Winter Greenhouse Research Articles

Heredity of flake- and stripe-variegated traits and their introduction into Japanese day-neutral winter-flowering sweet pea (Lathyrus odoratus L.) cultivars.

Sweet pea (Lathyrus odoratus L.) is a major cut flower in Japan, generally grown in greenhouses in winter to spring. The wild-type sweet pea is a long-day summer-flowering plant. The day-neutral winter-flowering ability, which allows cut-flower production in Japan, is a recessive phenotype that emerged by spontaneous mutation. Although Japanese winter-flowering cultivars and additionally spring-flowering cultivars, which have semi-long-day flowering ability generated by crossing the winter- and summer-flowering cultivars, have superior phenotypes for cut flowers, they have limited variation in color and fragrance. In particular, variegated phenotypes do not appear in modern winter- and spring-flowering cultivars, only in summer-flowering cultivars. We try to expand the phenotypic diversity of Japanese cut flower cultivars. In the processes, we introduced the variegated phenotypes by crossing with summer-flowering cultivars, and succeeded in breeding some excellent cultivars. During breeding, we analyzed the segregation ratios and revealed the heredity of the phenotypes. Here we review the heredity of these variegated phenotypes and winter-flowering phenotypes and their related genes. We also describe how we introduced the trait into winter-flowering cultivars, tracing their pedigrees to show both phenotypes and genotypes of the progeny at each generation. This knowledge is useful for the efficient breeding of new variegated cultivars.

Stolon Development and Cultural Production Practices of Winter-Grown Strawberries

ABSTRACTThe four experiments described here are part of a 5-year program focused on determining whether day-neutral and short-day strawberries would be suitable for commercial off-season/winter (temperate climate) production in greenhouses. All research was performed using container-grown plants fertigated through a capillary mat production system with heat supplied under the benches. The first experiment focused on stolon development. The second experiment investigated the influence of stolon removal on berry production and included the removal of flowers for the first three weeks. The third and fourth experiments were conducted as a comparison of university research (experiment 3) versus a commercial operation (experiment 4). In experiment one, of 13 cultivars, ‘AC Wendy’ plants produced significantly more stolons than the other cultivars. In experiment two, stolon production peaked at weeks 12 and 13, with ‘Chandler’ plants producing significantly more stolons (starting at week 9) than the other cultivars. At week 13, ‘Seascape’ plants produced more total berry weight than the other cultivars. The influence of stolon removal on total berry weight varied, with ‘Evie-2+’ plants (large crowns) producing higher total berry weight with the stolons on as compared to ‘Evie-2’ plants, which produced higher total berry weight with the stolons removed. In experiment 2, fruit production was low and was probably a result of deflowering for three weeks. Consequently, it may not be advisable to deflower during the ‘off-season’ for greenhouse-grown strawberries. In the final two experiments, which involved a commercial cooperator as well as the university greenhouse, it was found that of the five cultivars trialed, the same cultivars at both sites produced the maximum total berry weight. Stolon production differed at the two locations, but the optimal time for stolon removal was similar. Thus, it is recommended that for winter greenhouse production, stolons be removed initially at week 8 and then at weeks 11–12 of the production cycle.

Seasonal variations of mercury levels and human health risk in vegetables from Arid Oasis (Shihezi city), Xinjiang, Northwest China

ABSTRACTThe purpose of this study was to investigate the seasonal variations of mercury levels and human health risk in vegetables that were collected from farmland, home garden, and plastic greenhouse in summer and winter 2016 in Arid Oasis (Shihezi city), Xinjiang, Northwest China. The results showed that the levels of mercury in fresh vegetables were lower in winter (0.003–0.025 mg·kg−1) than in summer (0.001–0.035 mg·kg−1). Single factor pollution (P) in vegetables indicated that all vegetables were polluted in diverse levels. The exceeding rate in different vegetables was 0.00% to 88.89% in summer and 0.00% to 100% in winter compared with limits of pollutants in vegetables. The value of bio-concentration factor (BCF) revealed that the mercury absorption capacity of 10 species vegetables decreased in the following order: pea seedling > spinage > caraway > lettuces > pakchoi > celery > crowndaisy chrysanthemum > chives > spinach > shallot. The daily intake (DI) and target hazard quotient (THQ) of mercury for children (2–12 years), young adults (18–45 years), and quinquagenarian (>45 years) indicated that non-carcinogenic values were below the threshold values except one sampling sit from farmland around the industrial parks. Furthermore, the THQ of open field in summer was higher than plastic greenhouse in winter. Under the same pollution level, children had more non-carcinogenic risk than young adults and quinquagenarian.

