Paspalum Dilatatum Poir Research Articles

Seedling emergence of tropical perennial pasture species in response to temperature used to determine sowing time recommendations

Tropical pasture grasses and legumes can be highly productive and persistent and fill the summer-autumn feed gap typical of temperate pasture systems in southern Australia. However, more information is needed on optimum temperature range for seedling emergence because this will influence sowing time recommendations. A replicated field experiment was conducted at 5 locations in New South Wales over a 12-month period to determine the optimum temperature for emergence of a range of tropical species: Rhodes grass (Chloris gayana Kunth), Makarikari grass (Panicum coloratum L. var. makarikariense Gooss.), kikuyu grass (Cenchrus clandestinus (Hochst. ex Chiov.) Morrone), digit grass (Digitaria eriantha Steud.), panic grass (Megathyrsus maximus (Jacq.) B.K. Simon & S.W.L. Jacobs), paspalum (Paspalum dilatatum Poir.), Urochloa hybrid (Urochloa decumbens × U. ruziziensis × U. brizantha), 2 cultivars of Desmanthus virgatus (L.) Willd. (cultivars ‘Marc’ and ‘JCU2’), D. bicornutus (S. Watson), D. leptophyllus (Kunth) and D. pernambucanus (L.) Thell.). Rhodes grass emerged satisfactorily over the longest time across all sites, exhibiting the greatest temperature range over which emergence occurred, while Makarikari grass and panic grass had the narrowest temperature range for emergence. The temperature for 50% emergence differed between the tropical species and whether the soils were warming or cooling. Rhodes grass had the lowest 50% emergence temperature (17 °C) while paspalum had the highest (22 °C). Results showed that temperature for 50% emergence is a useful indicator for determining sowing time in warming soils.

Germination, overcoming seed dormancy and endozoochory dispersal by cattle of native species from natural grassland

AbstractNatural grasslands, one of the main ecosystems worldwide, are under threat and native species are desired when addressing restoration issues. The main processes for grasslands restoration success are plant establishment and seed addition in the soil. Thus, it requires overcoming barriers that prevent germination and seed dispersal strategies. This study aimed to assess the germination potential, treatments to overcome seed dormancy and endozoochory dispersal of forage native species by cattle. Seeds from 21 native species from the four most common botanical families (Poaceae, Asteraceae, Fabaceae and Cyperaceae) were collected in a natural grassland area (Pampa Biome) and used in the experiments. Experiment I: germination under controlled conditions of all species was carried out and compared to commercial forage (Paspalum notatum cv. “Pensacola”). Experiment II: three treatments to overcome seed dormancy (mechanical and chemical scarification; priming agent) were tested in six species. Experiment III: the recovery, viability and germination of native P. notatum Flüggé and Desmodium incanum DC seeds from cattle faeces were evaluated. The results show that Paspalum umbrosum Trin. and Saccharum angustifolium Nees have high germination potential when compared to commercial forage. The treatments to overcome seed dormancy increased the germination of D. incanum, Paspalum plicatulum Michx. and Paspalum dilatatum Poir. Total seed recovery of 15% (P. notatum) and 26% (D. incanum), without affecting seed viability, show that cattle are able to supply the soil seed bank with native species. Germination potential, treatments to overcome seed dormancy and endozoochory dispersal of forage native species may be exploited in natural grassland restoration.

Monitoring fall CO2 efflux of dallisgrass and hybrid bermudagrass: Implications for nonselective weed control

