ABSTRACT
Xanthomonas axonopodis pv. punicae (Xap) is a bacterial pathogen wreaking havoc in pomegranate cultivation. It causes bacterial blight disease dwindling yield and making fruit unfit for consumption. Physiological and histological investigations during host-pathogen interaction are prerequisite to assess the onset of defense mechanism in plants. Therefore, we tried to compare the pomegranate resistant (IC 318734) and highly susceptible (Ruby) genotypes challenged with Xap. The bacterial suspension containing Xap cells of 0.3 OD600 (~106 to 107CFU mL?1) was used for challenge inoculation. Uniformly grown resistant and highly susceptible plants were selected, the surface of leaves was pricked and spray-inoculated with bacterial suspension using native strain IIHR1 (NCBI Gen Bank ID: KT 222897). Simultaneously, the control plants were also sprayed with only distilled water and observed. A total of three replications with five plants per replication were maintained and evaluated under completely randomized design. Physiological investigations were recorded using Portable photosynthesis system (LCpro+, ADC BioScientific limited, UK) for one cycle of disease progression viz., 0, 1, 5, 10, 15 and 20 days after bacterial spray inoculation (DAI). Significant changes in gas exchange parameters were witnessed on pathogen inoculation. Higher reduction in mean percent change of photosynthetic and transpiration rate, instantaneous water use efficiency, internal CO2 content, stomatal conductance and relative water content were noticed in highly susceptible genotype than resistant one. On contrary, an increased percent mean change of intrinsic water use efficiency, carboxylation capacity and lignin was documented in resistant genotype. Relative injury caused due to bacterial infection was found high in highly susceptible genotype than resistant one. Histological investigations in highly susceptible and resistant genotype were studied on 20th day of Xap inoculation using Scanning Electron Microscopy. Highly susceptible genotype exhibited maximum deformed cells, tissues and other visible abnormalities upon Xap inoculation. Thus, this study forms a basis for effective disease management and breeding programmes in pomegranate.
ABSTRACT
Objective: Taking annual Tetrastigma hemsleyanum (Tetrastigma Radix) from three habitats, Taizhou, Minhou, and Shunchang, as materials to study the effects of different light intensity stress on the stomatal shape and leaf transpiration. Methods: The stomata, leaf transpiration rate, net photosynthetic rate, and stomal structure of T. hemsleyanum were observed using a scanning [0-2000 μmol/(m2·s)] to explore the optimal light intensity. Results: The stomata with surround and parallel distribution types were only distributed in the lower epidermis in the leaves of T. hemsleyanum; The transpiration rate, stomatal conductance, and net photosynthetic rate of T. hemsleyanum from the two habitat regions (Minhou and Taizhou) by rising after falling with the 30℃ stress, which suggested the stress could make the light intensity heavier. At the same time, the transpiration rate, stomatal conductance, and net photosynthetic rate of T. hemsleyanum from the habitat region Shunchang were rising. The stomatal type of leaves was 600 μmol/(m2·s) in Minhou, and 1900 μmol/(m2·s) in Shunchang, when the water utilization ratio of T. hemsleyanum leaves from the three habitats was higher. Conclusion: Different habitats and light intensity are the important factors of leaves transpiration in natural world, which is more beneficial to the growth of the root crops and suitable for the accumulation of flavonoids in plants.
ABSTRACT
A field experiment was conducted during rabi 2012-13 at research farm of Directorate of Sorghum Research, Rajendranagar, Hyderabad. The experiment was laid out in a split plot design, replicated thrice, with 10 Sorghum genotypes as main treatment (well watered and water stress conditions) and with 10 genotypes are sub treatments CRS 4, CRS 19, CRS 20, PEC 17, CSV 18, M 35-1, Phule chitra, Phule moulee, EP 57 and CRS 1). Photosynthetic rate and stomatal resistance at 15 and 30 DAF were positively and significantly correlated with grain yield while the transpiration rate at 15 and 30 DAF exhibited negative correlation with grain yield. SPAD chlorophyll meter reading (15 and 30 DAF) and chlorophyll content at 30 DAF had positively significant correlation with grain yield.
ABSTRACT
Objective: To provide basic theory for rational cultivation and comprehensive utilization of Perilla frutescens. Methods: The photosynthesis and growth characteristics were measured every 25 d from July 10th, 2013. Results: Logistic equation of dry matter weight was firstly established, and the slightly increasing stage was also called seedling stage (0-75 d); The flower budding stage was 76-84 d, the blooming stage was 85-95 d, and the 20 d was called period of accelerating growth stage; The period of decelerating growth was defoliation period (96-125 d). As was observed both specimens "a" and "b", chlorophyll content increased and reached the peak value during flower budding before going on a gradual decline, but not before that of soluble proteins. The Hill reaction, as well as Ca2+-ATPase and Mg2+-ATPase activities all reached the peak values just before blooming began; The photosynthesis rate was at peak twice during seedling stage, which was once more than in any other stage of the growth of Perilla frutescens. Strong positive correlation was observed between stomatal conductance and transpiration rate. Conclusion: For maximum yield of leaf, stem, or seed, harvesting should take place either before flowers bloom or after leaves fall. All growth-spurring measures should be implemented before growth rate reaches a zenith or risk not being effective.
ABSTRACT
Sob condições de campo, as plantas estão sujeitas a períodos de déficit hídrico no solo e na atmosfera, durante todo o seu ciclo de vida. Foi avaliado o desempenho de duas cultivares enxertadas de seringueira ("RRIM 600" e "GT 1"), mantidas na UNESP-IBILCE, em São José do Rio Preto, SP, com e sem suplementação hídrica, a partir da idade de quatro meses. A resistência máxima ao período seco ininterrupto, considerada quando cessou a realização de fotossíntese com ganho líquido, foi de 17 e 20 dias, respectivamente. Trinta e três dias após a suspensão do estresse, a recuperação das trocas gasosas foi bastante similar para as duas cultivares, e apenas a concentração de dióxido de carbono intercelular retornou a valores equivalentes aos dos controles. Apenas o incremento relativo da área foliar, para "GT 1", e da altura, para "RRIM 600", não diferiram aos do grupo controle (P=0,05). As curvas de resposta à luz indicaram, para ambos os clones, decréscimos para a irradiância de compensação e a taxa fotossintética (P=0,05). Embora parcial, a melhor recuperação após o estresse foi verificada para "GT 1".
During their life cycle, plants growing under field condition are subject to periods of air and soil water deficits. In this study was evaluated the performance of two scion cultivar of rubber tree ('RRIM 600' and 'GT 1') growing in São José do Rio Preto, SP, with and without water supplementation since the age of 4 months. The maximum resistance to the uninterrupted dry period, considered when net photosynthesis was ceased, was 17 and 20 days, respectively. Thirty-three days later the water stress was ceased, the gas exchange recovery for both cultivars were quite similar, but just the intercellular carbon dioxide concentration returned to similar values of the control group. Only the relative increment of leaf area to 'GT 1', and plant height of 'RRIM 600' was similar to the control group (P=0.05). The light curve response showed, for both clones, decrease of the compensation irradiance and photosynthetic rate (P=0.05). Although partial, the best recovery after water stress was observed for 'GT 1'.