A new approach for nondestructive quality assessment based on color measurement was developed for red radishes (Raphanus sativus L.). Postharvest changes in hue angle corresponded with changes in soluble and insoluble pectic substances linked to textural characteristics in `Nevadar' radishes. Changes in glucosinolates were related to changes in chroma and were associated with radish flavor. However, monosaccharides were not related to root color during the 4 days of postharvest period. Nevertheless, the data suggest that root color may be used as a rapid, inexpensive and reliable indicator of quality during the postharvest distribution of radish.
Effects of washing and storing soil core samples of apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf. (syn. M. domestica Borkh. non Poir.)] roots were studied to determine root losses from processing samples. Root losses were assessed by measuring root lengths before and after elutriation and storage at 4 °C (39.2 °F). The accuracy of the automated root length scanner to measure individual fine roots [<1 mm (0.04 inch) diameter] of varying lengths was evaluated by first measuring roots, then cutting the roots into 2 to 3 cm (0.79 to 1.18 inch) lengths and rescanning. There was a significant relationship between the measurement of cut and noncut roots (r 2 = 0.93). Losses from elutriating samples with cut and noncut roots indicated a mean loss of50% for samples with cut roots and 34% for samples with noncut roots (P ≤ 0.01). Total mean root loss (elutriation loss of noncut roots and degradation loss in cold storage) for the 12-month period ranged from 34% at month 0% to 53% at month 12 (P ≤ 0.01). Mean root degradation losses from long-term cold storage ranged from 6% at month 1 to 19% at month 12 (P ≤ 0.01). No losses were identified for roots with diameters of 1 to 5 mm (0.04 to 0.20 inch) and 5 to 10 mm (0.20 to 0.39 inch). A data correction curve was developed to correct root length data (<1 mm) for root losses associated with processing of soil cores.
substrate–sensor combination. Variance measurements were calculated on a layer basis as the average of the four sensors per layer. Root harvests. Three replicate trees of each species were randomly selected and destructively harvested in July 2010. The stem
Abstract
Intercellular space measurements of ‘Nugget’ and ‘Centennial’ sweetpotatoes were significantly different due to variety, evacuation and holding periods, and the interaction of curing with evacuation and holding periods but not different because of curing alone, root length, dry-matter content, or uncorrected specific gravity. To determine intercellular space accurately, evacuation time should be no less than 10 min and holding in water after evacuation no less than 15 min.
Root substrates (substrates) are commonly used in the production of containerized greenhouse and nursery crops ( Bunt, 1988 ; Nelson, 2003 ). Substrates are formulated from various inorganic and organic components such as peat, perlite, aged bark
Measurement of substrate pH entails procurement of the substrate solution and measurement of the solution pH. Acid-base reactions are completed at the time of testing. Determination of substrate pH during development of a titration curve is more complex because it involves initially the reaction of a base with the substrate. Five factors that can influence the resulting pH values were investigated in this study and include amount of water added to substrate, method to procure substrate solution for pH determination, chemical form of base used, time allowed for acid-base reaction and the addition of CaSO4. Substrate in this study consisted of 3 sphagnum peatmoss: 1 perlite (by volume) amended with wetting agent. Dolomitic limestone (6 g·L-1 substrate) was added to substrate for the water amount and solution procurement method experiments. Except for the water amount experiment, deionized water was added by weight to achieve 95% container capacity. Dishes were incubated at 20 °C for specified times. To identify the minimal level of water necessary to ensure complete contact between base and substrate for neutralization, additions equivalent to 95%, 100%, 120%, and 150% container capacity were tested. The 95% level proved adequate. The saturated media extraction and pour-through bulk solution displacement methods for pH determination resulted in higher pH measurements in the incubated substrate than the squeeze bulk solution displacement method. This indicated that the former two methods diluted the soil solution. The squeeze method was deemed most effective. NaOH resulted in higher pH endpoints than Ca(OH)2. This was apparently due to a higher affinity of Ca2+ for peatmoss exchange sites. Since Ca2+ is the predominant cation associated with liming materials for soilless substrates, Ca(OH)2 is more appropriate for titration. From the tested incubation times of 0, 2, 4, 8, 24, 48, and 96 hours, the duration of 24 hours was found to be adequate to allow complete reaction of base with substrate acidity. The best procedure for determining pH in a substrate titration situation included a water level of 95% container capacity, Ca(OH)2 base, an incubation time of 24 hours and the squeeze solution displacement method. The additional CaSO4 was not necessary. Chemical names used: calcium sulfate (CaSO4), sodium hydroxide (NaOH), calcium hydroxide [Ca(OH)2], calcium ion (Ca2+).
