The information on genotypic responses to the seasonal variation in the starch content, starch yield, and starch quality of cassava is limited. The objective of this research was to investigate the seasonal variation of starch characteristics of three cassava genotypes grown under irrigation. The experiment was conducted at four planting dates (20 April, 30 June, 5 October, and 15 December 2015). Three cassava genotypes (CMR38-125-77, Kasetsart 50, and Rayong 11) were evaluated in a randomized complete block design with four replications and the plants were harvested at 12 months. The planting date contributed the largest portion of the total variation in the starch content, starch yield, and starch granule size. The amylose content variability was heavily influenced by genotype. Cassava planted on 5 October or 15 December had greater starch content, starch yield, and starch granule in most genotypes. This was likely due to a higher temperature and solar radiation during the 3–9 months post-planting. CMR38-125-77 showed a consistently high starch content, starch yield, and high amylose content for most planting dates except for the starch yield on 20 April, of which Rayong 11 was the best. These findings will be useful for choosing suitable cassava genotypes for different growing seasons and for facilitating breeding efforts for high starch-yielding and high-quality cassava starch in the future.

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.

Drought severely limits sugarcane productivity in many regions of the world. This study characterized physiological responses to different drought durations in a diverse set of sugarcane genotypes in two crop cycles (plant and ratoon cane). A split-plot design was used where three drought treatments, namely, no drought (SD0), short-term drought (SD1), and long-term drought (SD2), were assigned to main plots and six diverse sugarcane genotypes to subplots. Drought reduced photosynthesis, leaf area index, and biomass yield. However, the study found significant differences in physiological responses to drought among genotypes in both crops. F03-362 (F₁), KK09-0358 (BC₁), and KK3 (cultivar) demonstrated greater tolerance to drought by maintaining comparatively higher photosynthetic activity, while KK09-0939 (BC₂) and TPJ04-768 (BC₁) were more sensitive. KK3 and UT12 (cultivar) consistently maintained comparatively higher levels of photosynthesis under drought in the ratoon crop, although stomatal conductance values were comparable to those of other genotypes. Drought significantly reduced dry matter in all genotypes, but more so in the two cultivars. The study demonstrated variable levels of sensitivity to drought among diverse genotypes with different physiological responses being induced by different drought treatments. This information is useful for sugarcane production management and breeding programs.

This study aims to evaluate seasonal variation on starch production of different cassava genotypes planted under irrigated condition. Three cassava genotypes (Kasetsart 50, Rayong 11 and CMR38-125-77) were evaluated in two different growing seasons, i.e., early rainy seasons (ERS) and post rainy seasons (PRS) for two years. A randomized complete block design with four replicates was employed in each growing season. The starch yield was more strongly associated with growing season (28.3%), whereas starch content, amylose content, amylose-amylopectin ratio were more associated with genotypes (19.9–30.7%). Planting cassava in the ERS had rapid growth rates of starch yield and granule size in early growth stages, whereas planting cassava in the PRS had rapid growth rates of these traits in the middle to late growth stages. Cassava planted in the PRS had higher starch yield than the ERS for most genotypes except for Rayong 11, which had no significant differences between growing seasons. The yield and content of starch and size of starch granule continuously increased from four to twelve months after planting (MAP) for most cassava genotypes. Unlike other genotypes, CMR38-125-77 in the ERS gave the highest starch yield and its granule at 10 MAP; however, at 12 MAP, it was still higher than other genotypes. CMR38-125-77 was a preferable genotype, since it had a faster rate of starch formation and more starch and amylose contents, as well as starch yield in both ERS and PRS.

Mid-season drought is increasingly recognized as a major constraint on tuber production in Jerusalem artichoke. The ability of different genotypes to maintain high yields under such conditions is a critical component of drought tolerance. This study aimed to investigate the effects of mid-season drought on tuber yield, biomass, harvest index, tuber water-use efficiency (WUEt), and biomass water-use efficiency (WUEb) across various Jerusalem artichoke genotypes with differing levels of drought tolerance. The experiment was conducted in pots using a 2 × 5 factorial combination in a randomized complete block design with four replications over two years. Factor A consisted of two water regimes: field capacity (FC) and mid-season drought. Factor B included five genotypes: JA 3, JA 125, JA 15, JA 89, and CN 52867. Mid-season drought significantly reduced tuber dry weight, biomass, WUEt, and WUEb, while increasing the harvest index. Significant differences were observed among genotypes for tuber dry weight, biomass, harvest index, WUEt, and WUEb under both water regimes. CN 52867 and JA 89 were characterized as drought-tolerant genotypes with high water-use efficiency and high yield potential. JA 3 was also noted for its lower yield reduction under stress. These three genotypes serve as valuable genetic resources for breeding programs aimed at developing progeny populations with enhanced yield potential and drought tolerance, particularly for mid-season drought-prone environments.