Performance of legume–grass mixtures in the West Balkan region

Three perennial legumes (alfalfa, red clover and birdsfoot trefoil) and four cool-season perennial grasses (orchardgrass, tall fescue, Italian ryegrass and red fescue) were grown in legume–grass combinations and in pure stands of individual species, at three locations in the West Balkan region (Novi Sad, Banja Luka and Pristina) in the period from 2012 to 2015. The study evaluated dry matter yield, legume–grass–weed proportion and forage quality. High annual forage yield of legume–grass mixtures can be obtained with proper selection of species and an appropriate legume–grass ratio. However, high and stable yield, particularly in the case of grasses, depends on the amount and schedule of precipitation as well as the cutting time. The mixtures and legume pure stands achieved better forage production both per cutting and on the annual basis and had better forage quality than grass pure stands.     

Regenerant wastewater irrigation and ion uptake in five turfgrass species

The effects of wastewater and high concentrations of chloride (Cl), magnesium (Mg²⁺), calcium (Ca²⁺), and potassium (K⁺) on ion uptake and growth of turfgrass species were studied. Simulated water softener regenerated wastewater was prepared based on 1.8 kg KC1 regeneration rate to attain ion concentrations of 30 mM of K⁺, 100 mM of Ca²⁺, 100 mM of Mg²⁺, and 420 mM of Cl^‐. It was diluted to 1/5, 1/10, and 1/20 concentrations with tap water for the irrigation studies. Wastewater irrigation did not affect the growth rates of the turfgrass. No significant increase of Ca²⁺, K⁺, and Mg²⁺ uptake was detected under the wastewater irrigation treatment. However, the Cl^‐uptake was significantly different between irrigation treatments. It was found that in the spring, in the turf plots irrigated by 1/20 concentration wastewater, an amount equivalent to 60% of the applied Cl^‐ was taken up and removed in the Kentucky bluegrass and perennial ryegrass clippings, and more than 80% was taken up by tall fescue, bermudagrass, and zoysiagrass. A lower percentage of the applied Cl^‐ was removed by the clippings when the turf was irrigated with higher wastewater concentrations. Soil exchangeable Mg²⁺ and Cl^‐ concentrations were slightly, but significantly, higher under the wastewater irrigation treatments. Soil salinity measured by electrical conductivity (EC) was not significantly affected by the 1/20 wastewater irrigation. The soil EC values of the turf plots irrigated with 1/10 and 1/5 wastewater were highest in the summer (10 and 14 dS m^‐1) and lowest in the winter (2 to 4 dS‐m^‐1). This study suggests that the turfgrass species are relatively tolerant to high Cl^‐ concentrations, and under appropriate management, regenerant wastewater can be used for turfgrass irrigation with minimal environmental impact.     

Uptake and Distribution of Nitrogen in Perennial Ryegrass: Effect of Additional Applications at Vegetative Growth

Abstract

Nitrogen (N) fertilization rate, form, and timing in perennial ryegrass (Lolium perenne L.) vary according to the purpose of the grass. Double or triple spring N applications are required in forage production of perennial ryegrass. Whereas in perennial ryegrass grown for seed production the effect of more than one application has not received much attention. The hypothesis is that in perennial ryegrass grown for seed production the utilization of applied N depends on the current N status. Perennial ryegrass was grown in a hydroponic system with two N rates: low‐N (0.2 mM) and high‐N (6.0 mM). After 47 days of growth, additional N was applied as double‐labeled ¹⁵NO₃ ^{? 15}NH₄ ⁺ on four successive occasions in order to distinguish between the recoveries of the initial N applications and the additional N applied. Growth parameters and N content were analyzed on five harvesting occasions. Additional N applications to plants with low N status were primarily used to increase both N content in all organs as well as shoot number. By contrast, in high‐N treatments, the additional N supplied was primarily used to increase total‐N content in leaves. In all treatments, leaves were the preferable storage organs for N, however, the results from the high‐N treatments suggest a shift to pseudo‐stems as the preferable storage organ when additional N was supplied. It is suggested that the current N concentration in perennial ryegrass determines the potential of the plants to utilize additional applied N.     

