Genetic determinants of pathogenesis by feline infectious peritonitis virus

Feline infectious peritonitis (FIP) is a fatal, immune-augmented, and progressive viral disease of cats associated with feline coronavirus (FCoV). Viral genetic determinants specifically associated with FIPV pathogenesis have not yet been discovered. Viral gene signatures in the spike, non-structural protein 3c, and membrane of the coronavirus genome have been shown to often correlate with disease manifestation. An "in vivo mutation transition hypothesis" is widely accepted and postulates that de novo virus mutation occurs in vivo giving rise to virulence. The existence of "distinct circulating avirulent and virulent strains" is an alternative hypothesis of viral pathogenesis. It may be possible that viral dynamics from both hypotheses are at play in the occurrence of FIP. Epidemiologic data suggests that the genetic background of the cat contributes to the manifestation of FIP. Further studies exploring both viral and host genetic determinants of disease in FIP offer specific opportunities for the management of this disease.     

Response to lime and P by several genetic sources of corn (Zsa mays L.) on a low pH and P soil in the greenhouse 1

The objective of this study was to investigate the response of 16 different genetic sources of corn (Zea mays L.) to lime and P application on a low pH and P Parsons silt loam soil in the greenhouse. A highly significant lime x P interaction was found for both dry matter production and P concentration. Phosphorus increased both dry matter production and P content of plant tissues with or without lime application. However, liming produced a detrimental effect when P was applied but no effect when no P was applied. Corn genetic sources showed a highly significant interaction with P treatment, but not with lime for both dry matter production and P concentration. The results suggest that improvement in corn growth could be achieved in a low P soil environment by genetic selection.     

Leaf area index response of four obsolete and four modern cotton cultivars to two nitrogen levels

The optimal nitrogen (N) rate for cotton (Gossypium hirsutum L.) production in the late 20th century is greater than it was in the middle of the century (112 versus 27 kg ha^‐1). Part of the reason for this difference is that modern cultivars exhibit a greater harvest index than obsolete cultivars. This greater harvest index helps to allow modern cultivars to utilize greater N rates. However, factors other than harvest index, such as the development of leaf area in response to N, may also play an important role. Therefore, the objective of this study was to characterize leaf area index (LAI) of four obsolete and four modern cultivars at a low and high fertilizer N level. Cotton was grown in the field for two years (1992 and 1993) with two locations each year. The locations were a Beulah fine sandy loam and a Dubbs silt loam. Two preplant fertilizer‐N rates were used, a low (22 kg N ha^‐1) and a high(112 kg N ha^‐1). Leaf area index was determined at three stages in each year (early, mid, and late season). Yield was determined at maturity. Averaged across years, locations, and cultivars, late‐season LAI increased from 2.32 at 22 kg N ha^‐1 to 3.15 at 112 kg N ha^‐1 by late season. In 1992, modern and obsolete cultivars had similar LAI responses to N at early and mid season but by late season, LAI of modern cultivars was greater under high N than the obsolete cultivars (3.53 versus 2.95). Lint yield of the four modern cultivars was 372 kg ha^‐1 greater than the four obsolete cultivars at 112 kg N ha^‐1 and 289 kg lint ha^‐1 greater at 22 kg N ha^‐1 in 1992. The LAI response to N level of the modern cultivars was similar to that of obsolete cultivars in 1993 at all three sampling dates. In 1993, the lint yield of modern cultivars was 238 kg ha^‐1 greater than obsolete cultivars under 112 kg N ha^‐1 and 182 kg lint ha^‐1 at 22 kg N ha^‐1. In summary, our results best support the hypothesis that the higher yield of modern cultivars at high fertilizer N is unrelated to their LAI.     

Starter fertilizer effects on grain sorghum hybrids grown on a soil high in residual phosphorus in a no‐tillage environment

Conservation tillage crop production systems have become common in the central Great Plains because they reduce soil erosion and increase water‐use efficiency. The high residue levels associated with no‐tillage systems can cause soils to be cool and wet which can reduce nutrient uptake and growth of crops. Starter fertilizer applications have been effective in improving nutrient uptake even on soils high in available nutrient elements. Resent research indicates that corn (Zea mays L.) hybrids differ in their responses to starter fertilizer. No information is currently available concerning grain sorghum [Sorghum bicolor (L.) Moench] hybrid response to starter fertilizer. The objective of this study was to evaluate grain sorghum hybrid responses to starter fertilizer in a no‐tillage environment on a soil high in available phosphorus (P). This field experiment was conducted from 1995 to 1997 at the North Central Kansas Experiment Field, located near Belleville, on a Crete silt loam soil (fine, montmorillonitic, mesic, Pachic Arguistoll). Treatments consisted of 12 grain sorghum hybrids and two starter fertilizer treatments. Fertilizer treatments were starter fertilizer [34 kg nitrogen (N) and 34 kg P₂O₅ ha^‐1] or no starter fertilizer. Starter fertilizer was applied 5 cm to the side and 5 cm below the seed at planting. Immediately after planting, N was balanced on all plots to give a total of 168 kg N ha^‐1. In all three years of the experiment, grain yield, total P uptake (grain plus stover), grain moisture content at harvest, and days to mid‐bloom were affected by a hybrid x starter fertilizer interaction. Starter fertilizer consistently increased yields, reduced harvest grain moisture, improved total P uptake, and reduced the number of days needed from emergence to mid‐bloom of Pioneer 8505, Pioneer 8522Y, Pioneer 8310, Dekalb 40Y, Dekalb 48, Dekalb 51, Dekalb 55, and Northrup King 524, buthadno effect on Pioneer 8699, Dekalb 39Y, Northrup King 383Y, and Northrup King 735. When averaged over the three years, starter fertilizer increased grain yield of responding hybrids (hybrids in which the 3‐year average grain yield was significantly increased by the application of starter fertilizer) by 920 kg ha^‐1. In responding hybrids, starter fertilizer reduced grain moisture at harvest by 54 g kg¹ and also shortened the period from emergence to mid‐bloom by five days. Starter fertilizer increased V6 stage aboveground dry matter production and N and P uptake of all hybrids tested. Results of this work show that in high residue production systems even on soils high in available P, starter fertilizer can consistently increase yield of some hybrids, whereas other hybrids are not affected.     

