a total of twenty local and foreign maize (zea mays l.) hybrids in five different maturity group were studied in mashhad for two years (2007-2008). temperature variations were created by two planting dates (5 may and 20 may). results indicated that both indices, gdd and chu, estimated heat units of different maturity hybrids and based on, created similar groups of hybrids. both indices showed s...

abstract precipitation is an important variable which is used in definition of drought. based on precipitation amounts, some indices are devised for drought monitoring including, the standardized precipitation index (spi) and the standard index of annual precipitation (siap). each of these drought indices are classified into some classes so that each class descripts a given severity of drought....

evaluating the quality and quantity of water resources is crucial for a sustainable development. one of the simplest methods that is able to indicate the conditions of water quality in a short period and at a low cost, compared with the physicochemical methods, is by using the biological water quality indices. identifying the contamination of water resources using biomarkers, especially indices...