Ivy Lynn Aoko; Dezzline Ondigo; Agnes Mumo Kavoo; Cornelius Wainaina; Leonard Kiirika
Abstract
We reported a simple colorimetric probe based on gold nanoparticles (AuNPs) for detecting Ralstonia solanacearum. The AuNPs were synthesized through reduction with citrate ion and characterized by ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), and transmission electron ...
Read More
We reported a simple colorimetric probe based on gold nanoparticles (AuNPs) for detecting Ralstonia solanacearum. The AuNPs were synthesized through reduction with citrate ion and characterized by ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The freshly synthesized AuNPs were brick red due to an intense surface plasmon absorption band at 520 nm. Upon interaction with synthetic gibberellic acid (GA3), a bathochromic shift occurred in the surface plasmon resonance (SPR) peak of AuNPs to higher wavelengths. The 'eye-ball' limit of detection was 0.2 ppm. This shift was accompanied by a change in the color of the AuNPs from brick red to purple. Soil samples were collected from the rhizosphere of tomato plants, exhibiting bacterial wilt symptoms and pure cultures of Ralstonia solanacearum isolated using a modified Kelman’s TZC medium. Gibberellins (GA) were extracted from the culture of R. solanacearum using ethyl acetate and characterized using fourier transform infrared spectroscopy (FT-IR). AuNP solution aggregation was induced by GA-mediated R. solanacearum. A color change from brick red to purple was also observed. The results illustrated the use of both SPR wavelength-shift sensing and visual color change to detect molecules of biological relevance.
Amin Reza Jamshidi; Ahmad Ghazanfari Moghaddam; Ahmad Reza Ommani
Abstract
Aeroponic planting is proved to be the one of the most efficient growing environments for many vegetable crops. In this technique, plants are cultivated in absence of soil and the required nutrients are directly supplied to the roots through a fogging system. In modern sprayers, water is atomized by ...
Read More
Aeroponic planting is proved to be the one of the most efficient growing environments for many vegetable crops. In this technique, plants are cultivated in absence of soil and the required nutrients are directly supplied to the roots through a fogging system. In modern sprayers, water is atomized by means of ultrasound waves. The aim of the present study was to investigate the effect of ultrasound waves on the nutrient solution and on yield and some yield components of tomato grown in a vertical aeroponic planting system. The investigation was conducted using a 3×3 factorial experiment based on a completely randomized design. The considered factors were ultrasonic frequency at three levels of 50 kHz, 107 kHz and 2.1 MHz and the fogging duration at three levels of 10, 15 and 20 min. The results indicated that, at frequency of 50 MHz, the nutrient solution had the lowest EC equivalent while the pH of the nutrient solution reached its highest value at 2.1 MHz. Generally, both EC and pH value of the nutrient solution were elevated by increase in the wave frequency, but they did not show a definite trend by changes in fogging duration. The ANOVA indicated that the interaction effect of the ultrasound frequency and fogging period had significant effect on the plant height, root weight and length, fruit weight, fruit length, plant yield and system performance. In general, the measured yield components decreased as frequency of the waves increased and the best results were obtained at 50 kHz frequency and 15 min fogging period.
Li Tao; Zhang Yu-Qi; Zhang Yi; Cheng Rui-Feng; Yang Qi-Chang
Abstract
Chinese solar greenhouse (CSG) is universally applied in northern China for producing horticultural products. CSG is characterized by the unbalanced structures with an arched front roof face to the south side and a thick wall as well as back roof in the north side. Such structures affect light distribution ...
Read More
Chinese solar greenhouse (CSG) is universally applied in northern China for producing horticultural products. CSG is characterized by the unbalanced structures with an arched front roof face to the south side and a thick wall as well as back roof in the north side. Such structures affect light distribution in the greenhouse. This study aims to investigate the light distribution properties in CSG from north to south sections, and to investigate tomato plant growth performance in the corresponding locations. Experiments were carried out in a CSG which was divided into three equal sections from north to south side. Tomato was grown in the greenhouse. Results showed that PAR intensity in the south and middle sections of CSG was permanently higher than the north section. This resulted in a distinct plant growth performance in CSG. Specifically, plants grown in the north section of CSG exhibited a shade avoidance response with stem elongation phenotype and leaf expansion. Furthermore, the north-plants showed lower leaf photosynthetic capacity which correlated with a lower total nitrogen and chlorophyll contents in comparison with the plants grown in the middle and south sections. Taken together, plants in the north section of CSG produced less total biomass than the middle and south section plants. We conclude that plant growth is not uniform in CSG due to heterogeneous light distribution which was caused by unbalanced greenhouse structures. This study may provide sound evidence for exploring a proper lighting strategy as well as fine crop management in CSG.
