Among various environmental factors, the effects of light quality and quantity on growth of vegetables and ornamental plants were investigated thoroughly in closed plant factories, whereas how solutes and minerals in hydroponics affect on growth of vegetables were poorly understood. In this study, we investigated the effects of salinity and nutrients on the growth of red leaf lettuce (Lactuca sativa L. cv. Mother-red). A closed plant factory with hydroponic cultures supplemented with sodium salt (NaCl) or seawater was employed for cultivation of lettuce. The fresh weight of lettuce grown in culture with NaCl was dramatically reduced when compared to those grown in standard culture or culture with seawater. The lettuces grown in the culture with NaCl or seawater contained higher amounts of sugar and anthocyanin, and the lettuce plants grown in the culture with seawater accumulated highest levels of photosynthetic pigments, chlorophylls and carotenoids. These results indicate that the addition of some solutes (e.g. NaCl) to the culture medium affect the size of plant as well as the levels of sugars and pigments in the plant, and suggest that the addition of seawater (20%) to the medium is effective to produce lettuces with higher quality and nutritional value.
Induction of a mutant DnaA protein (DnaA E204Q) with decreased intrinsic ATPase activity in cells was previously shown to cause overinitiation of chromosomal DNA replication and a dominant lethal phenotype. Here it is shown that the dominant lethality required incubation at high temperatures; cells harboring the expression plasmid of DnaA E204Q showed very weak colony formation ability (less than 1/10 S that of the wild-type DnaA) at 42³C, whereas they showed a normal colony formation ability at 28³C on LB agar plates. Overinitiation of chromosomal DNA replication caused by expression of DnaA E204Q also required incubation at high temperatures in LB medium. When the incubation was performed in synthetic (Tanaka) medium at 42³C, neither the dominant lethality nor overinitiation caused by expressing DnaA E204Q was observed. These results suggest that the dominant lethality and the overinitiation caused by expressing DnaA E204Q require culture conditions that provide a high potential for cell growth. z 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V.
In this study, the relationship has been examined between the bio-electric potential and the morphogenetic properties of Pholiota nameko,for investigating the optimum farming conditions for mushrooms from engineering considerations. Initially, the eff ect of wavelength of light stimuli on the morphogenetic properties was investigated, based on the bio-electric potential under blue light was greater than under red light. The experimental results indicated that progressed morphogenesis obtained under blue light created large bio-electric potentials. This was followed by an investigation of the response characteristics of the bio-electric potential with respect to environmental temperature( from 14℃ to 22℃). This was then used to analyze the dependence of the morphogenetic properties. The experimental results indicated that a maximum response occurred,with correspondingly favorable morphogenesis obtained,at 14℃. Based on the above results, it is concluded that the value of the bio-electric potential is an eff ective measure for the objective evaluation of farming production.
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