Heavy metal concentration in forage grasses and extractability from some acid mine spoils

Laboratory and greenhouse studies were conducted on several forage grasses, bermudagrass (Cynodon dactylon), creeping red fescue (Festuca rubra), Kentucky 31-tall fescue (Festuca arundinacea), oat (Avena sativa), orchardgrass (Dactylis glomerata), perennial ryegrass (Lolium perenne), sorghum (Sorghum bicolor), triticale (X. triticosecale Wittmack), and winter wheat (Triticum aestivum) grown on three Alabama acid mine spoils to study heavy metal accumulation, dry matter yield and spoil metal extractability by three chemical extractants (Mehlich 1, DTPA, and 0.1 M HCl). Heavy metals removed by these extractants were correlated with their accumulation by several forage grasses. Among the forages tested, creeping red fescue did not survive the stressful conditions of any of the spoils, while orchard grass and Kentucky 31-tall fescue did not grow in Mulberry spoil. Sorghum followed by bermudagrass generally produced the highest dry matter yield. However, the high yielding bermudagrass was most effective in accumulating high tissue levels of Mn and Zn from all spoils (compared to the other grasses) but did not remove Ni. On the average, higher levels of metals were extracted from spoils in the order of 0.1 M HCl>Mehlich 1>DTPA. However, DTPA extracted all the metals from spoils while Mehlich 1 did not extract Pb and 0.1 M HCl did not extract detectable levels of Ni. All of the extractants were quite effective in determining plant available Zn from the spoils. For the other metals, the effective determination of plant availability depended on the crop, the extractant, and the metal in concert.     

Sugarcane response to saline irrigation water

Salinity of irrigation water reduces yield and juice quality in sugarcane (Saccharum spp. hybrids), but cultivars vary in the degree of reduction. Genotypes which accumulate more potassium (K⁺) may be more resistant to salinity than genotypes that accumulate less K⁺. We examined the effect of irrigation water salinity on yield and juice quality in a cultivar with high conductivity, high K⁺ juice, ‘NCo 310’, and a cultivar with low conductivity, low‐K⁺ juice, ‘TCP 87–3388 ‘. Plants were grown in lysimeters containing 793 L of soil and irrigated with water of 0.01, 1.25, 2.93, or 4.70 dS m^‐1. Quality and component analyses were conducted on the juice of single stalks subdivided by length, and the juice from whole stalks. The two cultivars responded similarly to increased salinity, although juice of NCo310 had a higher mineral concentration, especially K⁺ and Cl^‐. Yield and most quality components were not significantly reduced by 1.25 dS m^‐1 water. The 2.93 and 4.70 dS m^‐1 treatments reduced stalk height and weight but not stalk numbers. The reduction in stalk height was due to decreases in number of internodes per stalk and mean internode length. Increasing salinity reduced total soluble solids and sucrose in juice, but increased Na⁺, K⁺, Mg⁺², Ca⁺² and Cl^‐ Within a stalk, sucrose increased from top to bottom, while K⁺ decreased. Sodium concentrations were sharply higher in the lowest section, especially in plants irrigated with saline water. Chloride concentration was approximately equal in all sections. An increase in K accumulation did not appear to increase the salt tolerance of NCo310.     

Responses of forage grasses to aluminum in solution culture

Growth, nutrient uptake and nutrient uptake efficiency differences in orchardgrass (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb), and timothy (Phleum pratense L.) were evaluated at 0, 100, 200, and 300 μM Al. In each of the species, cultivar differences were also compared. In the absence of Al stress, cultivars of orchardgrass outperformed other grasses. The presence of Al reduced shoot and root growth; however, the magnitude of the growth reduction depended upon the species and cultivars. The growth of shoots and roots showed a significant difference with respect to species, cultivars, treatment Al and their Interactions. Aluminum reduced the uptake of many essential nutrients. At 100 μM Al Potomac orchardgrass had the highest and climax timothy had the lowest mineral content. The efficiency ratio (ER) assisted in classifying grass entries into efficient and inefficient utilizers of the absorbed nutrients. The ER is defined as milligrams of dry shoot weight produced per milligram of element in the shoot. The ER for P, K, Cu and Zn gave a positive correlation with shoot weight; however, in general, negative relationships were observed for shoot growth and ER for Mg, Fe, and Mn. In all the species increasing Al concentration from 0 to 100 μM increased ER for Mg and decreased ER for K and Zn. With the exception of tall fescue cultivars, the ER for P was reduced by 100 μM Al. The species and cultivars used in this study showed inter‐ and intraspecific differences in growth, uptake, and ER for nutrients in the presence or absence of Al stress. Significant reduction in growth, even at 100 μM Al by all the three species of grass indicates that these grass species are far more sensitive to Al than the field crops. Therefore, experiments with levels of Al lesser than 100 μM would have given a better outlook on the performances of these grass species.     

