2nd Internode Research Articles

Optimized Phosphorus Application Enhances Wheat Stem Lodging Resistance Under Spring Low-Temperature Stress.

Spring low-temperature stress (LTS) has become a major limiting factor for the development of high yield, quality and efficiency in wheat production. It not only affects the function of wheat leaves and the development of spikes but also impacts stem lodging resistance, and may experience elevated risk of stem lodging. This study conducted a field pot experiment to assess the effect of phosphorus fertilizer application mode on wheat stem lodging resistance under spring LTS. Two wheat varieties, Yannong19 (YN19, cold-tolerant variety) and Xinmai26 (XM26, cold-sensitive variety) used as the experiment material. Two phosphorus fertilizer application models including traditional phosphorus application (TPA) and optimized phosphorus application (OPA) were employed. Temperature treatment was conducted at 15 °C (CK) and -4 °C (LT) in a controlled phytotron. Our results showed that spring LTS decreased the stem wall thickness and internode fullness, and altered stem anatomical structure and chemical composition, resulting in a decrease in wheat stem mechanical strength and lodging resistant index. Compared with TPA, the OPA increased the stem wall thickness and internode fullness. The thickness of the stem mechanic tissue layer and parenchymatous tissue, and the area of the large vascular bundle and small vascular bundle were increased by the OPA, which alleviated the damage to stem cell walls caused by spring LTS. At the same time, the OPA also increased the contents of lignin, cellulose, and soluble sugar, improving the C/N ratio in wheat stem. Due to the improved stem morphological characteristics, anatomical structure, and chemical compositions, the wheat stem exhibited enhanced lodging resistance, which increased the lodging resistant index of the 2nd and 3rd internodes of YN19 and XM26 by 27.27%, 11.63% and 14.15%, 15.73% at the dough stage compared with TPA under spring LTS. Meanwhile, OPA could not only alleviate the yield loss caused by spring LTS, but also increase the grain yield without spring LTS. This study indicated that OPA enhances wheat stem lodging resistance under spring LTS, and would be meaningful and practical for improving wheat resistance to low-temperature stress.

Assessment of the resistance to lodging of spring triticale based on the study of physical and mechanical properties

The results of the study of architectonics and physical and mechanical properties of the stems of selective forms of spring hexaploid triticale of different ecological and geographical origin are presented. Traits of 19 collection and breeding samples from the collections of the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR) and the Siberian Research Institute of Plant Growing and Selection - branch of the Federal Research Center of the Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences (SibNIIRS – branch of the Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences) served as research objects. Macrometric parameters were studied on 25 representative specimens of each breeding sample when they reached the phase of full ripeness during three years (2021–2023). The resistance of the stem to bending or fracture was determined on an experimental specimen manufactured at the SibNIIRS with a stable platform, bars for fixing the specimen and a slot for placing a dynamometer. The susceptibility of triticale plants to lodging was evaluated by a set of traits: weight of a 10-cm straw of the 2nd internode; stem resistance to breaking determined by the peak reading of an electronic dynamometer; stem tissue density of the 2nd internode. The studied samples differed significantly in these parameters and were characterized by different degrees of the resistance to lodging. Promising breeding specimens that can be used as sources of valuable traits have been identified based on the totality of the strength parameters. Application of the principal component method allowed to identify the marker trait "sum of lengths of the 2nd and 3rd internodes", which was determinant in providing high lodging resistance in the studied samples. A close relationship between the trait of 10-cm straw mass of the 2nd internode and the parameter of the stem resistance to breakage has been established. The conjugation of these characteristics will make it possible to identify the sources of valuable traits and purposefully carry out the selection process of triticale for resistance to lodging without attracting short-stemmed forms.

