Single Tiller Research Articles

Optimizing plant spatial competition can change phytohormone content and promote tillering, thereby improving wheat yield.

As an important type of interplant competition, line-spacing shrinkage and row-spacing expansion (LSRE) can increase the number of tillers and improve resource utilization efficiency in wheat. Wheat tillering is closely related to various phytohormones. However, it is unclear whether LSRE regulates phytohormones and their relationship to tillering and wheat yield. This study evaluated tillering characteristics, phytohormone content in tiller nodes at the pre-winter stage, and grain yield factors for the winter wheat variety Malan1. We used a two-factor randomized block trial design with two sowing spacings of 15cm (15RS, conventional treatment) and 7.5cm (7.5RS, LSRE treatment) at the same density and three sowing-date groups (SD1, SD2, and SD3). LSRE significantly promoted wheat tillering and biomass at the pre-winter stage (average increases of 14.5% and 20.9% in the three sowing-date groups, respectively) and shortened the accumulated temperature required for a single tiller. Changes in the levels of phytohormones, including decreased gibberellin and indole acetic acid and increased zeatin riboside and strigolactones, were determined by high-performance liquid chromatography and were shown to be responsible for the tillering process under LSRE treatment in winter wheat. LSRE treatment can improve crop yield by increasing the number of spikes per unit area and grain weight. Our results clarified the changes in tillering and phytohormones content of winter wheat under LSRE treatment and their correlation with grain yield. This study also provides insights into the physiological mechanisms of alleviating inter-plant competition to improve crop yield.

TPR domain coding gene ST2 may be involved in regulating tillering and fertility in rice

A decrease in the tiller number and male sterility will lead to a decline in the rice yield. Therefore, it is significant to study the molecular mechanism of controlling the tiller number and regulating the male reproductive development. The mutant st2 (single tiller 2) was induced by ethyl methane sulfonate (EMS) in the indica maintainer line Xinong 1B and showed single tillering and male sterility. I<sub>2</sub>-KI staining showed that the st2 pollen was aborted. The scanning electron microscope (SEM) observation underlined that the anther of st2 became smaller, the wax of the epidermis reduced, the inner wall shrank and the Ubisch body decreased, the pollen collapsed, and the germination pore developed abnormally. The genetic analysis discovered that the trait was controlled by a single recessive nuclear gene located on chromosome 3. LOC_Os03g05540 encoding a tetratricopeptide repeat (TPR) domain was identified as the candidate gene by sequencing. The quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that ST2 was highly expressed in the stem apical meristem (SAM) and the initial stage of meiosis during the anther development. The subcellular localisation indicated that ST2 is a nuclear and plasmic localisation protein. The homology analysis demonstrated that ST2 was evolutionarily conserved. These results laid a foundation for further study of the ST2 function.

A Modular Tray Growth System for Barley.

Determining when a barley plant starts and finishes meiosis is not trivial as when the spikelets undergo meiosis, the spike is not visible as it is still well within the leaf sheath on the developing tiller. This is a general constraint for any experiment involving meiosis, such as cytology, RNA extractions, or abiotic stress treatments aiming to target such a developmental stage. The lack of synchronicity between barley tillers within the same plant exacerbates the difficulty to determine the overall meiotic stage of a plant at a certain time.Given the lack of a nondestructive staging system for predicting the entry into meiosis and the problems of working with large pot plant systems, a modular plant growing is proposed. This system enables the growth of a high number of plants in a small surface, each producing a single tiller. The modular tray system was used to generate a nondestructive prediction tool for meiosis by using external morphological features. As an example, the system is used here for heat treating F1 plants in early meiosis stages to modify recombination.