AbstractChemical control options for dallisgrass (Paspalum dilatatum Poir.) are limited, inconsistent, and damaging to desirable species. Dallisgrass and hybrid bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt Davy] may enter dormancy at different times, allowing for safe, efficacious use of nonselective herbicides for dallisgrass control. Field experiments evaluated dallisgrass and hybrid bermudagrass dormancy by measuring plant respiration in fall and subjecting the carbon efflux data to a nonlinear exponential decay regression model fitted against cooling degree‐days (CDDs). Total plant respiration differed between the species at trial initiation. Dallisgrass exhibited higher net respiration, indicating that each species proceeded into dormancy at different rates. A postemergence dallisgrass control trial was initiated at 5 to 125 CDD22C to evaluate potential rates of quinclorac (1.5, 2.3, and 3.0 kg acid equivalent ha–1), monosodium methanearsonate (6.1, 9.1, and 12.1 kg a.i. ha–1), glyphosate (5, 7.6, and 10.1 kg a.i. ha–1), and thiencarbazone + foramsulfuron + halosulfuron (0.14, 0.18, and 0.22 .kg a.i. ha–1). Dallisgrass control 36 wk after the initial treatment was greatest with glyphosate (≥97%). Minimal bermudagrass survival was observed next spring in response to fall glyphosate. Total plant respiration per sample area differed between species at trial initiation. However, dallisgrass exhibited greater net respiration, indicating differences in behavior concerning the initiation and procession of dormancy between dallisgrass and bermudagrass. Microclimates such as shaded or low‐lying areas may yield different results. Further research should determine the significance of this phenomenon to use nonselective herbicides to control dallisgrass in bermudagrass.

Estimation of forage quality by near infrared reflectance spectroscopy in dallisgrass, Paspalum dilatatum, poir

Dallisgrass ( Paspalum dilatatum Poir.) is an economically important and widely cultivated forage crop for livestock feeding in the tropical, subtropical, and warm temperate regions because of good adaptation to unsuitable pasture conditions. In this study, 216 dallisgrass samples were used to develop near infrared reflectance calibrations to estimate five forage quality parameters: dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and ash. Second derivative pretreatment was applied for calibration of DM, CP and NDF while a first derivative pretreatment was used for ADF and ash. The coefficients of determination in the internal validation set (r 2) were 0.78 for DM, 0.80 for CP, 0.95 for NDF 0.75 for ADF, and 0.71 for ash. The relative predictive determinant ratios for calibration indicate that the NDF equations were acceptable for quantitative prediction of dallisgrass quality, whereas the DM, CP, ADF, and ash equations were useful for screening purposes. The near infrared prediction models developed in this study can be used for screening in the forage breeding researches to be carried out for five quality parameters in the future.

Impact of Verticutting on the Efficacy and Soil Activity of ALS-inhibiting Herbicides for Dallisgrass Control

Dallisgrass (Paspalum dilatatum Poir.) control with postemergence herbicides is inefficient and inconsistent from year to year. Control with acetolactate synthase (ALS)-inhibiting herbicides may be enhanced through root absorption, but herbicide movement through dense turfgrass canopies may be difficult. The objectives of this research were to evaluate the influence of verticutting on the postemergence control of dallisgrass and the presence of ALS-inhibiting herbicides within the soil profile. Long-term dallisgrass control [17 weeks after initial treatment (WAIT)] was enhanced in response to verticutting at one of two locations. This may be attributed to differences in turfgrass management (mowing height) before trial initiation that impacted dallisgrass carbohydrate content and herbicide absorption. However, dallisgrass control with certain herbicides was enhanced at the second location in response to verticutting at earlier rating dates. Thiencarbazone + foramsulfuron + halosulfuron (TFH) and trifloxysulfuron at 112 g·ha−1 a.i. and carrier volume of 1628 L·ha−1 (TRI High CV) following mowing + verticutting resulted in the greatest long-term control 17 WAIT at one of two trial locations, 86% and 85%, respectively. Greenhouse experiments confirmed that mowing + verticutting dallisgrass before treatment followed by irrigation led to an increase in herbicide presence within the soil profile, regardless of herbicide. Presence of TFH went from 6.4 to 8.2 mm, trifloxysulfuron at 28 g·ha−1 a.i. and carrier volume of 407 L·ha−1 went from 6.7 to 8.5 mm, and TRI High CV went from 8.6 to 11.8 mm.

Production of dallisgrass in response to NPK fertilizer in southwest China and its implications for cultivation

