Prostrate Growth Research Articles

Quantitative Evaluation of Leaf Morphology with Different Rice Genotypes Based on Image Processing

Prostrate growth 1 (PROG1) gene is vital in controlling the prostrate growth habit of rice. Studying the effect of PROG1 gene on rice canopy structure is crucial in elucidating the molecular mechanism of rice plant type evolution. Herein, the morphological characteristics of different rice genotypes were collected at different growth stages and leaf nodes using image processing techniques. The morphological characteristics included leaf length, leaf width, and leaf area. The image processing techniques involved boundary mean oscillation (BMO) filtering and minimum bounding rectangle extraction of the target image. On this basis, the effect of the PROG1 gene on rice leaf morphology was quantitatively assessed. Also, the feasibility of image processing techniques in detecting the morphological characteristics of rice leaves was discussed. Under the influence of the PROG1 gene, the length, width, and area of rice leaves decreased by 45.1%, 12.7%, and 44.8%, respectively, at the booting stage. Similarly, the length, width, and area of flag leaves decreased by 15.8%, 32.0%, and 33.7% at the heading stage and by 25.4%, 16.2%, and 19.7% at the filling stage, respectively, and that of secondary leaf reduced by 23.2%, 13.6%, and 54.2% at heading stage and by 24.1%, 17.3%, and 37.0% at filling stage, respectively. Furthermore, the length, width, and area of other leaves reduced by 32.3%, 9.8%, and 51.6% at the heading stage and by 28.6%, 7.3%, and 36.7% at the filling stage, respectively. The leaves in the rice canopy were shorter, narrower, and smaller in leaf area. Notably, no significant differences were found between image processing technology and manual measurement methods regarding the values of leaf morphological characteristics obtained ( P < 0.05 ). Thus, these results show that image processing technology is effective in studying the morphological characteristics of rice leaves. This study provides a reliable foundation for molecular breeding studies and will guide the application of the PROG1 gene in molecular breeding.

‘CHEVIGNON’: NUEVA VARIEDAD DE TRIGO DE INVIERNO PARA EL SUR DE CHILE

‘Chevignon’ is a winter wheat variety developed by ASUR Plant Breeding of France and introduced to Chile by the National Wheat Breeding Program at INIA Carillanca. The variety has medium plant height, intermediate cycle, with resistance to yellow rust (Puccinia striiformis West. f. sp. tritici Erikss), and powdery mildew (Blumeria graminis D.C. f. sp. tritici Marchal), moderate resistance to leaf rust (Puccinia triticina f. sp. tritici Erikss y Henn) and tolerance to septoria leaf blotch (Mycosphaerella graminicola (Fuckel) Sand). It is a high yielding winter wheat variety with good quality characteristics for direct baking. It has a prostrate growth habit at seedling stage, with high tillering production. Its leaves are pale green, with a semi-drooping flag leaf. The spike is white, semi-erect, and parallel in shape, compact and without awns. The grain is round, medium-sized, and pale red, with occasional variations in endosperm pigmentation. The adult plant height varies between 105 cm and 110 cm, with an average of 105 cm, and with moderate resistance to lodging. Heading growth stage occurred 5 days later than cultivar Maxwell and 8 to 10 days earlier than ‘Bicentenario INIA’ and ‘Kiron INIA’

Drought tolerant forb flora of a semi-arid protected savanna in the Lowveld of South Africa

Background: Increased frequency and intensity of droughts related to climate change are predicted to induce pressure on herbaceous communities. Considering that forbs contribute significantly to savanna ecosystem resilience, we investigated forb communities of a protected semi-arid savanna during an extensive drought.Objective: We identified drought-tolerant species with their related functional traits.Results: Drought-tolerant forb flora comprised of several plant families and species with overlapping traits, of which the ability to resprout was related to perennials, whereas succulence and prostrate growth form were typical annual forb dominance traits.Conclusion: Results highlight the functional importance of forbs and their resilience to drought events in protected areas.

