Field Evaluation of Cocksfoot,Tall Fescue and Phalaris for Dry Marginal Environments of South‐Eastern Australia. 1. Establishment and Herbage Production

Newly developed candidate cultivars of cocksfoot (Dactylis glomerata L.), phalaris (Phalaris aquatica L.) and tall fescue (Festuca arundinacea Schreb. = syn. L. arundinaceum (Schreb) Darbysh.) were evaluated over four years for persistence and productivity against current commercial cultivars in small plots at five locations selected for lower and less reliable rainfall and difficult soils (low pH and high Al) in south‐eastern Australia known to be marginally too dry for these grass species. The five locations were ‐ representing summer dominant rainfall, Inverell, in northern New South Wales (NSW); ‐ representing uniform rainfall; Trungley Hall, (medium rainfall), and Beckom (lower rainfall) both in southern NSW; and; representing a winter dominant pattern ‐ Eversley, (higher rainfall), and Bealiba, (lower rainfall), in central Victoria. The objective was to determine if the new candidate cultivars were more likely to persist and to be productive than current commercial cultivars. The study showed that most phalaris and cocksfoot treatments were highly productive in high rainfall years at one or both sites in southern NSW. However, all treatments had become much less productive by the end of the experimental period due to plant loss under hot, dry conditions in the final summer. At Bealiba in central Victoria, cocksfoot was the most productive species with several cocksfoot treatments of both subsp. hispanica and subsp. glomerata still present at the final harvest despite a hot and dry final summer‐autumn. Tall fescue was the most productive species in the two higher rainfall environments (Inverell, Eversley) although most treatments of all species performed well at those sites. Continental tall fescues were more productive on average than Mediterranean tall fescues at the strongly acidic Eversley site. As a result of this work, two of the new cocksfoot candidates (Moroccan Fine and AVH48 Selection) and one of the tall fescue candidates (Summer Active 1) have been licensed for commercial development and release.     

Interaction of plant genotype and management in the persistence of a perennial grass exposed to grazing and soil fertility stresses

Increased stocking rates under typical pasture improvement practices in southern Australia have often been associated with low persistence by sown perennial grasses subjected to continuous stocking. Cultivars of the perennial grass phalaris (Phalaris aquatica L.), which is widely used in southern Australia, vary in their phenology and growth habit. Winter‐active cultivars have also been developed with improved stress tolerances, viz. heavy grazing pressure (Holdfast GT) and acid soils (Advanced AT). This study examined the persistence of phalaris genotypes over 4 years under five management treatments: high P‐high stocking rate (18 sheep per hectare) rotationally stocked (HPRS); high P‐high stocking rate continuously stocked (HPCS); high P‐intermediate stocking rate (13·5 sheep per hectare) continuously stocked (HPCS13.5); low P‐low stocking rate (9 sheep per hectare) rotationally stocked (LPRS); and low P‐low stocking rate continuously stocked (LPCS). Basal frequency of phalaris declined rapidly under HPCS and LPCS in the first year of treatments when periods of low herbage mass occurred under low rainfall. Basal frequency in high P treatments stabilized and partially recovered but continued to decline in low P treatments. Holdfast GT survived the early decline in the HPCS treatment better than other winter‐active cultivars and similar to a known grazing tolerant, semi‐winter‐dormant cultivar. Advanced AT and older winter‐active cultivars were sensitive to continuous stocking but persisted better under rotational stocking or under a reduced rate of continuous stocking (HPCS13.5). Rotational management clearly promoted persistence of winter‐active phalaris, but long‐term persistence will be better ensured by combining management with the use of genotypes with grazing tolerance traits.     

Characterization of two races of the stem and bulb nematode (Ditylenchus dipsaci) in Israel

Two distinct races ofDitylenchus dipsaci in Israel were identified: one, which infects and damages onion and garlic, reproduces on pea, but does not infect phalaris grass; and a second, which infects and damages phalaris—and, probably, also ‘Saia’ oats—but fails to infect onion and garlic. A new ‘garlic’ race of the nematode does not appear to have been introduced into Israel together with the ‘Lavinia’ garlic cultivar, as previously speculated, but rather the introduced Lavinia clone is highly susceptible to the existing ‘onion and garlic’ race ofD. dipsaci.     

