Effect of waterlogging on growth and nitrogen content in the shoot of barley at different stages.

A pot experiment was carried out in a completely randomized design to examine the effect of waterlogging at seedling establishment, tillering and at the booting stages of barley. Barley was more susceptible particularly after germination has started. Thus a 6 day waterlogging starting at 4 day from planting totally killed seedlings before emergence. Before seed germination, the same duration only delayed emergence and reduced plant population to 77 percent of the control numbers. Waterlogging in outdoor at 26 degree Centigrade starting 1 and 3 days after planting killed seedlings of the latter set and 70 percent of the farmer set but at a cooler controlled temperature (6 degree Centigrade) there was only a delayed emergence and it made little differences to plants compared to the control. Before germination and after emergence temperature treatments did not bring about differences between waterlogged plants. Waterlogged at the 3 leaf-stage when barley had nearly started tillering did not inhibit tillering but decreased tiller survival. Four days waterlogging did not result in any effect but 8 and 12 days waterlogging resulted in smaller leaf areas, depressed growth through out the rest of the period and at grain filling the two treatments had less than 70 percent of the dry weight of the controls and a decreased total number of shoots and heads per plant. Leaves became yellow and green leaf length of the basal leaves progressively declined. Waterlogging did not affect the number of leaves appearing per plant. A 12 day waterlogging at the booting stage almost killed above ground shoots and the growth rate per day was greatly decreased. As a result, dry weight, fertile spikelets and grain yield per plant were significantly reduced. Nutrients (N,P,K of 1:1:1) addition at a concentration of 1 ml in 100 ml solution at a rate of 100 ml/pot a few days before the waterlogging started at 3 leaf-stage did not alter the response of plants to waterlogging in those plants waterlogged at tillering and booting stages. Waterlogging had no effect on percent N content in shoot determined at maximum tillering after 12 to 20 days of recovery. But later at the grain filling period percent N content in the waterlogged plants was above that of the controls. Similar results were obtained from those plants waterlogged at the booting stage.