Higher Tiller Density Research Articles

Optimizing Nitrogen Application Timing in No‐Till Soft Red Winter Wheat

As no‐till acreage increases, N management guidelines need re‐examination due to the potential effects of surface residue on N transformations and crop development. Our objectives were to determine: (i) if N applied at Zadok's Growth Stage (GS) 25 improves grain yield of no‐till winter wheat (Triticum aestivum L.), (ii) if any yield increase was the result of increased spring tillering, and (iii) if there is a critical tiller density above which N application at GS‐25 in no‐till wheat was not required. Research was conducted at three sites in North Carolina with seven site‐years between fall 1996 and spring 1999. A continuum of GS‐25 tiller densities was generated (161‐1774 tillers m−2) by planting at different seeding rates and dates in a randomized complete block design. Five N treatments were applied at GS‐25, and three were applied at GS‐30. Tillering response to early spring N, yield, and yield components were measured. increasing early spring N rates resulted in higher tiller densities at GS‐30, and GS‐25 tiller density was a significant covariate. With GS‐25 tiller densities >550 tillers m−2, yields were higher when all N was applied at GS‐30. In years without spring freezes, wheat with <550 tillers m−2 achieved optimum yields when spring N was applied at GS‐25. Manipulating the timing of spring N application can optimize early spring tillering and yield component formation.

Demography of three dominant sedges under contrasting grazing regimes in the High Arctic

Abstract. Tiller demography of Carex aquatilis ssp. stans, Carex membranacea, and Eriophorum angustifolium ssp. triste was investigated in ungrazed and grazed high arctic vegetation on central Ellesmere Island, Canada. Tiller birth, growth, flowering and death were studied from excavated clonal fragments, and tiller density and biomass were studied from excavated turfs. Five life‐cycle stages were determined: dormant buds, juvenile, mature, flowering and dead tillers. A stage‐based transition matrix model was developed to estimate the long‐term dynamics of the sedge populations and to compare life‐history strategies between ungrazed and grazed populations. Short‐term and retrospective models, based on the growth during the sampling year and during the lifetime of the clonal fragments, respectively, were compared to see how well the short‐term model can describe demography of long‐lived plants. According to the short‐term model, tiller populations were decreasing (λ < 1 except for C. membranacea), whereas the retrospective model indicated that the tiller populations were increasing. Tiller population growth rates did not differ between ungrazed and grazed habitats. Nevertheless, the similar growth rates may be obtained by balanced differences in the vital rates between plants of the two habitats. The plants in the ungrazed habitat tended to remain in their current life‐cycle stage, whereas plants in the grazed habitat moved quickly to the next stage and died earlier. C. aquatilis ssp. stans appears to gain a competitive advantage over the other species under intensive grazing, as indicated by the higher tiller density and greater below‐ground biomass in grazed vegetation. The greater amount of below‐ground biomass apparently buffers C. aquatilis ssp. stans against grazing better than the other species.

Tillering, Internode Development, and Dry Matter Partitioning in Creeping Bentgrass

High tiller density and stolon development are critical to wear tolerance and persistence of creeping bentgrass (Agrostis palustris Huds. synonym A. stolonifera L.). A better understanding of creeping bentgrass growth and development would be helpful in screening germplasm for improved turf characteristics. The objectives of this study were to determine tiller appearance and main stem elongation and development, and to determine above ground dry matter partitioning, in high and low tillering populations of creeping bentgrass grown under low light (150 μmol m−2 s−1). Individual, pregerminated seeds of cv. Emerald and germplasm UM67‐10 were transplanted into 10‐cm pots containing an 80:20 (v/v) sand:peat media. Two growth cabinet experiments were conducted under 16‐ and 8‐h photoperiod and 20/15°C day/night temperatures. Phenological development was monitored through 35 d after transplanting (DAT). Dry weight per tiller was correlated to tiller age for main stem and primary tillers (r = 0.98 and r = 0.99) and secondary tillers (r = 0.93 and r = 0.99) for UM67‐10 and Emerald, respectively, at 35 DAT. Dry weight per tiller was related to tiller elongation. Population differences for dry weight accumulationper day were significant (P = 0.05) for lower order tillers. The germplasm UM67‐10 initiated tillering earlier and main stem elongation later than Emerald. Tillers per plant were correlated to tiller appearance date. Elongating tiller weight within populations was related to main stem elongation date and its final length. Late season planting, when daylight is decreasing, will result in a bentgrass stand with fewer tillers per plant and with little elongated stem growth. Screening germplasm for tiller production in a growth cabinet may facilitate identifying grasses with high tiller density and improved wear tolerance.

