The Effect of Nitrogen Fertilization and Irrigation Frequency on Photosynthesis of Potatoes (Solanum tuberosum)

Photosynthetic Water Use Efficiency of Heritage and Modern Potatoes under Limited and Unlimited Water Environments

“…The high fluxes in Ci and T under PI reduced its photosynthetic WUE. This finding confirms that water and N deficiencies limit photosynthetic capacity [23] [32], whereas FI and PI improve photosynthetic capacity [22]. However, PI failed to use water sparingly on a canopy basis, as reported under a partial root zone drying irrigation strategy [22], because of very high T soon after irrigation.…”

“…In 2010/2011, both water and N deficits steadily decreased g s as once reported by Schapendonk [31]. Consequently, T and A n reduced under rain-fed and low N, as reported by Olesinski [23]. In contrast to rain-fed, partially irrigated potato achieved the highest Ci, g s and T, which consequently increased photosynthetic capacity, whilst reducing photosynthetic WUE due to high T. On the other hand, full irrigation moderately increased T and g s with reduced Ci, hence the high photosynthetic WUE and A n .…”

“…This is factual, because Ci is greatly affected by mesophyllic activity [31] and it is inversely related to A n [12]. However, this study results differ from Olensinski study [23], who found that Ci was not affected by water deficit and it also opposes Liu's findings [15] that photosynthetic WUE was higher under deficit irrigation than full irrigation. Photosynthetic WUE for rain-fed was lower than irrigated crops, possibly because A n for rain-fed decreased, while g s and T remained in the same range with the irrigated potato in the glasshouse and in the 2009/2010 field experiment, which is contrary to other studies [22] and [15].…”

“…However, the leaf water potential results for the 2009/2010 study did not demonstrate genotypic variability on leaf water potential possibly due to low drought intensity compared to 2010/2011, when they differed in leaf water potential, as once reported in the Andean region between water regimes [33]. The 2009/2010 study finding illustrated that potato leaf water potential is not as sensitive as gaseous exchange to water stress and hence it was not a very reliable indicator for cultivar tolerance to water stress, as formerly observed [23]. Regardless to Olesinskiobersation and 2009/2010 study findings, the 2010/2011 experiment showed that leaf water potential can also be used as an indicator for water stress among potato cultivars and for irrigation guidance.…”

“…Water deficit increases leaf VPD in potato [25], which consequently reduces g s and photosynthetic capacity [23] [29] [22]. In our studies, the A n , g s and T increased with irrigation and N, whereas leaf VPD and Ci declined with irrigation and N: Although N had no much significant influence as irrigation.…”