Propagation, physiology, and biomass of Giant Cane (Arundinaria gigantea) for conservation and restoration

Arundinaria gigantea is a native species to 22 states in the U.S. The species and its ecosystem are considered critically endangered, and the species has been reduced to 2% of its original extent. Our research goals were to; 1) examine methods for greenhouse propagation for restoration; 2) examine the physiology of cane at one of the only canebrakes on public land in SW MO, greenhouse propagated cane, and field planted cane; and 3) develop an allometric equation to estimate biomass of the canebrake. We used the number of shoots produced as a metric for propagation success. The number of new shoots depended on rhizome length, watering regime, and whether propagation was attempted with the rhizome alone or with an existing culm. We recorded 100% propagation success from every rhizome with culm cut at 2nd internode with regular watering on 8 x 15.6-inch pots having soil-mix/perlite media. Leaf chlorophyll values ranged from 329 umol/m2 in sun leaves to 354 umol/m2 in shade leaves in October 2022. During a mild drought summer 2022, leaves-maintained water potential of -1.8 MPa with photosynthetic rates as high as 12 umol CO2/m2/s. Biomass models based on pole diameter and height were established. We estimated 12,359.508 kg of biomass which is equivalent to 5.8 metric tons of carbon stored by a 0.17 ha canebrake at Mincy Conservation Area in SW MO. Our research provides baseline data for understanding the role of cane and canebrakes in ecosystem functioning in existing canebrakes, and habitats where cane could be restored.

Supplementary UV-A and UV-B radiation differentially regulate morphology in Ocimum basilicum.

UV-A- or UV-B-enriched growth light was given to basil plants at non-stress-inducing intensities. UV-A-enriched growth light gave rise to a sharp rise in the expression of PAL and CHS genes in leaves, an effect that rapidly declined after 1-2days of exposure. On the other hand, leaves of plants grown in UV-B-enriched light had a more stable and long-lasting increase in the expression of these genes and also showed a stronger increase in leaf epidermal flavonol content. UV supplementation of growth light also led to shorter more compact plants with a stronger UV effect the younger the tissue. The effect was more prominent in plants grown under UV-B-enriched light than in those grown under UV-A. Parameters particularly affected were internode lengths, petiole lengths and stem stiffness. In fact, the bending angle of the 2nd internode was found to increase as much as 67% and 162% for plants grown in the UV-A- and UV-B-enriched treatments, respectively. The decreased stem stiffness was probably caused by both an observed smaller internode diameter and a lower specific stem weight, as well as a possible decline in lignin biosynthesis due to competition for precursors by the increased flavonoid biosynthesis. Overall, at the intensities used, UV-B wavelengths are stronger regulators of morphology, gene expression and flavonoid biosynthesis than UV-A wavelengths.

Morphometric parameters of the stem of lodging-resistant spring triticale in the conditions of the West Siberian region

In the course of field and laboratory research, selection samples of spring hexaploid triticale were studied for their selection-valuable traits and lodging resistance. The correlation analysis revealed a correlation between the individual traits that determine lodging tolerance. The most stable relationship of lodging resistance is with the length of the second and third internodes and the breaking strength of the straw. An additional selection criterion for lodging resistance is the sum of the lengths of the 2nd and 3rd internodes. Non-lodging varieties with high grain productivity that have significant differences in architectonics have been identified. These samples can be promising in lodging resistance selection without the involvement of sources of short stalkedness, having a number of negative traits.

Improving rice grain yield and reducing lodging risk simultaneously: A meta-analysis

Smart agronomic management practices (e.g., employing lodging-resistant cultivars, appropriate fertilization, and applying plant growth regulators (PGRs)) can reduce crop lodging risk. However, their integrated effects on grain yield and lodging risk in rice paddies remain poorly defined. Here, we conducted a meta-analysis to examine the effects of agronomic practices on rice yield and lodging risk, synthesizing data from 68 published studies with 475 observations. Our results showed that compared with inbred varieties, hybrid rice increased grain yield by an average of 8.9%, and enhanced lodging index (LI) (increasing lodging risk with a higher LI) at the 1st (+23%) and 3rd (+17%) internodes with no significant effect at the 2nd internode. Inorganic nitrogen (N) fertilization increased both rice yield (+42%) and LI at the 2nd (+31%) and 3rd (+23%) internodes, but did not significantly affect LI at the 1st internode. The application of silicon (Si) and potassium (K) fertilizers increased rice yield by 7.2% and 18%, respectively, while simultaneously reducing LI by 14% and 19% at the 1st internode, by 15% and 21% at the 2nd internode, and by 4.5% and 18% at the 3rd internode. Prohexadione calcium and uniconazole increased rice yield by 6.7% and 8.3%, respectively, while paclobutrazol had no significant effect on rice yield. Prohexadione calcium and uniconazole reduced LI by 14% and 21% at the 1st internode, by 26% and 31% at the 2nd internode, and by 16% and 54% at the 3rd internode, respectively, whereas paclobutrazol only reduced LI at the 3rd internode by 12%. In conclusion, the application of Si, K, prohexadione calcium, and uniconazole is a promising strategy for improving rice yield and reducing lodging risk. In addition, we suggest that high-yielding practices (e.g., hybrid rice and inorganic N fertilization) and lodging-resistant practices (e.g., the application of Si, K, and PGRs) should be combined to increase grain yield and simultaneously reduce lodging risk in rice paddies.