Supplemental lighting with LEDs improves the biochemical composition of two Valerianella locusta (L.) cultivars

In recent years, light-emitting diodes (LEDs) have been introduced as a new source of supplemental lighting in winter greenhouse crop production to improve yield and quality. The aim of this study was to determine the effect of light supplementation with LEDs on the yield and the concentration of several health-promoting compounds in two cultivars of lamb’s lettuce (Valerianella locusta, L.), ‘Noordhollandse’ and ‘Hollandisher’ in a greenhouse cultivation in winter. Four different LED spectra used to extend the photoperiod (16 h day/8 h night) were tested: 10R:0B (100% red), 9R:1B (90% red, 10% blue), 8R:2B (80% red, 20% blue), and 7R:3B (70% red, 30% blue). The control plants were illuminated by high-pressure sodium (HPS) lamps. The photosynthetic photon flux density at the plant canopy level was approximately 200 μmol·m -2 ·s -1 in all treatments. The plants were harvested on the 45 th day of light treatment (60 days after sowing). In both cultivars, the 10R:0B LED light treatment resulted in the highest yield, but low concentrations of ascorbic acid, xantophylls, and phenolic compounds. Supplemental lighting with HPS lamps resulted in high concentrations of nitrate and carotenoids, but low fresh mass, ascorbic acid, and total phenols content. The addition of blue light in the spectrum increased antioxidant properties; however, certain effects were cultivar-dependent. High yields with the most satisfactory composition of soluble sugars, ascorbic acid, carotenoids, and polyphenols, as well as high antioxidant properties and reduced nitrate levels, in the leaves of the tested cultivars were obtained with 8R:2B LED lighting. Thus, supplemental lighting with 80% red and 20% blue light may be advantageous in greenhouse-cultivated V. locusta ‘Noordhollandse’ and ‘Hollandisher’ cultivars.

Strawberry cultivars vary in productivity, sugars and phytonutrient content when grown in a greenhouse during the winter

Abstract In many areas of the US, fresh locally grown berries are not available during the winter. With this in mind, a research study comprised of three experiments was conducted focused on cultivar selection for berry yield, number, sweetness and phytonutrient content. Using a capillary mat system with under bench heating within a double-layer polyethylene greenhouse, strawberries were grown in the Great Plains Region of the US during the winter. During experiment 1, 12 cultivars were grown; berries were weighed, counted and analyzed for sugars and phytonutrients. ‘Albion’ plants produced a high number/mass of berries, had relatively high sugar content but a lower level of phytonutrients when compared to other cultivars. Sugar and phytonutrients concentrations overlapped across cultivars and thus, one cultivar could not be statistically singled out as best. As all cultivars flowered and fruited, two additional 8-month-long experiments were conducted. It took only 7 weeks from potting of dormant crowns for most cultivars to produce fruit. Certain cultivars fruited more successfully during certain months than others, but this was not associated with response time. For example,’ ‘Albion’, ‘Chandler’, ‘Darselect’, ‘Evie-2′ and ‘Seascape’ plants consistently produced fruit October to early January while ‘AC Wendy’, ‘Cavendish’, ‘Honeoye’ and ‘Strawberry Festival’ plants mainly produced berries in March/April. Summed over experiment 2, ‘Albion’, ‘ Cavendish’, ‘Chandler’, ‘ Evie-2’, ‘Portola’ and ’Seascape’ plants produced the greatest mass of berries. ‘AC Wendy’ and ‘Darselect’ berries contained some of the highest levels of sugars while berries from ‘Chandler’, ‘Darselect’, ‘Evie-2′, ‘Seascape’ and ‘Strawberry Festival’ had some of the highest phytonutrient values. In the third experiment, of the 8 selected cultivars, ‘Evie-2′, ‘Evie−2+’ and ‘Portola’ plants had the highest total yield and average berry mass/plant. ‘Seascape’ and’ Chandler’ plants were second in total production. Glucose, fructose and sucrose levels varied across cultivars with ‘Chandler’ and ‘Seascape’ berries possessing the lowest level of total sugars. Phytonutrient values varied among cultivars with some having better flavonoids (‘Seascape’), phenols (‘Seascape’ and ‘Chandler’) and ant oxidant capacity (‘Seascape’, ‘Evie-2’ and ‘Cavendish’). Measurement of soluble solids concentration varied by week among the cultivars with ‘Seascape’, ‘Seascape+”, and “Albion” berries possessing higher levels than other cultivars such as ’Cavendish’. Overall, under these winter greenhouse conditions using capillary mat fertigation and an under-bench heat delivery system, strawberries were successfully produced for the off-season market.

