טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentStern Sivan
SubjectCharacterization of Root Uptake and its Dependence on Soil
Environmental Conditions by Geophysical Tools
DepartmentDepartment of Civil and Environmental Engineering
Supervisors Professor Alex Furman
Professor Shmuel Assulin
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

The main challenge to agriculture worldwide is to preserve maximal production capacity, while using minimal amount of water. In order to meet this challenge a quantitative and qualitative understanding of root growth and water uptake dynamics is needed. This research focuses on understanding the influence of environmental conditions on the root system activity, and specifically on the spatial and temporal behavior of root water uptake and in the produced biomass of the roots and the whole plant. The research used pepper plants, grown in sandy soil in greenhouse conditions during the summer for two months. Different environmental conditions were obtained by implementing three different irrigation management schemes (using the same amount of water but with different daily temporal distributions which also lead to different spatial distribution). The experimental layout included six growing tanks (barrels), three with and three without plants. TDR and ERT electrodes were installed at different depths in each tank to monitor soil moisture content with high spatial and temporal resolution. Each pair of tanks (with and without a plant) was treated in a different irrigation scheme. For all treatments the same daily amount of water was applied, increasing with plant development. The three different irrigation treatments considered differed from each other in discharge rate. The first treatment included the application of the daily dose in a single pulse using a 2 l\hr dripper. The second included application of the daily dose in a single pulse using a 0.25 l\hr dripper. In the third treatment, the same amount was supplied using a 2 l\hr dripper in 8 pulses, with 0.5 hr intervals between pulses. In addition to the growth tanks, a system of sandbags with identical size to the growth tanks was set up for destructive root mapping.

 The difference in discharge rate formed spatially and temporally different soil water distributions, namely different environmental conditions. Different dynamics of water resulted in differences in the daily and hourly root water uptake functions. Plant agronomic parameters show significant differences between the different treatments resulting from the existence of different environmental conditions. Close relationship between high daily transpiration and high root and canopy biomass was demonstrated throughout the experiment. where the pulses treatment showed the best utilization of the applied water, followed closely by the low discharge.