Effect of plant growth-promoting Bacillus sp. on color and clipping yield of three turfgrass species

A two-year irrigated field study was conducted to determine the effects of plant growth-promoting rhizobacteria (PGPR; Bacillus subtilis OSU-142 and Bacillus megaterium M3) as biofertilizer, and in combination with a chemical nitrogen (N) fertilizer, on turf color and clipping yield, and interaction of biofertilizer and chemical N fertilizers in perennial ryegrass (Lolium perenne L.), tall fescue (Festuca arundinacea L. Schreb.), and Kentucky bluegrass (Poa pratensis L.). The three turf species were tested separately in split-plot design experiments with three replications. Three fertilizer sources (ammonium nitrate only, ammonium nitrate + B. megaterium M3, and ammonium nitrate + B. subtilis OSU-142) were the main plots. N applications with monthly applications of 0.0, 2.5, 5.0, and 7.5 g N/m² were the subplots. Color ratings and clipping yields increased with increasing chemical N fertilizers in all species. Both Bacillus sp. significantly increased color ratings and clipping yields in perennial ryegrass and tall fescue. However, there were no significant differences among the three fertilizer sources in color and clipping yield of Kentucky bluegrass. The experiments showed that there is a small but significant benefit from applying biofertilizers for turf color, and that N fertilization may be reduced in some turf species when biofertilization are made for this purpose.     

Biochemical traits associated with growing sorghum genotypes with saline water in the field

Abstract

This study was aimed to determine biochemical traits related to higher phytomass production in sorghum genotypes irrigated with saline water. It was also attempted to consider whether or not forage yield production under non-saline conditions could be used as an index for for the selection of high yielding genotypes of sorghum under saline conditions. Forty-five sorghum genotypes were grown under field conditions using saline water or normal irrigation water in two growing seasons in Yazd, Iran. It appeared that salinity tolerance in sorghum genotypes, in addition to local adaption, was highly related to forage yield as well as some biochemical traits as carotenoid concentration, catalase activity, and K⁺/Na⁺ ratio. The screening method based on biochemical traits appeared to be applicable for identification of the salt-tolerant genotypes.     

Neotyphodium endophytes trigger salt resistance in tall and meadow fescues

Infection with Neotyphodium spp. endophytes increases resistance to drought stress and soil mineral imbalances in tall fescue (Festuca arundinacea Schreb. = Lolium arundinaceum (Schreb.) S. J. Darbysh.) and meadow fescue (Festuca pratensis Huds. = Lolium pratense (Huds.) Darbysh.). We hypothesized that resistance of these grasses to salinity stress may also be attributed to endophyte infection. Two tall fescue genotypes, Fa75 and Fa83, and one meadow fescue genotype, Fp60, infected (E+) with their endophytic fungi, Neotyphodium coenophialum (Glenn, Bacon and Hanlin) and N. uncinatum (Glenn, Bacon and Hanlin), respectively, and their noninfected counterparts (E–) were cultured in nutrient solution at three salinity levels of 0, 85, and 170 mM NaCl. Except for genotype Fa75, E+ plants exhibited higher leaf survival rates than E– clones at a high salinity level (170 mM). Root dry matter was higher in E+ than in E– plants, but shoot dry matter was not affected by endophyte infection. This resulted in a lower shoot‐to‐root ratio in E+ plants (1.63) compared with E– plants (2.40). Sodium (Na⁺) and chloride (Cl^–) concentrations were greater in roots of E– than in E+ clones. In shoots, Na⁺ and Cl^– concentrations were not affected by the endophyte. In contrast, E+ plants accumulated more potassium (K⁺), which resulted in a greater K⁺ : Na⁺ ratio in shoots of E+ than in those of E– plants. Our results show that endophyte infection reduced Na⁺ and Cl^– concentrations in tall fescue and meadow fescue roots but increased K⁺ concentrations in the shoots. Based on these results, we conclude that endophyte‐infected grasses may thrive better in salinity‐stress environments.     