Development of Paspalum accession plugs for turfgrass establishment

Abstract The selection of a genotype for lawn use must consider the plant survival rate and its soil covering ability, which is directly influenced by the growth of stolons and rhizomes. This study aimed to evaluate the growth and development of Paspalum accession plugs for turfgrass establishment. Plugs of six prostrate growth accessions of Paspalum lepton (PL 01), P. notatum (from PN 01 to PN 06) and Zoysia japonica (ZJ 01), which was used as the control treatment, were planted adding up to 7 treatments. At 63 days after planting, the survival rate, the number of shoots, the expansion capacity, plant height and soil coverage rate were evaluated. Moreover, at 72 days after planting, fresh and dry leaf, root, rhizome and/or stolon biomass, as well as root length were evaluated. Plugs of PL 01 presented the highest values regarding the number of shoots, the expansion capacity, soil coverage and the development of the root system with the largest biomass production. PL 01 and PN 05 along with ZJ 01 presented a high soil coverage rate and all the P. notatum (PN) accessions together with ZJ 01 maintained a lower plant height, but with a length root system higher than the control treatment ZJ 01. The P. lepton (PL 01) and P. notatum (PN 05) accessions can be recommended for turfgrass establishment using plug propagation methods.

Genome-Wide Association Mapping of Prostrate/Erect Growth Habit in Winter Durum Wheat.

By selecting for prostrate growth habit of the juvenile phase of the cycle, durum wheat cultivars could be developed with improved competitive ability against weeds, and better soil coverage to reduce the soil water lost by evaporation. A panel of 184 durum wheat (Triticum turgidum subsp. durum) genotypes, previously genotyped with DArT-seq markers, was used to perform association mapping analysis of prostrate/erect growth habit trait and to identify candidate genes. Phenotypic data of plant growth habit were recorded during three consecutive growing seasons (2014–2016), two different growth conditions (field trial and greenhouse) and two sowing periods (autumn and spring). Genome-wide association study revealed significant marker-trait associations, twelve of which were specific for a single environment/year, 4 consistent in two environments, and two MTAs for the LSmeans were identified across all environments, on chromosomes 2B and 5A. The co-localization of some MTAs identified in this study with known vernalization and photoperiod genes demonstrated that the sensitivity to vernalization and photoperiod response are actually not only key components of spring/winter growth habit, but they play also an important role in defining the magnitude of the tiller angle during the tillering stage. Many zinc-finger transcription factors, such as C2H2 or CCCH-domain zinc finger proteins, known to be involved in plant growth habit and in leaf angle regulation were found as among the most likely candidate genes. The highest numbers of candidate genes putatively related to the trait were found on chromosomes 3A, 4B, 5A and 6A. Moreover, a bioinformatic approach has been considered to search for functional ortholog genes in wheat by using the sequence of rice and barley tiller angle-related genes. The information generated could be used to improve the understanding of the mechanisms that regulate the prostrate/erect growth habit in wheat and the adaptive potential of durum wheat under resource-limited environmental conditions.

Switching the Direction of Stem Gravitropism by Altering Two Amino Acids in AtLAZY1.

From germination to flowering, gravity influences plant growth and development. A rice (Oryza sativa) mutant with a distinctly prostrate growth habit led to the discovery of a gene category that participates in the shaping of plant form by gravity. Each so-called LAZY gene includes five short regions of conserved sequence. The importance of each of these regions in the LAZY1 gene of Arabidopsis (Arabidopsis thaliana; AtLAZY1) was tested by mutating each region and measuring how well transgenic expression of the resulting protein variant rescued the large inflorescence branch angle of an atlazy1 mutant. The effect of each alteration on subcellular localization was also determined. Region I was required for AtLAZY1 to reside at the plasma membrane, which is necessary for its function. Mutating region V severely disrupted function without affecting subcellular localization. Regions III and IV could be mutated without large impact on function or localization. Altering region II with two conservative amino acid substitutions (L92A/I94A) had the profound effect of switching shoot gravity responses from negative (upward bending) to positive (downward bending), resulting in a "weeping" inflorescence phenotype. Mechanical weakness of the stem was ruled out as an explanation for the downward bending. Instead, experiments demonstrated that the L92A/I94A change to AtLAZY1 reversed the auxin gradient normally established across stems by the gravity-sensing mechanism. This discovery opens up new avenues for studying how auxin gradients form across organs and new approaches for engineering plant architecture for agronomic and other practical purposes.