The role of different stem segments in the deposition of water-soluble carbohydrates in winter wheat varieties under drought conditions

Aim. Evaluation of the role of different internodes and leaf sheaths of winter wheat stem in storage and remobilization of reserve water-soluble carbohydrates (WSC) under natural water deficit in order to develop effective criteria for selection of high-yielding genotypes. Methods. The specific content and total amount of WSC at the onset and the end of grain filling and the quantity of WSC remobilized in different parts of the stem were determined. Results. It was found that the main part of reserve WSC in plants of modern winter wheat varieties was accumulated and mobilized in the 2nd, 3rd and 4-5th (counting from above) internodes, the contribution of peduncle and leaf sheaths was much smaller. The highest WSC depositing capacity of all stem segments were found in the high-yielding variety Kyivska 17 and the lowest one in the less productive variety Poradnytsia. Conclusions. The values of accumulation and remobilization of WSC in the 2nd and 3rd from the top internodes can characterize the storage capacity of the stem and be used to assess the relationships with grain productivity in the breeding winter wheat in arid conditions.

Characteristics of lodging resistance of high-yield winter wheat as affected by nitrogen rate and irrigation managements

High yields of wheat are mainly obtained through a high level of nitrogen and irrigation supplementation. However, excessive nitrogen and irrigation supplication increase the risk of lodging. The main objectives of this work were to clarify the capacity of lodging resistance of wheat in response to nitrogen and irrigation, as well as to explore the effective ways of improving lodging resistance in a high-yield wheat cultivar. In this study, field experiments were conducted in the 2015–2016 and 2016–2017 growing seasons. A wheat cultivar Jimai 22 (JM22), which is widely planted in the northern of Huang-Huai winter wheat region, was grown at Tai'an, Shandong Province, under three nitrogen rates and four irrigation treatments. The lodging risk was increased with increased nitrogen rate, as indicated by increasing lodging index (LI) and lodging rate across both growing seasons. With nitrogen increasing, the plant height, the basal internode length and the center of gravity height, which were positively correlated with LI, increased significantly. While the density of the basal 2nd internode (for culm and leaf sheath) and cell wall component contents, which were negatively correlated with LI, decreased conspicuous along with nitrogen increased. Increasing irrigation supplementation increased the 2nd internode culm wall thickness, breaking strength and leaf sheath density within limits which increased stem strength. Among the treatments, nitrogen application at a rate of 240 kg ha–1 and irrigation application at 600 m3 ha–1 at both the jointing and anthesis stages resulted in the highest yield and strongest stem. A suitable plant height ensures sufficient biomass for high yield, and higher stem stiffness, which was primarily attributed to thicker culm wall, greater density of the culm and leaf sheaths and higher cell wall component contents are the characteristics that should be taken into account to improving wheat lodging resistance.

Potential Genetic Target Changes in Height and Branches -A Short Review on Osmir535

OsmiR535 is a member of the miR156/529/535 superfamily, which is one of the most conserved miRNA families in plants. OsmiR535 regulates the cold-stress response, modulates plant growth, and controls panicle design and grain length. However, the significance of OsmiR535 in plant drought and salinity responses is unknown. The miR535s identified in terrestrial plants were less conserved than miR156s during evolution, according to this study. Similar to OsmiR529 in rice, miR535 is expressed a very low level during vegetative growth but is significantly accumulated in early panicles. Overexpression of OsmiR535 in rice decreased plant height by reducing the length of the 1st and 2nd internodes. There was also a significant impact on panicle architecture due to the overexpression of OsmiR535. In addition, OsmiR535 overexpression inhibited the expression of OsSPL7/12/16, as well as OsDEP1, OsLOG, and OsSLR1. OsmiR535 regulates plant height, panicle architecture and grain form in rice in several ways, according to our findings