Characteristics of Modern Triticale Quality: The Relationship Between Carbohydrate Properties, α‐Amylase Activity,and Falling Number

Triticale is a high‐yielding cereal crop with potential to increase grain production for human consumption over the coming decades. Minimal targeted selection has been conducted to produce cultivars with α‐amylase, amylose, and nonstarch polysaccharide (NSP) content appropriate for a milling market. Nevertheless, genotypic variability exists. Standard quality screening methods used for wheat, including pasting properties, falling number, and quantification of α‐amylase activity were employed to assess the environmental and genotypic variability among modern triticale cultivars and to investigate the suitability of these tests for triticale. Samples of 11 triticale lines from four environments were compared with five wheat cultivars bred for various end uses. Triticale exhibited a greater range than wheat for most tested variables, and the ranges usually overlapped. Triticale exhibited higher NSP content, generally equivalent pasting properties, higher α‐amylase activity, and lower falling number on average compared with wheat checks. However, low falling number was not indicative of high α‐amylase activity; the relationship with NSP level and other factors is discussed, and caution is recommended for interpretation of previous research. Three cultivars with equivalent α‐amylase activity to wheat and two with partially waxy starch were identified. These findings have great significance for research and the emerging triticale milling market.     

Weather-Centric Rangeland Revegetation Planning

Invasive annual weeds negatively impact ecosystem services and pose a major conservation threat on semiarid rangelands throughout the western United States. Rehabilitation of these rangelands is challenging due to interannual climate and subseasonal weather variability that impacts seed germination, seedling survival and establishment, annual weed dynamics, wildfire frequency, and soil stability. Rehabilitation and restoration outcomes could be improved by adopting a weather-centric approach that uses the full spectrum of available site-specific weather information from historical observations, seasonal climate forecasts, and climate-change projections. Climate data can be used retrospectively to interpret success or failure of past seedings by describing seasonal and longer-term patterns of environmental variability subsequent to planting. A more detailed evaluation of weather impacts on site conditions may yield more flexible adaptive-management strategies for rangeland restoration and rehabilitation, as well as provide estimates of transition probabilities between desirable and undesirable vegetation states. Skillful seasonal climate forecasts could greatly improve the cost efficiency of management treatments by limiting revegetation activities to time periods where forecasts suggest higher probabilities of successful seedling establishment. Climate-change projections are key to the application of current environmental models for development of mitigation and adaptation strategies and for management practices that require a multidecadal planning horizon. Adoption of new weather technology will require collaboration between land managers and revegetation specialists and modifications to the way we currently plan and conduct rangeland rehabilitation and restoration in the Intermountain West.     

An operation-level prospective study of risk factors associated with the incidence density of lameness in Michigan (USA) equine operations

A prospective cohort study of lameness in Michigan equids was conducted using the Michigan Equine Monitoring System (MEMS) Phase-II database. MEMS Phase II was an equine health-monitoring study of 138 randomly-selected Michigan equine operations. Management and health-related data were collected for operations in two 12-month periods. The median incidence density of lameness was 2.8 cases per 10000 horse-days at-risk (Minimum = 0; 25th Quartale (Q) = 0; 75th Q = 10.2; Maximum = 48.5). Equine operation-management and environmental risk factors associated with the incidence density of lameness were assessed using multivariable Poisson regression. Management risk factors associated with the incidence density of lameness included the total operation horse-days monitored (3rd Q: Relative Risk (RR) = 0.46; 95% Confidence Interval (CI): 0.29–0.71 and 4th Q: RR = 0.24; 95% CI: 0.16–0.37), the veterinary-related services score (3rd Q: RR = 0.61; 95% CI: 0.39–0.96 and 4th Q: RR = 1.45; 95% CI: 1.01–2.08), the farrier-related services score (4th Q: RR = 1.60; 95% CI: 1.07–2.42) and operations having equids participating in exercise-related activities (RR = 1.71; 95% CI: 1.16–2.50). Environmental risk factors associated with the incidence density of lameness included operations with stalls having medium flooring (RR = 0.48; 95% CI: 0.35–0.65), operations with stalls having loose flooring (RR = 2.78; 95% CI: 1.88–4.10) and operations using straw-like materials for stall bedding (RR = 2.02; 95% CI: 1.53–2.68).