Selection of optimal reference genes for qRT-PCR analysis of shoot development and graviresponse in prostrate and erect chrysanthemums.

The prostrate cultivars of ground-cover chrysanthemum have been used in landscape gardening due to their small stature, large crown width and strong branching ability. qRT-PCR is a rapid and powerful tool for gene expression analysis, while its accuracy highly depends on the stability of reference genes. The paucity of authentic reference genes presents a major hurdle in understanding the genetic regulators of prostrate architecture. Therefore, in order to reveal the regulatory mechanism of prostrate growth of chrysanthemum stems, here, stable reference genes were selected for expression analysis of key genes involved in shoot development and graviresponse. Based on transcriptome data, eleven reference genes with relatively stable expression were identified as the candidate reference genes. After the comprehensive analysis of the stability of these reference genes with four programs (geNorm, NormFinder, BestKeeper and RefFinder), we found that TIP41 was the most stable reference gene in all of the samples. SAND was determined as a superior reference gene in different genotypes and during the process of shoot development. The optimal reference gene for gravitropic response was PP2A-1. In addition, the expression patterns of LA1 and PIN1 further verified the reliability of the screened reference genes. These results can provide more accurate and reliable qRT-PCR normalization for future studies on the expression patterns of genes regulating plant architecture of chrysanthemums.

OsBRXL4 Regulates Shoot Gravitropism and Rice Tiller Angle through Affecting LAZY1 Nuclear Localization

Rice tiller angle is a key agronomic trait that contributes to ideal plant architecture and grain production. LAZY1 (LA1) was previously shown to control tiller angle via affecting shoot gravitropism, but the underlying molecular mechanism remains largely unknown. In this study, we identified an LA1-interacting protein named Brevis Radix Like 4 (OsBRXL4). We showed that the interaction between OsBRXL4 and LA1 occurs at the plasma membrane and that their interaction determines nuclear localization of LA1. We found that nuclear localization of LA1 is essential for its function, which is different from AtLA1, its Arabidopsis ortholog. Overexpression of OsBRXL4 leads to a prostrate growth phenotype, whereas OsBRXLs RNAi plants, in which the expression levels of OsBRXL1, OsBRXL4, and OsBRXL5 were decreased, display a compact phenotype. Further genetic analysis also supported that OsBRXL4 controls rice tiller angle by affecting nuclear localization of LA1. Consistently, we demonstrated that OsBRXL4 regulates the shoot gravitropism through affecting polar auxin transport as did LA1. Taken together, our study not only identifies OsBRXL4 as a regulatory component of rice tiller angle but also provides new insights into genetic regulation of rice plant architecture.

Value of Sedum species as companion plants for nectar-producing plants depends on leaf characteristics of the Sedum