AbstractDallisgrass (Paspalum dilatatum Poir.), a warm‐season forage, is a perennial grass with high nutritional value, good palatability and high‐stress resistance in subtropical regions worldwide. However, very limited information is available on the cultivation of dallisgrass, especially in southwest China. Soils in different areas with pasture cultivation histories were collected and mixed evenly as substrate soil. Pot experiments after fertilization with nitrogen (N), phosphorus (P) and potassium (K) are used to analyze the dallisgrass growth characteristics, dry matter biomass (DM), photosynthetic characteristics, nutrient accumulation, agronomic efficiency (AE), partial factor productivity (PFP) and recovery efficiency (RE). A three‐factor (N, P, K) and five‐level (N: 0, 48.66, 120, 191.34 and 240 kg/ha; P: 0, 68.93, 170, 271.07 and 340 kg/ha; K: 0, 30.41, 75, 119.59 and 150 kg/ha) quadratic regression orthogonal rotation combination design was used with three experimental plots per management strategy for multiple comparisons within each harvest. Compared with no fertilization, the optimal treatment (OPT, N 48.66 kg/ha, P 68.93 kg/ha, K 119.59 kg/ha) increased yield by 46.3%, but the effect of NPK alone was not significant. This is because OPT improves the morphology and photosynthetic characteristics of dallisgrass, cause the dry matter during the growth period is significantly (p < .05) increased, and the average nutrient use efficiency (7.45%) under the OPT management measures was much higher than the under N, P and K fertilization alone (approximately 2.61 times). More meaningfully, we found that the demand for P and K fertilizer in dallisgrass in a typical subtropical mountainous region of China is higher than that for N. Overall, these findings have important implications for the cultivation of dallisgrass.

Detection of grassy weeds in bermudagrass with deep convolutional neural networks

AbstractSpot spraying POST herbicides is an effective approach to reduce herbicide input and weed control cost. Machine vision detection of grass or grass-like weeds in turfgrass systems is a challenging task due to the similarity in plant morphology. In this work, we explored the feasibility of using image classification with deep convolutional neural networks (DCNN), including AlexNet, GoogLeNet, and VGGNet, for detection of crabgrass species (Digitaria spp.), doveweed [Murdannia nudiflora (L.) Brenan], dallisgrass (Paspalum dilatatum Poir.), and tropical signalgrass [Urochloa distachya (L.) T.Q. Nguyen] in bermudagrass [Cynodon dactylon (L.) Pers.]. VGGNet generally outperformed AlexNet and GoogLeNet in detecting selected grassy weeds. For detection of P. dilatatum, VGGNet achieved high F1 scores (≥0.97) and recall values (≥0.99). A single VGGNet model exhibited high F1 scores (≥0.93) and recall values (1.00) that reliably detected Digitaria spp., M. nudiflora, P. dilatatum, and U. distachya. Low weed density reduced the recall values of AlexNet at detecting all weed species and GoogLeNet at detecting Digitaria spp. In comparison, VGGNet achieved excellent performances (overall accuracy = 1.00) at detecting all weed species in both high and low weed-density scenarios. These results demonstrate the feasibility of using DCNN for detection of grass or grass-like weeds in turfgrass systems.

Allelopathic interference of the exotic naturalized Paspalum dilatatum Poir. threatens diversity of native plants in urban gardens

Urban greening may enhance the distribution of exotic species that represent a threat for the native species in new urban systems. Paspalum dilatatum Poir. is one of the exotic naturalized species dominating in gardens of new urban ecosystems in Egypt. This study was conducted to evaluate the allelopathic interference of such species on the native plants in these habitats. The field study showed that the plots infested with Paspalum attained lower coverage, diversity and biomass of native plants than those free from it. Amaranthus viridis and Dactyloctenium aegyptium were completely absent from the sites involving P. dilatatum. Moreover, Paspalum-infested soils were of more water content, available nitrogen and extremely higher nitrogenase activity. In a greenhouse experiment, the rhizosphere soil under Paspalum reduced germination and growth of some native species, namely, Amaranthus viridis, Medicago lupulina, Melilotus indicus and Plantago amplexicaulis. Moreover, growth inhibition was inversely related to the seed size of these tested species. The spectrophotometric analysis revealed that higher contents of phenolics and flavonoids were detected in the Paspalum-infested soils in comparison with free ones. Besides, the high performance liquid chromatographic (HPLC) analysis indicated the presence of some free phenolics and flavonoids with higher concentrations in Paspalum-infested soils. The results indicate that the exotic naturalized P. dilatatum had negative effects on coverage, biomass and diversity of the native species in urban gardens. The obtained inhibition in these criteria was not attributed to soil characteristics. Furthermore, the significant reduction in germination and growth of the target species under greenhouse conditions could be attributed to the higher phenolic and flavonoid contents in the Paspalum-infested soils. These findings suggest that allelopathy had, at least, partial role in the negative impact caused by P. dilatatum. This species may also represent a threat for the native plant communities in new urban ecosystems.

