Seasonal Variation in Diurnal Photosynthesis and Chlorophyll Fluorescence of Four Genotypes of Cassava (Manihot esculenta Crantz) under Irrigation Conditions in a Tropical Savanna Climate

Supranee Santanoo,Sanun Jogloy,Piyada Theerakulpisut,Sittiruk Roytrakul,Kochaphan Vongcharoen,Poramate Banterng,Nimitr Vorasoot

doi:10.3390/agronomy9040206

Supranee Santanoo, Sanun Jogloy + Show 5 more

Open Access

https://doi.org/10.3390/agronomy9040206

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Abstract

Photosynthesis performance during early vegetative growth is an important physiological trait determining yield of cassava, but limited information is currently available for the tropical savanna climate of Asia. Diurnal photosynthesis and chlorophyll fluorescence of the three-month-old plants of four commercial cassava genotypes (Rayong 9, RY9; Rayong 11, RY11; Kasetsart 50, KU50 and CMR38-125-77) grown under irrigation, were investigated in three seasons i.e., rainy, cool and hot. The mean daily net photosynthetic rate (Pn) across genotypes in the rainy season (11.75 µmolCO2/m2/s) was significantly lower than that in the cool season (14.60 µmolCO2/m2/s). Daily mean Pn in the hot season was 14.32 µmolCO2/m2/s. In the rainy season, maximum photochemical quantum yield of PSII (Fv/Fm) and effective quantum yield of PSII photochemistry (ΦPSII) were significantly higher than the other seasons, while electron transfer rate (ETR) and non-photochemical quenching (NPQ) were significantly lower. Genotypic variation was observed during the hot season in which RY11 had the highest and CMR38-125-77 the lowest mean daily Pn. The prominent mechanism to avoid damages from stress during afternoon in the hot season was to reduce leaf temperature by enhancing transpiration for RY11; to close stomata early for RY9, and to increase NPQ for CMR38-125-77.

Highlights

Cassava (Manihot esculenta Crantz) is one of the most significant crops for food security and the main food source for more than 0.8 billion people in Africa and Asia [1,2]
The environmental conditions under which the cassava plants of the three planting dates (PD-Jun, plants established on November 2015 (PD-Nov) and plants established on December 2015 (PD-Dec)) were growing were recorded from the date of planting until the plants were three-month-old as shown in Table S1
The values of mean daily PAR for the three planting dates were similar ranging from 412–429 μmol/m2 /s

Summary

Introduction

Cassava (Manihot esculenta Crantz) is one of the most significant crops for food security and the main food source for more than 0.8 billion people in Africa and Asia [1,2]. Storage root yield of cassava varies considerably depending on cultivars, climate, growing conditions, crop management and planting time [7,8]. While the highest recorded experimental yield potential was 80 to 90 t ha−1 under near optimal edaphic–climatic conditions [9,10], the average yield in Thailand was recorded at 18.83–24.15 t ha−1 [11]. This yield gap might be due to a lack of sufficient agro-advisory information about cassava genotypes suitable for planting in different seasons and appropriate management practices for the different growing seasons [12]

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