The Effects of Different Levels of Nitrogen on Yield and Yield Components of Rainfed Wheat in Two Regions of North Khorasan

To study the effects of different levels of nitrogen fertilizer on yield and yield components of cultivars of rainfed wheat a study was done in the crop year 2012-2013 as factorial in a randomized complete block design with 3 replications, in 2 research stations of Kohne Kand city in Bojnord and Shirvan dryland research station. The treatments of study contain cultivars of wheat in 4 levels (Rasad, Sabalan, Cross Sabalan and Azar 2) and 4 levels of nitrogen fertilizer (75, 50, 25 and 0 kilograms nitrogen per hectare). The results showed that the yield in Shirvan was significantly higher than that in Bojnoord. Moreover, the impact of cultivar and nitrogen on yield and yield components was significant in both regions and among different cultivars Azar 2 has the highest yield in both regions and the lowest yield was for cross Sabalsn in Shirvan and Sabalan in Bojnoord. Furthermore, yield increased by increasing the nitrogen in both regions but there was no significant difference between levels 50 and 75 kilograms per hectare. Among yield components except the number of spikes per square meter, others had a high correlation with yield.

Rice (Oryza sativa L.) nutrient management using mycorrhizal fungi and endophytic Herbaspirillum seropedicae

Integrated nutrient management with biological and chemical fertilizers can improve rice （Oryza safiva L.） productivity, bio-fortification, soil health and fertility. Accordingly, this study was planned to evaluate the combined effects of biological fertilizers including arbuscular mycorrhizal （AM） fungi （Glomus mosseae） and free-living nitrogen-fixing bacteria （Herbaspi- rillum seropedicae）, as well as chemical fertilizers on the yield and nutrient contents of wetland rice under field conditions. Seedlings were inoculated with AM fungi and the bacteria in the nursery and were then transplanted to the field. The experi- ment was carried out as a split factorial design with three replicates. Treatments included three rates of nitrogen （N 1, N2 and N3） and phosphorous （P1, P2 and P3） fertilizers （100, 75 and 50% of the optimum level） in the main plots and mycorrhizal and bacterial treatments in the sub plots. The total of urea （g） used per plot was equal to N1=200, N2=150 and N3=100 at three different growth stages （seeding, tillering and heading） and the total of P （g） per plot used once at seeding using triple super phosphate including P1 =16, P2=13 and P3=10. Plant growth and yield as well as the concentration of nitrogen （N）, phosphorous （P）, potassium （K）, iron （Fe）, and zinc （Zn） were measured in the soil, straw and grains. N-fertilizer and biological fertilizers had significant effects on root, shoot and grain yield of rice, however, P-fertilizer just significantly affected root and shoot dry weights. Interestingly, analyses of variance indicated that biological fertilization significantly affected all the experimental treatments except straw N. AM fungi, N1 and P1 resulted in the highest rate of rice growth and yield. The interactions of chemical and biological fertilization resulted in significant effects on grain Zn, Fe, P, and N as well as soil Fe, K and N. The highest rate of grain nutrient uptake was resulted by the combined use of biological fertilization and the medium level of chemical fertilization. Interestingly, with decreasing the rate of chemical N fertilization, rice nutrient use efficiency increased indicating how biological fertilization can be efficient in providing plants with its essential nutrients such as N. However, the highest rate of soil and straw nutrient concentration was related to the combined use of biologicalfertilization and the highest rate of chemical fertilization. We conclude that biological fertilizer, （mycorrhizal fungi and H. seropedicae） can significantly improve wetland rice growth and yield （resulting in the decreased rate of chemical fertilizer）, espe- cially if combined with appropriate rate of chemical fertilization, by enhancing nutrient uptake （fortification） and root growth.

Two Iranian Rice Cultivars’ Response to Nitrogen and Nano-Fertilizer

This experiment was carried out as split factorial in randomized complete blocks design with three replications in Sari, Iran during 2013 and 2014. Rice cultivars were chosen as the main factor including Tarom Mahalli and Tarom Hashemi. Nitrogen rates (34 and 69 kg N ha−1 and nitroxin) with nano-particle (nano-potassium, nano-silicon and control) selected as the subfactor. The results indicated that the amount of total tiller per hill and fertile tiller per hill for Tarom Hashemi was more than Tarom Mahalli in both years. The highest paddy yield in both years was observed for Tarom Hashemi, the main reason behind it is increasing panicle length and fertile tiller number for this cultivar. For Tarom Hashemi, the highest paddy yield (5000 kg⋅ha−1) was produced with 34 kg N ha−1 and nano potassium application. For Tarom Mahalli, the highest paddy yield 4657 kg⋅ha−1 was obtained with nitroxin and nano potassium consumption. The highest harvest index was achieved with nitroxin and nano-silicon consumption. Therefore, nano particle consumption in both cultivars resulted in improved yield.