THE EFFECT OF EVAPOTRANSPIRATION DEFISIT 0N WATER PRODUCTIVITY AND GROWTH OF SOYBEAN PLANTS (Glycine max L. Merrill)

Abstract

Soybean is an efficient source of vegetable protein. National soybean production continues to decline during
2010-2012. The lowproductivity of soybean is one of them caused by drought stress. Therefore, it is necessary to
use cultivation techniques which can improve the efficiency of water use, ie with deficit irrigation. Deficit
irrigation can be evaluated by calculating the amount of crop water productivity. The purpose of the research is
to calculate andcompare themagnitude of cropwater productivity andgrowth of three varieties of soybeanplants
in each treatment evapotranspiration deficit. Researchwas conducted in September 2014 -December 2014 in the
greenhouse of IntegratedField Laboratory and LaboratoryofWaterResourcesand LandDepartment ofAgriculture,
University of Lampung.The experimentwas conducted using a factorial in completely randomized design (CRD)
with two factors that is soybean varieties which consists of three varieties: Kaba, Tanggamus, and Willis and
deficit ETC which consists of three levels: 1.0 x ETC, 0.8 x ETC, and 0.6 x ETC. Data were analyzed with Analysis Of
Variance (Test F), then continued by LSD test at the significance level of 5% and 1%. Results showed that: (1)
based on the total leaf area, Kaba and Wilis varieties of soybean plants have started stress at week 2nd in the
treatment ET2 (0,8 x ETC), varieties Tanggamus began stress on the 3rd week of the treatment ET3 (0,6 x ETC).
Eventually based on the production of soybeans plant, varieties Tanggamus andKaba remains stress in treatment
ET2 (0,8 x ETC) except varietiesWillis on ET3 (0.6 x ETC), (2) the crop water productivity was not significantly
different between treatments except treatment Tanggamus varieties ET3 deficit (0, 6 x ETC), (3) Kaba varieties
have the highest production in the amount of 20.22 grams,while the cropwater productivity of the highest of the
Wilis varieties is equal to 0.5 kg/m3.
Keywords: evapotranspiration, deficit irrigation, soybeans