Abstract
Although cassava can be planted throughout the year, its starch qualities may vary based on the date of planting. Seasonal variation on starch content, starch yield, starch granule size and amylose content of cassava cv. Rayong 9 grown under irrigated and rainfed conditions were studied for four planting dates in Thailand. A randomized complete block design with four replications was used in each planting. Planting dates consisted of hot-dry (20-Apr), early-rainy (30-Jun), late-rainy (5-Oct) and cool seasons (15-Dec). At final harvest, planting date accounted for the largest variations for starch yield (60.8%), starch granule size (38.2%), amylose content (50.5%) and ratio of amylose to amylopectin (53.7%), whereas starch content was affected more by water regime (52.1%). Supplemental irrigation did not significantly increase starch yield and other parameters for most planting dates, except for starch yield of the crop planted in the hot-dry season. This indicated that irrigation at the late-growth stages (during Sep to Mar) for the crop planted in the hot-dry season helped to increase starch yield; however, irrigation was unnecessary for other planting dates once cassava was established. The crops planted in the late-rainy and cool seasons had a greater starch content and starch yield than other planting dates for both irrigated and rainfed crops, whereas the crop planted in the hot-dry season had high starch yield for the irrigated crops only. In this study, the crops planted in the early-rainy season showed the worst performances for starch content and starch yield for both irrigated and rainfed crops. The data provided information on the responses of starch yield and its characteristics under irrigated and rainfed conditions at different planting dates, which can be useful for designing cultural practices with respect to water management and planting period in order to obtain optimum starch yield and qualities.
Highlights
IntroductionAgronomy 2020, 10, 412 marginal environments, making it an ideal food security and subsistence crop
Cassava (Manihot esculenta Crantz) is an important industrial crop in many countries, and it is considered as a staple food for the rural areas of the tropics because of its inherent adaptation to Agronomy 2020, 10, 412; doi:10.3390/agronomy10030412 www.mdpi.com/journal/agronomyAgronomy 2020, 10, 412 marginal environments, making it an ideal food security and subsistence crop
2–8 MAP, the crop planted in this planting date received lower temperatures, lower solar radiation, lower ambient relative humidity and shorter photoperiod, which occurred during the period of canopy and root development to high translocation of carbohydrates from shoot to storage roots
Summary
Agronomy 2020, 10, 412 marginal environments, making it an ideal food security and subsistence crop. It can be used for animal feed and biofuels [1,2]. Cassava has a long crop cycle in which the growing period of nearly 12 months covers all seasons of the year. Cassava genotypes have been shown to respond differently to weather conditions during the growth periods of different planting seasons [8,9,10]. The weather cycles associated with the crop cycles of cassava planted at different planting dates of the year, especially for drought events occurring at different growth stages, might cause different performances of the crop. Understanding on crop responses to drought stress is of great significance and a fundamental part of abiotic stress-breeding schemes and sustainable agriculture [11]
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