Introducing nectar-producing plants to green roofs and other urban green infrastructure has been attempted to support pollinator activities. Green roofs can be drought-prone, placing limitations on the success of plant growth and nectar production in the absence of irrigation. Plant species differ greatly in water usage patterns, so companion planting with low and high water users has been proposed to increase performance of high water use species, including species important for urban pollinators. Additionally, crassulacean acid metabolism (CAM) plants such as Sedum tend to have low water usage and are reported to improve health condition of neighbors. However, Sedum species differ in morphological and physiological traits such as leaf shapes and the speed at which they switch to CAM, resulting in water usage differences during drought that could affect neighboring plants. This study quantifies the effects of companion planting with CAM plants (Sedum album, Sedum kamtschaticum) on nectar-producing plants (Fagopyrum esculentum, Trifolium repens), focusing on target plant growth form and leaf traits of neighboring Sedum. The health condition of F. esuculentum and soil water contents were improved significantly when they were planted together with S. album, which has small leaves and rapid CAM induction. Therefore, suppression of evapotranspiration of neighboring CAM plants could have positive effects on erect growth form nectar species. In contrast, the health condition of T. repens, which shows prostrate growth, was not affected by neighboring CAM plant species. Judging from these results, growth characteristics including leaf traits of neighboring Sedum and growth forms of the target plants could be important factors determining the effects of companion planting in urban green infrastructure.

Lidar and RGB Image Analysis to Predict Hairy Vetch Biomass in Breeding Nurseries

Core Ideas Early‐season biomass is conventionally phenotyped by subjective visual estimates. RGB image data are highly predictive of biomass in hairy vetch breeding plots. Lidar and RGB image data can be combined to accurately predict sward biomass. Remote sensing could increase genetic gain potential for biomass in cover crops. Hairy vetch (Vicia villosa Roth) is an annual legume grown as a forage and cover crop. To improve cover crop function, traits such as biomass production are of high interest for cover crop breeders. However, direct phenotypic methods for biomass production are destructive. Breeders have thus relied on subjective, visual scoring of biomass, which is generally correlative but not quantitative or absolute. We evaluated two low‐cost remote sensing tools, lidar and red–green–blue (RGB) image analysis, for their potential to predict biomass in vivo. We evaluated these tools in two common forage breeding scenarios, spaced‐plant and sward‐plot nurseries, at three Minnesota locations following the winter of 2016–2017. Ground cover from RGB image binarization had a significant and linear relationship with aboveground biomass in spaced plants (R2 = 0.93) and sward plots (R2 = 0.89). However, once the image area from sward plots became saturated with vegetative pixels, a near‐exponential relationship would occur. Because of the prostrate growth habit of hairy vetch, RGB image analysis was more appropriate at lower plant densities, such as spaced‐plant nurseries. Conversely, the dimensionality of lidar sensing gave it greater predictive ability at higher plant densities where RGB analysis could not detect vertical increases in biomass. Lidar measures of sward‐plot height were also linearly and strongly related to dry‐matter biomass in sward plots (R2 = 0.80). When we combined RGB and lidar data to predict sward‐plot biomass in a multiple mixed‐effect regression model, we were able to explain more biomass variation than with the use of either phenotypic tool as a single predictor (R2 = 0.94).

Evaluation of Steam Application for Weed Management in Citrus

Abstract. In this study, a weed steamer was developed, and several steam treatments were utilized to maintain and control the growth of weeds in a citrus grove. Two factors affecting the steam treatment were studied: (i) tractor speed (low, 1.2 km/h; and high, 1.7 km/h); and (ii) steam flow rate (low, 15 L/h; and high 53 L/h). The weed control treatments included various combinations of steam flows and tractor driving speeds, a post-emergent herbicide (paraquat) treatment, and an untreated check for comparison purposes. Randomized experiments were conducted to evaluate the efficacy of each application. It was found that steam applications at high flow rate provided 93%-97% burndown damage of the weed foliage within 3 days after application. Weed re-growth was observed in steam applications, especially with low flow-rate applications. The combination of low tractor speed and high steam flow-rate was the most effective of the steam treatments tested (84% total weed burndown at 12 days after application). This treatment was found effective in controlling weeds like goatweed and sedges. Florida pusley was the least affected by steam due to its prostrate growth nature that prevents an adequate coverage of steam on the entire plant. Based on the observations from this study, the steam application has the potential to be a non-chemical and sustainable strategy for weed management in citrus tree rows. Keywords: Citrus production, Herbicide, Steam application, Weed control.