Potential Genetic Target Changes in Height and Branches-A Short Review on OsmiR535

It is a member of the miR156/529/535 superfamily, which is one of the most conserved miRNA families in plants. OsmiR535 regulates the cold-stress response, modulates plant growth, and controls panicle design and grain length. However, the significance of OsmiR535 in plant drought and salinity responses is unknown. The miR535s identified in terrestrial plants were less conserved than miR156s during evolution, according to this study. Similar to OsmiR529 in rice, miR535 is expressed a very low level during vegetative growth but is significantly accumulated in early panicles. Overexpression of OsmiR535 in rice decreased plant height by reducing the length of the 1st and 2nd internodes. There was also a significant impact on panicle architecture due to the overexpression of OsmiR535. In addition, OsmiR535 overexpression inhibited the expression of OsSPL7/12/16, as well as OsDEP1, OsLOG, and OsSLR1. OsmiR535 regulates plant height, panicle architecture and grain form in rice in several ways, according to our findings.

Survey of wheat straw stem characteristics for enhanced resistance to lodging

Lodging is one of the major constraints that threaten crop productivity. Although the relationship between cell walls and straw strength has been well recognized, little relevant research has been done in wheat, particularly on the monomer composition and structural characteristics of cell wall polymers and the arrangement of vascular bundles. In this study, we systematically investigated cell wall- and straw-related traits in a range of wheat germplasm resources and culm mutants using a high-throughput platform for cell wall analysis. We found that varieties with higher breaking force exhibited higher levels of crystalline cellulose but fewer hemicellulose components than other varieties. The lignin content was not consistent with the breaking force; instead, the lignin monomer constitution might be important because a significantly higher proportion of p-hydroxyphenyl (H) and guaiacyl (G) but a lower proportion of syringyl (S) monomers of lignin was found in the higher breaking force group. The crystallinity detected by X-ray diffraction was positively correlated with breaking force, indicating that the physical/chemical properties of polysaccharides also deserve attention. In terms of anatomical characteristics, the varieties with higher breaking force had a lower number and area of smaller vascular bundles in the peripheral sclerenchyma than other varieties. These results, together with the finding of a highly significant correlation between stem breaking force and straw fresh weight, 2nd internode width, flag leaf width and SiO2 content, should provide systematic information for breeding for lodging resistance.

DBW222 (Karan Narendra): A new high-yielding, lodging-tolerant wheat variety for North Western plains of India

DBW222 is characterized by potential yield of 8210 kg ha-1 under high fertility when sown in timely conditions in North India. It possesses better agronomic attributes and has better adaption to sowing time, high rust resistance, quality attributes, and lodging tolerance because of a shorter 2nd internode and wider diameter.

The multiple roles of OsmiR535 in modulating plant height, panicle branching and grain shape

The miR156/miR529-SPL module acts a vital role in regulating plant growth and development. Though miR535 shows very high sequence identity to miR156 and miR529, it is still unknown whether miR535 could control plant growth and development. In this study, we performed the evolutionary analyses of miR535s in land plants and found that miR535s were less conserved than miR156s during evolution. In rice, miR535 expressed at a very low level during the vegetative growth but highly accumulated in young panicles, which is similar with OsmiR529, but opposite to OsmiR156. Expectedly, OsmiR535 overexpression in rice reduced plant height by decreasing the 1st and 2nd internode length. Furthermore, OsmiR535 overexpression imposed great influence in panicle architecture, such as more but shorter panicles, and fewer primary/secondary panicle branches. Moreover, OsmiR535 overexpression increased the grain length, but did not affect grain width. Through quantitative real-time PCR analyses, we further revealed that OsmiR535 overexpression repressed the expression of OsSPL7/12/16, as well as the OsSPLs downstream panicle related genes, including OsPIN1B, OsDEP1, OsLOG and OsSLR1. Taken together, our findings suggest that OsmiR535 multiply modulates plant height, panicle architecture and grain shape possibly by regulating OsSPLs genes in rice.

