Sweetpotato Responses to Mid‐ and Late‐Season Soil Moisture Deficits

Abstract

Soil moisture‐dependent, quantitative information on sweetpotato [Ipomoea batatas L. (Lam)] plant processes is vital for crop management and modeling because of the projected shrinking and uneven distributions of rainfall and irrigation water supply due to climate change. This study was conducted to quantify the growth, physiology, biomass, and storage root yield responses of sweetpotato under four evapotranspiration‐based irrigation treatments (100, 60, 40, and 20% ET) in sunlit growth chambers. Irrigation treatments were imposed from 41 to 97 d after transplanting. Midday leaf water potentials (LWP) and soil moisture contents were measured throughout the experiment. Gas exchange and other physiological measurements were recorded during last 3 wk of the experiment. Plant growth and developmental parameters were measured at 97 d after transplanting. The midday LWP was strongly and linearly correlated with soil moisture content showing the interplay between these two processes. Net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) declined while photosynthetic water‐use efficiency (Pn/Tr) increased with decreasing LWP. Both total chlorophyll content and cell membrane thermostability (CMT) declined linearly with decreasing LWP. Vine length, leaf area, and node number per plant decreased linearly, by 3.2 cm, 96.6 cm2, and 0.39 no. plant−1, respectively, per unit change in ET‐based irrigation. The optimum soil moisture for total plant and storage root dry weights were obtained under the irrigation treatments of 100 and 72% ET, respectively. Biomass partitioning to storage roots declined linearly and leaf and stem portioning increased with increased irrigation. Outcomes of this research will help producers schedule irrigation to maximize yield and researchers to develop sweetpotato crop models.

Phenological and physiological evaluation of first and second cropping periods of sorghum and maize crops

“…The physiological changes caused by the ageing of foliar tissues contribute to a reduction in water loss rates during plant development, which has an intrinsic relationship with the transpiration of plants (Tardieu, ). In fact, lower transpiration values may be interesting for plants in drought conditions, as they prevent water loss and ensure a higher degree of hydration to plant tissues, and consequently greater water‐use efficiency (Gajanayake & Reddy, ). Plants with lower transpiration values for the same photosynthesis value are more efficient in water use and have greater tolerance to drought (Hepworth, Doheny‐Adams, Hunt, Cameron, & Gray, ).…”

Physiological assessment of water deficit in soybean using midday leaf water potential and spectral features

“…Makbul et al (2011), reported a 28% decrease in chlorophyll content when the leaf water potential decreased from −0.88 to −1.18 MPa in soybean. Decreased chlorophyll content and increased carotenoids contents during drought stress have been reported in many species (Wang et al 2003;Gajanayake and Reddy 2016;Wijewardana et al 2016), depending on the severity and duration of the stress. Loss of chlorophyll content is considered as the main cause of reduced photosynthesis under drought stress.…”

“…photochemical damage to PS II under water-limited conditions. Decreased chlorophyll and increased carotenoid contents have been reported for many crop species under soil moisture stress (Massacci et al 2008;Guha et al 2010;Gajanayake and Reddy 2016). Carotenoids form a key part of the plant antioxidant defense system; however, they are susceptible to oxidative damage.…”

Ultraviolet (UV) B effects on growth and yield of three contrasting sweet potato cultivars

“…Previous studies showed that, in general, soil moisture, soil and air temperature, nitrogen fertilizers are such environmental factors (Meyers 2014). More specifically, the early-season soil moisture, temperature, and nitrogen fertilizer determine root initiation; and the mid-and late-season ones determine biomass and yield (Villagarcia et al 1998, Ukom et al 2009, Gajanayake et al 2013Gajanayake and Reddy 2016).…”