Effect of different vase solutions on postharvest longevity of cut foliage <i>Ophiopogon</i> <i>japonicus</i>

Ophiopogon japonicus (L.f.) Ker-Gawl (family Liliaceae) is an export-oriented foliage plant with attractive white-green strips. The vase life of this cut foliage ends when the leaves loose turgidity and/ or bright green colour. Thus, to enhance the vase life of O. japonicus, effect of 0.25, 0.5, and 1.0 mM CuSO4.5H2O, 10, 20, and 30 g/L sucrose and combination of sucrose with 0.5 mM CuSO4.5H2O as holding treatments, 20 g/L and 30 g/L sucrose solutions as 24 h pulsing treatments and 6-Benzylaminopurine 5, 10, 20 mg/L BAP were tested. Relative fresh weight of leaves, solution uptake rate and vase life were assessed. Vase solution bacterial enumerations were carried out to evaluate the effectiveness of CuSO4.5H2O as a biocide. To investigate the function of BAP, amount of chlorophyll was quantified using leaf pigment extracts. The vase life of O. japonicus could be extended from 5.1 days to 12.5 days by giving BAP based vase solutions. Chlorophyll contents of leaves dipped in BAP solutions were significantly higher than the control (distilled water). CuSO4 solutions did not show any significant antibacterial effects compared to the control. According to vase life data, the most effective vase solutions were CuSO4.5H2O (0.5 mM), sucrose 20 g/L with CuSO4.5H2O (0.5 mM) as holding treatments, sucrose 20 g/L and 30 g/L as pulsing treatments and BAP treatments (5, 10, 20 mg/L)

Soil application of rice husk as a natural silicon source to enhance some chemical defense responses against foliar fungal pathogens and growth performance of Bitter Gourd (<em>Momordica charantia L.</em>)

Rice husk is a natural Silicon (Si) source. This study evaluated the effect of rice husk in two different forms; ground rice husk (GRH) and rice husk ash (RHA) on downy mildew in bitter gourd (Momordica charantia L.) leaves caused by Pseudoperonospora sp. Rice husk was added to the growing medium to achieve the final concentration of 200 mg Si /kg soil. Si accumulation in leaves, disease severity, plant growth parameters, cuticle-epidermal layer thickness, chlorophyll content, total phenolic content, peroxidase (POD) and polyphenol oxidase (PPO) activity of leaves were measured. Husk treatment lowered the downy mildew severity significantly (p &lt; 0.05) in leaves although the difference between the effects of two husk forms was insignificant. Numbers of leaves, flowers and fruits in husk-treated plants were significantly higher (p &lt; 0.05) than those in control plants. Cuticle-epidermal layer thickness in GRH, RHA-treated and control plants were 16.8 ± 1.21, 18.2 ± 0.98 and 13.2 ± 1.27 μm respectively. Total phenol content, POD, PPO activity and chlorophyll content in rice husk-treated plants were significantly (p &lt; 0.05) higher than that of control plants. The enhanced disease resistance in rice husk-treated plants appears to be positively associated with the higher accumulation of silicon and Si-enhanced phenolic content and increased activity of PPO and POD enzymes in leaves

The Evolution of Ethylene Signaling in Plant Chemical Ecology

Ethylene is a key hormone in plant development, mediating plant responses to abiotic environmental stress, and interactions with attackers and mutualists. Here, we provide a synthesis of the role of ethylene in the context of plant ecology and evolution, and a prospectus for future research in this area. We focus on the regulatory function of ethylene in multi-organismal interactions. In general, plant interactions with different types of organisms lead to reduced or enhanced levels of ethylene. This in turn affects not only the plant's response to the interacting organism at hand, but also to other organisms in the community. These community-level effects become observable as enhanced or diminished relationships with future commensals, and systemic resistance or susceptibility to secondary attackers. Ongoing comparative genomic and phenotypic analyses continue to shed light on these interactions. These studies have revealed that plants and interacting organisms from separate kingdoms of life have independently evolved the ability to produce, perceive, and respond to ethylene. This signature of convergent evolution of ethylene signaling at the phenotypic level highlights the central role ethylene metabolism and signaling plays in plant interactions with microbes and animals