Genome-Wide Identification, Phylogeny, and Expression Analysis of ARF Genes Involved in Vegetative Organs Development in Switchgrass.

Auxin response factors (ARFs) have been reported to play vital roles during plant growth and development. In order to reveal specific functions related to vegetative organs in grasses, an in-depth study of the ARF gene family was carried out in switchgrass (Panicum virgatum L.), a warm-season C4 perennial grass that is mostly used as bioenergy and animal feedstock. A total of 47 putative ARF genes (PvARFs) were identified in the switchgrass genome (2n = 4x = 36), 42 of which were anchored to the seven pairs of chromosomes and found to be unevenly distributed. Sixteen PvARFs were predicted to be potential targets of small RNAs (microRNA160 and 167). Phylogenetically speaking, PvARFs were divided into seven distinct subgroups based on the phylogeny, exon/intron arrangement, and conserved motif distribution. Moreover, 15 pairs of PvARFs have different temporal-spatial expression profiles in vegetative organs (2nd, 3rd, and 4th internode and leaves), which implies that different PvARFs have specific functions in switchgrass growth and development. In addition, at least 14 pairs of PvARFs respond to naphthylacetic acid (NAA) treatment, which might be helpful for us to study on auxin response in switchgrass. The comprehensive analysis, described here, will facilitate the future functional analysis of ARF genes in grasses.

Effects of Seed Dressing with Uniconazole Powder on Lodging Resistance of Culm in Common Buckwheat

Lodging is one of the important factors affecting the yield and quality of common buckwheat(Fagopyrum esculentum M.) worldwide. Ningqiao 1, a cultivar of common buckwheat with moderate lodging resistance was used in this study to investigate the dynamic changes of lodging behavior, yield, culm snapping resistance, lodging index, culm morphological characteristics and culm anatomical structure seed dressing with uniconazole powder(0, 100, 200, and 300 mg kg–1). The results indicated that seed dressing with uniconazole powder had significantly effects on the lodging resistance of culm in common buckwheat. With the increase of uniconazole powder concentration, the yield, culm snapping resistance, diameter of the 2nd internode, dry weight of the 2nd internode, filling degree, mechanical tissue layer number, mechanical tissue thickness, culm wall thickness, vascular bundle number, and vascular bundle area showed an increased-decreased trend, whereas, the lodging percentage, lodging index, plant height, culm gravity height, culm fresh weight, and length of the 2nd internode showed an decreased-increased trend. In this case, the treatment of seed dressing with 200 mg kg–1 uniconazole powder could optimize the culm structure, improve the culm quality, reduce the lodging risk, and enhance the yield of common buckwheat.

Effect of Planting Density of Mechanically Transplanted Pot Seedlings on Yield, Plant Type and Lodging Resistance in Rice with Different Panicle Types

In order to identify the suitable planting density and high-yielding charcteristices of mechanically transplanted pot seedlings of rice(PS) with different panicle types, and clarify the effect of planting density on plant type and loding resitance, a field experiment was conducted using rice cultivar with three panicle types in 2012 and 2013. By setting high, medium and low planting density treatments and using mechanically transplanted carpet seedling as control(CK), we investigated yield and its components, panicle traits, canopy leaf system configuration, physical properties of culm and lodging resistance. Resluts showed as follows:(1) With decreasing planting density, yield of three density treatments in the large panicle cultivar increased firstly and then reduced which was higher than that of CK;,and yield of three density treatments reduced progressively for the medium and small panicle cultivar. With decreasing planting density, number of panicles in all cultivars reduced significantly, and spikelets per panicle increased markedly, but there was no significant difference in grain-filled percentage and 1000-grain weight.(2) With decreasing planting density, in all cultivars with PS, panicle length, grain density, grain weight per panicle, No. of primary branch, No. of secondary branch, No. of grains of primary branch and No. of grains of secondary branch showed a tendency of increase, and were higher than those in CK, but it showed a decreasing tendency in ratio of No. of primary branch to No. of secondary branch and ratio of No. of grains of primary branch to No. of grains of secondary branch.(3) Leaf length, leaf width, leaf basal angle, drooping angle of top three leaves and specific leaf weight from flag leaf to the 3rd leaf in all cultivars with PS were enhanced with decreasing planting density, and were higher than those in CK except for leaf basal angle and drooping angle.(4) With decreasing planting density, length of basal 1st, 2nd, and 3rd internodes were shortened, and culm diameter, culm wall thickness, dry matter weight per unit internode of basal inernodes, neck internode length, stalk length, plant height and gravity center height were increased.(5) The breaking resistance and bending moment of basal 1st, 2nd and 3rd internodes were increased with decreasing planting density, but lodging index was decreased. Therefore, for increasing yield with PS, the large panicle cultivar should reduce planting density appropriately, and increase grain number per panicle; the medium panicle cultivar should coordinate number of panicles and spikelets per panicle, getting a large amount of the total spikelets; the small panicle cultivar should depend on number of panicles. When the plant density reduced in PS, panicle traits and top three leaves area could be improved, but leaf basal angle and drooping angle could be increased; meanwhile, it was benefical to shorten the length of basal internodes and increase culm diameter, culm wall thickness and dry matter weight per unit internode, resulting in enhanced breaking resistance and reduced lodging index.