Effect of fertilization and harvest frequency on yield and quality of tall fescue and smooth bromegrass

Abstract

Fertilization and harvest frequency affect yield and quality of forages. The purposes of this experiment were to determine (i) the effects of fertilization and frequent harvesting on yield and quality of tall fescue (Festuca arundinacea Schreb.) and smooth bromegrass (Bromus inermis Leyss.) and (ii) the efficiency of N in animal waste as compared with inorganic N fertilizer for forage production of these cool season grasses. ‘Fawn’ tall fescue and ‘Southland’ smooth bromegrass were grown in the greenhouse on Pullman clay loam topsoil (fine, mixed thermic Torrertic Paleustoll) under eleven fertilizer treatments and two harvest regimes. Nitrogen fertilizer increased yields, N and K concentrations and K/(Ca + Mg) ratios and decreased P, Ca, and Mg concentrations. Phosphorus and K fertilizers did not affect yields but applied P increased P and tended to decrease N and Ca concentrations. Applied K tended to increase Ca concentrations. Recovery of N from feedlot manure ranged from 0.8 to 14%, whereas, recovery from NH₄NO₃ averaged 64%. Harvesting at 3‐week rather than at 6‐week intervals reduced yields 25%; however, N and P removal were higher under the 3‐week harvest regime. Even though forage production was reduced under heavy utilization, the grasses required more N fertilizer under heavy than under lighter utilization. The two grasses produced similar yields under the 3‐week cutting regime and at N rates through 340 kg/ha under the 6‐week cutting regime. Tall fescue yields were higher with the higher N rates under the 6‐week cutting regime. Smooth bromegrass forage was higher than tall fescue forage in N, K, and Ca, whereas tall fescue forage was higher in P and Mg.     

Establishment techniques in under-sown perennial ryegrass for seed production

Abstract

Establishment methods have proven to be of major importance for grass-seed production. The objective of this research was to test the effect of different sowing techniques on plant establishment and the subsequent seed yield. Perennial ryegrass (Lolium perenne L.) is used as the model grass due to its large importance in Danish agriculture.

In a three-year trial six different methods of under-sowing of perennial ryegrass in a spring barley cover crop were employed. Perennial ryegrass was either sown directly at different depths within the spring barley (Hordeum vulgare L.) rows or placed 2, 6, or 12 cm from the spring barley rows. Results of dry-matter yield indicate that the best establishment of the grass occurred when placing the grass 6 or 12 cm from the cover-crop row, and this is of importance in less vigorous grasses. Overall, no seed-yield difference has been observed for perennial ryegrass when placing the grass 2, 6, or 12 cm from the cover-crop row. Placement of the ryegrass seed crop 6 cm from the cereal row showed that a significant yield increase of 34–71 kg ha^?1 can be obtained compared with sowing in the cereal row.     

Mudflat soil amendment by sewage sludge: Soil physicochemical properties,perennial ryegrass growth,and metal uptake

Abstract

The fast pace of cropland loss in China is causing alarm over food security and China’s ability to remain self-reliant in crop production. Mudflats after organic amendment can be an important alternative cropland in China. Land application of sewage sludge has become a popular organic amendment to croplands in many countries. Nevertheless, the land application of sludge to mudflats has received little attention. Therefore, the objective of the present work was to investigate the impact of sewage sludge amendment (SSA) at 0, 30, 75, 150 and 300 t ha^?1 rates on soil physicochemical properties, perennial ryegrass (Lolium perenne L.) growth and heavy metal accumulation in mudflat soil. The results showed that the application of sewage sludge increased organic matter (OM) content by 3.5-fold while reducing salinity by 76.3% at the 300 t ha^?1 rate as compared to unamended soil. The SSA reduced pH, electric conductivity (EC) and bulk density in mudflat soil, increased porosity, cation exchange capacity (CEC) and contents of nitrogen (N), phosphorus (P), exchangeable potassium ions (K⁺), sodium ions (Na⁺), calcium ions (Ca²⁺) and magnesium ions (Mg²⁺) in comparison to unamended soil. There were 98.0, 146.6, 291.4 and 429.2% increases in fresh weight and 92.5, 132.4, 258.6 and 418.9% increases in dry weight of perennial ryegrass at 30, 75, 150, and 300 t ha^?1, respectively, relative to unamended soil. The SSA increased metal concentrations of aboveground and root parts of perennial ryegrass (p < 0.05). The metal concentrations in perennial ryegrass were Zn > Cr > Mn > Cu > Cd > Ni, and the metal concentrations in roots were significantly higher than aboveground parts. The metal accumulation in perennial ryegrass correlated positively with sludge application rates and available metal concentrations in mudflat soil. Land application of sewage sludge was proved to be an effective soil amendment that improved soil fertility and promoted perennial ryegrass growth in mudflat soil. However, heavy metal accumulation in plants may cause food safety concern.     

