, respectively) but not by CAG species or harvest date. Tiller density of SG followed the same pattern as yield (2011 = 75 m−2; 2012 = 147 m−2). Thus, this study provided no evidence that any of the three CAGs, when planted for two consecutive years into dormant SG, regardless of harvest date, had a negative effect on SG yield or stand vigor; therefore, overseeding CAGs may be a practical way for producers to improve land resource use when growing SG. However, evaluation of production costs for CAGs indicated that May harvests would be required for overseeding to be cost‐effective.

Do agricultural grasses bred for improved root systems provide resilience to machinery-derived soil compaction?

The increasing frequency of droughts and floods on grasslands, due to climate change, increases the risk of soil compaction. Soil compaction affects both soil and forage productivity. Differing grasses may counteract some effects of compaction due to differences in their root architecture and ontogeny. To compare their resilience to soil compaction, three Festulolium (ryegrass and fescue species’ hybrids) forage grass cultivars comprising differing root architecture and ontogeny were compared in replicated field plots, together with a ryegrass and tall fescue variety as controls. Pre‐compaction soil and forage properties were determined in spring using > four‐year‐old plots to generate baseline data. Half of each field plot was then artificially compacted using farm machinery. Forage dry matter yield (DMY) was determined over four cuts. After the final harvest, post compaction soil characteristics and root biomass (RB) were compared between grasses in the non‐compacted and compacted soils. Pre‐compaction data showed that soil under Festulolium and ryegrass had similar water infiltration rates, higher than soil under tall fescue plots. Tiller density of the Festulolium at this time was significantly higher than fescue but not the ryegrass control. Forage DMY was significantly lower (p < .001) with compacted soil at the first cut but, by the completion of the growing season, there was no effect of soil compaction on total DMY. Tall fescue had a higher total DMY than other grasses, which all produced similar annual yields. Soil bulk density and penetration resistance were higher, and grass tiller density was lower in compacted soils. Root biomass in compacted soils showed a tendency for Festulolium cv Lp × Fg to have higher RB than the ryegrass at 0–15 cm depth. Overall, findings showed alternative grass root structures provide differing resilience to machinery compaction, and root biomass production can be encouraged without negative impacts on forage productivity.