Effects of Nitrogen Fertilizer and Planting Density onthe Lignin Synthesis in the Culm in Relation to Lodging Resistance of Buckwheat

Lodging is an important constraint limiting buckwheat yield and quality by bending or breaking culm on buckwheat production worldwide. This study was conducted with Ningqiao 01, a moderate lodging resistance cultivar of buckwheat, to determine whether lignin synthesis and lodging resistance of buckwheat are affected by nitrogen fertilizer and planting density. The results showed that the lignin content at the bottom of the 2nd internode was significantly and negatively correlated with lodging index and lodging percentage, but significantly and positively correlated with snapping resistance. The snapping resistance rose and then fell with the increase of nitrogen fertilizer. The snapping resistance decreased with the increase of planting density. The lodging index increased with the increase of nitrogen fertilizer and planting density. The lignin content and its related enzymes activities decreased with the increase of nitrogen fertilizer and planting density. These results suggested that the lignin content is closely related to the lodging resistance of buckwheat, and a higher lignin content could strengthen the lodging resistance of buckwheat. The increase of nitrogen fertilizer and planting density significantly increased the risk of lodging by decreasing the lignin content and its related enzymes activities at the bottom of the 2nd internode.

Effects of Chlormequat-Uniconazole 30% Micro-Emulsion on Stem Physical and Chemical Characteristics of Rice

倒伏是限制寒地水稻高产潜力充分发挥的因素之一。试验以垦稻12为材料，于水稻拔节初期叶面喷施30％矮·烯微乳剂，研究其对水稻茎秆形态建成、物质积累及产量构成因素的调控作用。结果表明，30％矮．烯微乳剂1．2Lhm^-2处理，能够显著缩短茎秆基部第1、第2节间的长度，增加基部节间粗度；显著缩小茎秆细胞宽度，增强细胞排列紧实度；改善茎秆的抗折性，茎秆弯曲折断强度和径向压缩强度比对照分别提高152．4％和82．5％；显著提高水稻齐穗期茎秆基部节间的碳氮比和灌浆后期茎秆中纤维素、半纤维素和木质素含量，显著降低处于固定伸长期的第2节间GA3含量；改善水稻产量构成因素，提高了产量。综上所述，30％矮·烯微乳剂有利于提高水稻茎秆的抗倒伏能力，增加水稻产量。

Effects of Row-Spacing on Canopy Structure and Yield in Different Plant Type Rice Cultivars