The forage grass Paspalum dilatatum tolerates partial but not complete submergence caused by either deep water or repeated defoliation

Grazing, flooding and their combination are major disturbances that could affect plant performance in humid grasslands. We performed two experiments to study the tolerance of the forage grass Paspalum dilatatum Poir. to different submergence depths and defoliation frequencies. First, we addressed whether this species can shift from the escape strategy to ‘quiescence’ when completely submerged for 30 days. Second, we explored to what extent partial or complete submergence produced by defoliation compromises plant regrowth. The results showed that regardless of the depth of water at submergence, P. dilatatum always responded by attempting to expose its leaf area above water, by increasing the tiller angle and/or blade length (i.e. tiller height). Partially submerged plants showed a reduction in starch concentration (89%) but biomass was unaffected, whereas completely submerged plants did not survive. After one defoliation event, 77% of aerial biomass of partially submerged plants was removed and the concentration of carbon reserves (water-soluble carbohydrates and starch) decreased to half that of control plants. A second event of defoliation (20 days later) of plants with few reserves removed 50–52% of shoot biomass and compromised plant survival, with plants dying before the end of the experiment. In conclusion, P. dilatatum does not tolerate prolonged conditions of complete submergence caused by either deep water columns or repeated defoliation.

Responses of Ten Weed Species to Microwave Radiation Exposure as Affected by Plant Size1

Abstract There is interest in alternative weed control methods to herbicide use, especially among those interested in organic approaches. The use of microwave radiation as a weed control method appears to be a good alternative because it does not produce chemical residues in the environment. A study was conducted to determine the impact of plant age on weed control using microwave radiation. Ten weed species, representing monocots and dicots, were selected for this study: southern crabgrass (Digitaria ciliaris (Retz.) Koeler), dallisgrass (Paspalum dilatatum Poir.), false green kyllinga (Kyllinga gracillima Miquel), fragrant flatsedge (Cyperus odoratus L.), yellow nutsedge (Cyperus esculentus L.) common ragweed (Ambrosia artemisiifolia L.), white clover (Trifolium repens L.), pitted morningglory (Ipomoea lacunosa L.), henbit (Lamium amplexicaule L.) and field bindweed (Convolvulus arvensis L.). In general, weed species become more tolerant of microwave treatments as they increased in size, as 8 to 10 week-old plants were injured less than 4 to 6 week-old plants. Most grass species regrew when treated at 90 and 180 joules.cm−2 of microwave radiation. Pitted morningglory and common ragweed showed the highest susceptibility to microwave radiation among all treated weed species. The increase in a weed's biomass over time probably increases the amount of microwave radiation necessary for heating samples to the thermal threshold required for control. Index words: Nonchemical control, microwave, weed age, weed maturity, thermal weed control. Species used in this study: southern crabgrass (Digitaria ciliaris (Retz.) Koeler); dallisgrass (Paspalum dilatatum Poir.); false green kyllinga (Kyllinga gracillima Miquel); fragrant flatsedge (Cyperus odoratus L.); yellow nutsedge (Cyperus esculentus L.); common ragweed (Ambrosia artemisiifolia L.); white clover (Trifolium repens L.); pitted morningglory (Ipomoea lacunosa L.); henbit (Lamium amplexicaule L.); field bindweed (Convolvulus arvensis L.).

Determining the Microwave Radiations Exposure Level Needed for Weed Control Using a Stationary and Running Belt Microwave Radiations Applicator System1