Effects of CO2 fertilization on photosynthesis and growth of cut Anthurium andraeanum in solar greenhouse in winter

Aiming at the problem of the acute shortage of CO2 in winter production of cut Anthurium andraeanum in solar greenhouse, the effect of CO2 fertilization on photosynthetic characteristics and growth performance of A. andraeanum 'Fire' was investigated. Three treatments with different concentrations of CO2 were designed, i.e., 700, 1000 and 1300 Μmol·mol-1, with receiving no extra CO2 as the control. The results showed that for the CO2-fertilized plants, the photosynthetic rate, intercellular CO2 concentration and water use efficiency were significantly greater than those in the control plants after CO2 fertilization for 60 days, and the largest increase range was observed in the 1000 Μmol·mol-1 CO2 treatment, whereas the stomata conductance was significantly reduced compared with the control. Meanwhile, the contents of soluble sugar, starch and soluble protein in CO2-fertilized plants were significantly higher than those in control plants. Moreover, the quality of cut flowers with CO2 fertilization was remarkably superior to control flowers in term of the parameters including spathe size, spathe color, peduncle length, leaf growth performance and peduncle growth rate. The most superior improvement was observed in the 1000 Μmol·mol-1 CO2 treatment. It was therefore concluded that CO2 fertilization of 1000 Μmol·mol-1 could effectively improve the winter production of cut A. andraeanum in solar greenhouse.

イチゴ栽培ハウスにおける冬季日照不足の改善策としての LED 補光の検討

イチゴ栽培ハウスにおける冬季日照不足の改善策としての LED 補光の検討

EFFECT OF MINERALS ON SOME BIOMETRICAL PARAMETERS OF GREEN HOUSE TOMATO

In the present study, the length of growth and developmental stages and some biometrical parameters of tomato grown in winter greenhouse were investigated in relation to mineral fertilizer doses and combinations. Results of the study demonstrated that flowering synchrony of both the variants P150K150N150 and P150K150N350, basic norms of nitrogen in which increased by 100 to 200 kg and the variants N250P250K250, basic norms of triangular mineral fertilizer in which, increased by 100 kg was later by 5 to 10 days than the variants, which have no fertilizers and other combined doses. It also revealed growth of vegetative organs of the plant is stimulated, whereas the growth of reproductive organs inhibited. Investigation of growth rates of main stem of the tomato plant for each variants shows height of main stem is 368 cm for no fertilizer variant, 381 cm for N150P150, and 387 cm for N150P150K250 variant, which is the tallest among other variants. It is taller by 19 cm than control.

Experimental Research on Insulation Technology by Plastic Greenhouse in Sewage Treatment Plant of Northeast Region

The insulation technology by plastic greenhouse was studied in northeast area. The numerical simulations and experiments were conducted in this paper. The temperature distribution in the greenhouse and flow characteristics were analyzed. The results showed that the greenhouse insulation played a good role in thermal insulation effect, rather than absorbed solar radiation heat. The temperature fluctuation reduced because of the insulation of greenhouse in winter. A stable environment was contributed to the high effective operation of the sewage treatment. The effect of wedge-shaped greenhouse was better than that of arch-shaped one when the temperature of sewage in the outlet was only considered, for the average temperature of air in the greenhouse rose 3–5°C, the temperature of sewage in the outlet rose 5.5–8.5°C. Thus, it was an effective measure to fill the recycled waste heat into the greenhouse in northeast region.

