پديد آورندگان :
بهشتي، عليرضا سازمان تحقيقات و آموزش كشاورزي، مشهد - مركز تحقيقات و آموزش كشاورزي و منابع طبيعي خراسان رضوي - بخش تحقيقات اصلاح و تهيه نهال و بذر , سيدكابلي، احسان دانشگاه آزاد اسلامي واحد نيشابور - دانشكده كشاورزي - گروه زراعت
چكيده فارسي :
يكي از مهمترين عوامل موثر بر اختلاف عملكرد در ژنوتيپ هاي سورگوم علوفه اي (Sorghum bicolor L. Moench) چگونگي دريافت و جذب تشعشع فعال فتوسنتزي تحت تاثير ميزان و چگونگي توزيع نيتروژن مصرفي مي باشد. به منظور ارزيابي تشعشع فعال فتوسنتزي تجمعي (CPAR) و كارايي مصرف نور(RUE) در شرايط تقسيط و عدم تقسيط كود نيتروژن، طرح آماري به صورت كرت هاي خرد شده در قالب بلوك هاي كامل تصادفي و در سه تكرار بر روي 15 ژنوتيپ سورگوم علوفه اي (لاين هاي اميد بخش) به اجرا درآمد. در طول آزمايش، صفات شاخص سطح برگ، عملكرد ماده خشك و ميزان تشعشع فعال فتوسنتزي جذب شده طي پنج مرحله نمونه برداري اندازه گيري و محاسبه شد. نتايج تجزيه واريانس نشان داد اثر ژنوتيپ بر عملكرد ماده خشك گياه و كارايي مصرف نور معني دار (p≤0.05) بود و حداكثر و حداقل آن به ترتيب 20/17 و 13/56 تن در هكتار براي ماده خشك و 4/18 و 3/06 گرم بر مگاژول براي كارايي مصرف نور به ترتيب به ژنوتيپ هاي kfs17 و kfs10 اختصاص داشت. شيوه توزيع نيتروژن و اثر متقابل نيتروژن و ژنوتيپ بر شاخص سطح برگ معني دار (p≤0.05) بود و توزيع دوباره نيتروژن موجب افزايش شاخص سطح برگ به ميزان نه درصد و همچنين PAR تجمعي به ميزان دو درصد شد. نتايج اين بررسي حاكي است كه اختلاف در عملكرد ماده خشك ژنوتيپ-هاي سورگوم علوفه اي ناشي از اختلاف درهر دو جزء موثر در توليد ماده خشك يعني كارايي مصرف نور و PAR تجمعي بود.
چكيده لاتين :
Introduction
Dry matter production is a function of photosynthesis active radiation absorption (APAR) and radiation use
efficiency. Sorghum genotypes are different in total dry matter, but the reason of these different is not clear.
Producing dry matter is affected by nitrogen distributing method, but the way of this effectiveness on producing
of dry matter in sorghum genotypes is not also specified. This paper focused on evaluation of receiving and
absorbing PAR, which is affected by nitrogen usage method in forage sorghum genotypes, and reasons of the
differences between these genotypes in production of dry matter. The variation in efficiency of APAR depends
on two chemical and morphological characteristics of the vegetation, including canopy nitrogen content
(NCANOPY) and the canopy average for mass per unit of area (Merea).
Material and Methods
In order to investigate the cumulative photosynthetically active radiation (CPAR) and radiation use efficiency
(RUE) under distributing of nitrogen side dressing and non-distributing conditions, an experiment was conducted
at Khorasan Razavei Agriculture and Natural Resources , Research Center Mashhad , Iran. The statical method
was according to spilt plots base on randomized complete block design with three replicates. The main plots
were fifteen forage sorghum genotypes (Promising lines kfs1, kfs2, kfs3, kfs6, kfs7, kfs8, kfs9, kfs10, kfs11,
kfs12, kfs13, kfs15, kfs16, kfs17, kfs18) and the subplots consisted of distributing of nitrogen side dressing and
non-distributing. The samples were obtained 5 times during the growing season for determination of some
characteristics including dry matter (TDM), leaf area index (LAI) and Photosynthetically active radiation (PAR).
Then total dry matter (TDM), cumulative Photosynthetically active radiation (CPAR) and radiation use
efficiency (RUE) were calculated by these traits. Absorbed radiation measured by Sub Scan model SSI-UM-
1.05 on five location of each plot on bottom and top of each plot at 12 o’clock each day, five times by
destructive samples. Radiation use efficiency (RUE) calculated by regression lines obtained by slope of total dry
matter (TDM) and cumulative radiation use absorption (CPAR) by this equation Y=a0*x.
Results and Discussion
The results showed that the effect of genotype on total dry matter was significant (p<0/05). The maximum
and minimum were 20.17 t/ha and 13.56 t/ha belonged to genotypes (14) and (8), respectively. The nitrogen
fertilizer distributing method and interaction of nitrogen and genotype on leaf area index were significant
(p<0/05). Nitrogen distribution caused leaf area index and photosynthetically active radiation (PAR) to grow up
to %9 and %2, respectively. The genotypes had significant effect on radiation use efficiency. The maximum and
minimum RUE observed as 4.18 g/mJ2and 3.06 g/mJ2 these were related to genotypes 14 and 8, respectively. Conclusion
Splitting nitrogen fertilization in forage sorghum genotypes caused increasing of total dry matter, while
absorbed PAR increased cumulatively. A comparison between methods of nitrogen usage showed that a little
change in increasing radiation use efficiency occurred by changing the nitrogen splitting method, versus non
splitting condition in sorghum genotypes. The results illustrated, these two components (e.g. cumulative
photosynthetically active radiation and radiation use efficiency) are affected by nitrogen fertilization distributing
method in forage sorghum genotypes, as well as nitrogen distribution effect on increscent of cumulative PAR,
leaf area index and radiation use efficiency. Results of this study showed that the differences of total dry matter
in sorghum genotypes is due to both two parameters of cumulative photo synthetically active radiation and
radiation use efficiency
