Osmotic adjustment in wheat flag leaf in relation to flag leaf area and grain yield per plant

BackgroundSalinity stress causes ion toxicity and osmotic imbalances, leading to oxidative stress in plants. Antioxidants are considered ameliorators of saline stress and could develop salinity tolerance in crop plants. To ascertain the role of antioxidants in inducing osmotic adjustment in salt stressed wheat flag leaf in terms of compatible solutes accumulation, water relations parameters and osmotic adjustment as well as flag leaf area and grain yield per plant, in addition, flag leaf anatomy were examined.ResultsSalt stress up to 11.5 dSm-1 causes a significant reduction in water potential, osmotic potential, as well as relative water content, and water content. On the other hand, turgor potential and osmotic adjustment were significantly increased due to inducing increasing the higher accumulation of compatible osmolytes which leads to decreasing flag leaf area and grain yield per plant.Application of both antioxidants, in particular, ascorbic acid increased significantly flag leaf area, and grain yield per plant due to osmotic adjustment and maintaining leaf turgor potential as a consequence of increasing leaf water potential, water content and relative water content as compared to control plants. On the other hand, application of both antioxidants under all salinity levels, nullify the harmful effects of salinity on flag leaf area and grain yield per plant due to increasing osmolyte accumulation, maintaining turgor potential and osmotic adjustment.Anatomically, increasing salinity levels decreased thickness of leaf blade at midrib region, thickness of mesophyll tissue, tangential dimension of midrib vascular bundle, thickness of upper and lowerepidermis, thickness of big motor cell, and tangential dimension of big xylem vessel. Treatment with either ascorbic acid or tocopherol at 100 mg/L and their interactions with salinity increased all the above mentioned parameters in both nonsalinized and salinized plants. Ascorbic acid is the most effective in this concern.ConclusionIn conclusion, wheat plants responded to an increased ion influx in their cells by increasing the osmolytes synthesis and accumulation under salt stress, which further increased with antioxidants treatment and helped in maintaining the osmotic balance

Joint Spatial Modeling of Recurrent Infection and Growth with Processes Under Intermittent Observation

In this article we present new statistical methodology for longitudinal studies in forestry where trees are subject to recurrent infection and the hazard of infection depends on tree growth over time. Understanding the nature of this dependence has important implications for reforestation and breeding programs. Challenges arise for statistical analysis in this setting with sampling schemes leading to panel data, exhibiting dynamic spatial variability, and incomplete covariate histories for hazard regression. In addition, data are collected at a large number of locations which poses computational difficulties for spatiotemporal modeling. A joint model for infection and growth is developed; wherein, a mixed non-homogeneous Poisson process, governing recurring infection, is linked with a spatially dynamic nonlinear model representing the underlying height growth trajectories. These trajectories are based on the von Bertalanffy growth model and a spatially-varying parametrization is employed. Spatial variability in growth parameters is modeled through a multivariate spatial process derived through kernel convolution. Inference is conducted in a Bayesian framework with implementation based on hybrid Monte Carlo. Our methodology is applied for analysis in an eleven year study of recurrent weevil infestation of white spruce in British Columbia