Response of Safflower to (N.P.K) Fertilizer Combinations and Plants Distribution

To find out the effect of fertilizer levels and of plants distribution on safflower yield, an experiment was conducted in Iraq - Al-Diwaniyah Governorate in the growing season 2020/2021, The experiment included three replicates with 60 experimental units, and it included combinations levels of fertilization(F1F2, F3 and F4) which represented the following fertilizer levels(N0, P0, K0) (N140, P80, K40) (N160, P100, K60) (N180, P120, K80)Kg.h−1, in addition to five planting distribution (D1, D2, D3, D4 and D5) follows (30 × 30, 40 × 40, 50 × 50, 60 × 60 and 70 × 70 cm). The results showed that the fertilization level(N180, P120, K80) it gave the highest mean of seed weight and head diameter, which amounted to(23.12 g and 2.88cm) respectively. As for the plant distribution D5, Gave the highest of weight of the yield of petals, Head diameter and plant heads number reached to (2.23 g, 2.93 cm, 83.14 head. plant−1) respectively. While the superiority of the treatment D4 was in In seeds number per head 44.88 seed. head−1. Therefore, plants distribution between plants can be reduced with increased fertilization from NPK in the area.

111 Metsulfuron and variable nitrogen application rates on infected tall fescue: effects on stocker performance, forage yield, nutritive value, ergovaline concentration and botanical composition

Chemical seed-head suppression of endophyte infected tall fescue (Lolium arundinaceum) improves stocker cattle performance but may decrease forage yield. Spring nitrogen application increases tall fescue growth with a concomitant increase in ergot alkaloids, produced by the symbiotic endophyte Epichloë coenophiala. We hypothesized that greater amounts of nitrogen applied to tall fescue would increase forage yield and offset losses in forage production from chemical suppression of seed-heads with metsulfuron without effect on alkaloid concentration. Ninety-six steers (270 ± 20 kg) were randomly assigned to one of sixteen paddocks (1.8 ha) on April 18 and continuously grazed for 57 d. Paddocks were blocked by previous use (n = 4) and randomly assigned to one of four treatments; no metsulfuron, no nitrogen (NEGCON), metsulfuron with 0 (MET0), 67 (MET67), or 134 (MET134) kg/ha of ammonium nitrate, applied March 11. Steers grazing MET0 paddocks were removed 17 d early due to insufficient forage availability. Steer weight, forage yield, forage nutritive value and ergot alkaloids in forage samples were measured monthly. Seed-head frequency and species composition were determined in June. Metsulfuron application reduced (P < 0.01) tall fescue seed-heads by 80%. Metsulfuron decreased (P = 0.03) ergovaline but ergovaline increased (P < 0.01) at each monthly sampling across treatments. Nitrogen had no impact on ergovaline concentration (P = 0.50). Forage yield tended to be least (P = 0.07) for MET0, intermediate for NEGCON and MET67, and tended to be greatest for MET134 (P = 0.08). Steer ADG was not affected by treatment (P < 0.80). Metsulfuron decreased NDF (P=0.02) regardless of fertilization rate. Forage CP increased with fertilization (P < 0.01) and no differences were detected between NEGCON and MET0 (P = 0.45). Species composition was not impacted (P >0.07) by treatment. Metsulfuron decreased seed-head growth and ergovaline concentration in tall fescue. Additional nitrogen fertilizer ameliorated forage yield lost to metsulfuron application but did not impact steer gain.

Population Genetic Structure of Claviceps purpurea in Cool-Season Grass Seed Crops of Oregon

Ergot, caused by Claviceps purpurea, is a primary disease concern in irrigated cool-season grass seed production systems of Oregon. In order to better understand the genetic diversity, population structure, and the epidemiology of C. purpurea in grasses grown for seed, 226 isolates were obtained using a hierarchical sampling strategy from two fields each of Kentucky bluegrass (n = 102) and perennial ryegrass (n = 124) and characterized using 12 microsatellite markers. A total of 194 unique multilocus genotypes (MLGs) were identified in this study. There were moderate levels of genotypic diversity (H = 3.43 to 4.23) and gene diversity (Hexp = 0.45 to 0.57) within fields. After clone correction, analysis of molecular variance revealed that 66% of the genetic variation occurred between the two C. purpurea isolates collected from the same seed head of individual plants, indicating that many of the seed heads bearing multiple sclerotia were infected by ascospores rather than conidia. However, the majority of the clonal isolates obtained in this study were collected from the same seed head (i.e., the two isolates were identical MLGs), indicating a role of conidia (honeydew) in secondary infections within seed heads. Genetic differentiation was observed between populations from different hosts (22%) but was confounded by geography. The standardized index of association ranged from 0.007 to 0.122 among the four populations, suggesting potential outcrossing and differences in the relative contribution of ascospores and conidia to ergot among the fields. The results from this study provide insights into the epidemiology of ergot in cool-season grass seed crops of Oregon.