Two japonica rice varieties, Longjing 20 (more tillers and curved panicle type, MCP) and Longjing 21 (few tillers and half erect panicle type, FEP), were used to study the effects of row-spacing on canopy structure, morphological characteristics and yield. The results showed that the percentage of productive tiller reduced first, and increased afterwards as row-spacing increasing. The relationship between row spacing and the percentage of productive tiller fitted a quadratic regression. The effects of row spacing on leaf area index (LAI) at later tillering stage and the highest stem number per square meter also followed a quadratic regression relationship with increasing first and then reducing. The effects of row-spacing on primary branch were larger than the secondary branch in Longjing 20. However, the trend in Longjing 21 was opposite. The relationship between row spacing and seed setting rate of the secondary branch or panicle was negatively correlated. An extreme significant negative correlation was obtained between seed setting rate of secondary branch in Longjing 20. There was no significant positive correlation between row-spacing and yield in Longjing 20 (R2=0.68). However, the negative correlation between row-spacing and yield of Longjing 21 was extremely significant (R2=−0.96**). The canopy structure of MCP was more sensitive to row-spacing. The positive correlation between row spacing and the length of the flag leaf (R2=0.89**), the width of the flag leaf (R2=0.85*), the length of the last internode (R2=0.85*), the length of the last 2nd internode (R2=0.96**) or the length of the panicle (R2=0.91**) was significant or extremely significant in Longjing 20, but not in Longjing 21. The wider row-spacing promoted the accumulation of the dry matter of panicle, stem and leaf and the yield formation in MCP. The best row-spacing in Longjing 20 was 30 cm. For Longjing 21, the narrower row-spacing was better. The best row-spacing of it was 21 cm. These results suggested that improved the population environment of MCP or the utilization of the free space in the field of FEP could be reached either by wider row-spacing or narrow row-spacing.

Drift algae, an invasive snail and elevated temperature reduce ecological performance of a warm-temperate seagrass, through additive effects

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 450:67-80 (2012) - DOI: https://doi.org/10.3354/meps09552 Drift algae, an invasive snail and elevated temperature reduce ecological performance of a warm-temperate seagrass, through additive effects Hannes Höffle1, Thomas Wernberg2,3,4,*, Mads S. Thomsen2,4, Marianne Holmer1 1Institute of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark 2UWA Oceans Institute & School of Plant Biology, University of Western Australia, 35 Stirling Highway, Nedlands, 6009 Western Australia, Australia 3Australian Institute of Marine Science, 39 Fairway, Nedlands, 6009 Western Australia, Australia 4Centre for Marine Ecosystems Research, Edith Cowan University, 270 Joondalup Drive, Joondalup, 6017 Western Australia, Australia *Corresponding author. *Email: thomas.wernberg@uwa.edu.au ABSTRACT: Seagrasses are under pressure from multiple concurrent threats, including rising temperatures, invasive species and nutrient-driven algal accumulations. We quantified the abundance of drift algae and the invasive snail Batillaria australis in 3 Halophila ovalis seagrass beds in the Swan River Estuary (Perth, Western Australia), and tested in an aquarium experiment for interactive effects of temperature (21 vs. 27°C), cover of drift algae Chaetomorpha linum (0 vs. 1.4 kg fresh wt m−2) and presence (0 vs. 120 snails m−2) of B. australis on the ecological performance of H. ovalis. The survey showed that drift algae varied considerably between sites and sampling times, and sites experienced average loads of 0.4 to 0.8 kg fresh wt m−2 and extreme loads up to 2.5 kg fresh wt m−2. In contrast, invasive snails were constantly abundant at all sites at all collection times (mean abundance: 489 snails m−2). In the laboratory experiment, drift algae caused increased shoot mortality and leaf loss rate, and suppressed the formation of new nodes. Drift algae also decreased the depth of the sulphide horizon in the sediment and the oxygen concentration in the water column at night, suggesting increased risk of hypoxia. Invasive snails reduced the biomass of H. ovalis leaves and roots, increased leaf plastochrone interval and decreased the depth of the sulphide horizon. Finally, elevated temperature increased leaf loss and reduced leaf biomass, and, in the presence of drift algae, also reduced the length of the 2nd internode. We found relatively few significant higher-order interactions, suggesting a dominance of additive effects of stress. We conclude that temperature, drift algae and invasive snails are already affecting the ecological performance of H. ovalis in Swan River, and that these seagrass beds are likely to come under further pressure if these stressors increase in the future. KEY WORDS: Global warming · Eutrophication · Introduced species · Swan River · Western Australia · Halophila ovalis · Batillaria australis Full text in pdf format Supplementary material PreviousNextCite this article as: Höffle H, Wernberg T, Thomsen MS, Holmer M (2012) Drift algae, an invasive snail and elevated temperature reduce ecological performance of a warm-temperate seagrass, through additive effects. Mar Ecol Prog Ser 450:67-80. https://doi.org/10.3354/meps09552 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 450. Online publication date: March 29, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.