00/02960 Influence of coal volatiles compositions on NO x and SO x emissions

Switchgrass (Panicum virgatum L.) has been developed into a major herbaceous bioenergy crop for the production of cellulosic biofuels in North America and many counties in European. As cultivar selection has a major impact on the ultimate biomass productivity, we evaluated the adaptability and yield potential of 12 switchgrass cultivars including both upland and lowland ecotypes from 2010 to 2013 in the Beijing region, Northern China. Plant height was measured after anthesis, but phytomer number and tiller density were investigated at harvest. One single autumn harvest was carried out each year and biomass yields were determined. It was found that the lowland cultivars ‘Alamo’, ‘Kanlow’ and ‘NewYork’ produced the most biomass for their better performances in number of phytomers per tiller and mass per phytomer, though upland cultivars had higher tiller density. ‘Cave-in-rock’ and ‘Trailblazer’ had better biomass production among the upland cultivars and they were also recommended for planting together with lowland ones for their excellent cold tolerance in this region.

Tiller dynamics of Spartina maritima in successional and non-successional mediterranean salt marsh

Tiller demography was compared in two populations of Spartina maritima present at similar elevations in the coastal saltmarshes of Odiel (Huelva, S.W. Spain). The successional population consisted of colonizing tussocks in a littoral lagoon, and the non-successional population comprised a stable sward that had fringed a major channel for 40 years. At both sites S. maritima was replaced by Arthrocnemum perenne at higher elevation, where sediments were less reducing. Rapid, consistent sediment accretion confirmed the successional nature of the lagoon site but there was little net accretion in the stable sward. Census of permanent quadrats at the successional site chronicled moving concentric ‘waves’ of high tiller density as tussocks expanded. Initially high densities declined after one year to low values at the end of the second year but they had almost recovered after 3 years. The decline represented a combination of reduced numbers of births and increased numbers of deaths. Tiller densities were substantially higher in the stable sward and showed relatively small fluctuations with time. The underlying risk of tiller mortality was similar in the two populations for much of the time but after two years there was increased mortality, mainly associated with flowering, at the successional site; very few tillers flowered in the sward. This mortality contributed to a shift to a younger age structure in the successional population. Data aggregated over consecutive 3-monthly periods were examined for density dependence. None was found in the successional population. In the sward population there was evidence of density-dependent adult and juvenile mortality of tillers, particularly over the first 18 months of the study, when there were compensatory responses to subtle variations in density. The lack of density dependence and relatively low peak density of about 2000 m-2 near to the leading edges of the expanding tussocks at the successional site suggest that tiller placement there was regulated mainly by physiological mechanisms affecting rhizome growth and bud development in well integrated clones.

Productivity, and composition of smooth and meadow bromegrass mixtures with alfalfa under frequent cutting management

The value of smooth bromegrass (Bromus inermis Leyss.)–alfalfa (Medicago sativa L.) mixtures for pastures in central Alberta is limited by poor seasonal distribution of yield and low alfalfa persistence. Regrowth of meadow bromegrass (Bromus riparius Rehm.) exceeds that of smooth bromegrass. The effect of these grasses on yield, seasonal distribution and sward composition when grown in mixtures with alfalfa was evaluated. The DM yield of binary mixtures of Carlton or Manchar smooth bromegrass, or Regar meadow bromegrass with Peace or Beaver alfalfa was examined under a four-cut system at three sites in central Alberta for 3 yr. Annual yield was similar at all sites. Alfalfa cultivar did not consistently affect yield, but annual yield of meadow bromegrass-mixtures was 9 to 19% higher than mixture containing smooth bromegrass at Lacombe. Summer and fall production of meadow bromegrass mixtures was 18 to 53% and 40 to 69% greater (P ≤ 0.0001) than smooth bromegrass mixtures. Tiller weight of smooth bromegrass equalled or exceeded that of meadow bromegrass, so superior regrowth of meadow bromegrass mixtures was due to higher tiller density. Over 3 yr, annual yield of the alfalfa component was similar in smooth bromegrass- and meadow bromegrass mixtures, but alfalfa yield decreased (P ≤ 0.0001) 43 to 70% due to dramatic declines in alfalfa stem density. Competition from the associated grass and frequent defoliation reduced alfalfa longevity. Key words: Smooth bromegrass, Bromus inermis Leyss., alfalfa, Medicago sativa L., mixtures, pasture, sward structure