Abstract There is a demand for nonchemical weed control strategies, with microwave radiations one possible option. Accurately measuring a weed's exposure level to microwave radiations is a challenge when there is a gap between when electricity is applied to the magnetron and actual production of microwave radiations. This gap causes an error in the calculation of actual energy needed for weed management. Any misinterpretation over-estimates the required energy load, adversely affecting the perceived value of the technology. Studies were conducted to eliminate the existing lag period. A running belt prototype was built for this purpose using two magnetrons producing 900 watt each installed on a treadmill with a power supply. There was significant improvement in the precision for calculations of total energy required for weed control. These anatomically diverse weeds showed more uniform thermal injuries and greater control using the running belt prototype system than a stationary unit. The LD50 for broadleaf weeds treated with microwave radiations using the running belt system ranged from 31.2 joules.cm−2 for common ragweed (Ambrosia artemisiifolia L.) to 36.8 joules.cm−2 for pitted morningglory (Ipomoea lacunosa L.). In comparison, treatment of weeds with microwave radiations using the stationary mode system resulted in a range of LD50 values of 64.5 joules.cm−2 for common ragweed to 155.1 joules.cm−2 for white clover (Trifolium repens L.). Similarly, the LD50 values for grasses treated with microwave radiations using the running belt system ranged from 34.3 for dallisgrass (Paspalum dilatatum Poir.) to 69.5 joules.cm−2 for southern crabgrass [Digitaria ciliaris (Retz.) Koeler]); in comparison, the range in LD50 values for grasses treated with stationary system was 136.1 to 182 joules.cm−2. The LD50 values for sedges treated with microwave radiations using the running belt system ranged from 29.2 joules.cm−2 for yellow nutsedge (Cyperus esculentus L.) to 78.1 joules.cm−2 for fragrant flatsedge (Cyperus odoratus L.); in comparison, the range in LD50 values for the stationary mode system was 119.4 joules.cm−2 for fragrant flatsedge to 145.9 joules.cm−2 for yellow nutsedge. Index words: Nonchemical control, weed control, efficacy, prototype, weed management.

Differential incidence of the lemma on seed germination among different Paspalum dilatatum genotypes

Abstract: Paspalum dilatatum Poir. is a promising perennial summer grass forage for temperate regions, but among other factors, slow stand establishment has hindered its adoption. One of the reasons may be seed dormancy. Intraspecific variability in seed dormancy has been reported in P. dilatatum, but the mechanisms underlying this variability remain unclear. In this paper, we focus on the role of seed external covering structures on germination, particularly the lemma. Seeds of apomictic and sexual biotypes of P. dilatatum were subjected to acid scarification and removal of the lemma to study their germination, imbibition rate and sensitivity to ABA. Seeds without lemma showed higher germination than other treatments in dormant genotypes. We found that the lemma delayed but did not prevent water uptake in any genotype. Comparing sexual biotypes, P. dilatatum subsp. flavescens showed higher lemma-imposed dormancy than P. dilatatum “Virasoro”, and also higher seed dormancy at the caryopsis level. The thickness of the lemma was not different between these biotypes, so this trait did not explain differences in dormancy. Intraspecific variability of seed dormancy in this species may be attributable to the lemma incidence, however differences in the caryopsis component of seed dormancy should be considered.

Performance of Heifers Grazing Bermudagrass Pastures Strip or Solid Seeded with Clovers

Core Ideas Strip‐seeding of clovers into bermudagrass swards resulted in similar clover stand percentage compared with solid planting of clovers. Heifers grazing pastures that were strip seeded performed similarly to heifers grazing clovers that were seeded in solid stands. Red clovers persisted longer into the summer than either white or subterranean clovers. Red clover provided greater animal performance than white and subterranean clovers. Even though clovers can provide improved forage quality and reduced N fertilization when grazing stocker calves on warm‐season grass pastures, stand establishment remains a concern. The objective of this research was to determine if alternative methods of seeding legumes into warm‐season perennial swards could improve legume establishment. This research took place on 18, four‐acre mixed bermudagrass [Cynodon dactylon (L.) Pers.], crabgrass [Digitaria ciliaris (Retz.) Koeler], and dallisgrass (Paspalum dilatatum Poir.) pastures at the University of Arkansas Southwest Research and Extension Center Stocker Unit. Pastures were seeded in October of 2013 to white (Trifolium repens L.), red (Trifolium pratense L.), or subterranean (Trifolium subterraneum L.) clovers either in solid stands at the recommended rate (2.0, 8.0, and 11 lb/acre, respectively) or in four 0.25‐acre strips at twice the recommended seeding rate in a 3 × 2 factorial arrangement of treatments with three pasture replications per treatment combination. Growing heifers (n = 216; 614 ± 44.4 lb) grazed pastures from May to September 2014 and April to September 2015. Red clover was present later into the summer than white or subterranean clovers, but there were no differences due to seeding method. At the end of the grazing season, heifer bodyweight and gain was greater when grazing red clover than when grazing subterranean clover. Strip‐seeded clovers in only 50% of the pasture area provided similar stands to conventional solid seeding and equivalent animal performance. Red clover grew later into the summer grazing season and provided greater animal performance than white and subterranean clovers.