SEVERAL ELEMENTS OF SEED PRODUCTIVITY IN CUCUMBER CULTIVARS BRED AT VNIISSOK

Routine breeding work for cucumber cultivar and hybrid maintenance and their multiplication is carried out at Laboratory of Cucumber and Gourd Breeding and Seed Production, VNIISSOK. The original seeds of 5-6 cultivars or lines of cucumber are annually produced in open field and winter greenhouses at Experimental Production Division, FGBNU VNIISSOK. The seed productivity of cucumber depended on the number of seed bearers on the plant, size of seed bearers and a number of seeds in a fruit, as well as seed plumpness and seed fineness and etc. The condition of growing, such as meteorological factors, nutrition rates, cultivation technology, diseases and pests, cultivar specification influence on seed productivity and the traits mentioned above. The results given summarized multi-year data on 1000 seed weight and number of seeds in a fruits of bee-pollinated cultivars and hybrids, such as ‘Izyaschiy’, ‘Muromskiy 36’, ‘Viyaznikovskiy 37’, ‘Vodoley’, ‘Electron 2’, ‘Yedinstvo’, ‘Korotishka’, ‘Krepish F 1 ’, ‘Brunet F 1 ’. In open field the 1000 seed weight significantly varied among cultivars from 16.6 g. in ‘Viyaznikovskiy 37’ to 24.1 g. in ‘Yedinstvo’. The cultivars ‘Muromskiy 36’, ‘Viyaznikovskiy 37’ and ‘Izyaschiy’ were of the earlies ripening ones and had frailest seeds. Mid ripening cultivars ‘Edinstvo’ was distinguished by the biggest and plumpest seeds that were produced in open field as well as in greenhouse. 1000 seed weight in most cucumber cultivars was higher in open field than in greenhouse by 3.5-10.7 g., whereas this difference was more significant among hybrids. The film mulching increased 1000 seed weight. In seed fruits of bee-pollinated cultivars ‘Vodoley’ and ‘Electron 2’ and ‘Yedinstvo’, there were 250-259 seeds. This characteristic was the most stable in ‘Yedinstvo’. A problem with seed production occurs in cultivars of bush type ‘Korotishka’ and ‘Maliyutka’ because of the small number of seeds in a fruit as compared with other cultivars.

TERMS OF CULTIVATION FOR BEE-POLLINATED CUCUMBER KARAMBOL F1 IN WINTER GLASS GREENHOUSES

The group of bee-pollinated hybrids of cucumber is one of the most demanded for growing in greenhouses in winterspring period. There are ‘Atlet F 1 ’ ‘Karambol F 1 ’ ‘Magnit F 1 ’ ‘Kartel F 1 ’ and also hybrids pollinators ‘Kazanova F 1 ’, ‘Begunok F 1 ’ ‘Bodriyachok F 1 ’, which occupy about 800 hectares of area in winter greenhouses. All hybrids have attractive appearance, high taste qualities, and are transportable. Buttons are in a great demand and have a high price during all the time of cultivation, from February to July. However, the bee-pollinated cucumbers in later period are also in need, particularly for end of year celebrations. The possibility to grow these bee pollinated cucumbers like ‘Karambol F 1 ’ in these terms of cultivation is regarded in the article.

Performance of three numerical models to assess winter chill for fruit trees—a case study using cherry as model crop in Germany

The Meckenheim fruit growing region in Western Germany may be affected as a consequence of climate change by lack of chilling, i.e. a cold period in the winter required for tree species to flower in the subsequent spring. As sweet cherry requires high chill, 160 potted trees of three sweet cherry cultivars with threefold different chilling requirements were cultivated in a large experiment over 4 years, either in the orchard or in an unheated greenhouse (simulated climate change). The orchard temperatures in the warmer winter (6.0 °C) exceeded those in the unheated greenhouse (4.7 °C) in the cold winter. Chilling computations for this region showed that cherry trees of low chill cultivar ‘6000CZ’ required 22.3–26.6 chill portions (CP), medium chill cv. ‘Brooks’ about 37.9–54.4 CP and the high chill cv. ‘Schneiders spate Knorpelkirsche’ about 54.4–79.3 CP for a natural flowering. Cherry trees cv. ‘6000CZ’ receiving <300 CH, cv. ‘Brooks’ <500 CH and cv. ‘Schneiders spate Knorpelkirsche’ <700 CH were unable to flower, equivalent of 50 % of the assumed chilling optimum of the respective cultivar. Maximum chill accumulation in this region is currently achieved, so that warmer winters may reduce the available chill. The beginning of leaf drop was identified as a suitable initiation point for computing chill accumulation. Overall, the work has shown that environmental change has an effect on chilling availability in Meckenheim and possibly other fruit growing regions along 50°N. The insights gained ultimately highlight the need for cross-sectoral, adaptive management practices that jointly target a sustainable regional development.