Amelioration of calcareous saline sodic soils through phytoremediation and chemical strategies

Abstract. The worldwide occurrence of saline sodic and sodic soils on more than half a billion hectares warrants attention for their efficient, inexpensive and environmentally acceptable management. These soils can be ameliorated by providing a source of calcium (Ca²⁺) to replace excess sodium (Na⁺) from the cation exchange sites. Although chemical amendments have long been used to ameliorate such soils, the chemical process has become costly during the last two decades in several developing countries. As a low‐cost and environmentally acceptable strategy, the cultivation of certain salt tolerant forage species on calcareous sodic and saline sodic soils, i.e. phytoremediation, has gained interest among scientists and farmers in recent years. In a field study conducted at three calcareous saline sodic sites (pH_s=8.1–8.8, EC_e=7.8–12.5 dS m^–1, SAR=30.6–76.1) in the Indus Plains of Pakistan, we compared chemical and phytoremediation methods. There were four treatments; two involved plants: Kallar grass (Leptochloa fusca (L.) Kunth), and sesbania (Sesbania bispinosa (Jacq.) W. Wight). The other two treatments were uncropped: soil application of gypsum and an untreated control. All treatments were irrigated with canal water (EC=0.22–0.28 dS m^–1). The plant species were grown for one season (5–6 months). Sesbania produced more forage yield (34 t ha^–1) than Kallar grass (23 t ha^–1). Phytoremediation and chemical treatments resulted in similar decreases in soil salinity and sodicity, indicating that phytoremediation may replace or supplement the more costly chemical approach. The soil amelioration potential of sesbania was similar to that of the Kallar grass, which suggests that moderately saline sodic calcareous soils can be improved by growing a forage legume with market value.     

GROWTH,YIELD, AND ION RELATIONS OF STRAWBERRY IN RESPONSE TO IRRIGATION WITH CHLORIDE-DOMINATED WATERS

Strawberry is listed as the most salt sensitive fruit crop in comprehensive salt tolerance data bases. Recently, concerns have arisen regarding declining quality of irrigation waters available to coastal strawberry growers in southern and central California. Over time, the waters have become more saline, with increasing sodium (Na⁺) and chloride (Cl^?). Due to the apparent extreme Cl^? sensitivity of strawberry, the rising Cl^? levels in the irrigation waters are of particular importance. In order to establish the specific ion causing yield reduction in strawberry, cultivars ‘Ventana’ and ‘Camarosa’ were grown in twenty-four outdoor sand tanks at the ARS-USDA U. S. Salinity Laboratory in Riverside, CA and irrigated with waters containing a complete nutrient solution plus Cl^? salts of calcium (Ca²⁺), magnesium (Mg²⁺), Na⁺, and potassium (K⁺). Six salinity treatments were imposed with electric conductivities (EC) = 0.835, 1.05, 1.28, 1.48, 1.71, and 2.24 dS m^?1, and were replicated four times. Fresh and dry weights of ‘Camarosa’ shoots and roots were significantly higher than those of ‘Ventana’ at all salinity levels. Marketable yield of ‘Camarosa’ fruit decreased from 770 to 360 g/plant as salinity increased and was lower at all salinity levels than the yield from the less vigorous ‘Ventana’ plants. ‘Ventana’ berry yield decreased from 925 to 705 g/plant as salinity increased from 0.835 to 2.24 dS m^?1. Relative yield of ‘Camarosa’ decreased 43% for each unit increase in salinity once irrigation water salinity exceeded 0.80 dS m^?1. Relative ‘Ventana’ yield was unaffected by irrigation water salinity up to 1.71 dS m^?1, and thereafter, for each additional unit increase in salinity, yield was reduced 61%. Both cultivars appeared to possess an exclusion mechanism whereby Na⁺ was sequestered in the roots, and Na⁺ transport to blade, petiole and fruit tissues was limited. Chloride content of the plant organs increased as salinity increased to 2.24 dS m^?1 and substrate Cl increased from 0.1 to13 mmol_cL^?1. Chloride was highest in the roots, followed by the leaves, petioles and fruit. Based on plant ion relations and relative fruit yield, we determined that, over the range of salinity levels studied, specific ion toxicity exists with respect to Cl^?, rather than to Na⁺ ions, and, further, that the salt tolerance threshold is lower for ‘Camarosa’ than for ‘Ventana’.     