Comparison of winter-active phalaris with the Australian cultivar under rotational grazing. 2. Dry matter on offer, pasture composition and animal production

Composition and amount of pasture on offer and animal productivity are presented from an experiment in which 2 'winter-active' cultivars (Sirosa, Holdfast) and a breeding population (Perla Retainer) of phalaris (Phalaris aquatica L.) bred for rapid growth in autumn and winter were compared with the original cultivar, Australian, under rotational grazing at 15 wethersfha for 3 years at 2 sites near Canberra. A change of cultivar rank in phalaris herbage on offer occurred in winter of the second year, whereby Australian became the highest ranked cultivar, reflecting its 50-70% higher basal area and 70% higher tiller density. However, pastures of the winter-active lines had an average 30% more phalaris on offer per unit basal area and per tiller, and a larger component of other, mainly annual, grass. This resulted in total pasture on offer at least equivalent to that of Australian pastures, and possibly more herbage production in autumn and winter. Sheep on the winter-active phalaris pastures were slightly heavier on average due mainly to higher weight gains in the first half of the year. These sheep produced an average over both sites of 7% more wool than sheep on Australian pastures, the advantage being higher at a site with dense phalaris (10%, P<0.01) than at a site with shallow, coarse-textured soil and less phalaris (3.5%, P = 0.11). It was concluded that pastures of the winter-active phalaris lines can give higher wool production than pastures of Australian phalaris, but not necessarily because of higher amounts of phalaris in the pasture. Benefits in the long term would also depend on persistence. Breeders of phalaris should aim to increase yield per unit of basal area if animal production gains in the short term are to be made in this environment, but compromises may be necessary between productivity and long-term persistence.

Characterisation of the Kangaroo Valley ecotype of perennial ryegrass (Lolium perenne)

A breeding program commenced in 1992 to produce perennial ryegrass (Lolium perenne) cultivars based on the Kangaroo Valley perennial ryegrass (KVPR) ecotype with improved winter and late season growth, disease resistance, and persistence. Perennial ryegrass plants (9000) were collected from 45 sites within the Kangaroo Valley and Shoalhaven flood plain in August 1992. Using principal component analysis, site differences were greatest for N percentage, Mg and Na concentration, and A1 saturation. Collections were space planted along with standard cultivars (Banks, Ellett, Embassy, Grasslands Lincoln, and Vedette) at Berry, New South Wales (34�48'S), and Timboon, Victoria (38'32'S), with 50 treatments and 10 replicates. Plants were visually scored for seasonal yield, rust incidence, greenness, leafiness, persistence, habit, and tiller density at both sites. At Berry, leaf angle, leaf width, and heading date were determined. Despite the differences in moisture, temperature, and growth indices between the 2 test sites, seasonal yield scores (mean of 100 plants) at Berry and Timboon were highly genetically correlated (r = 0.79-0.99). Standard cultivars were higher yielding with higher tiller density but with a greater rust incidence than collections (P < 0.01). Collections originating from the Shoalhaven flood plain were higher yielding with greater tiller density than plants from the Kangaroo Valley (P < 0.01), although differences were not as great as site of origin differences would suggest. Selections have been made for polycross half-sib formation, and half-sib evaluation will take place at a number of sites to determine the average general combining ability of parent selections for synthetic cultivar production.

