Effect of Growth Regulators and Ethanol on Termination of Dormancy in Potato Tubers

The main objective of this study was to find the best practice of inducing the sprouting of dormant potato tubers. We compared two protocols of breakage of dormancy, which are based on dipping excised potato eyes in an aqueous solution of gibberellic acid (GA₃) and kinetin (standard 1) or in the aqueous solution of GA₃, thiourea, and daminozide (standard 2), with a newly reported approach based on ethanol. We tested the effect of ethanol alone or in combination with GA₃ and/or kinetin on dormancy release and sprouting of the potato tubers. As a model, we used two potato genotypes (cultivars Pasat and Dorota), with long dormancy of 5 and 10 weeks respectively. We showed that the standard 2 was the most effective treatment both for dormancy breaking and in promoting sprout growth, especially for cv. Dorota, for which the treatment induced 82.3% of tuber eye-plugs to sprout 28 days after treatment and to produce 93.2% of emerged plants after subsequent 28 days of cultivation in the greenhouse. For this cultivar, similar efficacy was observed for the combination of 4% ethanol with GA₃ and kinetin. The same concentration of ethanol combined with GA₃ but without kinetin was the most efficient treatment for breaking dormancy of cultivar Pasat. However, the difference between the various treatment combinations was statistically insignificant. Ethanol alone or in combination with kinetin poorly induced breakage of dormancy, confirming the main role of GA₃ in artificial dormancy breaking. Thus our study showed that the standard 2 is the most effective approach for breakage of dormancy at least with long term-dormancy cultivars.     

The delay of flowering time in almond: a review of the combined effect of adaptation,mutation and breeding

Regulation of flowering time in almond, as in other Prunus species, is a complex process involving both chill and heat requirements. Following exposure to appropriate consecutive periods of cold and warm temperatures, the buds break dormancy and sprout or flower depending on bud type. To maximize flowering and subsequent vegetative growth and fruit set, chilling and ensuing warm temperature requirements have to be fully satisfied. Because of its potential for very early flowering, flowering time in almond is a major determinant of its adaptation to new environments. In colder regions, Late-flowering is often necessary to avoid frost damage during and just after flowering. Consequently, the selection of delayed flowering times remains an important objective in almond improvement programs. Flowering time is considered a quantitative though highly heritable trait. In addition, a dominant gene (Late flowering, Lb), originally identified in a spontaneous mutation of the Californian almond cultivar ‘Nonpareil’, was also described. The objective of this review is a comparative analysis of the effects of regional adaptation, breeding and mutation on the delay of flowering time in new almond cultivars. Findings indicate that the adaptation of almonds from the Mediterranean basin to colder regions in Northern Europe and America has been mainly achieved through delayed flowering. These adapted late-flowering cultivars have usually been developed by selecting desired quantitative genes within each regional germplasm. Additional progress thus appears achievable with a more comprehensive understanding of the quantitative and qualitative genetics controlling this trait. The use of molecular markers for the early selection of genes conferring late flowering, including both spontaneous mutations as well as unique regional germplasm, should allow development of even later cultivars including ultra-late cultivars flowering as into April.     

Occupancy pattern of a long-horned beetle in a variegated forest landscape: linkages between tree quality and forest cover across spatial scales

Context

Interactions between landscape-scale processes and fine-grained habitat heterogeneity are usually invoked to explain species occupancy in fragmented landscapes. In variegated landscapes, however, organisms face continuous variation in micro-habitat features, which makes necessary to consider ecologically meaningful estimates of habitat quality at different spatial scales.

Objectives

We evaluated the spatial scales at which forest cover and tree quality make the greatest contribution to the occupancy of the long-horned beetle Microplophorus magellanicus (Coleoptera: Cerambycidae) in a variegated forest landscape.

Methods

We used averaged data of tree quality (as derived from remote sensing estimates of the decay stage of single trees) and spatially independent pheromone-baited traps to model the occurrence probability as a function of multiple cross-scale combinations between forest cover and tree quality (with scales ranging between 50 and 400 m).

Results

Model support and performance increased monotonically with the increasing scale at which tree quality was measured. Forest cover was not significant, and did not exhibit scale-specific effects on the occurrence probability of M. magellanicus. The interactive effect between tree quality and forest cover was stronger than the independent (additive) effects of tree quality and particularly forest cover. Significant interactions included tree quality measured at spatial scales ≥200 m, but cross-scale interactions occurred only in four of the seven best-supported models.

Conclusions

M. magellanicus respond to the high-quality trees available in the landscape rather than to the amount of forest per se. Conservation of viable metapopulations of M. magellanicus should consider the quality of trees at spatial scales >200 m.

     

Some Nutritional Characteristics of Enzymatically Resistant Maltodextrin from Cassava (<Emphasis Type="Italic">Manihot esculenta</Emphasis> Crantz) Starch

Cassava (Manihot esculenta Crantz) native starch was treated with pyroconversion and enzymatic hydrolysis to produce a pyrodextrin and an enzyme-resistant maltodextrin. Some nutritional characteristics were quantified for both compounds. Pyroconversion was done using a 160:1 (p/v) starch:HCl ratio, 90 °C temperature and 3 h reaction time. The resulting pyrodextrin contained 46.21% indigestible starch and 78.86% dietary fiber. Thermostable α-amylase (0.01%) was used to hydrolyze the pyrodextrin at 95 °C for 5 min. The resulting resistant maltodextrin contained 24.45% dextrose equivalents, 56.06% indigestible starch and 86.62% dietary fiber. Compared to the cassava native starch, the pyrodextrin exhibited 56% solubility at room temperature and the resistant maltodextrin 100%. The glycemic index value for the resistant maltodextrin was 59% in healthy persons. Its high indigestible starch and dietary fiber contents, as well as its complete solubility, make the resistant maltodextrin a promising ingredient for raising dietary fiber content in a wide range of foods, especially in drinks, dairy products, creams and soups.     