Topsoil removal and carbon addition for weed control and native grass recruitment in a temperate-derived grassland in northern New South Wales

Restoring the grassy understorey to temperate woodlands in south-eastern Australia is often disregarded due to a poor understanding of the techniques involved. The natural recruitment of native grasses is uncommon in the remnants of some of these woodlands, so the restoration of the grass layer is often dependent on interventions to overcome restoration barriers. Soil enrichment from agricultural fertilisers favours the invasion of exotic broadleaf weeds and grasses, and is one of the primary barriers to the successful recruitment and establishment of native grasses, which dominated before agricultural development. This study on the Northern Tablelands of New South Wales investigated the effects of different weed control treatments – scalping, glyphosate (Roundup®) herbicide, and combinations of glyphosate with carbon (sugar and sawdust) addition and a control (nil treatment) recruitment of native grasses and weed emergence after broadcast seeding. The experimental site was a mown grass lawn consisting of fescue (Festuca arundinacea Shreb.), cocksfoot (Dactylis glomerata L.) and paspalum (Paspalum dilatatum Poir). Native grass recruitment varied significantly between treatments. The maximum number of recruits in scalped plots was 29 recruits m–2 compared with an average of <2 recruits m–2 for the glyphosate and glyphosate carbon combinations. Scalping reduced soil nitrogen from 0.6% in non-scalped plots to 0.1% and phosphorus from 191.6 ppm to 40.3 ppm. Maximum weed cover occurred in the glyphosate herbicide treatment (45%), whereas combinations of glyphosate plus either sugar or sawdust maintained weed cover at 13%. The present study suggests that scalping may be a successful intervention strategy because it has the potential to significantly improve native grass recruitment compared with other restoration methods used in this study. Scalping allows more time for native grasses to germinate and establish in the absence of competitive fast-growing exotic weeds.

Canal geometry, flow velocity, dallisgrass (paspalum dilatatum poir.) density and soil phosphorous effects on hydraulic resistance of vegetated canals

Adi yalancı darı Paspalum dilatatum Poir. sulama kanallarında akışı azaltmakta ve işletme-bakım sorunlarına neden olmaktadır. Bu çalışma, otlanmış kanallarda Adi yalancı darı’nın pürüzlülük katsayısını nasıl etkilediğini ve topraktaki mevcut fosfor ile adi yalancı darı kuru ağırlığı arasındaki ilişkiyi araştırmak amacıyla yapılmıştır. Ayrıca; çalışma İran’da Mogan ovasında bulunan otlanmış kanallardaki pürüzlülük katsayısı ile adi yalancı darı yoğunluğu ve topraktaki mevcut fosfor miktarı arasındaki ilişkiyi belirlemeyi de amaçlamaktadır. Araştırma sonucunda; pürüzlülük katsayısı değerleri 0.01-0.032 arasında değişmiş ve ortalama olarak 0.09 olarak bulunmuştur. Diğer değişkenlerin olmadığı varsayıldığında, adi yalancı darı ile otlanmış kanallardaki pürüzlülük katsayısı değişkenlerini, sadece akış hızı ve kanal eğiminin etkilediği söylenebilir. Bu nedenle; bağımlı değişken olarak pürüzlülük katsayısını, bağımsız değişken olarak da akış hızı ve kanal eğimini kapsayan regresyon modeli geliştirilmiştir. Otlanmış kanalların kenarlarında ve tabanındaki mevcut fosfor miktarı 4.2’den 37 mg kg-1’e kadar yükselmiştir. En yüksek kuru madde miktarı 16.7 mg kg-1 fosfora sahip kanaldan 100 m2’ye 16 kg olarak elde edilmiştir. Ayrıca, akış hızı fonksiyonu, kanal eğimi, adi yalancı darı yoğunluğu ve mevcut toprak fosforunu pürüzlülük katsayısı olarak tanımlayan başka bir model de geliştirilmiştir. Sonuç olarak; kanallardaki adi yalancı darı yoğunluğunu azaltmak için fosfor kaynaklarının belirlenmesi ve sulama kanallarının dağılımının sınırlandırılmasının gerekli olduğu önerilmektedir

