Micropropagation of Walnut (Juglans regia L.)

Abstract

The objective of this work was to establish regeneration protocol for walnut (Juglans regia L.) by multiplication of shoots from axillary buds. Different concentrations of TDZ (0.0, 1.0, 2.5, 5.0 mg/l), IBA (0.0, 1.0, 2.5, 5.0 mg/l) or IBA together with TDZ were investigated to optimize regeneration for the multiplication in the NGE (Sanchez) culture medium. Multiplication rate increased with increased concentration of TDZ or IBA together with TDZ. The highest mean multiplication rate was observed in the fourth subculture with 2.5 mg/l TDZ + 2.5 mg/l IBA reaching 5.33 shoots per explant. The shoots supplemented with 5 mg/l IBA (62.71%) had higher number of rooted shoots than those supplemented with 2.5 mg/l IBA (45.66%). With 73.24% of rooting, the shoots rooted on medium containing 2.5 mg/l IBA after etiolation application had higher number of rooted shoots than those supplemented with 5 mg/l IBA with 64.69% of rooting after etiolation application. The highest mean survival rate of the shoots was observed in 2.5 mg/l TDZ + 2.5 mg/l IBA reaching 35.27%. Results showed that walnut in vitro micropropagation is feasible and the best growth percentage was obtained in 5.0 mg/l TDZ, and 2.5 mg/l TDZ with 2.5 mg/l IBA.

Optimizing micropropagation conditions for a recalcitrant ninebark (Physocarpus opulifolius L. maxim.) cultivar

“…Similarly, a synergetic influence of BA and NAA was noticeable in Ruta graveolens when the combinations of the most favorable concentration of BA with variant concentrations of NAA were tested: supplementation of NAA resulted in a better shoot proliferation rate and the best regeneration (Faisal et al 2018). In Juglans regia the best proliferation results were obtained with 1 mg•L −1 of BA plus 0.01 mg•L −1 of IBA (Kepenek and Kolagasi 2016). During multiplication phase the auxin IAA or IBA was always present in culture media used for seven ornamental plants differing in sensitivity towards cytokinins BA or Kin (Vardja and Vardja 2001).…”

Effects of Different Culture Media Compositions on In Vitro Micropropagation from Paradox Walnut Rootstock Nodes

“…In the study carried out by Tetsumura et al (2002) on different walnut varieties, the highest shoot number was obtained as 1.7, while the highest shoot length was determined as 1.97 cm. In another study carried out by Kepenek and Kolağası (2016), the highest number of shoots obtained per explant was found to be 5.32, while the shoot length was 3.88 cm. In our study node explants with surface sterilization were transferred to the specified media for shoot induction.…”

“…Darkening due to oxidation of the phenolic component in explants, internal contamination sources in explants, difficulties in adaptation to the culture medium, rooting and transfer to the soil are the most important problems of walnut micropropagation. Many scientific studies on walnut micropropagation have been published since the 1980s, but there is still not enough information to establish an accurate micropropagation protocol depending on the species (Kepenek & Kolağası, 2016;Licea-Moreno et al, 2020). Fidancı (2005) stated in his research using Şebin and KR-2 walnut varieties that the most important problem encountered during the cultivation phase of micropropagation is contamination and darkening.…”

“…In another study conducted by Kepenek and Kolağası (2016) in J. regia L., it was determined that the multiplication rate increased depending on the TDZ and IBA concentrations. It was also stated that the highest multiplication number (5.33 shoots) was obtained in NGE medium containing 2.5 mg/L TDZ and 2.5 mg/L IBA (Kepenek & Kolağası, 2016).…”

“…As a result, the researchers stated that some walnut cultivars should be grown in environments with higher mineral concentrations than DKW nutrient media, and that higher Cu and myo-inositol levels may be effective in increasing the growth rate and rooting rate of walnut explants (Vahdati et al, 2009). In another study conducted by Kepenek and Kolağası (2016) in J. regia L., it was determined that the multiplication rate increased depending on the TDZ and IBA concentrations. It was also stated that the highest multiplication number (5.33 shoots) was obtained in NGE medium containing 2.5 mg/L TDZ and 2.5 mg/L IBA (Kepenek & Kolağası, 2016).…”