An inexpensive system for maintaining desired water potentials throughout seed germination was developed. During hydration, a water reservoir at the base of inclined petri dishes allowed continual saturation of filter paper on which seeds were placed. During dehydration, seeds were exposed to equilibrium vapor pressures above saturated salt solutions. Constant temperature, necessary to prevent condensation of water vapor, was achieved via a small (0.2 A) fan that furnished and circulated heat throughout an insulated chamber in which salt solutions were placed. By operating the chamber above ambient laboratory temperature, interior cooling was not required. The system allowed manipulation of the rate, degree, and frequency of dehydration episodes to which germinating seeds were exposed.
The accelerated aging vigor test subjects seeds to high temperatures (41°C) and relative humidity (about 100%) for short durations (usually 72 hours). These recommendations, however, have been developed for large-seeded agronomic crops and may be too severe for small-seeded flower crops that deteriorate rapidly during storage such as impatiens. We examined the effect of aging regime duration (48, 72, and 96 hours) and temperature (38 and 41°C) as well as relative humidity using three saturated salt solutions (KCl–87% RH, NaCl–76% RH, and NaBr–55% RH) on two commercial impatiens seed lots differing in seed vigor but not percentage germination. The greatest differences in percentage germination after 4 days were found among the treatments of 48 hours for KCl, 72 hours for NaCl, and 96 hours for NaBr. While any of these saturated salt solutions may be used in a commercial situation to determine impatiens seed vigor, we suggest that a total 7-day test period consisting of 72 hours aging at 41°C using saturated NaCl with germination being determined 4 days after aging is most convenient.
Rancidity is a major problem during the storage of shelled peanuts and walnuts. Blanched peanuts, blanched dry roasted peanuts, blanched oil roasted peanuts (all of them extra large Virginia variety) and shelled Persian walnut (Chandler variety) were maintained in closed jars at 37 C. Relative humidity was controlled by saturated salt solutions at 20% and 55%. Oxygen concentration was 21% or reduced to 0.1% by flushing with nitrogen.
Samples were taken every 2 weeks for 10 weeks. Peroxide values were measured and volatiles were analyzed to determine the rancidity of the samples. Oxygen concentrations in the jars and nut moisture were also measured.
Dry roasted peanuts were the most susceptible to rancidity. Blanched peanuts, without any roasting process, were the most stable. The results quantified the importance of oxygen as a major factor in rancidity at the relative humidities studied. It was concluded that it is possible to quantitatively control the rancidity process by decreasing the oxygen concentration surrounding the nuts.
Impatiens (Impatiens wallerana Hook.f.) flower seeds are believed to be sensitive to storage temperature and humidity conditions. A study was conducted to evaluate seed quality changes occurring during a 1-year period of storage under various temperature and humidity combinations. Four seed lots of `Super Elfin Red' and `Super Elfin White' impatiens were studied. Constant humidity treatments were obtained using saturated salt solutions; 15% relative humidity (RH) with LiCI, 25% RH with KAc, 33% RH with MgCl2, and 43% RH with K2CO3. Constant temperature treatments were 5, 15, and 22C. At 3-month intervals, replicate samples were sown in plug flats in the greenhouse. Seed quality was evaluated as the percentage of usable seedlings 21 days from sowing. Rapid deterioration of seed quality was seen under high temperature and high humidity storage conditions. Seeds became less sensitive to humidity at 5C. Conditions of 20% to 25% RH and 5C are recommended for impatiens seed storage.
Seed moisture content (MC) has been considered the most important factor controlling physiological reactions in seeds, and MC changes with relative humidity (RH) and temperature (T). This relationship is revealed by studying the interaction of RH and T at equilibrium. Cucumber (Cucumis sativus L.), lettuce (Lactuca sativa L.), maize (Zea mays L.), onion (Allium cepa L.), pea (Pisum sativum L.), and watermelon (Citrullus lanatus M. & N.) seeds were equilibrated over sulfuric acid (1% RH) and various saturated salt solutions (5.5% to 93% RH) at temperatures from 5 to 50 °C. Best-fit subset models were selected from the complete third-order model MC = β0 + β1 *RH + β2 *T + β3 *RH2 + β4 *T2 + β5 *RH*T + β6 *RH3 + β7 *T3 + β8 *RH*T2 + β9 *RH2*T, using Mallows' minimum Cp as the selection criterion. All six best subset models (R 2, 0.98 to 0.99) had the same functional form, MC = β0 + β1 *RH + β2 *T + β3 *RH2 + β5 *RH*T + β6 *RH3 + β9 *RH2*T. Coefficients had essentially the same respective values among all species except onion and pea, for which some coefficients were statistically different from those of the other species (P ≤ 0.05). All models indicated that seed MC increased as RH increased and decreased as T increased; but RH had the greater influence. The inverse relationship between seed MC and T, although slight, was evident in the response surfaces. The interaction effect of RH and T on MC was significant at P ≤0.001. These results suggest that orthodox seed species respond similarly to T and RH. This in turn suggests that a common model could be developed and used for optimizing seed storage environments.
relief ( Baldos et al., 2014 ; Santhoshkumar and Veena, 2012 ). When using sealed desiccation chambers, specific levels of RH can be established and maintained using saturated salt solutions ( Winston and Bates, 1960 ; Young, 1967 ), but proportions of
subsamples to 12 saturated salt solutions ( Table 1 ). We prepared saturated solutions by placing 100 g of reagent grade salts into 150-mm petri dishes. With the exception of P 2 O 5 , we slowly mixed distilled, deionized water into the salts until a slush or
and maintained using saturated salt solutions in airtight desiccators, and three storage temperatures (5 °C, 20 °C, and ambient). Seed viability for C. angustifolia was optimized at storage temperatures of 5 and 20 °C when maintained at RH levels of
with the bottom removed and a piece of rigid plastic mesh to separate the seed from the salt solution was used as a moisture chamber. Seven saturated salt solutions and a control without a salt solution were used to produce seed moisture levels of 2
to be applied to the seeds by storing the unsealed packets containing the seeds for 28 d in three desiccators containing different saturated salt solutions ( Commander et al., 2009 ; Turner et al., 2009 ). Saturated salt solutions of lithium chloride