Chin J Plan Ecolo ›› 2018, Vol. 42 ›› Issue (5): 585-594.DOI: 10.17521/cjpe.2018.0016

• Research Articles • Previous Articles     Next Articles

Seasonal changes of photosynthetic characteristics of Alpinia oxyphylla growing under Hevea brasiliensis

CHENG Han-Ting,LI Qin-Fen,LIU Jing-Kun,YAN Ting-Liang,ZHANG Qiao-Yan,WANG Jin-Chuang()   

  1. Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences/Danzhou Scientific Observing and Experimental Station of Agro-Environment, Ministry of Agriculture of the People’s Republic of China, Haikou 571101, China
  • Received:2018-01-12 Revised:2018-04-08 Online:2018-05-20 Published:2018-07-20
  • Contact: Jin-Chuang WANG

Abstract:

Aims The development of ecological agriculture by agroforestry models could improve resource utilization. The Hevea brasiliensis-Alpinia oxyphylla agroforestry system is among the largest agroforestry models in rubber plantation. In this study, we aimed to investigate the physiological strategies that allow Alpinia oxyphylla, a perennial herb widespread under-growing the Hevea brasiliensis, to cope successfully with the environmental factors with the seasonal changes of the tropical monsoon climate.

Methods Gas exchange and light response curve measurements as well as pigment content determinations were performed periodically throughout different seasons on A. oxyphylla growing in the rubber plantation by a portable leaf gas exchange system (LI-6400).

Important findings (1) The diurnal change of the net photosynthetic rate had a V-shaped pattern in March, which decreased to be the lowest at 14:00. The diurnal changes of the Pn in June, September, and December increased to the peak at 10:00 and then began to decline slowly. The daily average and maximum of the net photosynthetic rate during the monsoon season (June and September) were much higher than those in the dry season (March and December), which suggested that A. oxyphylla had the physiological strategy to environmental changes in different seasons. The severe soil moisture deficit inhibits photosynthetic CO2 assimilation due to the decline of stomatal conductance in March. (2) The light compensation point and dark respiration rate of March generally were higher than those of other seasons (June, September and December), but the maximum net photosynthetic rate and light saturation point were on the contrary. The discrepancies that may be related to the photosynthetic enzymatic activity were restrained by the dry conditions, which caused the occurrence of photoinhibition, the increased respiration, and decreased photosynthetic capacity. (3) The net photosynthetic rate in March was negatively correlated with air temperature, but positively correlated with air humidity. Air temperature and air humidity in combination inhibited photosynthesis of A. oxyphylla in March. However, photosynthetic active radiation was a pivotal factor to photosynthesis of A. oxyphylla in September and December.

Key words: photosynthetic characteristics, environmental factor, Alpinia oxyphylla, seasonal change, diurnal change of photosynthesis