Screening Rice Cultivars for Resistance to Bacterial Leaf Blight.

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most serious threats to rice production. In this study, screening of rice for resistance to BLB was carried out at two different times and locations; that is, in a greenhouse during winter and in an open field during summer. The pathogenicity of Xoo race K1 was tested on 32 Korean rice cultivars. Inoculation was conducted at the maximum tillering stage, and the lesion length was measured after 14 days of inoculation. Five cultivars, Hanareum, Namcheon, Samgdeok, Samgang, and Yangjo, were found to be resistant in both the greenhouse and open-field screenings. Expression of the plant defense-related genes JAmyb, OsNPR1, OsPR1a, OsWRKY45, and OsPR10b was observed in resistant and susceptible cultivars by qRT-PCR. Among the five genes tested, only OsPR10b showed coherent expression with the phenotypes. Screening of resistance to Xoo in rice was more accurate when conducted in open fields in the summer cultivation period than in greenhouses in winter. The expression of plant defenserelated genes after bacterial inoculation could give another perspective in elucidating defense mechanisms by using both resistant and susceptible individuals.

Effect of different levels of nitrogen on rhizosphere bacterial community structure in intensive monoculture of greenhouse lettuce.

Pyrosequencing-based analyses revealed significant effects among low (N50), medium (N80), and high (N100) fertilization on community composition involving a long-term monoculture of lettuce in a greenhouse in both summer and winter. The non-fertilized control (CK) treatment was characterized by a higher relative abundance of Actinobacteria, Acidobacteria, and Chloroflexi; however, the average abundance of Firmicutes typically increased in summer, and the relative abundance of Bacteroidetes increased in winter in the N-fertilized treatments. Principle component analysis showed that the distribution of the microbial community was separated by a N gradient with N80 and N100 in the same group in the summer samples, while CK and N50 were in the same group in the winter samples, with the other N-level treatments existing independently. Redundancy analysis revealed that available N, NO3−-N, and NH4+-N, were the main environmental factors affecting the distribution of the bacterial community. Correlation analysis showed that nitrogen affected the shifts of microbial communities by strongly driving the shifts of Firmicutes, Bacteroidetes, and Proteobacteria in summer samples, and Bacteroidetes, Actinobacteria, and Acidobacteria in winter samples. The study demonstrates a novel example of rhizosphere bacterial diversity and the main factors influencing rizosphere microbial community in continuous vegetable cropping within an intensive greenhouse ecosystem.

Analysis of yield components and dry matter production in a simplified soilless tomato culture system by using controlled-release fertilizers during summer–winter greenhouse production

We investigated the use of a simplified soilless tomato culture system fertilized with controlled-release fertilizers (CRF) in northern Japan. The utility of this system was assessed by measuring plant growth, fruit yield, yield components, light interception by plant canopy and nutrient use during August–January. Five levels of fertilizer (5–15g N per plant) were applied using CRF in a closed system and these were compared with plants given liquid fertilizer (LF) with an electrical conductivity (EC) control in an open system. The CRF was supplied in a water recirculation tank. Total N supply in the LF system (19.7g N per plant) was higher than in the CRF treatments. In the latter, fresh fruit yield increased with higher fertilizer levels up to 12.5g N. The fruit yields at 12.5 and 15.0g N were similar to those with the LF system. The high fresh fruit yield was caused by high dry matter yield regardless of the CRF treatments, which showed similar dry matter distribution to fruit. A high correlation was noted between cumulative light interception and total dry matter production. Although both were high, dry matter distribution to fruit was lower in the LF system than in the CRF treatments. Overall, however, these effects resulted in similar dry and fresh fruit yields between CRF and LF treatments, with excessive vegetative growth in the LF system. We conclude that the closed CRF application system reduced 37% of nutrient use but still gave a fruit yield equivalent to that obtained by culturing with the open LF system and EC-based management.

