Effects of Foliar Nano-nitrogen and Urea Fertilizers on the Physical and Chemical Properties of Pomegranate (Punica granatum cv. Ardestani) Fruits

Abstract

<jats:p>The aim of this study was to compare the effects of foliar fertilization with a nitrogen (N) fertilizer containing nanoparticles (nN) with those of foliar fertilization with urea on the characteristics of pomegranate fruits cv. Ardestani. The experiment was carried out using a completely randomized block design with five treatments and four replications (trees) per treatment during two consecutive years, 2014 and 2015. Two foliar applications of nN (0.25 and 0.50 g N/L, equivalent to ≈1.3 and 2.7 g N/tree or 0.9 and 1.8 kg N/ha; nN1 and nN2, respectively) and urea (4.6 and 9.2 g N/L, equivalent to ≈24.4 and 48.8 g N/tree or 16.3 and 32.5 kg N/ha; U1 and U2, respectively) were applied at full bloom and 1 month later, and trees not treated with any N fertilizer were used as a control. Results show that foliar N fertilization increased fruit yield (by 17% to 44%) and number of fruits per tree (by 15% to 38%). The highest fruit yields (17.8 and 21.9 kg/tree) and number of fruits per tree (62.8 and 70.1/tree) were obtained with the treatment nN2 (1.8 kg N/ha), whereas the lowest fruit yields (12.4 and 16.2 kg/tree) and number of fruits per tree (45.5 and 55.3/tree) were recorded in the control trees. The treatments U1 and nN2 increased fruit length (the latter only in the second season), whereas the treatment U1 increased average fruit weight (10% to 11%). The treatment nN2 increased aril juice and total soluble solids (TSS) in both seasons and titratable acidity (TA) only in the first one, whereas the treatment U1 increased TSS in both seasons and aril juice and TA in the second season. Treatments nN2 and U1 also increased total sugars and decreased total anthocyanins. On the other hand, fruit diameter, fruit cracking, peel thickness, aril content, weight of 100 arils, juice pH, maturity index, antioxidant activity, and total phenolic compounds were unaffected by N fertilization. Nitrogen fertilization increased the leaf concentration of N, whereas the leaf concentrations of P, K, Mn, and Zn were unaffected. Results indicate that pomegranate fruit yield was improved similarly with two applications (at full bloom and one month later) of nN fertilizer at a rate of 1.8 kg N/ha and with two applications of urea at a rate of 16.3 kg N/ha. Furthermore, fruit quality was improved more with the nN fertilizer at a rate of 1.8 kg N/ha than with two applications of urea at a rate of 16.3 kg N/ha.</jats:p>

Effect of Mineral, Nano and Bio Nitrogen Fertilization on Nitrogen Content and Productivity of Salvia officinalis L. Plant

“…Nano urea interestingly increased essential oil production. Davarpanah et. al., (2017) indicated that the two foliar applications of nN (0.25 and 0.50 g N/L, equivalent to '1.3 and 2.7 g N/tree or 0.9 and 1.8 kg N/ha; nN1 and nN2, respectively) and urea (4.6 and 9.2 g N/L, equivalent to '24.4 and 48.8 g N/tree or 16.3 and 32.5 kg N/ha; U1 and U2, respectively) were applied at full bloom and 1 month later.…”

The use of nanotechnology to increase quality and yield of fruit crops

“…The latter study also indicated that the increase in phenolic components was due to an increase in the expression of genes coding for the biosynthesis of phenolic compounds induced by Zn and B . Treatment with N‐containing NFs at 0.25 (N1) and 0.50 (N2) g L −1 also improved the quality of pomegranate fruits by increasing aril juice (mL 100 g −1 arils) (control: 62.5; N1: 63.3; N2: 68.3), total sugars (g 100 g −1 juice) (control: 14.18; N1: 14.56; N2: 15.54) and TA (%) (control: 1.74; N1: 1.84; N2: 1.89) of fruits . An increase in N concentration improved turgor pressure, carbohydrate supply and translocation of organic acids .…”

“…Spraying NMs and nanocomposites containing essential macronutrients and micronutrients had positive effects on the fertilization and production of fruits in several fruit trees.…”

“…Nitrogen‐containing NFs release N when plants face a shortage of this element . Spraying N‐NPs at 0.25 and 0.50 g L −1 to pomegranate branches and leaves increased fruit yield (0.25 g L −1 : 18.9; 0.50 g L −1 : 21.9 kg per tree) more than a spray with urea (4.60 g L −1 : 21.2; 9.20 g L −1 : 19.1 kg per tree) while spraying with N‐containing NFs at the full bloom stage and 1 month later was very effective, increasing leaf N concentration by 2% relative to the non‐NP control . Generally, N has physiological and metabolic roles in supplying carbohydrates which are necessary for flowering and fruit set …”

“…Some studies have shown that using NFs is better than normal fertilizers in improving growth, yield and fruit quality of different fruit crops …”