The root systems of dormant l-year-old apple (Malus domestics Borkh. `Starkrimson') grafted on seedling rootstock were dipped for 15 seconds in one of six dye treatments or a water control. Trees were destructively harvested at 15, 30, and 90 days after treatment to monitor new root and shoot growth and effectiveness of dyes for distinguishing between regenerated roots and those present at planting. Neutral red and methylene blue allowed effective separation of new and old roots through 90 days after treatment, and had few adverse effects on root or shoot growth, with a water control being the standard. Crystal violet and safranin-O allowed effective separation between regenerated and previously existing roots, but these dyes adversely affected new root and shoot growth. Alizarin red S and Hantover meat branding ink were ineffective for distinguishing between regenerated and previously existing roots by 15 days after treatment.
This research study evaluates the effectiveness of a recently introduced irrigation-plant production system, multipot box system (MPBS), for moderating root zone temperature (RZT) compared with the conventional nursery containers. The study also deals with the development, calibration, and validation of a series of models that can be used to predict maximum (max) and minimum (min) RZTs using commonly available input variables. The Viburnum odoratissimum (Ker.-gawl.) was used as the test plant. Models were calibrated in the fall growing season and validated during the summer. The RZT was used as the dependent variable while the max and min air temperatures (Tmax and Tmin) and/or incoming solar radiation (Rs) were used as independent variables. The color of the MPBS had an effect on plant growth. Plants grown in the white MPBS had higher growth indices, shoot and root dry weights, and number of stems as compared with the plants in the black MPBS or the conventional (control) system (CS). White MPBS maintained cooler RZTs than the max air temperature during both seasons. Also, white MPBS maintained cooler RZTs than the black MPBS and CS during the two seasons. In both seasons, water temperature in the black MPBS was higher than the temperature in the white MPBS contributing to the high RZTs in the black MPBS. The RZT of the black MPBS and CS exceeded the critical value (40 °C), which is cited in the literatures as negatively impacting root growth, water and nutrient uptake, leaf area, plant survival, root and shoot dry weights, water status, and photosynthesis. The RZT in the CS was above 45 °C for most of the summer season and plants were exposed to this extreme temperature for a few hours a day during most of the summer. The white MPBS provided a better environment and enhanced plant growth. For regions where ambient air temperature ranged from 2 to 41 °C, the white MPBS can provide adequate and effective RZT protection for plants grown in No. 1, 3.8-L standard black conventional containers. Predicted RZT values were well correlated with measured values in all systems. Rs did not have an effect on predicting RZTmax in the MPBS treatments. Wind speed did not contribute to predicting RZT in any production systems. The root mean square error between measured and predicted RZT was relatively low ranging from 0.9 to 2.8 °C. Models were able to explain at least 74% of the variability in RZTs using only Tmax, Tmin, and/or Rs. Models developed in this study should be applicable for estimating RZTs when similar management and cultural practices are present. Models of this study are practical, simple, and applicable to predict RZTs where ambient air temperature ranges from 1.9 to 40 °C. Model results should not be extrapolated beyond these limits.
particle size distribution measurements were taken for each substrate. Sieve sizes used for particle size distribution were 3.35 mm, 1.68 mm, 0.422 mm, 0.251 mm, 0.125 mm, and 0.066 mm. Cuttings were planted 5 cm deep into the randomly assigned rooting