A Diagnostic Assay to Detect Herbicide Resistance in Annual Bluegrass (Poa annua)

Turfgrass managers currently have few readily available means of evaluating herbicide resistance in annual bluegrass during the growing season. Research was conducted to determine if agar-based diagnostic tests developed for agronomic weeds could be used to reliably confirm herbicide resistance in annual bluegrass harvested from golf course turf. Annual bluegrass phenotypes with target-site resistance to acetolactate synthase (ALS; R3, R7), enolpyruvylshikimate-3-phosphate synthase (EPSPS; R5), and photosystem II (PSII; R3, R4) inhibiting herbicides were included in experiments along with an herbicidal susceptible phenotype (S). Single tiller plants were washed free of soil and transplanted into autoclavable polycarbonate plant culture boxes filled with plant tissue culture agar amended with a murashigee-skoog medium and trifloxysulfuron (6.25, 12.5, 25, 50, 75, 100, or 150 μM), glyphosate (0, 6, 12, 25, 50, 100, 200, or 400 μM), or simazine (0, 6, 12, 25, 50, 100, 200, or 400 μM). Mortality in agar was assessed 7 to 10 days after treatment (depending on herbicide) and compared to responses observed after treating individual plants of each phenotype with trifloxysulfuron (28 g ai ha-1), glyphosate (1120 g ae ha-1), or simazine (1120 g ai ha-1) in an enclosed spray chamber. Fisher’s exact test (α = 0.05) determined that mortality in agar with 12.5 μM trifloxysulfuron and 100 μM glyphosate was not significantly different than treating whole plants via traditional spray application. Mortality with all concentrations of simazine in agar was significantly different than that observed after treating resistant and susceptible phenotypes via traditional spray application. Our findings indicate that an agar-based diagnostic assay can be used to detect annual bluegrass resistance to ALS- or EPSPS-inhibiting herbicides in less than 10 days; however, additional research is needed to refine this assay for use with PSII-inhibiting herbicides.

Morpho-physiological responses of sugarcane crop under waterlogging condition

The aim of this study was to investigate the effect of waterlogging on morphological and physiological traits of sugarcane variety CoC 24. Various morphological attributes were recorded under waterlogged and normal condition. Morphological parameters viz., plant height, number of internodes, number of tillers, stalk diameter, number of nodes and nodes carrying roots increasedby 18.46, 34.6, 45.65, 48.14, 3 2.14 and 52.63%, respectively, over control. The initiation of new nodal root was noted in this variety, whereas the ability to maintain root surface area by increase in longest root length and nodal root development near soil surface was also found in CoC (SC) 24. CoC (SC) 24 under flood condition at different stress periods produced more number of green leaf of 37.97%, number of dry leaf of 50% and higher growth rate than in control condition. This was possible due to the presence of constitutive aerenchyma in this variety. Hence, under stress conditions, it can easily survive by using oxygen which is preserved by aerenchyma cell, which provides a continuous system of interconnected aerial spaces of lower resistance for oxygen transport from aerial shoots to submerged roots, allowing root growth and soil exploration under anaerobic conditions. Root characters viz., number of roots, root length, root volume, root fresh and dry weight had increase over control by 64.9, 10.3, 22.07, 12.6 and 37.17%. Thus, CoC (SC) 24 variety has adventitious roots, which have high porosity, help plants to continue with water and nutrient uptake under flooding conditions, replacing in some way the functions of older root system. Under waterlogged condition, the relative water content (RWC) showedonly 1.08% increase over control condition, but water retention capacity showed 20% increase over control condition. Leaf area index and specific leaf area showed 19.04 and 41.38% decrease over control but specific leaf weight, whole plant fresh weight and dry weight had 41.49, 20.65 and 9.5% increase over control condition. The juice quality viz., brix percentage, purity percentage and pol percentage showed decrease over control condition by 4.9, 1.08 and 5.97, respectively. Yield parameters viz., single cane weight, tiller production, millable cane and cane yield were higher in CoC (SC) 24 plant crop (13.35, 3.28, 3.06 and 1.3%, respectively) under waterlogged than control condition. Based on the results, it was suggested that CoC (SC) 24 could tolerate waterlogged condition. This study also indicates that plant crops need certain post-waterlogging crop management.

TALEN-mediated targeted mutagenesis produces a large variety of heritable mutations in rice.

