Pecan (Carya illinoinensis) production in Georgia holds significant economic importance nationally. It is an energy-intensive practice with a very low output-to-input ratio. Pecan byproducts, notably pecan shells and husks, account for up to 49% of the nut but are underutilized. A greenhouse experiment was conducted at the USDA facility in Byron, Georgia in 2023 to study the feasibility of composted pecan shells as a growing media amendment for container-grown pecan seedlings. The composted pecan shell was collected from a local pecan grower’s three-year-old composted pile, while fresh goat manure was sourced from the Fort Valley State University’s farm. Various ratios (25, 50, 75, and 100%) of composted pecan shells, along with biochar, goat manure, and chicken manure, were compared to a commercial soil mix (control). All the growing amendments underwent steam sterilization at 98°F for a couple of hours to eliminate any potential contaminants such as weeds, bacteria, fungi, and parasites. Each treatment combination was placed in individual floats to sow the one-year-old stratified ‘Elliott’ seeds. Once the seedlings developed two juvenile leaves, they were transferred to 3-gallon pots to evaluate further soil and plant physiological parameters. The treatments were arranged in a randomized complete block design with four blocks, each containing one treatment combination. Various soil and plant parameters were evaluated monthly, including soil electrical conductivity and temperature, plant size, photosynthesis, stem water potential, and chlorophyll content, to assess the impact of soil amendments on soil and pecan seedling growth. Results determined that composted pecan shell outperformed others in terms of germination (~80%), while none of the seeds germinated in any chicken manure treatment combination. Remarkably, the growth performance of pecan seedlings under different pecan shell ratios was comparable to those grown in commercial soil mix, biochar, and goat manure, indicating good plant health. The stem water potential values overall ranged above -6 Bar, suggesting no signs of plant water stress throughout the study. However, the 100% goat manure treatment consistently showed seedlings with significantly lower chlorophyll content and photosynthetic activity, leading to the smallest plant size compared to the control and biochar treatments. These findings highlight the potential of composted pecan shells as a sustainable soil amendment for container-grown pecan seedlings, offering a novel approach to repurpose pecan byproducts to enhance soil quality, promote sustainable agriculture practices, and serve as an additional income source to pecan growers, thus contributing to the economic viability of pecan production in Georgia.
Lack of dormant chilling is a major problem in producing pistachio trees in locations with warm periods during the winter time. In the past years, some locations in California have received insufficient winter chilling which has led to late bloom and crop reduction. Horticultural oil has been used as a rest-breaking agent to promote bud break and improve production. However, there is limited information regarding the merit of chill portion spray timing and the physiological mechanism behind bloom advancement by oil application. In the present study, three locations in California, North (Colusa County), Central (Madera County) and South-Western Fresno County (Cantua Creek) were selected for oil spray applications while Hydrogen cyanamide (Dormex®) was sprayed at Cantua Creek site. Tree of cv. Kerman (female) and Peters (male) on UCB-1 rootstock were sprayed with horticultural oil (IAP 440) @ 6% v/v or Dormex @4% at various chill portion (CP) accumulation milestones. Bloom period from bud swell to full bloom, tree yield, yield components, non-structural carbohydrates and macro and micro nutrients in buds and bark of pistachio shoots were analyzed. NMR-based metabolomics analysis was conducted to investigate the changes in metabolic profiles induced by exogenous oil or Dormex® application. Results showed that oil spraying in two southern locations advanced bud break but not in the northern site showing each location respond to oil spray differently. In Cantua site, Dormex® and oil spray at CP55 could significantly increase the yield while in Madera, oil spray at CP59 showed the highest yield. Results also showed that oil spray at different CPs and Dormex® could change the trend of soluble sugars and starch in bark and bud of pistachio trees. In Cantua, Dormex® significantly increased nitrogen (N), phosphorous (P), sulfur (S), boron (B), copper (Cu) and zinc (Zn) mobilization towards bud swell. Moreover, oil spray increased N, P, S in all CPs at all locations. A multivariate analysis conducted to compare the metabolite changes in control samples of bark and bud with these two rest-breaking agents led to the identification of nine metabolites that show a significant change in at least one of the comparisons (Creatine, Aspartate, Sucrose, Asparagine, Succinate, Fumarate, Leucine, Adenosine, and Uridine). It seems that oil and Dormex® applications can significantly increase the yield of pistachio trees by advancing bud break, improving bloom synchrony and also, by changes in carbohydrate, nutrients and metabolite changes in bark and bud of pistachio tree.
The state of Georgia is one of the states leading in pecan production in the U.S. However, the seminal papers on water management using state-of-art techniques like eddy-covariance system and micro lysimeters are far and few. Much of the information available on water-use efficiency arises from earlier studies done in the Southwest. However, crop varieties, Georgia soils, and rainfall, when coupled with a long, hot and humid climate of the Southeast, lead to contrasting water management practices from that of the Southwest. The present paper addresses the water needs of pecans in trees six to ten-year old throughout different physiological stages of the orchard in Georgia using the current irrigation schedule. Several record-breaking temperatures and the shifting rainfall patterns have had an important impact on pecan production. This precipitation variability further exacerbates the needs to tailor water-use efficiency to these new normal conditions. Along with the in situ meteorological data and soil moisture information, an eddy-covariance system is installed in Hawkinsville, Georgia. This poster shows how southeastern pecan orchards have different water requirements for optimum yield. This paper focuses on the differences between the current schedule, irrigation application at the farm and water-use data from the present study. Such results obtained likely for the first time will help to devise water management practices, optimize irrigation scheduling leading to increased water conservation and yield. Keywords: water-use efficiency, production, climate change