The manipulation of grass swards for summer‐calving dairy cows

AbstractTwo experiments examined the effects of different defoliation treatments in spring on sward morphology and animal performance in mid‐season and late season. Three treatments were applied in both experiments: Control (C), sward grazed by cows in spring to 6–8 cm grass height. Grazed Aftermath (GA). sward grazed by cows in spring to 3–4cm and allowed to regrow before being grazed by summer‐calving cows, Silage Aftermath (SA), sward not grazed in spring, but a primary cut taken and the sward allowed to regrow before being grazed by summer‐calving cows. The aim of treatment GA was to produce a sward with a high tiller density and high intake characteristics to meet the forage intake requirements of continuously grazed summer‐calving cows, without resorting to offering forage buffers. Experiment 1 was conducted in 1989 on a sandy loam soil and Experiment 2 in 1990 on a heavy loam soil.In both experiments the GA treatment led to high live tiller density and live: dead tiller ratios compared with the C and SA treatments. Differences in sward morphology were also detected by applying double normal distribution analyses to measurements of grass height. The GA treatment also increased sward herbage mass and, to a limited extent, herbage metabolizable energy and crude protein contents. The results from Experiment 1 suggested that these sward effects lead to increased herbage dry‐matter intake (as estimated by the n‐alkane technique) and milk yield in cows grazing the GA sward. However, in Experiment 2, where conditions for grass growth in mid‐season were more favourable than in Experiment 1, the differences in sward morphology produced in spring were quickly lost in June and July. There were therefore no differences in herbage intake or milk yield in the second experiment. Herbage intakes (kgDMd−1± s.e.d) estimated in July for cows on treatments C, GA and SA were 11·0, 13·4, 10·1 ± 2·16 for Experiment 1 and 10·7, 11·1, 11·2 ± 2·32 for Experiment 2. Average milk yield (kgd−1± s.e.d.) for cows on treatments C, GA and SA were 26·1, 28·0, 25·6 ± 0·31 (Experiment 1) and 28·5, 27·3, 28·4 + 0·58 (Experiment 2).The results suggested that acceptable milk yields can be obtained from grazing summer‐calving cows, without offering forage buffers, by applying high stocking rates (low grass heights) in spring. However, the benefits of this manipulation could be lost by lax grazing in mid‐season.

Regrowth of Bromegrass Species, a Bromegrass Interspecific Hybrid, and Meadow Foxtail in a Short‐Season Environment

AbstractRegrowth in pastures is critical to economic production in short‐season areas. This study compared regrowth characteristics among three Bromus genotypes and meadow foxtail (Alopecurus pratensis L.) during late summer and fall. Growth analyses were conducted and yield components were determined in ‘Carlton’ smooth bromegrass (B. inermis Leyss.), ‘Regar’ meadow bromegrass (B. riparius Rhem.), an experimental strain (S9044) derived from F2 plants of a smooth ✕ meadow bromegrass cross, and common meadow foxtail. Seven weeks of plant regrowth after severe defoliation were characterized during 1985 and 1986 at Lacombe, AB, Canada (52° 28' N lat). The variation among the three grass species and the interspecific hybrid that was most critical to regrowth yield occurred during the first 21 to 28 d after defoliation. Smooth bromegrass consistently yielded less dry matter (DM) and had lower crop growth rates (CGR) than the other genotypes. Smooth bromegrass seemed limited most by a slowly developing leaf area index (LAI) as a result of a low and slowly developing tiller density. S9044 was improved over smooth bromegrass for regrowth yield and traits related to rapid regrowth. S9044 approached equilibrium tiller density quickly and had a large leaf area per tiller, which resulted in a higher leaf area expansion rate than in smooth bromegrass. Meadow bromegrass had CGR and DM yield similar to S9044, but the average LAI for meadow bromegrass was only 71% of that for S9044. Meadow bromegrass compensated for a small LAI with a specific leaf weight that was 1.4‐fold higher than S9044. When soil water was adequate, meadow foxtail produced regrowth equal to S9044 and meadow bromegrass through rapid development of leaf area of moderate specific leaf weight and a relatively large tiller size, given a high tiller density. As exhibited by meadow bromegrass, high specific leaf weight combined with rapid tiller development are traits associated with regrowth yield that may be worth exploiting in developing germplasm for short‐season areas where small LAI may be the norm.

Biska creeping bentgrass

Biska is a creeping bentgrass cultivar (Agrostis palustris Huds.) selected for increased tiller density, dark green colour and seed yield. In comparison with other bentgrasses, Biska has shown higher tiller densities and higher seed yields under Manitoba conditions.Key words: Cultivar description, creeping bentgrass, Agrostis palustris Huds.

