INTRODUCTION
Decrease of leaf growth in rice can occur because water stress in period of seed formation, when maximum leaf area
is needed for yield increase. The reasons of decrease in leaf growth in water stress are reduce of flexibility in cell
walls, osmotic potential and turgor pressure [10]. Access of water is main factor for plant yield in semi-arid areas
[4]. Rice is more sensitive to drought stress in vegetation stage and stress in this stage caused to more decrease of
yield compare to reproductive stage [3]. Silicon increase growth by increase of tiller number, leaf area and
photosynthesis activities in lower leaf, it can be cause vertical position in leaves, stability, increase percentage of
filled spikelets and grain yield [5]. Silicon increased grain yield by increasing of total number of spikelet per
panicle, percentage of filled spikelets, 1000-seed weight and decrease of lodging [9]. Silicon is necessary for
stability of plant yield [6]. Aims of this experiment were to find the sensitive phase of rice growth to water
deficiency, consider effect of silicon amount and discontinue of irrigation on yield and its components and to find
effect of silicon concentration to deal with water discontinue in different stages.