Seasonal variation in photosynthesis performance of cassava at two different growth stages under irrigated and rain-fed conditions in a tropical savanna climate

Abstract

Seasonal variations in photosynthesis of cassava cv. Rayong 9 (RY9) under irrigated and rain-fed conditions were evaluated at the age of three and six months after planting (MAP). Photosynthetic light-response (P N /I) curves revealed that cassava leaves attained the highest maximum net photosynthetic rates (P Nmax ) in the rainy season, followed by the hot one, while the lowest P Nmax was found in the cool season. Photosynthetic potential of the 3-month-old plants was mostly higher than that of the 6-month-old plants, and the seasonal variation in photosynthetic capacity was also more apparent in the younger plants. P N /I curves were used to predict daily net photosynthetic rate (P N ) for each season based on daily average solar radiation data. The predicted P N were considerably lower than the P Nmax values. This indicated that solar radiation is a limiting factor for photosynthesis, particularly in the rainy season. The data provided basic information for breeding cassava genotypes with enhanced photosynthesis during the period of unfavorable environment. Furthermore, the data are potentially useful in modeling photosynthesis and crop growth as affected by environmental factors.

Dynamics of photosynthetic responses in 10 rubber tree (Hevea brasiliensis) clones in Colombian Amazon: Implications for breeding strategies

“…In the present study, this condition was evidenced by a lower A in the rainy season. However, in the rainy period, the g s and E were higher, which favored stomatal opening as a result of higher RH values and lower values of AT and VPD [52]. Likewise, the positive correlation observed between A and g s and the daytime pattern of these parameters in both periods suggest that both processes lead to a higher photosynthetic performance in the morning hours, where there is greater stomatal openings, favoring higher assimilation rates of CO 2 [53].…”

“…Several studies have also reported an increase in photosynthesis in the dry period in the Amazon region because water is not a limiting factor, but light is [55–57]. Although the dry evapotranspiration period is greater because of an increase in radiation and temperature [49], a partial closure of the stomata would be expected because of a higher VPD [52,58] as compared with the rainy period, possibly because of the deep root system of rubber trees, combined with the hydraulic redistribution of the roots [59,60].…”

Physiology, Growth and Yield of Different Cassava Genotypes Planted in Upland with Dry Environment during High Storage Root Accumulation Stage

“…The same leaves were then preadapted to a dark period for one hour by fixing special tags on each leaf blade before measurements were retaken. After one hour of dark adaptation, the sensor cup was fitted on the leaf for measurement of maximum quantum efficiency of photosystem II photochemistry (Fv/Fm) [12,14,[18][19][20][21]. Relative water content (RWC) for those the same leaves as Pn and chlorophyll fluorescence evaluations were recorded between 9.00-10.00 a.m., where 1 cm 2 in leaf area was collected using a leaf disc borer.…”

Starch Accumulation and Granule Size Distribution of Cassava cv. Rayong 9 Grown under Irrigated and Rainfed Conditions Using Different Growing Seasons

“…Consequently, it resulted in reduced photosynthesis capacity and crop growth [35][36][37]. Likewise, Vongcharoen et al [38] indicated that the lowest leaf photosynthesis of cassava was recorded during the cool season when compared to the rainy and hot seasons, when solar radiation is a limiting factor. Temperatures below 17 • C or above 30 • C inhibited leaf growth and starch yield of cassava, and low relative ambient humidity caused partial stomatal closure, resulting in reduced crop growth [26,37].…”