Legume Compatibility of Reed Canarygrass Clones Related to Agronomic and Other Morphological Traits

Legume compatibility, the ability of a forage grass genotype to persist in a legume mixture without losing the legume stand, is needed in genetic materials intended for use in perennial grass‐legume mixtures, but limited information exists about appropriate selection criteria for forage grass compatibility with legumes. Data on nine agronomic and morphological traits of 14 reed canarygrass (Phalaris arundinacea L.) clones grown alone were used to explain their compatibility with alfalfa (Medicago sativa L.) or with birdsfoot trefoil (Lotus corniculatus L.) in binary mixtures subjected to a hay management. A second objective was to choose traits to use as components of a selection index for legume compatibility. Data on the nine traits of the 14 clones grown alone were summarized by principal component analysis. The nine first principal components were then reorganized into three uncorrelated factors, each of which described a different combination of principal components. Clones with high Factor I scores exhibited some combination of high dry‐matter yield (DMY), high tiller weight, early maturity, and height. Clones with high Factor 2 scores exhibited some combination of high DMY, high tiller density, high leaf area per ground area, and low rhizomatous spreading ability. Clones with high Factor 3 scores exhibited some combination of high specific leaf weight, low leaf area per ground area, and erectness of leaves. Factors 1 and 2 were equally important in describing the variability among the 14 clones, and Factor 3 was about 30% less important. Factors 1 and 2 often explained variability for reed canarygrass DMY and legume concentration in alfalfa and birdsfoot trefoil mixtures, but Factor 3 was never significant (P > 0.10). Selection on a spaced‐plant basis for higher DMY, early maturity, increased height, higher tiller density, and lower rhizomatous spreading ability should improve the legume compatibility of reed canarygrass in legume‐dominated stands managed for hay production.

Comparison of herbage production under continuous stocking and intermittent grazing

AbstractThe possibility of increasing the herbage utilized over a grazing season was investigated in a study comparing continuously stocked steady‐state swards maintained at optimum height (3.5 cm) with intermittently grazed swards. The intermittent systems were designed (a) to allow periodic increase in leaf area and hence growth rate, (b)to ensure that the accumulated herbage was eaten before it senesced, and (c) lo retain high tiller density by alternating periods of herbage accumulation with periods of continuous stocking.Two treatments (no animals or animal numbers reduced to half those on the 3.5 cm steady‐state treatment) were used during the 17‐18‐d periods of herbage accumulation. Grazing down was completed in 3–4 d, after which two treatments (14 d or 28 d) were used for the intervening periods of continuous stocking when sward height was maintained at 3.5 cm.Herbage production was estimated using the tissue turnover technique, with tiller population densities and rates of growth, senescence and net production per tiller measured at frequent intervals.Intermittent grazing treatments where animals were removed during herbage accumulation resulted in changes in tiller size and number, and in growth rates, but not senescence rates, per tiller such that short‐term deviations in the net rate of herbage production occurred compared with the continuously stocked control. The periods of advantage during phases of herbage accumulation were counterbalanced by those of disadvantage during the subsequent steady‐state phases. Where animal numbers were reduced during herbage accumulation, sward conditions differed little from those of the continuously stocked control, implying that intake per individual animal was increased.It was concluded that intermittent grazing systems offered no advantage over simpler continuous stocking systems, provided that a flexible approach to conservation was incorporated to allow control of sward conditions on the grazed area.

SOME EFFECTS OF SPRING DEFOLIATION AND DROUGHT ON PERENNIAL RYEGRASS SWARDS

An automatic rain-out shelter and an oscillating sprinkler irrigator were used to give contrasting wet and dry soil moisture regimes during summer in ryegrass swards, which had been differentially mown (7.5 ems vs 2.5 ems) during spring to create differences in tiller density. Swards with a higher tiller density before drought had a higher tiller density after drought. Although there was no effect of spring defoliation on summer production, there was a trend for pastures with a higher tiller density to recover more quickly after drought. The effect of water stress was to reduce herbage yield to only 8% of that of irrigated treatments. This was attributed to reductions in tiller density and rates of leaf extension and -~rnrn---r=,.+.n.ce. Water stresa- also increased the kiieis of lamina soluble sugars. Rewatering after moisture stress resulted in compensatory growth which partly offset the yield loss incurred during stress. Keywords: Spring grazing management, dryland, water stress, perennial ryegrass, sward dynamics, lamina soluble sugars.

