نویسندگان
1 دانشگاه اصفهان
2 مرکز تحقیقات کشاورزی و منابع طبیعی اصفهان
3 دانشگاه زابل
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
1- Introduction
Crop development is qualitative changes planned that led the plant to ripening. Factors such as water available, nitrogen and photosynthetic materials are affected growth and development. Under irrigated conditions expected that all of factors except climate elements be controlled. Thus, only climate elements able to change of plant growth and development and under these conditions, temperature and day length have more effective than the other elements. In every site, planting date determined adaptation of developmental stages to day length and temperature during growth season.
2- Methodology
Data from planting dates trials conducted over the Kabootar-Abad Agricultural Research Station during 2003-2009 were used to develop models for estimating development rate of three varieties, Arak, Zendeh Rud and Goldasht. To calculate of developmental rate of every stage, duration of every stage was inversed. To determine model of development rate of every stage, development rate considered as dependent variable and day length, thermal variables and combination of these considered as independent variables in step wise regression. A step of regression was considered appropriate if the highest R2 was accompanied by the significant (pâ¤0.05) regression coefficient. Evaluation of model accuracy and sensitivity was performed, using the data of 2008-2009 that there was not any role in forming of models.
3- Discussion
No. of days from planting to emergence, emergence to heading, emergence to flowering, emergence to ripening and flowering to ripening were affected by planting dates. By increasing temperature, developmental stage periods decreased. Day length had the most effect on emergence to heading and emergence to flowering period and by increasing it, decreased. Tmean was the only variable that entered to model and explained about 76% of development rate of varieties emergence period. About 83% of development rate of emergence to heading stage was determined by TmaxÃDL. T2maxÃDL2 explained about 92% of development rate of emergence to flowering stage. T2maxÃDL2 with T4max explained about 81% variations of developmental rate of emergence to ripening stage. T3max was the only variable that entered the model of development rate of flowering to ripening stage and expressed about 47% variations of it.
4- Conclusion
Contribution of thermal and day length parameters in determining of rate of different developmental stages is not constant. This may be related to different physiological nature of developmental stages and differences reactions of these stages to climatologic, edaphic and agronomic elements and interaction among them and with genotype of plant. Entrance of a variable to a model may be related to amount of variables variance and correlation among them and it may there are not physiological reasons for this.
کلیدواژهها [English]