The aim of this study was to investigate the effect of waterlogging on morphological and physiological traits of sorghum (Sorghum bicolor L. Moench) cultivars. Four sorghum cultivars, cv. Wray, Keller, Bailey (sweet cultivar) and cv. SP1 (forage cultivar) at five expanded leaf stage were subjected to 20 days of waterlogging and drained pots were kept as the control. Twenty days of waterlogging did not cause a significant difference in shoot and root biomass among cultivars. Flooding reduced leaf area (69%), plant height (30%) and youngest leaf expansion rate of all cultivars but severely reduced in SP1 (35-80%). Flooding promoted leaf senescence of all cultivars and biomass allocation to shoot (increase in shoot/root) in Wray, Keller and Bailey, but increased biomass partitioning to root in SP1. The initiation of new nodal root was noted in SP1, whereas the ability to maintain root surface area by increase in longest root length and nodal root development near soil surface was found in Wray. Photosynthetic rate, stomatal conductance and transpiration rate were severely reduced under waterlogging conditions of sweet cultivars (65-78%), but enhanced over the control in forage cultivar (56%). The ability to conserve root surface area, allocate more biomass to shoot during waterlogging and develop root near soil surface may support new growth in Wray, whereas the ability to maintain leaf gas exchange parameters in SP1 was due to the active nodal root growth. Nevertheless, there was no relationship between photosynthetic rate and shoot growth of sorghum under anaerobic conditions.

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A declining farm labor force and increasing water scarcity worldwide are forcing rice farmers to adopt directseeding rice production. Under this production system, speed of germination, field emergence, and crop yield depend prominently on rice seed vigor. We hypothesized that seed priming can enhance rice seed vigor and agronomic performance. The objective of this study was to evaluate the effect of GA 3 and wood vinegar seed priming on seed vigor, seedling performance, and grain yield in farmer's fields. The experimental design was a split-split plot with four replications and planted in Thailand between April to December 2013 and 2014. Two rice cultivars (KDML 105 and RD6) were main plots; two planting methods (broadcast and row) were sub-plots, and three seed priming treatments (GA 3 , wood vinegar, and untreated control) were sub-sub-plots. Seed priming enhanced speed of germination and final germination percentage under both laboratory and field condition. However, soil moisture availability during flowering and seed formation significantly affected agronomic performance. Wood vinegar-primed seeds had greater shoot growth and plant population at maturity, while GA 3-primed seed had more rapid germination. Yieldrelated agronomic performance characteristics of tillers plant −1 and yield in ton ha −1 were significantly higher for primed seed, and weed biomass was significantly reduced in 2013. Here, we show for the first time that wood vinegar is a sustainable alternative to chemicals for seed priming. Also, when water is available during flowering and seed development, wood vinegar priming increases grain yield and reduces weed pressure.

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