Silverleaf nightshade (Solanum elaeagnifolium Cav.) is a noxious weed that threatens agricultural productivity and biodiversity worldwide. The long‐term management of soil seedbanks along with the aboveground populations of silverleaf nightshade has the potential to effectively control the species in its introduced range. Implementation of this strategy requires insights into the germination behavior of the weed in response to various environmental stimuli and endogenous cues. We assessed the morphology and germination of silverleaf nightshade seeds from an agricultural farm, native rangelands, and an urban site in Texas, USA. The effects of growth substrate, phytohormones, and salt treatments on seed germination were also evaluated to identify potential stimulus that can be used to manipulate germination in the species. Results of the study showed that silverleaf nightshade seeds from the agricultural farm were the largest, while those from the Littlefield rangeland were the smallest. Seeds collected from the urban site and agricultural farm have higher germination rates than those sampled from the rangelands. Compared to domesticated crops, silverleaf nightshade seeds require longer imbibition time. Seed germination was better in potting mix than in sand or combined potting mix and sand and was significantly reduced by salt and abscisic acid treatments. Overall, results of the study highlight the crucial role of local environments in conditioning the transgenerational adaptation of species, particularly with respect to germination. Recommendations for silverleaf nightshade control are presented based on the observed variations in the germination behavior of populations within specific ranges.

The field experiments were conducted during kharif 2012 and 2013 to study the incidence and severity of sheath blight (Rhizoctonia solani) in relation to meteorological parameters under different planting methods. The experiments comprise of three dates of transplanting (15 th June, 30 th June and 15 th July), two rice varieties (PR-118 and PR-116) and two planting methods (furrow planting and conventional planting). Sheath blight incidence and severity were significantly lower in 15 th June transplanted crop followed by 30 th June table and 15 th July during both the crop seasons and were significantly more in variety PR-116 as compared to variety PR-118. It was more in conventional transplanted crop as compared to bed transplanted crop. Correlation analysis showed that among all the meteorological parameters considered, maximum air temperature and morning relative humidity were key factors to govern this disease in the field. A maximum temperature around 34 °C and a minimum temperature around 26 °C were found to be favourable for the spread of sheath blight after its establishment in the field. High relative humidity (more than 90%) facilitates the spread of this disease. The disease incidence and severity were negatively correlated with maximum temperature, minimum temperature, evening relative humidity and rainfall and positively correlated with morning relative humidity and sunshine hours during both the crop growing seasons. Sheath blight incidence can be reduced by 8-9% by bed planting method.

Cotton is a tropical/subtropical crop and is innately susceptible to cold. Using an approach that integrates morphological, biochemical, and transcriptome analyses, the study aimed to understand the molecular underpinnings of phenotypic adjustments in cotton seedlings under cold stress. Exposure of six cotton accessions to 15°C during the seedling stage significantly reduced chlorophyll content, stomatal conductance, plant height, and biomass, but increased malondialdehyde and proline production. Comparative transcriptome profiling of the cold-sensitive accession SA 3781 grown under low and normal temperatures showed the upregulation of genes related to the production of reactive oxygen species (ROS) under cold stress. Despite a similar upregulation of genes encoding metabolites that can scavenge ROS and provide osmoprotection for the cell, the stressed plants still exhibited oxidative stress in terms of lipid peroxidation. This may be due in part to the upregulation of abscisic acid synthesis genes and downregulation of chlorophyll synthesis genes effecting lower stomatal conductance and chlorophyll contents, respectively. Additionally, stomatal closure which is required to avoid the cooling effect and dehydration under cold conditions may have contributed in reducing the net photosynthetic rates in plants exposed to low temperature. These findings provide an insight into the expression of key genes regulating the phenotypic changes observed in cotton in response to cold stress.

No abstract

No abstract