261 Prescribed burning of endophyte-infected tall fescue pastures: Effects on forage production, ergot alkaloid concentrations, and stand composition

Prescribed fire may be a non-chemical alternative for seedhead suppression in endophyte-infected tall fescue forage systems. A study was conducted to observe the effects of a single prescribed burn on seed head production, ergot alkaloid concentration, forage production, forage quality, and stand composition in K31 tall fescue plots (endophyte infection=96%). Treatments of an undisturbed control (CON), March mow (MOW), March burn (EARLY), and April burn (LATE) were randomly applied to 56 square meter plots with ten replicates per treatment. Plots were sampled for forage quality and ergot alkaloid concentrations monthly from May to October. Forage production and species composition was recorded in June and October. Fescue seedhead count was conducted in May. After June sampling, plots were clipped to a height of 10 cm and litter was removed to simulate spring grazing. CON had greater (P < 0.01) total forage production in June than other treatments. MOW had greater (P < 0.01) forage production (≤107 kg/ha) than EARLY and LATE in June. There was no effect (P = 0.30) of treatments on forage production in October. LATE burn reduced (month × trt; P = 0.02) ergovaline concentration in June but all treatments were above the established threshold (150 ppb) for fescue toxicosis. Fescue seed head frequency was decreased (P < 0.01) by 50% in LATE plots. There was no treatment effect (P ≥ 0.22) on forb and non-fescue grass frequency in May, but warm season grass frequency was greater (P < 0.01) in LATE plots in October. Crude protein in LATE was greater than other treatments in May and both LATE and CON were greater than other treatments in June (P < 0.01). Neutral detergent fiber for LATE was less than other treatments in May and June (P < 0.01). Under conditions of this experiment, prescribed fire decreased seed head count and ergot alkaloid concentration, with a modest reduction in forage production.

Growth behavior and glyphosate resistance level in 10 biotypes of Echinochloa colona in Australia

Recently, poor control of Echinochloa colona with glyphosate has been reported in no-till agriculture systems of the northern grain region (NGR) of Australia. Two experiments were conducted using 10 biotypes of E. colona selected from the NGR of Australia to understand differences in their growth behavior and resistance pattern. Growth studies revealed that these biotypes differed in plant height (53-70 cm plant−1), tiller production (30-52 tillers plant−1), leaf production (124-186 leaves plant−1) and seed head production (37-65 seed heads plant−1). Days taken to seed heads and shoot biomass in these biotypes ranged between 40-48 d and 21-27 g plant−1, respectively. Seed production in these biotypes ranged between 5380 and 10244 seeds plant−1; lowest for biotype B17/25 and highest for biotype B17/13. Correlation studies revealed that seed number plant−1 had a positive correlation with plant height (r = 0.67), tiller number plant−1 (r = 0.89), leaf number plant−1 (r = 0.73), seed heads plant−1 (r = 0.78), seed head weight (r = 0.79), shoot biomass (r = 0.77) and root biomass (r = 0.46). The glyphosate dose-response study showed a wide range of responses in these biotypes and the glyphosate dose required to reduce 50% biomass (GR50 values) was estimated between 217 to 2159 g a.e. glyphosate ha−1. GR50 values of biotypes B17/16, B 17/34 and B17/35 were 719, 2159 and 884 g ha−1, respectively, making them 3, 10 and 4-fold resistant to glyphosate compared with the susceptible biotype B17/37. Growth behavior and seed production potential in these biotypes had no correlation with the resistance index. These results suggest that some biotypes of E. colona are highly problematic; for example, biotype B17/34 was not only highly glyphosate-resistant, but also produced a high seed number (9300 seeds plant−1). This study demonstrated that there is a possibility of great risk with the increased use of glyphosate for managing E. colona in the NGR of Australia. The results warrant integrated weed management strategies and improved stewardship guidelines are required for managing glyphosate-resistant biotypes of E. colona and to restrict further movement of resistant biotypes to other regions of Australia.

