Seasonal Variations in Canopy Size and Yield of Rayong 9 Cassava Genotype under Rainfed and Irrigated Conditions

Abstract

The objectives of this study were to investigate the effect of seasonal variation on canopy size, and the effect of canopy size on light penetration of ‘Rayong 9′ cassava under irrigated and rainfed conditions. Rayong 9 was planted under two water regimes in a randomized complete block design with four replications in May and November for two years. At final harvest, years were significantly different (p ≤ 0.05) for biomass, shoot dry weight, and harvest index and contributed to large portions of total variations in shoot dry weight (56.8%) and HI (44.5%). Planting date was a significant source of variations in all measured characters, and it contributed to the largest portions of variations in biomass, storage root dry weight and storage root fresh weight (46.1–60.9%). Water regimes were not significantly different for most characters except for harvest index (p ≤ 0.01). The canopy of the crop planted in May grew rapidly in early growth stages in the rainy season and then slowly after the rainy season. The canopy of the crop planted in November grew rapidly in the middle to the late growth stages. Irrigation did not significantly increase root yield although it slightly increased canopy development, leaf area index (LAI), light penetration and photosynthesis. Irrigation at the late growth stages of the crop planted in May significantly increased storage root yield. Irrigation at these growth stages helped maintain canopy development, LAI and light penetration.

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

“…Planting dates accounted for the largest proportion of variation for most cassava traits (38.2%-60.8%), except for starch content, which was greatly affected by water regimes (52.1%). These results were similar to a previous investigation of cassava biomass and storage root yield reported by Mahakosee et al [22]. They reported that planting date had a greater effect in comparison to water regimes and planting date by water regime interactions.…”

“…Studies by El-Sharkawy et al [31] and Saithong et al [32] indicated that a temperature range between 25 to 35 • C during early to mid-growth stages is optimum for cassava crop growth and results in increased activities of the enzymes involved in photosynthesis and the synthesis of starch. High temperatures and high solar radiation during the early to mid-growth stages also increased canopy size, leaf growth rate and leaf area index [22,33,34].…”

Seasonal Variation in Canopy Size, Light Penetration and Photosynthesis of Three Cassava Genotypes with Different Canopy Architectures

“…In Asia, the early growth stages of cassava planted during the early rainy season will be subjected to higher rainfall, temperature, RH and SR than those planted in the late rainy season. However, drought will often hit early rainy season plantings when they are in the later growth stages, reducing canopy size (CS) and yield [9][10][11].…”

“…These factors affect the change in canopy of cassava and cassava genotypes respond differently to environmental changes. While the responses of CS on seasonal variation under different water regimes had been reported, they generally use only one genotype [11]. Therefore, the objective of this study was to determine canopy architecture, light penetration and photosynthesis of three cassava genotypes under different seasonal variations.…”

Identifying Suitable Genotypes for Different Cassava Production Environments—A Modeling Approach

“…It was clearly evident that lower values of simulated total crop and storage root dry weights for planting dates in May, June, July, August, and September could be explained by lower total amounts of rainfall during the growth stages of high above-ground development and high carbohydrate translocation to the storage root (Table 5). In a recent field experiment in Thailand under rainfed conditions, Mahakosee et al [52] found that a dry period during the late growing stages of cassava planted in May resulted in lower total crop biomass and storage root dry weights of the Rayong 9 genotype than for the December planting date. Growth stage 1 = leaf development and formation of root system (0-3 months after planting); Growth stage 2 = development of stems and leaves (3-6 months after planting); Growth stage 3 = high carbohydrate translocation to the roots (6-10 months after planting); Growth stage 4 = declining phase (10-12 months after planting); all four cassava growth stages were described by Alves [53].…”