Interaction effects between planting method and plant density on seed yield and some physiological characteristics of peanut (Arachis hypogaea L.) new lines in Guilan

Peanut is one of the most important oilseed plants with indeterminate growth habit, which its seed and meal contains a range of 40-50% and 30-50% oil and protein on a dry seed basis, respectively. In many countries, peanut is planted as ridge method which help to control weeds by mechanical methods using rotary or cultivator. Also, a suitable plant density per unit area can improve photosynthetic process and enhance quantitative and qualitative yield in peanut seed. In the present study, we evaluated the influence of planting method and plant density on seed yield and physiological characteristics in some new lines of peanut under Guilan climatic condition.

In order to determine the best planting method and plant density to improve seed yield of some new lines of peanut, two experiments carried out in 2017 - 2018 cropping seasons as split-split plot based on randomized complete block design with three replications in Rasht, Iran. Two planting methods (Flat and Ridge), three plant density per hectare (D1=125000, D2= 100000 and D3= 83333) and five new lines of peanut (128, 176, 192, 201 and 208) comprised experimental treatments as main, sub and sub-sub plots, respectively.

Results showed that 192 new line produced the greatest seed yield per hectare (3128 kg/ha), seed number per pod (2.08) and biological yield (8983 kg/ha) in response to flat method and D1 plant density. Also, the interaction effect between flat planting method, 100000 plant per hectare and 176 line showed the highest seed oil content (57.67 %). The highest harvest index (40.29%) was observed in 128 new line under flat planting method and 100000 plant per hectare.

In general, results showed that the flat planting method, 125000 plant per hectare and 192 new line of peanut caused to enhance seed yield of peanut under Guilan climatic condition. In this experiment, flat planting method had superiority to ridge planting method and new lines of peanut were differ for seed yield per unit area. The results of this experiment, indicated that peanut seed yield enhanced due to increase of plant density per unit area which could be caused by improvement of solar radiance absorption, exceed of photosynthetic capacity, optimized uses of field unit area and decline of inter plant competition. Based on results of this experiment, flat planting method, 125000 plant per hectare and 192 new line of peanut could be recommendable in direction to enhance seed yield of peanut under Guilan climatic condition