K. Murakami, T. Hamasaki, M. Nemoto, S. Inoue, T. Hirota
{"title":"Photosynthetic and respiratory activities of spinach in an unheated greenhouse during winter in Sapporo, Japan","authors":"K. Murakami, T. Hamasaki, M. Nemoto, S. Inoue, T. Hirota","doi":"10.2480/AGRMET.D-20-00033","DOIUrl":null,"url":null,"abstract":"Leafy vegetables cultivated in greenhouses during the winter are sometimes exposed to cold air from outside the greenhouse to enhance sugar and nutrient content. To analyze the possible involvement of photosynthetic and respiratory activities in this process, we evaluated the gas-exchange activity of spinach ( Spinacia oleracea L. ) plants cultivated in an unheated greenhouse in mid-winter in Sapporo, where the daily mean air and soil temperatures are approximately - 5 and 0 ° C, respectively. Shoot fresh weight showed little increase, whereas the net leaf photosynthetic rate ( P n ) attained 20 µmol m -2 s -1 and the CO 2 concentration in the greenhouse ( [CO 2 ] ) was sometimes lower than 200 µmol mol -1 , which was suggestive of active photosynthetic CO 2 uptake. After its peak in the morning, P n decreased in the afternoon, presumably owing to ‘midday depression’ caused by suppressed water uptake in the root zone. Observed diurnal [CO 2 ] change was consistent with a significant CO 2 uptake during the daytime. The change also suggested that respiration was active immediately after sunset and suppressed at night. In addition, we calculated the whole-greenhouse CO 2 emission rate ( R ) as a measure of night respiration in the plants, taking into account the air ventilation of the greenhouse. The R value was positive under sub-zero air temperatures in the greenhouse and was positively correlated with the nighttime air and soil temperatures. These experimental data suggest active photosynthesis and respiration of winter-sweetened spinach in the greenhouse, despite the low air and soil temperatures and growth retardation, and implies their involvement in the","PeriodicalId":56074,"journal":{"name":"Journal of Agricultural Meteorology","volume":null,"pages":null},"PeriodicalIF":1.4000,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"3","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Agricultural Meteorology","FirstCategoryId":"97","ListUrlMain":"https://doi.org/10.2480/AGRMET.D-20-00033","RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"AGRICULTURE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 3
Abstract
Leafy vegetables cultivated in greenhouses during the winter are sometimes exposed to cold air from outside the greenhouse to enhance sugar and nutrient content. To analyze the possible involvement of photosynthetic and respiratory activities in this process, we evaluated the gas-exchange activity of spinach ( Spinacia oleracea L. ) plants cultivated in an unheated greenhouse in mid-winter in Sapporo, where the daily mean air and soil temperatures are approximately - 5 and 0 ° C, respectively. Shoot fresh weight showed little increase, whereas the net leaf photosynthetic rate ( P n ) attained 20 µmol m -2 s -1 and the CO 2 concentration in the greenhouse ( [CO 2 ] ) was sometimes lower than 200 µmol mol -1 , which was suggestive of active photosynthetic CO 2 uptake. After its peak in the morning, P n decreased in the afternoon, presumably owing to ‘midday depression’ caused by suppressed water uptake in the root zone. Observed diurnal [CO 2 ] change was consistent with a significant CO 2 uptake during the daytime. The change also suggested that respiration was active immediately after sunset and suppressed at night. In addition, we calculated the whole-greenhouse CO 2 emission rate ( R ) as a measure of night respiration in the plants, taking into account the air ventilation of the greenhouse. The R value was positive under sub-zero air temperatures in the greenhouse and was positively correlated with the nighttime air and soil temperatures. These experimental data suggest active photosynthesis and respiration of winter-sweetened spinach in the greenhouse, despite the low air and soil temperatures and growth retardation, and implies their involvement in the
期刊介绍:
For over 70 years, the Journal of Agricultural Meteorology has published original papers and review articles on the science of physical and biological processes in natural and managed ecosystems. Published topics include, but are not limited to, weather disasters, local climate, micrometeorology, climate change, soil environment, plant phenology, plant response to environmental change, crop growth and yield prediction, instrumentation, and environmental control across a wide range of managed ecosystems, from open fields to greenhouses and plant factories.