CRISPR/Cas9 and TALEN are currently the two systems of choice for genome editing. We have studied the efficiency of the TALEN system in rice as well as the nature and inheritability of TALEN-induced mutations and found important features of this technology. The N287C230 TALEN backbone resulted in low mutation rates (0-6.6%), but truncations in its C-terminal domain dramatically increased efficiency to 25%. In most transgenic T0 plants, TALEN produced a single prevalent mutation accompanied by a variety of low-frequency mutations. For each independent T0 plant, the prevalent mutation was present in most tissues within a single tiller as well as in all tillers examined, suggesting that TALEN-induced mutations occurred very early in the development of the shoot apical meristem. Multigenerational analysis showed that TALEN-induced mutations were stably transmitted to the T1 and T2 populations in a normal Mendelian fashion. In our study, the vast majority of TALEN-induced mutations (~81%) affected multiple bases and ~70% of them were deletions. Our results contrast with published reports for the CRISPR/Cas9 system in rice, in which the predominant mutations affected single bases and deletions accounted for only 3.3% of the overall mutations.

Physiological Attributes of Transplant <i>Aman</i> Rice (Cv. Brri Dhan52) as Affected by Tiller Seedlings and Urea Super Granules

The experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, Bangladesh to investigate the effect of age of tiller seedlings, number of tiller seedlings hill-1 and application of urea super granules (USG) on some physiological attributes of transplant Aman rice cv. BRRI dhan52. The experiment consisted of two ages of tiller seedlings viz. 25- and 35-day old, three levels of tiller seedlings hill-1 viz.1, 3 and 5 seedlings hill-1 and three USG levels viz. 0, 1.8g and 2.7g USG per four hills in every alternate row. The experiment was laid out in a randomized complete block design with three replications. The effect of age of tiller seedlings, number of tiller seedlings hill-1 and USG application were significant on crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR) and leaf area index (LAI). The highest CGR and RGR were found by transplanting 35-day old tiller seedlings during the period at 15-30 and 60-75 DAT when 5 tiller seedlings hill-1 were transplanted. The highest NAR was observed at 60-75 DAT with transplanting 5 tiller seedlings hill-1 and the lowest one was recorded at 30-45 DAT. The highest LAI was found at 35-day old tiller seedlings during the period at 60 and 75 DAT when 5 tiller seedlings hill-1 were transplanted. CGR and RGR were found highest by applying 1.8 g USG at 45-60 and 60-75 DAT while NAR was the highest with application of 2.7g USG at 60-75 DAT and lowest one was found in control (0 g USG) at 45-60 and 60-75 DAT. The highest LAI was found by applying 1.8g USG at 15, 30, 45 and 60 DAT and the lowest one was found at 60 DAT in control and at 15, 30 and 45 DAT when 2.7g USG was applied. The highest LAI and CGR were found in older tiller seedlings (35- day old) by transplanting five tiller seedlings hill-1 fertilized with 1.8g USG whereas the highest RGR and NAR were obtained in younger tiller seedlings (25-day old) by transplanting single tiller seedling hill-1 fertilized with 1.8g USG per four hills of every alternate row.DOI: http://dx.doi.org/10.3329/pa.v24i1-2.19094 Progress. Agric. 24(1&2): 17 - 27, 2013

Absorption, Translocation, and Metabolism of Aminocyclopyrachlor in Tall Fescue (Lolium arundinaceum)

