اثر گیاه پیش‌کاشت و سطوح کود نیتروژن بر برخی صفات آگرواکولوژیک گیاه خرفه(portulaca oleraceae l.)

به‌منظور بررسی اثر گیاه پیش کشت و میزان کود نیتروژن بر صفات آگرواکولوژیک گیاه خرفه (portulaca oleraceae l.)، آزمایشی طی سال زراعی 93-1392 در مزرعه تحقیقاتی دانشگاه کشاورزی و منابع طبیعی رامین خوزستان به صورت فاکتوریلاسپلیت در قالب طرح بلوک‌های کامل تصادفی با سه تکرار انجام شد. در این آزمایش، عامل مصرف کود نیتروژن از منبع اوره در پنج سطح شامل: n1 شاهد یا بدون مصرف کود، n2-75 کیلوگرم نیتروژن خالص در هکتار، n3-100 کیلوگرم نیتروژن خالص در هکتار،n4-125 کیلوگرم نیتروژن خالص در هکتار و n5-150 کیلوگرم نیتروژن خالص در هکتار و دو نوع گیاه پیش کشت شامل: -p1 گندم نان رقم چمران p2 -شبدر برسیم به عنوان عامل دوم مورد بررسی قرار گرفتند. چین برداری (c) نیز به عنوان عامل سوم در کرت‌های فرعی قرار گرفت. نتایج نشان داد که تناوب زراعی و مصرف کود نیتروژن در گیاه پیش کاشت اثر معنی‌داری بر تمامی صفات داشت، در حالی‌که اثر چین‌برداری تنها بر برخی صفات مانند عدد کلروفیل‌متر و درصد پروتئین برگ معنی‌دار بود. کاربرد کود نیتروژنه با میزان150 کیلوگرم در هکتار باعث افزایش میزان صفات عملکردی گردید اما نتایج موید این موضوع بود که در زمان استفاده از شبدر به‌عنوان پیش کشت می‌توان میزان کود کاربردی را بدون کاهش در میزان عملکرد کمی و کیفی گیاه تعدیل نمود .

Effect of Preceding Crop and Nitrogen Fertilizer on Some Agroecological Traits of Purslane (Portulaca oleraceae L.)

Introduction;Application of nitrogen fertilizers is one the main practices to increase the yield of agricultural products. However, the addition of high and unbalance amount of fertilizers led to negative consequences on the environment, reduction of fertilizer use efficiency and increase cost of production. Crop rotation is one of the most effective methods to increase nitrogen efficiency at agricultural ecosystems, stated that type of planted crop in previous years can alter soil condition and hence enhance the yield of the next crop. Recent studies revealed that crop rotation alone is not capable of providing required nutrients for plant growth. Hence, if uptake nutrients by plants were not recycled, the crop rotation system would not fully beneficial. Therefore, incorporation of crop rotation and fertilization could be considered as a suitable solution to have stable and highquality crop yield with environmental protection. Based on stated notes, this experiment was conducted to find the most effective nitrogen fertilizer level and reduction of fertilizer use in Purslane farms by crop rotation.;Materials and Methods;This experiment was conducted with factorial split plot based on randomized complete block design with three replications at Ramin Agriculture and Natural Resources University of Khuzestan during 20122013. Nitrogen fertilizer (Urea) was at five levels: (N1Control, N275kg.ha1, N3100 kg.ha1, N4125kg.ha1 andN5150kg.ha1. Two preceding plants P1 Wheat, P2Bersim Clover and cutting (C) was placed at sub plot. Plant cutting of Purslane was done in two times. Anova performed by SAS 9.1 and means were compared by (LSD) at the error probability of 0.05%.;  ;Results and discussion;Results of the experiment showed that plant height was affected by the amount of applied fertilizer rate. The increase in fertilizer rate led to more plant height. The first cutting, stem diameter was increased by higher fertilizer rate and the highest stem diameter (5.41 cm) was achieved at 125 kg N.ha1. At the second cutting, there was no significant difference among fertilizer treatments. First and second cutting the value of chlorophyll in bersim increased and the highest value was observed in 150 kg N. ha1. At first cutting, little difference between 150 kg N × wheat and 150 kgN × clover on the fresh and dry weight leaves of purslane was observed. But in second cutting, the highest fresh and dry weight leaves was observed in the high level of nitrogen × clover.;The increase in fertilizer rate was led to a higher dry weight of Purslane due to increase in stem length, a number of leaves and fresh and dry weight of leaf. The highest fresh weight (26.34 g.plant1) belonged to 150 kg N and bersimpreceding at the second cutting. Plant dry weight showed that maximum plant dry weight was at the first cutting with 125 kg N and bersimpreceding which showed no significant difference of 150 kgN.ha1. Results showed that the first and second cutting had the higher leaf protein with 12.61 and 14.43 % for bersimpreceding and 150 kg N.ha1 treatments.;Conclusion;Based on results of this experiment, it is stated that response of Purslane to preceding is different and cutting legume plant as preceding could improve physiochemical properties of soil and increase the crop yield. The response of Purslane to preceding and fertilizer treatment was different. Application of 125 kg N.ha1 with berismpreceding could produce equal or higher yields compare to 150 kg N.ha1. Application of higher nitrogen led to more watery stem plants and higher plant weight. Generally, due to the medicinal application of this plant, application of suitable crop rotation and optimization of nitrogen fertilizer in a rotational system with preservation of soil fertility, environmental protection, water quality and biodiversity could increase input efficiency and enhance crop quality.