Soil Temperature and Maize Nitrogen Uptake Improvement Under Partial Root-Zone Drying Irrigation

Soil temperature is a major effective factor on the soil and plant biological properties.Irrigation can affect soil temperature and thereby induces a temperature effect on plant growth,which may result in an economic increase due to higher yield and plant nutrition.A ?eld experiment was carried out to investigate the effects of three irrigation strategies including full irrigation(FI),partial root-zone drying(PRD) and de?cit irrigation(DI) on soil temperature and the consequent results on the grain yield and N uptake of maize(Zea May L.).Soil temperature was measured by time domain re?ectometry(TDR) sensors during the 2010 growing season.Irrigation treatments were applied from 55 to 107 d after planting.The PRD treatment caused soil temperature to be in a favorable domain for a longer period(for over 60% of the measuring dates) as a consequent result of water movement to deeper soil layers compared with the other treatments;the PRD treatment also reduced soil temperature at deeper soil depths to below the maximum favorable soil temperature for maize root growth,which resulted in deeper root penetration due to both water availability and favorable soil temperature.Compared to the FI treatment,the PRD treatment increased root water uptake by 50% and caused no signi?cant reduction in total N uptake,while this was not observed in the DI treatment partially due to the negative temperature effect of DI on plant growth,which consequently affected the water and nutrient uptake.A longer vegetation period in the PRD treatment was observed due to higher leaf N concentrations and no signi?cant reduction in maize grain yield occurred in the PRD treatment,compared with those in the FI treatment.Based on the results,having 15.2% water saving during the whole growing season,the PRD irrigation would positively affect soil temperature and the water and nutrient uptake as a consequent,which thereby would prevent signi?cant reduction in maize grain yield.

Assessing effects of deficit irrigation techniques on water productivity of tomato for subsurface drip irrigation system

Water resources are subjected to ever-increasing supply constraints due to extensive agricultural water demand for irrigated lands.Therefore,water-saving irrigation strategies need to be explored.The present study was conducted to explore the possibilities of using regulated deficit irrigation(RDI)and partial root zone drying irrigation(PRD)methods as water-saving irrigation techniques for subsurface irrigation.The objective of this study are to assess the effects of RDI and PRD irrigation on the water productivity of vegetable crops(tomato)under SSD systems in arid climatic conditions,and to compare the responses of tomato crops to PRD,RDI,and FI under an SSD system in terms of productivity,crop quality,and the amount of water saved.The field experiment was conducted during the fall 2014-2015 and 2015-2016 seasons in an experimental field located on an educational farm owned by the Faculty of Food and Agriculture Sciences Department,King Saud University,Riyadh,Kingdom of Saudi Arabia.An area of 102.7 m^(2)(13 m×7.9 m)was allocated for the experiment to manage three treatments:RDI,PRD,and full irrigation(FI).The RDI and PRD treatments received 70%of the irrigation water volume of FI.Each was replicated three times.The most important results indicated that the soil water content(SWC)for the RDI and PRD treatments was lower than that of the FI treatments.FI had the highest stomatal conductance values(gs),while PRD had the lowest stomatal conductance values.The photosynthetic rate(A_(n))was lower under RDI and PRD compared to FI.However,there was no significant change in A_(n) between treatments for most readings taken during both time periods,which means that the water saving treatments(PRD and RDI)did not affect the net photosynthesis rate,thereby enhancing irrigation water use efficiency(IWUE)under DI treatments.The water-saving irrigation techniques decreased transpiration rate(T)compared to the FI treatment.The values of the abscisic acid(ABA)contents were higher under PRD and RDI than FI.The marketable yield under the FI treatment yielded the highest values.The fruit quality parameter results showed that the RDI and PRD treatments increased the total soluble solids,vitamin C,and titratable acidity of tomato compared to the FI treatment.Most of the minimum IWUE values were associated with FI.These results indicate the effects of deficit levels on IWUE.