Ozone Tolerance Found in Aegilops Tauschii and Primary Synthetic Hexaploid Wheat

Modern wheat cultivars are increasingly sensitive to ground level ozone, with 7–10% mean yield reductions in the northern hemisphere. In this study, three of the genome donors of bread wheat, Triticum urartu (AA), T. dicoccoides (AABB), and Aegilops tauschii (DD) along with a modern wheat cultivar (T. aestivum ‘Skyfall’), a 1970s cultivar (T. aestivum ‘Maris Dove’), and a line of primary Synthetic Hexaploid Wheat were grown in 6 L pots of sandy loam soil in solardomes (Bangor, North Wales) and exposed to low (30 ppb), medium (55 ppb), and high (110 ppb) levels of ozone over 3 months. Measurements were made at harvest of shoot biomass and grain yield. Ae. tauschii appeared ozone tolerant with no significant effects of ozone on shoot biomass, seed head biomass, or 1000 grain + husk weight even under high ozone levels. In comparison, T. urartu had a significant reduction in 1000 grain + husk weight, especially under high ozone (−26%). The older cultivar, ‘Maris Dove’, had a significant reduction in seed head biomass (−9%) and 1000 grain weight (−11%) but was less sensitive than the more recent cultivar ‘Skyfall’, which had a highly significant reduction in its seed head biomass (−21%) and 1000 grain weight (−27%) under high ozone. Notably, the line of primary Synthetic Hexaploid Wheat was ozone tolerant, with no effect on total seed head biomass (−1%) and only a 5% reduction in 1000 grain weight under high ozone levels. The potential use of synthetic wheat in breeding ozone tolerant wheat is discussed.

Dynamics of Dry-Down in Seed, Head and Stalk from Sunflower Genotypes Sprayed with Chemical Desiccants After Physiological Maturity

Chemical desiccation can advance the sunflower harvest time. Paraquat has been extensively used, but other less risky chemicals, as Carfentrazone and Saflufenacil, can rise as an alternative. Moisture levels of seed, head and the upper portion of stalk are all relevant for mechanical harvesting, but dry-down dynamics of each tissue is unknown. The aim was to study the dry-down dynamics of seed, head and stalk in sunflower genotypes sprayed with Paraquat, Carfentrazone and Saflufenacil after physiological maturity. Seven experiments were carried out in the field in Argentina (from 29 to 39º S) during 2014/2015 and 2015/2016. The genotypes used included hybrids and female inbred lines of both oil and confectionery types. The dry-down of sunflower plant was accelerated by desiccants with Paraquat, reducing seed and stalk moisture to a greater extent. The head moisture remained very high (>80 and 70%) during several days after application, without differences among desiccants and control. Dynamics of seed, head, and stalk moisture was not associated to vapor pressure deficit or meteorological conditions after chemical application. Loss of green color of leaves was not a reliable indicator of seed dry-down dynamics. Seed germination was not affected by chemical desiccation on either oil-type or confectionery female plants. Under broad conditions of these experiments, the Paraquat was effective for seeds/grains and stalks drying in both sunflowers hybrids and inbred lines. The slowly drying of heads makes it necessary to continue investigating with new doses and combinations of desiccants to ensure an optimal harvest. Desiccants were safe for seed germination, which benefits their usefulness in the seed industry.

Photosynthetic regulation in seed heads and flag leaves of sagebrush-steppe bunchgrasses

Native sagebrush-steppe bunchgrass populations are threatened by the spread and dominance of exotic invasive annual grasses, in part due to low, episodic seed production. In contrast, the widespread exotic bunchgrass, crested wheatgrass, readily produces viable seed cohorts. The mechanisms underlying these differences are unclear. To address this, we measured seed head specific mass (g m−2) and net photosynthetic assimilation (Anet) as a function of internal [CO2] (A/Ci curves) in pre- and post-anthesis seed heads and flag leaves of crested wheatgrass and four native bunchgrasses to determine if differences in allocation and photosynthetic characteristics of seed heads was consistent with differential reproductive success. Crested wheatgrass seed heads had 2-fold greater specific mass compared to the native grasses, concurrent with greater CO2-saturated photosynthesis (Amax), mesophyll carboxylation efficiency (CE), and higher intrinsic water-use efficiency (WUEi; Anet/stomatal conductance (gs)), but with similar relative stomatal limitations to photosynthesis (RSL). Post-anthesis seed head Amax, CE, RSL and gs decreased in native grasses, while crested wheatgrass RSL decreased and CE increased dramatically, likely due to tighter coordination between seed head structural changes with stomatal and biochemical dynamics. Our results suggest native sagebrush-steppe bunchgrasses have greater stomatal and structural constraints to reproductive photosynthesis, while the exotic grass has evolved seed heads functionally similar to leaves. This study shows elucidating reproduction-related ecophysiological mechanisms provide understanding of plant attributes that underlie restoration success and could help guide the development of native plant materials with functional attributes needed to overcome demographic bottlenecks that limit their restoration into degraded sagebrush-steppe.