بررسي رابطه عومل آب و هوايي و مراحل فنولوژيك گندم در استان گلستان

Evaluation of Weather Factors and Phonological Stages of Wheat in Golestan Province

Though plant growth and development is a function of genetic characteristic but the effects of weather factors are important as well. Since weather factors have complicated relationship with plant growth and development stages. Each stage of plant growth should receive optimum temperature and growth degree days (GOD) to enter to the next stages. Therefore sowing date, intercultural operations and growth period should be adjusted in order to match with plant development optimum conditions. Thus, phonologic stages of wheat (Tajan variety) were studied in Hashernabad agrometeorological Research Station in Gorgan city in 2003-2004. Results showed that during emergence period plants did not received enough rainfall to fulfill uniform germination. In tailoring period the plant were faced with shortage of light and rainfall and also temperature in emergence and stemming periods was less than optimum. Reducing of temperature in these periods was caused of spike and spikelet initiation. Also necessary temperature for leaf appearance was not supplied. On the other hand increasing of temperature was caused thermal tension in periods of pollination and grain filling resulted reduction of grain weight and yield.