Response of Grafted Juglans nigra to Increasing Nutrient Availability: Growth, Nutrition, and Nutrient Retention in Root Plugs

Abstract

<jats:p>We examined growth and nitrogen (N), phosphorus (P), potassium (K), and microelement nutrition of grafted black walnut (<jats:italic>Juglans nigra</jats:italic> L.) seedlings exposed to increasing nutrient supply and grown in the greenhouse for 18 week. Plants were potted and grafted within the first 4 week, then fertigated once each week for a 7-week period with a varying nutrient solution of 20N–4.4P–16.6K that delivered 0, 1160, 2320, and 4620 mg N/plant. Plants were harvested at week 18. There was a positive mean growth response to increased fertilization, although trends were statistically similar across treatments. Leaf nutrient concentration ranged from 22 to 31 g · kg<jats:sup>–1</jats:sup> N, 5 to 14 g · kg<jats:sup>–1</jats:sup> P, and 19 to 25 g · kg<jats:sup>–1</jats:sup> K. The 2320 mg N/plant treatment increased leaf nutrient content 18% to 86% for N, 33% to 303% for P, and 23% to 58% for K compared with the control. Nitrogen efficiency decreased with increased N supply. Increased nutrient retention in the growing medium at higher fertility suggests root plugs could serve as immediate critical nutrient sources for grafted black walnut seedlings after outplanting. Study results suggests nursery fertilization can be used to improve the nutritional quality of grafted black walnut as well as store nutrients in root plugs for later utilization to benefit early establishment success.</jats:p>

Forty years of study on interactions between walnut tree and arbuscular mycorrhizal fungi. A review

“…Based on analyses of nutrient levels in healthy leaf samples and comparisons with standards recognized to be non-limiting for plant growth, nutrient deficiency in the genus Juglans occurs for leaf N, P, and K contents below 22, 1, and 12 g per kg of dry matter, respectively (Table 6). Fertilization enhances walnut value (Brockley 1988;Jones et al 1995;Jacobs et al 2005b;Salifu et al 2006). For example, annual applications of N and P at rates of 310 kg and 620 kg per ha for 4 years significantly increased J. nigra nut production and leaf nutrient levels (Ponder 1998).…”

Organic substrate for transplant production in organic nurseries. A review

“…Chemical properties of the formulated growing media also affect plant growth and nutritional response in different ways (Salifu et al 2006). The most important characteristics of growing media that determine the suitability of the substrate are included in Table 3 (Raviv et al 2002).…”

Walnut (Juglans spp.) ecophysiology in response to environmental stresses and potential acclimation to climate change

“…In 19-year-old black walnut, estimated above-ground dry biomass (kilograms) was strongly related to total nitrate (NO 3 − , r 2 =0.73) and total annual NO 3 − production (r 2 =0.41, Paschke et al 1989). In 2-year-old black walnut rootstock, fertigation treatments increased leaf nutrient content by 18% to 86% for N compared with the nontreated control after one growing season (Salifu et al 2006). Increases in P, from 33% to 303%, and K, from 23% to 58%, were also found in comparison with the control (Salifu et al 2006).…”

“…In 2-year-old black walnut rootstock, fertigation treatments increased leaf nutrient content by 18% to 86% for N compared with the nontreated control after one growing season (Salifu et al 2006). Increases in P, from 33% to 303%, and K, from 23% to 58%, were also found in comparison with the control (Salifu et al 2006). Two additional studies on fertilization of black walnut seedlings (Nicodemus et al 2008a, b) indicate that a mixed N source is preferred over NO 3 − or NH 4 + alone to maximize productivity.…”