Boron and pigment content in alfalfa affected by nano fertilization under calcareous conditions

Boron is among the necessary nutrients for plant growth and yield production, and it can improve the nutritional properties of forage crops. However, at higher levels it maybe toxic adversely affecting plant growth and forage quality. Plant boron concentration is affected by different parameters including boron fertilization, soil, climate, plant species, etc. A new era in the field of plant fertilization is the use of nano technology. Accordingly, a factorial field experiment on the basis of a complete block design in six replicates was conducted in a 300-hactare agro-industry area. The objectives were to investigate the effects of different boron treatments on alfalfa (Medicago sativa L.): 1) boron concentration, and 2) pigment contents including chlorophyll a, b, total, and carotenoids. Six regions with different properties were selected for the experiment; the soil samples were collected using GPS. The experimental treatments including: 1) soil type (S1-S6), 2) boron sources including boric acid (B1) and nano boron fertilization (B2), and 3) number of spraying (zero-, one-, two-, and three-time) were tested. The nano structure of boric acid-copper in an aqueous medium was produced using the chemical reduction method. The results indicated that soil type, boron source and number of spraying significantly affected (P ≤ 0.01) alfalfa boron concentration and pigment content. The mean of alfalfa boron concentration by B1 and B2 was 103.52 and 111.52% higher than control. The three-time spraying significantly increased B concentration related to the other spraying treatments (P ≤ 0.05) as it resulted in a 207.81% increase compared with the control treatment. The three-time spraying resulted in the highest increase of pigment contents (P ≤ 0.05) including chlorophyll a, b, total, and carotenoids compared with the other treatments. Although the highest boron and pigment contents were resulted by the three-time spraying, the combined use of B2 and the two-time spraying was the most optimum treatment (non-toxic) significantly increasing alfalfa boron and pigment contents (P ≤ 0.05). It would be possible to produce alfalfa at large amounts and with suitable forage quality using boron nano fertilization (synthesized and tested in this research work) under calcareous conditions.