Growth Analysis of Shading Effects in Several Kinds of Vegetables Cultivated in a Plastic House
1981 Volume 19 Issue 1 Pages 9-15
Details
1981 Volume 19 Issue 1 Pages 9-15
Young plants of several kinds of vegetables were grown in a plastic house, and changes of their growth parameters caused by shading with white cheeseclothes (about 70% of the solar radiation in the plastic house) were compared to clarify the difference of their shade tolerance.
1. Growth analysis were carried out 6 times on cucumber, eggplant, lettuce and radish in the first group, 29 times on cabbage and 27 times on mitsuba (Cryptotaenia japonicaHassk.) in the second group at various seasons. The average values of meteorological factors within the plastic house during the experimental periods were almost the same for all the vegetables except eggplant which had a little higher radiation and temperature.
2. In the first group NAR decreased 16%, LWR did not change, and SLA increased 6% by shading, so that RGR decreased 10%. In the second group NAR decreased 14%, LWR did not change, and SLA increased 5 % by shading, so that RGR decreased 10%. Increase of RLGR by shading occurred only in mitsuba (8%) . The changes of ULWR were almost the same as RGR in all the vegetables tested.
3. RGR of root was most depressed by shading compared with the other parts of plants, and there was a trend that the shading effect on RGR was stronger in leaf blades than in petioles in all the vegetables having petioles, except mitsuba in which there was no difference between them.
4. In cabbage and mitsuba of which growth parameters were analysed about thirty times, the shading effects on the growth parameters in the warm period and in the cold period were compared on the basis of the mean day temperature. The effects were all the same in the two periods.
5. The reaction of RLGR in mitsuba to shading was different from that of the other vegetables. RLGR of mitsuba increased clearly by shading. All the growth parameters except RLGR were affected by shading in the same way in all the vegetables. Therefore, the effects of shading given in a short period on the growth parameters seem to be the same in all the vagetables, but if the shading is prolonged, the effects might be different in mitsuba, one of shade plants growing natively in woodlands in Japan.