RESPONSE OF ORNAMENTAL SUNFLOWER CULTIVARS ‘SUNBEAM’ AND ‘MOONBRIGHT’ TO IRRIGATION WITH SALINE WASTEWATERS

To explore the possibility that saline wastewaters may be used to grow commercially acceptable floriculture crops, a study was initiated to determine the effects of salinity on two pollen-free cultivars of ornamental sunflower (Helianthus annuus L.). ‘Moonbright’ and ‘Sunbeam’ were grown in greenhouse sand cultures irrigated with waters prepared to simulate wastewaters commonly present in two inland valley regions of California: 1) San Joaquin Valley (SJV) where saline-sodic drainage waters are dominated by sodium (Na⁺) and sulfate (SO ^2? ₄ ) and 2) Coachella Valley (CV) where major ions in tailwaters are Na⁺, chloride (Cl^?), SO ^2? ₄ , magnesium (Mg²⁺), calcium (Ca²⁺), predominating in that order. Ten-day-old seedlings were subjected to five salinity treatments of each water composition, each replicated three times. Electrical conductivities (EC) of the irrigation waters were 2.5, 5, 10, 15, and 20 dS·m^?1. Flowering stems were harvested when about 75% of the ray flowers were nearly horizontal. Stem length and fresh weight, flower and stem diameter were measured. Mineral ion concentrations in upper and lower stems, upper and lower leaves were determined. Sodium was excluded from the young tissues in the upper portions of the shoot and retained in the basal stem tissue. Inasmuch as sunflower is also a strong potassium (K)-accumulator, K⁺/Na⁺ selectivity coefficients were unusually high in the younger shoot organs. Despite a five-fold increase in substrate Ca²⁺ in both solutions, shoot-Ca decreased as salinity increased and this cation was retained in the older leaves. A few of the lower leaves of plants irrigated with ICV waters at EC = 10 dS·m^?1 and higher, exhibited necrotic margins which were undoubtedly caused by high concentrations of Cl^? in the tissues. Flowering stems produced in all treatments met florist quality standards in terms of diameters for stems (0.5 to 1.5 cm) and blooms (8 to 15 cm). Across treatments, stem lengths ranged from 60 to 175 cm. Both ornamental sunflower cultivars proved to be good candidates for production of marketable flowering stems using moderately saline wastewaters.     

北京地区常用草坪草的耗水规律及适宜灌溉量研究

研究了在北京地区不同供水条件下，草地早熟禾、高羊茅、多年生黑麦草、野牛草、结缕草和狗牙根整个生长季的蒸散量差异和耗水规律。结果表明，蒸散量主要与草坪草的生物学特性有关，受水分条件影响；冷季型草坪草中多年生黑麦草耗水最少，暖季型草坪草中结缕草耗水最少；通过比较坪草和北方主要农作物的K_C值，得出草坪与大田作物的需水量相当；北京地区常用草坪草整个生长季的适宜灌溉量为：高羊茅(391.8 mm)>草地早熟禾(368.3 mm)>多年生黑麦草(315.1 mm)>狗牙根(300.7 mm)>野牛草(184.0 mm)>结缕草(110.5 mm)。     

EFFECTS OF NITROGEN APPLICATION TIMING ON GROWTH AND QUALITY OF A TURFGRASS MIXTURE

A 3-year field study was conducted to determine the influence of nitrogen (N) application timing on the growth and quality of a turfgrass mixture consisting of perennial ryegrass (Lolium perenne L.), Kentucky bluegrass (Poa pratensis L.), creeping red fescue (Festuca rubra var. rubra L.), and chewings fescue (Festuca rubra var. commutata Gaud.) under irrigated conditions. Nitrogen was applied annually at the rate of 30 g m^?2 year^?1, with six application regimes: control (no N), single spring (30 g m^?2), single fall (30 g m^?2), spring + fall (15 + 15 g m^?2), spring + summer + fall (10 + 10 + 10 g m^?2), and monthly from April through September (5 g m^?2).