Agro-morphology and forage nutritive value of white prairie clover [Dalea candida(Michx.) Willd.] populations native to the Canadian prairies

White prairie clover [Dalea candida (Michx.) Willd.] is native to the dry prairies and hillsides of the Northern Great Plains. A study was initiated in 2012 with six white prairie clover populations collected from the Canadian Prairies. Plant growth characteristics, forage biomass, seed yield, and forage nutritive values were evaluated using a randomized complete block design in a field near Swift Current, SK. Three populations from Argyle, Carlowrie, and Big Grass Marsh (NCP588) in Manitoba displayed erect-type growth while those from Douglas Provincial Park and Stewart Valley in Saskatchewan and Writing on Stone Provincial Park in Alberta exhibited prostrate growth. The populations did not differ for mean biomass yield (79–104 g plant−1, p = 0.54) and mean seed yield (6.6–9.1 g plant−1, p = 0.69); however, they differed for bloom stage nutritional parameters such as acid detergent fibre (25%–30%, p = 0.04), neutral detergent fibre (34%–41%, p < 0.01), crude proteins (15%–18%, p < 0.01), phosphorus (0.24%–0.29%, p = 0.02), and iron content (144–360 ppm, p = 0.01). To our knowledge, this is the first report of comparative phenotypic, nutritional, and propagation study of native white prairie clover populations of Canada. The constraints and opportunities for successful domestication of white prairie clover as a forage crop are discussed.

Deletions linked to PROG1 gene participate in plant architecture domestication in Asian and African rice

Improving the yield by modifying plant architecture was a key step during crop domestication. Here, we show that a 110-kb deletion on the short arm of chromosome 7 in Asian cultivated rice (Oryza sativa), which is closely linked to the previously identified PROSTRATE GROWTH 1 (PROG1) gene, harbors a tandem repeat of seven zinc-finger genes. Three of these genes regulate the plant architecture, suggesting that the deletion also promoted the critical transition from the prostrate growth and low yield of wild rice (O. rufipogon) to the erect growth and high yield of Asian cultivated rice. We refer to this locus as RICE PLANT ARCHITECTURE DOMESTICATION (RPAD). Further, a similar but independent 113-kb deletion is detected at the RPAD locus in African cultivated rice. These results indicate that the deletions, eliminating a tandem repeat of zinc-finger genes, may have been involved in the parallel domestication of plant architecture in Asian and African rice.

Earliest Triassic metazoan bioconstructions from East Greenland reveal a pioneering benthic community in the immediate aftermath of the end-Permian mass extinction

Abstract Marine benthic ecosystems collapsed during the catastrophic end-Permian mass extinction, and subsequently endured a protracted phase of biotic recovery under harsh environmental conditions. In particular, metazoan reef communities almost totally disappeared and were replaced by microbe-dominated mounds during the latest Permian–earliest Triassic. Here we report the stratigraphically oldest exclusively metazoan bioconstructions from earliest Triassic (mid-Induan) strata in East Greenland — these formed within the first ca 300 ka after the Permian-Triassic boundary. Unlike the multitaxic sponge-microbe and bivalve-based buildups recorded from the Early Triassic peri-paleoequatorial Panthalassan and Tethyan margins, the East Greenland bioaccumulations developed within a restricted Boreal mid-paleolatitude seaway, and comprised a monospecific primary framework of microconchid ‘lophophorate’ tubes with shell fragments and phosphatic debris cemented by biogenic calcite. Prostrate growth of the microconchids likely facilitated their accretion into successive sheet-like biostromes and small bioherms. These are associated with a regional paleoenvironmental shift towards well‑oxygenated bottom waters, and locally punctuated sedimentation that created a favorable habitat. Although microconchids were both abundant and geographically widespread throughout the earliest Triassic, such buildups formed solely by these metazoans have not been reported from that time frame outside the Boreal Realm. These apparently flourished in the absence of more stable complex communities, and suggest that a locally variable, rather than ubiquitously sequential revival of metazoan bioconstruction activity took place in the immediate aftermath of the end-Permian extinction. However, these may also suggest that ecological recovery of benthic marine ecosystems following the end-Permian mass extinction might have started earlier in higher paleolatitudes.