QUALITY CHARACTERISTICS OF THE MIXTURES OF SOME WARM SEASON PERENNIAL GRASSES WITH ALFALFA (Medicago sativa L.) UNDER IRRIGATED CONDITIONS OF CUKUROVA

ABSTRACT This research was conducted to determine forage quality characteristics of duo (alfalfa + one grass) and trio ( alfalfa + two grasses) mixtures of some warm season perennial grass species such as dallis grass ( Paspalum dilatatum Poir.), Rhodes grass ( Chloris gayana L.) and Bermuda grass ( Cynodon dactylon (L.) Pers.) with alfalfa as well as their pure sowings under irrigated conditions of Cukurova during the years of 2009-2011. In the study, crude protein contents, crude protein yields, acid detergent fiber contents (ADF), neutral detergent fiber contents (NDF) and relative feed values (RFV) of the mixtures and pure sowings were determined. The experimental design was completely randomized block design with three replications. The results of the study showed that there were significant differences among mixtures and pure sowings in the forage quality characteristics. The highest crude protein yield (2.32 t ha -1 ) was obtained from the mixture of dallis grass + alfalfa. The highest crude protein ratio (20.6 %) and RFV (164.8) was obtained from the pure alfalfa. The highest ADF (40.2 %) and NDF (70.9 %) was obtained from the pure dallis grass. The result of the study indicated that duo mixture of alfalfa with dallis grass may be used to establish artificial pastures under irrigated conditions of Cukurova or of similar ecologies owing to its high forage quality and high crude protein yield. Key words: Warm season perennial grasses, alfalfa, mixture, quality

Host preference and suitability of grasses for Oebalus pugnax.

The rice stink bug, Oebalus pugnax (Fabricius) (Hemiptera: Pentatomidae: Carpocorini), though graminaceous, discriminates among its numerous host grass species. This could represent a feeding preference, it could be related to host suitability for growth and development. To clarify the role of host grass discrimination, two laboratory studies were conducted: (1) free-choice tests to evaluate preferences of O. pugnax among 11 wild host grass species found in three rice-producing counties of the central Mississippi Delta (MS, USA), and (2) no-choice tests to evaluate the impact of rice (Oryza sativa L.), junglerice [Echinochloa colona (L.) Link], and dallisgrass (Paspalum dilatatum Poir.) (all Poaceae), on the development of O. pugnax from second instar to adult. In the free-choice test, four experiments were conducted, each with four sets of host grass species and observed 1, 2, 4, 8, and 16 h after release in cages. Approximately 4 h was necessary for O. pugnax to settle on preferred host grasses. Oebalus pugnax showed a feeding preference for junglerice over all 10 other grass species. Bahiagrass, Paspalum notatum Flueggé, was the least preferred. The no-choice tests showed significant effect of host grass species on O. pugnax mean development time of nymphal survival to adults. Survival of nymphs was lower and mean development time was longer on dallisgrass compared to rice and junglerice. Knowledge of O. pugnax rate of growth and development on host grasses could be useful in the future development of rice integrated pest management strategies.

Variability in germination behaviour ofPaspalum dilatatumPoir. seeds is genotype dependent

AbstractDallisgrass (Paspalum dilatatumPoir.) is a warm‐season grass, native to South America. Its adoption as a pasture crop has been hindered by low seed germination and slow establishment. However, variability in germination behaviour for this species has never been systematically analysed. ForPaspalumspp., dry‐storage and moist cold or warm pre‐conditioning treatments have been reported as effective for the relief or breaking of seed dormancy. In the present work, seed germination responses at 32°C were assayed for sixteenP. dilatatumgenotypes, representing its known natural genetic variability, to two moist pre‐conditioning treatments (at 5 and 20°C) and without pre‐conditioning, and three seed storage periods (0, 3 and 6 months). Pre‐conditioning at 20°C showed high germination percentages (>80%), with ratios equal to or higher than pre‐conditioning at 5°C, suggesting that cold is not required to break dormancy. Longer storage times resulted in increases in germination responses for most of the genotypes, while other biotypes showed no effect. BiotypesVirasoro andChirú showed a remarkably different behaviour with higher germination percentages of untreated freshly harvested seeds. Our results show that diversity for traits involved in seed germination exists among naturally occurringP. dilatatumgenotypes and the characterization of these traits should be addressed during ecotype characterization and evaluation of potential domesticates of this species.