Color, turf quality, clipping weights, and shoot density were correlated with fertilizer rates and application timing in this study. Fertilization monthly or every 2 months resulted in more uniform color and turf quality and less clipping weights than with comparable heavy spring and fall fertilizations. Heavy N applications in the fall did not cause winter injury and produced significantly darker color and more uniform appearance in early spring than other N applications. All N-fertilization regimes increased shoot density, but spring fertilization stimulated density the most. Nitrogen applied monthly or every 2 months was enough to enhance the color, turf quality, and shoot density of the turf during the growing season but did not greatly affect the growth rate.     

Microsatellite markers and genetic diversity assessment in Lolium temulentum

Lolium and Festuca are two important genera of cool-season forage and turf grasses worldwide. Lolium temulentum L. (darnel ryegrass) has been proposed as a model species for genomics studies of cool-season forage and turf grasses. A study with 41 darnel ryegrass, three tall fescue (Festuca arundinacea Schreb.), two tetraploid fescue (F. glaucescens), and two meadow fescue (F. pratensis) genotypes was initiated to (i) identify a set of microsatellite (simple sequence repeats) markers useful for L. temulentum L., and (ii) to utilize such markers for assessing the genetic variability of L. temulentum accessions collected from different geographical regions of the world. A total of 40 tall fescue (TF) EST-SSRs and 60 Festuca–Lolium (F × L) genomic SSRs were screened on a subset of eight genotypes. The selected 30 tall fescue EST-SSRs and 32 F × L genomic SSRs were used for further analysis of genotypes. The TF-EST- and the F × L genomic-SSRs identified 10.3 and 9.3 alleles per marker, respectively with an average polymorphic information content (PIC) value of 0.66. The phenogram based on 319 EST-SSR and 296 genomic SSR fragments, grouped L. temulentum accessions into three major clusters except for accession ABY-BA 8892.78. Lolium temulentum accession ABY-BA 8892.78 did not cluster with any other accession. The Festuca clusters were distantly related with darnel ryegrass clusters with a similarity coefficient of 0.26. The selected set of tall fescue EST- and F × L genomic SSRs were useful in assessing L. temulentum genetic diversity and could benefit the genetic improvement of members of the Festuca–Lolium complex.     

Is the salt tolerance of maize related to sodium exclusion? I. Preliminary screening of seven cultivars

Maize (Zea mays L.) plants in the early stage of development were treated with 80 mM sodium chloride (NaCl) with or without supplemental calcium (Ca²⁺) (8.75 mM) for a seven day period. The effects of salinity on dry matter production and shoot and root concentrations of sodium (Na⁺), Ca²⁺, and potassium (K⁺) were measured for seven Pioneer maize cultivars. Salinity significantly reduced total dry weight, leaf area, and shoot and root dry weight below control levels. For all seven cultivars, Na⁺concentrations were reduced and leaf area was significantly increased by supplementing salinized nutrient solutions with 8.75 mM calcium chloride (CaCl₂). The two cultivars with the lowest shoot and root Na⁺ concentrations under NaCl‐salinity showed the greatest increases in total, shoot and root dry weights with the addition of supplemental Ca. Shoot fresh weight/dry weight ratios for all cultivars were decreased significantly by both salinity treatments, but supplemental Ca²⁺ increased the ratio relative to salinity treatments without supplemental Ca. Root fresh weight/dry weight ratios were decreased only by salinity treatments with supplemental Ca. With NaCl‐salinity, cultivars which had lower shoot and root Na⁺ concentrations were found to be more salt sensitive and had significantly lower amounts of dry matter production than those cultivars which had higher shoot and root Na⁺ concentrations. It was concluded that Na⁺ exclusion from the shoot was not correlated with and was an unreliable indicator of salt tolerance for maize.