Production from a drought-prone Northland pasture direct drilled with 3 grass cultivars

Abstract A ryegrass/white clover dairy pasture on a volcanic soil was direct drilled with ‘Grasslands Nui’ perennial ryegrass (Lolium perenne L.) (15 kg/ha), ‘Grasslands Matua’ prairie grass (Bromus catharticus Vahl.) (40 kg/ha), and ‘Grasslands Mara’ phalaris (Phalaris aquatica L.) (20 kg/ha) 3 days after the break of a 15-week drought. Seeds were drilled into 25 mm bands sprayed with either paraquat (0.22 kg a.i./ha) or glyphosate (2.88 kg a.i./ha), or into unsprayed pasture. Both herbicides reduced the growth of resident pasture within the sprayed bands, but Maru was the only sown species with a higher tiller density in sprayed than in unsprayed treatments after 28 days. Band sprayed herbicides had no effect on DM production of mown pasture in each of 2 years. Matua-sown pastures yielded 14% more DM than unsown control pasture, but Nui and Maru pastures had no significant effect on annual production.

GRAZING MANAGEMENT OF PERENNIAL RYEGRASS/ WHITE CLOVER PASTURE IN-LATE SPRING

The patterns of herbage accumulation and the tiller dynamics of a "Grasslands Nui" perennial ryegrass dominant pasture were compared under two grazing intensity treatments in late spring. Rank stemmy herbage developed with lax grazing whereas dense leafy pasture developed with close grazing. Dead herbage and uneaten stems in rank pastures shaded photosynthetic tissue. Leafy swards had a higher herbage accumulation rate and a higher tiller density than stemmy swards. Methods of achieving leafy pasture on farms by combinations of hard grazing, forage conservation and mechanical topping are discussed briefly.

Relations Between Genet and Tiller Population Dynamics: Survival of Phalaris Tuberosa Tillers After Clipping

(1) Glasshouse populations of Phalaris tuberosa were established from seed at four different genet densities, and allowed to grow until all four populations had similar tiller density. The tiller populations were then clipped at four different heights. (2) The population with highest starting density retained a higher tiller density than the other three. Its tiller survival under all clipping treatments was lower, so that the density of surviving tillers was independent of initial genet density. (3) At the three highest sowing densities, tiller survival was independent of clipping height, but at the lowest sowing density it depended strongly on clipping height, because the lowest sowing density produced a size-class distribution with fewer small and more large tillers. Small tillers survived well at all clipping heights, while large tillers survived less well and were particularly susceptible to close clipping. (4) Survival under clipping in these tiller populations can be understood in terms of their size-class distribution and their density. The genet structure of the populations had only an indirect influence, via the size-class distribution.

Compensatory Growth of Tall Fescue Following Drought1

AbstractEnhancement of growth following short periods of drought stress has been reported in several crop species. If such enhancement follows summer drought‐stress of cool‐season forage grasses, the increased yield from summer irrigation may be offset partially by compensatory growth during fall. Therefore, a 3 year field study was conducted to compare growth responses of tall fescue (Festuca arundinacea Schreb.) grown with and without supplemental irrigation from June through August. Soil was Mexico silt loam (Udollic Ochraqualf) and fertilizer was applied in spring and following each cutting. Plots were harvested six times in 1971, five times in 1972, and four times in 1973. A residual harvest was made on 21 May 1974.During summer the plants that were irrigated had greater forage yields, greater tiller density, greater weight per tiller, higher leaf elongation rates, and higher concentration of water‐soluble carbohydrates (WSC) in leaf tissue as compared with plants that were water‐stressed. Concentration of WSC in stem bases during summer was higher in the water‐stressed plants. Fall growth of plants that had been water‐stressed during summer was greater than that of those that had been irrigated. The enhancement of growth or compensatory effect was associated with higher concentration of WSC in stem bases during late summer, and faster leaf elongation and greater weight per tiller during fall of the previously water‐stressed plants as compared with the summer‐irrigated plants.Compensatory growth following drought stress was still evident the following spring, as indicated by the higher tiller density and greater forage yield. However, the collective compensatory yield of the water‐stressed plants during fall and spring was not great enough to compensate for lower yields during summer. In the third year of the study normal rainfall during summer was higher than duing the first 2 years, and no compensatory growth was noted during fall or the following spring.During the 3‐year study, total yield for the irrigated treatments was 4% larger than that for the water‐stressed treatment. The major response to irrigation was a shift in season of production. Management and breeding objectives should consider the effect of summer irrigation or summer drought on the subsequent performance of cool‐season forage grasses.