Evaluation of Particle Size Influence on Proximate Composition,Physicochemical, Techno-Functional and Physio-Functional Properties of Flours Obtained from Persimmon (<Emphasis Type="Italic">Diospyros kaki</Emphasis> Trumb.) Coproducts

The aim of the work was to study the influence of particle size in the composition, physicochemical, techno-functional and physio-functional properties of two flours obtained from persimmon (Diospyros kaki Trumb. cvs. ‘Rojo Brillante’ (RBF) and ‘Triump’ (THF) coproducts. The cultivar (RBF and THF) and particle size significantly affected all parameters under study, although depending on the evaluated property, only one of these effects predominated. Carbohydrates (38.07–46.98 g/100 g) and total dietary fiber (32.07–43.57 g/100 g) were the main components in both flours (RBF and THF). Furthermore, insoluble dietary fiber represented more than 68% of total dietary fiber content. All color properties studied were influenced by cultivar and particle size. For both cultivars, the lower particle size, the higher lightness and hue values. RBF flours showed high values for emulsifying activity (69.33–74.00 mL/mL), while THF presented high values for water holding capacity (WHC: 9.47–12.19 g water/g sample). The bile holding capacity (BHC) and fat/oil binding values were, in general, higher in RBF (19.61–12.19 g bile/g sample and 11.98–9.07, respectively) than THF (16.12–12.40 g bile/g sample and 9.78–7.96, respectively). The effect of particle size was really evident in both WHC and BHC. Due to their dietary fiber content, techno-functional and physio-functional properties, persimmon flours seem to have a good profile to be used as potential functional ingredient.     

<Emphasis Type="Italic">Lupinus albus</Emphasis> Conglutin Gamma Modifies the Gene Expressions of Enzymes Involved in Glucose Hepatic Production <Emphasis Type="Italic">In Vivo</Emphasis>

Lupinus albus seeds contain conglutin gamma (Cγ) protein, which exerts a hypoglycemic effect and positively modifies proteins involved in glucose homeostasis. Cγ could potentially be used to manage patients with impaired glucose metabolism, but there remains a need to evaluate its effects on hepatic glucose production. The present study aimed to analyze G6pc, Fbp1, and Pck1 gene expressions in two experimental animal models of impaired glucose metabolism. We also evaluated hepatic and renal tissue integrity following Cγ treatment. To generate an insulin resistance model, male Wistar rats were provided 30% sucrose solution ad libitum for 20 weeks. To generate a type 2 diabetes model (STZ), five-day-old rats were intraperitoneally injected with streptozotocin (150 mg/kg). Each animal model was randomized into three subgroups that received the following oral treatments daily for one week: 0.9% w/v NaCl (vehicle; IR-Ctrl and STZ-Ctrl); metformin 300 mg/kg (IR-Met and STZ-Met); and Cγ 150 mg/kg (IR-Cγ and STZ-Cγ). Biochemical parameters were assessed pre- and post-treatment using colorimetric or enzymatic methods. We also performed histological analysis of hepatic and renal tissue. G6pc, Fbp1, and Pck1 gene expressions were quantified using real-time PCR. No histological changes were observed in any group. Post-treatment G6pc gene expression was decreased in the IR-Cγ and STZ-Cγ groups. Post-treatment Fbp1 and Pck1 gene expressions were reduced in the IR-Cγ group but increased in STZ-Cγ animals. Overall, these findings suggest that Cγ is involved in reducing hepatic glucose production, mainly through G6pc inhibition in impaired glucose metabolism disorders.     

Defining the validity of a biochemical index of soil quality

 The native soils of Galicia (NW Spain) exhibit a biochemical equilibrium such that total soil N is a function of five biochemical and microbiological parameters: microbial biomass C, mineralized N, phosphomonoesterase, β-glucosidase and urease activities. To investigate whether the ratio of the total N calculated from biochemical soil properties (Nc) and the total N as measured by the Kjeldahl method (Nk; Nc/Nk) can be used as an index of soil quality, we determined these variables and consequently the ratio in three kinds of disturbed soils: an artificially Cu-contaminated soil, two lignite mine soils, and a number of arable soils. In none of the studied soils did the individual biochemical parameters respond consistently to the factors influencing soil quality, but in all cases soil degradation was reflected by the Nc/Nk value, which differed more or less markedly from 100%. Nc/Nk can therefore be used for the rapid evaluation of soil degradation, since it distinguishes among biochemically balanced soils, soils in a transient state of high microbiological and biochemical activity and degraded soils. It can also serve as a reliable basis for the rapid calculation of the "ecological dose" (ED₅₀) of soil pollutants. The use of Nc/Nk as an objective index of the biochemical quality of soils is recommended. Received: 20 December 1998