The domestication of plant architecture in African rice.

Plant architecture is a key agronomical factor determining crop yield and has been a major target of cereal crop domestication. The transition of plant architecture from the prostrate tiller of typical African wild rice (Oryza barthii) to the erect tiller of African cultivated rice (Oryza glaberrima) was a key step during domestication of African rice. Here we show that PROG7 (PROSTRATE GROWTH 7), a zinc-finger transcription factor gene on chromosome 7, is required for the prostrate growth of African wild rice. Mutations in the promoter region of prog7 reduced the level of gene expression in the tiller base, leading to erect growth in African cultivated rice. Sequence comparison and haplotype analysis show that 90 varieties of cultivated rice from 11 countries carry the same mutations in the prog7 region. A strong signal in a 60-kb genomic region was detected around the prog7 gene, suggesting that the region was under strong positive selection during the domestication process. Identification of the PROG7 gene provides new insights into the molecular basis of plant architecture in crops and facilitates investigation of the history of domestication of African rice.

CHARACTERIZATION OF SOME ALGERIANS AND FOREIGN LENTIL ACCESSIONS BY QUALITATIVE TRAITS

In the present study an attempt has been made to characterize lentil accessions based on qualitative traits. There were variations among 44 lentil accessions. Erect growth habit was observed in 24 % of the accessions where 8% were from Algeria. Conversely, prostrate growth habit was observed in 34% of the accessions. The majority of the remaining accessions (41.32%) were intermediate. Stem with anthocyanin pigmentation was showed in 44% of the accessions, whereas, 56% had no pigmentation (green stem). About half of the accessions had grey green leaves (53%) and 23% of accessions were light green. Among the characters, flower color showed the highest variation. White flowers were observed in 64% accessions and violet flowers were found in 36% accessions. Flowers, with violet stripes in the standard petal (SVE) were observed in 44% accessions and the majority (56%) lacked violet stripes. Yellow cotyledons were observed in 61% accessions, while the rest (39%) had red cotyledons. The majority of accessions (81%) were observed with brown testa while 14% were green and 5% had yellow testa. Absence of seed coat pattern was observed in 69% accessions. However, 8% accessions with spots, 5% with dots, 16% were marbled and the remaining 2% were complex. Flattened seed shape was observed in 60% of accessions. Conversely, globose shape was observed in 40% of the accessions, among of them 27% were from Algeria.

Towards the identification of a gene for prostrate tillers in barley (Hordeum vulgare L.).

Tiller angle, an important agronomic trait, contributes to crop production and plays a vital role in breeding for plant architecture. A barley line V-V-HD, which has prostrate tillers during vegetative growth and erect tillers after booting, is considered the ideal type for repressing weed growth and increasing leaf area during early growth. Genetic analysis identified that the prostrate trait in V-V-HD is controlled by a single gene. A double haploid population with 208 lines from V-V-HD × Buloke was used to map the prostrate growth gene. Ninety-six SNP markers were used for primary mapping, and subsequently, SSR and InDel markers were used for fine mapping. The gene was fine-mapped to a 3.53 Mb region on chromosome 3HL between the markers InDelz3028 and InDelz3032 with 52 candidate genes located in this region. Gene annotation analysis of the 52 genes within the target region indicated that a gene involved in zinc-ion binding (gene ID HORVU3Hr1G090910) is likely to be the candidate gene for prostrate growth in V-V-HD, and is linked to the denso/sdw gene. Association analysis showed that prostrate plants were shorter, flowered later.