Synthetic auxin herbicides are commonly used in forage, pasture, range, and turfgrass settings for dicotyledonous weed control. Aminocyclopyrachlor (AMCP) is a newly developed pyrimidine carboxylic acid with a chemical structure and mode of action similar to the pyridine carboxylic acids—aminopyralid, clopyralid, and picloram. Injury to sensitive dicotyledonous plants has been observed following exposure to monocotyledonous plant material previously treated with pyridine compounds. The absorption, translocation, and metabolism of AMCP has been documented in susceptible broadleaf weeds; however, no information is available, to our knowledge, regarding AMCP fate in tolerant Poaceae, which may serve as the vector for off-target plant injury. Based on this premise, research was conducted to characterize absorption, translocation, and metabolism of AMCP in tall fescue.14C-AMCP was applied to single tiller tall fescue plant foliage under controlled laboratory conditions at North Carolina State University (Raleigh, NC). Radiation was quantified in leaf wash, treated leaf, foliage, crown, roots, and root exudates at 3, 12, 24, 48, 96, and 192 h after treatment (HAT).14C-AMCP was rapidly absorbed by tall fescue, reaching 38 and 68% at 3 and 48 HAT, respectively. Translocation of14C-AMCP was limited to the foliage, which reached maximum translocation (34%) at 96 HAT. Most of the recovered14C-AMCP remained in the leaf wash, treated leaf, or foliage, whereas minimal radiation was detected in the crown, roots, or root exudates throughout the 192-h period. No AMCP metabolism was observed in tall fescue through the 192 HAT. These data suggest AMCP applied to tall fescue can remain bioavailable, and mishandling treated plant material could result in off-target injury.

Codonopsis pilosula twines either to the left or to the right

AbstractWe report the twining handedness of Codonopsis pilosula, which has either a left- or right-handed helix among different plants, among different tillers within a single plant, and among different branches within a single tiller. The handedness was randomly distributed among different plants, among the tillers within the same plants, but not among the branches within the same tillers. Moreover, the handedness of the stems can be strongly influenced by external forces, i.e. the compulsory left and right forming inclined to produce more left- and right-handed twining stems, respectively, and the reversing could make a left-handed stem to be right-handed and vice versa. We also discuss the probable mechanisms these curious cases happen.

Crescimento, desenvolvimento e produção de sementes da planta daninha capim-branco (Chloris polydactyla)

O presente trabalho teve por objetivo caracterizar o crescimento, o desenvolvimento e a produção de sementes da planta daninha capim-branco (Chloris polydactyla). Para isso, foram realizadas 16 avaliações periódicas de crescimento, quantificando-se fenologia, área foliar e massa seca (total, parte aérea e raízes) das plantas. Foram, também, calculadas as taxas de crescimento absoluto (G) e relativo (R). Quantificaram-se o número de racemos florais de 28 plantas, o comprimento de 100 racemos aleatórios e o número de sementes presentes em 100 unidades de 10 mm de racemo, após o florescimento. Observou-se que o capim-branco é uma espécie com desenvolvimento e crescimento iniciais lentos, uma vez que iniciou o florescimento e a posterior produção de sementes apenas aos 112 dias após a semeadura. Trata-se de uma espécie com grande potencial final de crescimento e produção de sementes, uma vez que um único perfilho e toda a planta foram capazes de produzir mais de 3.000 e 30.000 sementes, respectivamente. O crescimento inicial lento dessa planta daninha pode desfavorecer a competição interespecífica no interior dos campos agrícolas, em especial na cultura da cana-de-açúcar, onde é encontrada com maior freqüência, colonizando carreadores e bordas de talhão. No entanto, sua alta produção de sementes sugere ser uma planta daninha que poderá aumentar em importância na cultura.

Establishment and Seedling Growth of Big Bluestem and Switchgrass Populations Divergently Selected for Seedling Tiller Number

Selection at the seedling stage in grass breeding would be extremely useful if seedling traits are correlated to desired agronomic traits. The objective of this study was to evaluate seedling morphological development, plant growth, and field establishment of big bluestem (Andropogon gerardii Vitman) and switchgrass (Panicum virgatum L.) populations that were developed by divergent selection for seedling tiller number while selecting for high shoot weight. Six populations were evaluated: (i) ‘Pawnee’ big bluestem base, (ii) ‘Pathfinder’ switchgrass base, (iii) big bluestem multiple tiller, (iv) big bluestem single tiller, (v) switchgrass multiple tiller, and (vi) switchgrass single tiller. Field plots were seeded in spring 1999 and 2000 in a Kennebec silt loam (fine‐silty, mixed, superactive, mesic Cumulic Hapludolls). Plants were excavated and evaluated during the growing season for shoot weight, root weight, and morphological stage of shoot and root systems. There were no major population differences in shoot weight, root weight, and morphological root stage. Shoot stage was higher for multiple tiller populations than single tiller populations 6 wk after emergence. Stand counts for all populations exceeded 10 seedlings per linear m of row, which is considered an acceptable stand density, and there were no consistent differences among populations. Populations divergently selected for seedling tiller number did not differ in ability to become established under field conditions because root systems apparently were not altered by the selection for seedling tiller number and weight. These results suggest that selection for high shoot weight did not improve seedling vigor in the field.