Field Evaluation of Cocksfoot,Tall Fescue and Phalaris for Dry Marginal Environments of South‐Eastern Australia. 2. Persistence

Perennial grasses provide forage and environmental benefits in the agricultural systems of southern Australia, but persistent cultivars are lacking for the lower rainfall inland margins (<600 mm average annual rainfall). Potential new cultivars of cocksfoot (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb. = syn. Lolium arundinaceum (Schreb.) Darbysh.) and phalaris (Phalaris aquatica L.) have been developed in response to this need. These and older cultivars were evaluated for persistence at five sites in south‐eastern Australia from 2009 to 2013. A wide range in rainfall was experienced, but survival was principally reduced by a severe spring–summer–autumn drought in the final year in which all species began to decline in persistence once the spring 2012 to autumn 2013 cumulative climatic moisture deficit became higher than about 700 mm and declined very severely at deficits over 1000 mm. The highly summer‐dormant cocksfoot ssp. hispanica control cultivar Kasbah showed outstanding survival of this event in the cropping zone of southern New South Wales, but not at the drier of two sites with acidic soils in central Victorian where all cocksfoot cultivars showed similar survival. Potential new summer‐active tall fescue cultivars survived well at the higher rainfall Victorian site and under high rainfall in northern NSW. All tall fescue cultivars experienced high mortality during a period of high moisture stress in the spring of the establishment year in southern NSW, but the Mediterranean cultivar Grasslands Flecha MaxP gradually recovered. Differences among phalaris cultivars were not large with new cultivars of North African origin being marginally more persistent at the drier site in southern NSW. Comparisons with results from the Mediterranean Basin are discussed. Although there was no clear evidence of differences in persistence between the new and old cultivars, some of the new cultivars were considered to show potential for commercial release.     

北固山湿地优势植物氧化酶及环境适应性的研究

对镇江北固山湿地优势植物芦苇、旱苗蓼及虉草的不同器官在不同月份的多酚氧化酶、过氧化氢酶的活性进行了研究。结果表明:3种植物不同月份多酚氧化酶、过氧化氢酶活性差异明显,酶活性在各器官中的分布也不相同;3种植物多酚氧化酶、过氧化氢酶的活性顺序为芦苇>旱苗蓼>虉草,且地下部分的酶活性明显略高于地上部分,酶活性与植物的生长量成正比例关系。酶活性高低反映了湿地植物环境适应性的强弱,多酚氧化酶、过氧化氢酶通过各自的生理作用对植物生理代谢起到了保护作用。结合湿地水文情势调查分析,得出了水文情势对优势植物的分布与扩展有重要的控制意义,湿地植物因水位的脉动变化、环境季节性变化及其自身的生理功能产生了抗活性氧、转化有害酚类、抗涝等生理抗性,形成了很好的环境适应机制。     

Progress in improving aluminium tolerance in the perennial grass,phalaris

Aluminium (Al) tolerance of 11 cultivars, breeding populations and accessions of the perennial grass, phalaris (Phalaris aquatica L.), was investigated in low ionic strength nutrient solutions. The populations were chosen to determine whether a program to improve the tolerance of phalaris to acid soils had resulted in improved Al tolerance. Populations derived by backcrossing genes from a more Al-tolerant species, P. arundinacea L. (AT populations), were significantly more Al tolerant than populations based on pure P. aquatica. Smaller levels of improvement in Al tolerance had also been achieved within P. aquatica through a combination of selection in Al solutions and at acid soil field sites. The response of roots and shoots to Al stress was similar. Some differences in ranking were obtained depending on whether Al tolerance was defined by actual growth in Al solution or growth relative to the zero Al treatment. Performance in nutrient solution containing Al was highly correlated with second year yield and persistence at a field site with acid soil high in Al to depth. Actual root dry weight in nutrient solution containing Al gave a slightly higher correlation with the field data than root weight relative to the zero control. A tendency for root dry weight to segregate in the presence of Al was observed in some P. aquatica populations but not in the AT populations. It was concluded that a significant improvement in the Al tolerance of phalaris has been achieved through a program to introgress genes from P. arundinacea into P. aquatica.     