Gene Discovery and Molecular Marker Development, Based on High-Throughput Transcript Sequencing of Paspalum dilatatum Poir

Background Paspalum dilatatum Poir. (common name dallisgrass) is a native grass species of South America, with special relevance to dairy and red meat production. P. dilatatum exhibits higher forage quality than other C4 forage grasses and is tolerant to frost and water stress. This species is predominantly cultivated in an apomictic monoculture, with an inherent high risk that biotic and abiotic stresses could potentially devastate productivity. Therefore, advanced breeding strategies that characterise and use available genetic diversity, or assess germplasm collections effectively are required to deliver advanced cultivars for production systems. However, there are limited genomic resources available for this forage grass species.ResultsTranscriptome sequencing using second-generation sequencing platforms has been employed using pooled RNA from different tissues (stems, roots, leaves and inflorescences) at the final reproductive stage of P. dilatatum cultivar Primo. A total of 324,695 sequence reads were obtained, corresponding to c. 102 Mbp. The sequences were assembled, generating 20,169 contigs of a combined length of 9,336,138 nucleotides. The contigs were BLAST analysed against the fully sequenced grass species of Oryza sativa subsp. japonica, Brachypodium distachyon, the closely related Sorghum bicolor and foxtail millet (Setaria italica) genomes as well as against the UniRef 90 protein database allowing a comprehensive gene ontology analysis to be performed. The contigs generated from the transcript sequencing were also analysed for the presence of simple sequence repeats (SSRs). A total of 2,339 SSR motifs were identified within 1,989 contigs and corresponding primer pairs were designed. Empirical validation of a cohort of 96 SSRs was performed, with 34% being polymorphic between sexual and apomictic biotypes.ConclusionsThe development of genetic and genomic resources for P. dilatatum will contribute to gene discovery and expression studies. Association of gene function with agronomic traits will significantly enable molecular breeding and advance germplasm enhancement.

Performances of Some Perennial Warm Season Grasses Alfalfa (Medicago sativa L.) Mixtures under Mediterranean Conditions

This research was conducted to determine forage yield and botanical composition of duo (alfalfa + one grass) and trio ( alfalfa + two grasses) mixtures of some warm season perennial grass species such as dallis grass (Paspalum dilatatum Poir.), Rhodes grass (Chloris gayana L.), Bermuda grass (Cynodon dactylon (L.) Pers.) Guineae grass (Panicum maximum Jacq.), blue couch grass (Digitaria didactyla Willd) and finger grass (Digitaria milanjiana (Rendle) Stapf) with alfalfa (Medicago sativa L.) as well as their pure sowings under irrigated conditions of Mediterranean during the years of 2011 and 2012. In the study, green herbage yield, dry matter yield, alfalfa proportion in dry matter yields and land equivalent ratio (LER) were determined. The experimental design was completely randomized block design with three replications. According to the results, it was determined that the ratios of warm season grasses in the botanical composition of the mixtures declined with the establishment age while rate of alfalfa in the botanical composition of the mixtures increased. Increasing the rate of alfalfa in the botanical composition of the mixtures also increased hay quality of the mixtures. The mixtures gave higher dry matter yield than pure sowings of the species. The highest green herbage yield (98.14 t ha1) was obtained from the mixture of Rhodes grass + alfalfa. The highest dry matter yield (22.46 t ha1) was obtained from the mixture of dallis grass + Guinea grass + alfalfa. The highest value of land equivalent ratio (LER) (1.49) was obtained from the mixture of bermuda grass +Rhodes grass + alfalfa. From the results of the study, it was concluded that Guinea grass and finger grass did not show good adaptaion to the Cukurova conditions due to low temperatures during the winter season. Bermuda grass, Rhodes grass, blue couch grass and dallis grass could be used to establish pasture mixtures with alfalfa, having long grazing season and giving high hay yield and quality. Before the establishment of such pasture mixtures, it was needed to research proper mixture ratios and proper management techniques of the mixtures