Divergent Selection for Seedling Tiller Number in Big Bluestem and Switchgrass

Selection at the seedling stage in forage grass breeding would be extremely useful if seedling traits are highly heritable and correlated to desired agronomic traits. Objectives of this study were to determine the response to selection for high shoot weight and divergent selection for seedling tiller number in big bluestem (Andropogon gerardii Vitman) and switchgrass (Panicum virgatum L.) seedlings and obtain estimates of realized heritability for these traits. Base populations were breeding populations of ‘Pawnee’ big bluestem and ‘Pathfinder’ switchgrass. Divergent selection for single or multiple (three or more) tiller(s) 6 to 8 wk after planting in a greenhouse produced four populations [big bluestem high seedling weight, multiple tiller (BBMT); big bluestem high seedling weight, single tiller (BBST); switchgrass high seedling weight, multiple tiller (SWMT); and switchgrass high seedling weight, single tiller (SWST)], which were planted in isolated polycross nurseries. Seed from polycross nurseries was used to conduct a second cycle of selection. Populations were evaluated in greenhouse studies for fresh weight and tiller number of seedlings. Seedling fresh weight was increased in BBST and SWST Cycle 2 populations, and divergent selection for tiller number resulted in populations significantly different from the base population. Realized heritability estimates for seedling tiller number in big bluestem and switchgrass were 0.26 and 0.23, respectively. The effect of genetic modification of seedling tiller number and shoot weight on establishment under field conditions and on mature plant phenotypes will need to be determined.

Effects of Induced Resistance on Disease Severity/Yield Relations in Mildewed Barley

AbstractField experiments showed that the treatment of winter barley with microbial metabolites produced by a Bacillus subtilis strain led to increased yields in spite of a remaining mildew infection. Disease severity/yield relations obtained on a single tiller basis for either mildew infection at EC 75 or area under disease progress curve (AUDPC) were negatively correlated for untreated plants (R2= 89%, 94%) while this relation did not exist for inducer‐treated ones (R2= 10%, 13%). Despite an increasing infection density. yields of main tillers of inducertreated plants were not decreased. On the other hand area under green leaf area curve (AUGLAC) showed a higher correlation with grain yield (R2= 89%) of inducer‐treated plants. Possible explanations for the mitigated damaging effect of powdery mildew were expected in carbohydrate metabolism. especially carbohydrate formation and translocation. Assimilation rates of flag leaves of inducer‐treated barley with similar infection densities to those of untreated plants were increased over a prolonged period and even exceeded those of non infected ones. In inducer‐treated plants the export of 14CO2 from flag leaves into ears remained unimpaired by mildew infection and the allocation of assimilates to grains was highest at late stages of grain filling. Obviously plants were stimulated by inducer treatments to compensate for the damaging effect of powdery mildew and to tolerate mildew infection without yield loss.

Heritability of response to moisture stress in a New Zealand North Island hill country ryegrass collection grown with and without nitrogen fertiliser

Abstract The heritability of ryegrass plant response to moisture stress and nonstressed conditions under nil and 3.5 kg nitrogen (N)/week was measured. 39 parent plants (6 clones/parent) and progeny seedlings (6 × 3/parent) were grown in a simulated hill soil profile at 5 cm spacing. One half of the soil bin received 3.5 kg N/week and the other half zero N. A single harvest and tiller count was taken in December. Water was withheld for 85 days, the bin flooded, and dry weight and tiller counts were noted. A second bin was planted with parents and progeny of plants selected for morphological traits. Added N increased tiller number and plant dry weight in the pre-drought measurement with a smaller effect on post-drought measurements. There was a strong phenotypic correlation between tiller number and dry weight post-drought measurement. Seedling-derived offspring were more vigorous than the clonally propagated parental generation. The results indicate significant genetic effects on the ability of ryegrass p...