Sodium and potassium effects on cation concentration and yield of lucerne and phalaris grown separately and together

Abstract

Lucerne (Medicago sativa L.) and phalaris (Phalaris aquatica L.) were grown separately and together in a pot trial on a yellow‐brown pumice soil with three rates of sodium (Na) and two rates of potassium (K) in factorial combination. Lucerne alone had a low Na concentration but growing phalaris as a companion grass produced herbage with a Na concentration adequate for stock. Na application increased the Na concentration in phalaris and the mixture of phalaris and lucerne much more than in lucerne alone; had little effect on K concentration; slightly reduced Mg concentration; and greatly reduced Ca concentration but not as much in lucerne as in phalaris or the mixture with lucerne. K application increased K concentration and reduced Na, Ca and Mg concentrations throughout. Yield of phalaris grown alone and in combination with lucerne was increased significantly by Na application when K concentration in the plants was low. Yield of lucerne was not affected by Na application and it is concluded that Na did not substitute for K in this species. It is concluded that field trials are warranted to investigate the possibility of growing a special purpose mixture of lucerne and phalaris on New Zealand yellow‐brown pumice soils to provide feed that has adequate Na for grazing animals.     

The genetic correlation of panicle shattering with the intact rachilla form of seed retention in Phalaris aquatica L.

Panicle shattering and seed retention are distinct characters that influence seed dispersal in Phalaris aquatica L.(phalaris). One form of seed retention in phalaris is the result of the thickening of the rachilla (intact rachilla) and disruption of the rachilla-break age mechanism. This form of seed retention results in seed dispersal as seed-retaining panicle fragments, providing an opportunity to reduce ant predation of seed, and thereby increase the potential for seedling recruitment. A genetic analysis of panicle shattering and the intact rachilla form of seed retention was conducted on parental clones and derived half-sib families of across between the seed retaining cultivar Atlas PG and the non-seed retaining cultivar Sirocco, grown as spaced plants over two seasons in the field. A simulation of panicle shattering of the parents and families was also devised under glasshouse conditions. The narrow-sense heritability of panicle shattering in the field was 51 ± 10% and 58 ± 12%,on the basis of half-sib family means and parent-offspring regression, respectively,and its genetic correlation with panicle shattering under simulated conditions was24 ± 8%. The narrow-sense heritability of the intact rachilla form of seed retention was 70 ± 17% on a half-sib family mean basis. Seed retention had a negative genetic correlation of 71 ± 19% with panicle shattering, posing a difficulty for breeding seed-retaining cultivars with readily shattering panicles. However, it was considered likely that the two traits were controlled by independent sets of genes and that this association could be broken. This association is discussed in the context of breeding cultivars with seed dispersal characteristics that promote seedling recruitment under conditions of ant predation of the seed bank. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effects of contrasting seasonal growth patterns on composition and persistence of mixed grass‐legume pastures over 5 years in a semi‐arid Australian cropping environment

Perennial grass‐based pastures are uncommon in phased cropping rotations in south‐eastern Australia, where rainfall often limits production and persistence. The high reliance on pure legume‐based pastures limits overall pasture productivity and has adverse effects on environmental parameters such as weed incursion and ground cover. A field experiment was monitored over 5 years to examine the relative productivity of the temperate perennial grasses, phalaris (Phalaris aquatica) and cocksfoot (Dactylis glomerata) and determine whether contrasting seasonal activity enhances their persistence when grown in mixtures with lucerne (Medicago sativa) and annual legumes. Phalaris swards were shown to increase cumulative aboveground biomass by up to 96% and 32%, and in year 5 reduce annual grass emergence by between sevenfold and threefold compared to annual legume and lucerne/annual legume mixed swards, respectively. Only swards that included phalaris maintained ground cover above 70% in each autumn of the experimental period. Swards based on the highly summer dormant cocksfoot cultivar, Kasbah, were generally less productive over all, despite the cocksfoot showing a high level of persistence and good recovery following drought. Grass‐based swards that included lucerne were observed to produce ~35% greater legume biomass than a sward sown only to annual legumes. Cumulative legume biomass was greatest in lucerne swards in the absence of perennial grasses. The experiment was unable to demonstrate a consistent benefit in production and persistence associated with contrasting seasonal growth patterns. However, mixtures containing a range of functional types were consistently shown to enhance productivity over the duration of the experiment compared to less diverse swards. The potential to substantially increase forage productivity and ground cover, while reducing incursion by annual grass weeds, by including well‐adapted perennial grasses in mixtures with lucerne and annual legumes should be utilized.