Search Results

You are looking at 41 - 46 of 46 items for

  • Author or Editor: M.L. Smith x
Clear All Modify Search

Tolerance of increased salinity by tomato is of great importance to the tomato processing industry, where increased conductivity of up to 6 dS m-1 is used to increase specific yield components. A new line of miniature dwarf tomato, Lycopersicon esculentum Mill. cv. Micro Tom, was evaluated for photosynthetic response to elevated salinity. Tomatoes were grown in solution batch culture and subjected to constant salt treatments of 2.4 (control), 7.6, 12.8, or 18 dS m-1. Weekly photosynthetic measurements were made beginning week 4 on the most recent fully open leaf or leaf opposite a fruit. Net photosynthesis decreased across all salt treatments over the last six weeks of sampling. As salinity level increased, net photosynthesis decreased compared to the control. The 18 dS m-1 treatment reduced net photosynthesis relative to 12.8 and 7.6 dS m-1. Although salinity increased succulence, limitations to net photosynthesis were due to diminished utilization of intercellular CO2, rather than reduced internal CO2 concentration or stomatal conductance.

Free access

Abstract

The objective of our research is to understand the genetic basis of embryogenesis. Somatic embryogenesis from carrot culture was chosen as the experimental system because of its simplicity and the ease with which it lends itself to obtaining a large number of embryos for genetic and biochemical experiments. Our general philosophy is to avoid media manipulation and to focus on gene expression during embryogenesis. One approach is to isolate genes preferentially expressed at specific stages of embryogenesis, and then to study the role of these genes in development.

Open Access

Field studies were conducted in North Carolina in 2019 and 2020 to determine the effect of a reduced-tillage, high-residue rye (Secale cereal) cover crop system on soil health, and growth and storage root yield of sweetpotato (Ipomoea batatas) cultivars having upright (NC04-0531 or NC15-650) or prostrate (Covington or Bayou Belle) vining characteristics. Sweetpotato canopy width expanded quicker in the conventional tillage system than the reduced-tillage rye system. Prostrate sweetpotato cultivars had greater late-season canopy widths than upright cultivars. Soil bulk density of raised beds was greatest in the reduced-tillage rye system, but both systems remained within the U.S. Department of Agriculture recommended range for soil bulk density. The conventional-tillage system resulted in 17% more marketable roots; however, no differences were observed in total marketable root weight between systems. ‘Covington’ and ‘NC15-650’ had greater marketable yield than ‘NC04-0531’ but less marketable yield than ‘Bayou Belle’.

Open Access

Annual legume ground covers were evaluated in pecan (Carya illinoinensis) orchards to supply nitrogen and increase beneficial arthropods. Treatments were established at two sites, each with 5 ha of a `Dixie' crimson clover (Trifolium incarnatum) /hairy, vetch (Vicia villosa) mixture and 5 ha of grass sod. Data indicated that the legume mixture supplied over 100 kg·ha-1 N to the pecan trees. Beneficial arthropods were greater in orchards with legume ground covers than in orchards with a grass groundcover. Lady beetles and green lacewings were the most important spring predators, and green lacewings were the most important fall predator. The Species distribution on the ground covers differed from that in the canopy. Coleomegilla maculata lengi, Hippodamia convergens and Coccinella septempunctata were the most abundant lady beetle species in the legume ground covers, and Olla v-nigrum, Cycloneda munda, and Hippodamia convergens were the most abundant species in the pecan canopies. Beneficial arthropods appeared to suppress injurious pecan aphids.

Free access