Yield reduction of oat cultivars in relation to disease development caused by barley yellow dwarf virus

The effects of barley yellow dwarf virus on the development, grain yield and yield components of oat cultivar Veli and breeding lines Hankkija 78152 and 78033 were studied in two years. Cultivar differences to BYDV infection were best observed at a low infection level. Single tiller analysis indicated close correlation between symptom severity and reduction in main yield components. Early infection caused greatest yield losses in all cultivars. BYDV strongly reduced both plant height and harvest index. Mild infection reduced the grain yield by 2—8 %, but severe infection by 36—41 %. The number of grains and panicle weight were strongly reduced, but the 1000-grain weight was only slightly affected after severe BYDV-infection. Implications of these results for disease control are discussed.

Annual variations in the severity of attack by Argentine stem weevil on perennial ryegrass

Experiments on the effects of Argentine stem weevil (Listronotus bonariensis (Kuschel)) predation on perennial ryegrass (Lolium perenne L.) were carried out at Palmerston North from 1978 to 1986. A tagged tiller technique was used to assess the probability that any tiller would be attacked by Argentine stem weevil larvae. After grazing by sheep, a single tiller was tagged with a plastic ring at 25 sites 15 cm apart along line transects through each plot, and examined twice weekly throughout the seasons during which Argentine stem weevil is active. Annual variation at Palmerston North was substantial, with the probability of a low endophyte 'Grasslands Nui' perennial ryegrass tiller being attacked ranging from 55% to 95%. ASW annual larvae production calculated from the probability of tiller site damage and the tiller site density varied from 800 to 3000/m'. Variations in the severity of attack of this magnitude are sufficient to explain the variability in the success of sowings of low endophyte grass. Variations in annual larvae production were not correlated with weather parameters, but may be related to natural cyclic disease infestations. Keywords Argentine stem weevil, 'Grasslands Nui' perennial ryegrass, endophyte

The Influence of Defoliation on the Distribution of Assimilates in Lolium multiflorum Lam

Autoradiographs were made of plants of Lolium multiflorum Lam. after 14COa had been fixed by selected leaves. The results showed that labelled compounds were not translocated to other tillers but were moved to the whole root system. This pattern of distribution was changed when all or some of the tillers on the plant were defoliated. Where a single undefoliated tiller remained, it initially supplied the cut tillers with 14C-containing products, thus reintegrating a system of apparently independent tillers. When all the tillers were partially defoliated, labelled compounds were no longer translocated to the root system. A further experiment suggested that root reserves were not mobilized for regrowth following defoliation. These results are discussed in terms of the integration of a grass plant in the vegetative state.

Leaf arrangement in Ragi (Eleusine coracana Gaertn.) and its significance

Unlike other millets and the cereal crops, the Ragi plant, though typically grass-like, has a peculiar build and appearance. The plant is often compared to a chandelier in general outline. A study of the plant was made to resolve the reason for this and it was found to be due to the packing of a large number of leaves that have conspicuous leaf bases on short slender culms... The total number of leaves including that of tillers (at an average of two tillers per plant-more may be found depending upon spacing and other cultural practices) may be 63-72, a single tiller having as much as 24 leaves. But the plant grows to a height of 90 to 120 cm. only. The culm of ragi is slender and has an average thickness of 0.69 cm. at the base and 0-23 cm., just below the earhead (peduncle). It may be quite probable that the slender culm derives support from the ensheathing leaf bases, to bear the burden of the leaves and the earhead. The leaf bases are longer than the internodes, especially the lower internodes. The several layers of bases that arise successively from the nodes that are close together, render the necessary support as well as protection to the slender culm. It was also observed that the support derived from the leaf bases, do not sustain throughout, but fails at a time when most needed.