Impacts of Wastewater Irrigation on Growth, Yield and Salts Uptake of Barley

Treated wastewater is promising water resource as alternative or supplementary source for fresh water to be used in agriculture specially for areas of water shortage and crops with good potential of tolerating saline water. In this study long-term irrigation with fresh and wastewater on growth and yield of seven non-local cultivars (S42IL107, BW284, BW281, G400, Scarlett, Bowman and BW290) of Barley (Hordeum vulgare L.) showed that (1) barley cultivars irrigated with both fresh and wastewater had in general the same growth vigor and growth nature, (2) The cultivars irrigated with wastewater gave nearly twice the yield of that irrigated with freshwater. BW290 cultivar showed the best and highest yield among the seven cultivars while S42IL107 had the weakest prostrate growth, (3) The use of wastewater in irrigation increased the nitrogen (N), Phosphorous (P) and potassium (K) contents in soil profiles affecting its texture, (4) barley proved to be a salt-tolerant crop with considerable economic importance, Barley could tolerate saline water until (5µs) without any shortage in the yield of the crop, and (5) barley irrigated with both wastewater and freshwater needed nearly the same time to emergence, stem elongation, flowering and maturity and consequently, wastewater irrigation of barley is a promising water resource as alternatives for fresh water.

Comparative transcriptome analysis provides new insights into erect and prostrate growth in bermudagrass (Cynodon dactylon L.)

Bermudagrass (Cynodon dactylon L.) is a prominent warm-season turf and forage grass species with multiple applications. In most C. dactylon cultivars and accessions, erect-growing stems (shoot) and prostrate-growing stems (stolon) often coexist. These two types of stems are both formed through tillering but grow in two directions with different tiller angles. Elucidating the mechanism of tiller angle regulation in bermudagrass could provide important clues to breed cultivars with different plant architectural features for diverse usage. In this study, we compared the stem internode transcriptome of two bermudagrass wild accessions with extremely different tiller angles and stem growth directions. A total of 2088 and 12,141 unigenes were preferentially expressed in prostrate-growing wild accession C792 and erect-growing wild accession C793, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology-based Annotation System (KOBAS) analyses further indicated that light- and gravity-responsive genes were enriched in accession C792, whereas lignin synthesis-related genes were enriched in accession C793, which well explains the difference in lignification of vascular bundles and mechanical tissues in the two accessions. These results not only expand our understanding of the genetic control of tiller angle and stem growth direction in bermudagrass but also provide insight for future molecular breeding of C. dactylon and other turfgrass species with different plant architectures.

Functional traits prolonging photosynthetically active periods in epiphytic cephalolichens during desiccation

By fluorescence imaging, we quantified how hydration traits and thallus size determine the duration of photosynthetic activity during drying in light and darkness for sympatric populations of three epiphytic old forest cephalolichens differing in specific thallus mass (STM) and growth form. Maximal PS II efficiency (FV/FM) during drying in darkness and effective PSII yield (ФPSII) during drying in light (200μmolm−2s−1) was repeatedly monitored in lichens under controlled conditions, using chlorophyll fluorescence imaging with simultaneous recordings of wet mass. STM shaping the water holding capacity (WHC), water content in percent at start (WC), and water loss rate per thallus area (WLR) in combination determined the duration of active periods during desiccation between (r2adj=0.86) and within species (r2adj=0.60–0.92). Lobaria pulmonaria with the lowest STM and the most upright growth form experienced the shortest active periods, Lobaria amplissima with the highest STM and the most prostrate growth form had the longest periods. Across the more compact species (L. amplissima, L. virens), WLR strongly declined with increasing thallus size, but weakly in the loosely attached L. pulmonaria. ФPSII, a proxy of photosynthesis, exhibited suprasaturation depression at maximal hydration. Fluorescence imaging allowed a rapid, non-invasive evaluation of the contribution of various functional traits to active periods in entire thalli during desiccation. A thick, prostrate growth form prolongs active periods by maximizing water storage, whereas a thin, loosely attached growth form uses a more flexible hydration strategy with shorter active periods.