Photorespiration of cassava (Manihot esculenta crantz) and amaranth (Amasus L Merr) Smooth Cayenne

Name: Pornchai Paiboon

LCSH: Kasetsart University -- Dissertations. Ph.D. (Agricultural Biotechnology) 2020

Classification :.LCCS: SB211.C3

LCSH: Kasetsart University. -- Interdisciplinary Graduate Program -- Dissertations

LCSH: Cassava -- Photosynthesis

LCSH: Cassava -- Photorespiration

LCSH: Hyperbaric oxygenation

Abstract: The light response function of C3 cassava cv. Huay Bong 60 and C4 green amaranth cv. AS220 were evaluated under 3 levels of [CO2] inside the leaf chamber (Ca) at 400, 800, and 1,200 µmolCO2 molair-1 with 2 levels of [O2] at 21% and 2%. The result showed that under the ambient air (amb.=Ca 400 µmolCO2 molair-1 with 21% [O2]), cassava leaf had maximum gross photosynthetic rate (Pmax) of 31 µmolCO2 m-2 s-1, which was in par with C3 fast-growing crops such as rice and eucalyptus. The light saturation range was 1,100-1,300 µmolPPF m-2 s-1. Elevation of Ca could increase Pmax (26-76% increase) more than the lowering of [O2] (6-33% increase), as higher Ca enhanced carboxylation as well as suppressed oxygenation. However, the combination of low 2% [O2] with triple Ca enabled Pmax to rise to 61.2 µmolCO2 m-2 s-1, or 97% increase, as the photorespiration (Rp) showed a drastic drop (75%) from 12.4 to 3.1 µmolCO2 m-2 s-1. C4 amaranth had the greater Pmax than cassava, as its net photosynthesis (A) was unsaturated under full sunlight at 2,500 µmolPPF m-2 s-1 and Rp was closed to zero. Under 2% [O2] with triple Ca, the highest Pmax of amaranth was 76. molCO2 m-2 s-1. Carboxylation efficiency (CE) and Ci-based CO2 compensation point () were obtained from the CO2 response measurements under varying Ca, ranging from 0-2,000 µmolCO2 molair-1. Under amb., CE of cassava was 183 mmol m-2 s-1 and  was 65 µmolCO2 molair-1 at leaf temperature of 33.4C. In comparison, CE of amaranth was 564 mmol m-2 s-1 and its  was closed to zero. Although CE of cassava was remarkedly high among the C3 leaves, its level was 3 times smaller than that of amaranth. The high  of cassava, within the range of typical C3, agreed with its high Rp. A of amaranth reached its plateau very quickly at current Ca of 400 µmolCO2 molair-1, so any increase in Ca was not beneficial to its carboxylation process. Cassava, on the other hand, did not have its saturating A until Ca increased by 3-4 times the current level. Therefore, carboxylation process of cassava showed good response to the elevated Ca, which could increase its A by 93% to be as high as 53 µmolCO2 m-2 s-1.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Suntaree Yingjajaval

Role: Thesis Advisor

Created: 2020

Modified: 2025-07-02

Issued: 2025-07-02

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2563/pornchai-pai-

CallNumber: SB211.C3 .P67

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degraee

Descipline: Agricultural Biotechnology

Grantor: Kasetsart University

©copyrights Kasetsart University

ลำดับที่.	ชื่อแฟ้มข้อมูล	ขนาดแฟ้มข้อมูล	จำนวนเข้าถึง	วัน-เวลาเข้าถึงล่าสุด
1	pornchai-pai-all.pdf	2.94 MB

ใช้เวลา

0.02249 วินาที