Mitsuru Hayashi

Effectiveness of a sugarcane-fish combination as bait in trapping swimming crabs

Abstract Swimming crabs are known to be highly sensitive to saccharides, in response to which they show strong food searching behaviour. This study was done to examine the possibility of using sugarcane as an attractant in basket traps for Portunus pelagicus and Charybdis japonica during their reproductive season. A bait combination of sugarcane and fish was found more effective than fish bait alone, whereas sugarcane alone was ineffective. The use of the sugarcane-fish combination resulted in an extremely male-biased catch of P. pelagicus, one result of which would be the conservation of the population of this crab.

Effects of Various Carbon Sources and Their Combinations on in vitro Growth and Photosynthesis of Banana Plantlets

abstract The effects of various carbon sources, sucrose, glucose and fructose alone or in combination on the in vitro growth of banana plantlets were studied. Banana plants were cultured on the media supplemented with these carbon sources at 0.08 M for 13 weeks. The water potential of the medium was the highest in the medium supplemented with sucrose + glucose (-0.3 MPa), and was significantly lower in the medium supplemented with fructose alone or in combination with other carbon sources (-0.7 to -1.0 MPa) than in the other media. The leaf water potential was also the highest in the plants cultured on the medium supplemented with sucrose + glucose, and lowest in the plants cultured on that with fructose. The leaf water potential of plants cultured on sucrose + glucose, sucrose and glucose correlated well with their growth and photosynthetic activity, but the correlation was not observed in the plants cultured on fructose alone or in combination with other carbon sources. Plants cultured on fructose had a lower chlorophyll content (400 ptg dm-2) and lower photosynthetic rate (3 μmol02 m-2 s-1) than those cultured on sucrose + glucose (15,950 μgdm-2 for chlorophyll and 8.5 μmol02 m-2 s-1 for photosynthesis), and these differences were statistically significant. Both chlorophyll content and photosynthetic oxygen evolution were the highest in the plants cultured on sucrose + glucose, and the superior growth of plants on this medium was attributed to their high photosynthetic efficiency.