RADISH SEED PRODUCTION (TRANSPLANTATION CULTURE); STANDARD OF ORGANISATION FOR MODEL TECHNOLOGICAL PROCESS

The standard of organization for model technological process of seed production was elaborated at VNIISSOK. Requirements established are for implementation of technological operation at radish seed production as transplantation culture as followed: seed plant growing in polyhouses to produce elite seeds, seedlings planting out, plant nursing, harvesting and postharvest processing. The standard is aimed to provide the qualified work in radish seed production through transplantation culture. Radish seed plants for elite seed production are grown on warmed soil beds in winter greenhouses with use of plastic roofing or in plastic houses supplied with heating system. Seeds with germination not less than 85 % according to GOST 32592-2013 are taken for seed production aims. Hand sowing under marker ensures the identical all-around nutrition for plants that is particularly important when growing and selecting the seed plants (1 hectare - 55-60 thousand seed plant roots). Approbation of seed plants is carried out just before harvesting. The terms of seed plant planting are the earliest. Scheme of planting is 70 x 15 - 20 (cm), 60 x 30 (cm) or 90 x 15 (cm). To protect the seed production plantation of radish against weeds, diseases and pests, the pesticides are allowed to apply in accordance with State Catalogue of Pesticides and Agrochemicals, permitted to use in the territory of Russian Federation. Postharvest desiccation of seed plants enables to yield radish by means of direct combining. Radish seeds after processing on sowing qualities have to meet all sowing requirements according to the acting standard. The standard of organization is agreed and affirmed in 2016 CTO 45727225-52-16.

Seasonal Variations on Quality Parameters of Pak Choi (Brassica rapa L. subsp. chinensis L.)

The aim of this study is to determine the changes in quality of pak choi in successive growing seasons. Experiments were carried out in a PE covered cold greenhouse in late autumn-early winter and late winter-early spring growing period in Turkey (41°11’ N, 27°49’ E). Results showed that morphological features, the leaf area (73.82 mm2), leaf length (31.21 mm), average leaf width (2.70 mm), maximum leaf width (3.92 mm), mass (95.27 g) and moisture content values of leaves (0.90% w.b.) were higher in late autumn-early winter period but leaf thickness (0.33 mm) contents were higher in late winter-early spring period. Yield characteristics investigated were affected by season and were found relatively higher in late autumn-early winter than late winter-early spring growing period. And it was 5713 kg ha-1 in late autumn-early winter growing period and 5034 kg ha-1 in late winter-early spring growing period. In point of the dry matter content investigated were affected by season, and were higher in late autumn-early winter than late winter-early spring growing period. It was 12.4% in late autumn-early winter growing period and 10.25% in late winter-early spring growing period. Account of total protein of plants grown in late autumn-early winter (25.16%) was higher than in late winter-early spring (22.45%) growing period. Sowing time did affect ascorbic acid content significantly. It was 44.21 mg.100-1 g in late autumn-early winter growing period and was recorded as 38.02 mg.100-1 g in late winter-early spring growing period. Color parametres L, a, b values were measured as 27.92; -6.98 and 8.53 in late autumn-early winter and as 21.64; -5.48; 7.49 late winter-early spring. Sowing time did affect color parameters content significantly. Late autumn-early winter growing time result was higher than in late winter-early spring growing time. With regard to mineral content N (4.67%), P (0.65%), Cu (9.32 ppm), Fe (879.6 ppm) and Zn (49.13 ppm) values were higher in plants grown in late autumn-early winter in comparison with plants grown in late winter-early spring as K (4.45%), Ca (2.36%), Mg (0.41%) and Mn (62.25 ppm) values of plants were higher in late winter-early spring growing period. Results of the study indicated that different weather conditions influenced the pak choi yield and the chemical composition of the leaf as well. Pak choi with its relatively short cultivating period, easy growing, and dietary value can be a good alternative crop for late autumn-early winter growing period in cold greenhouses.

Role of photoperiod in the development and reproduction of Harmonia axyridis (Coleoptera, Coccinellidae)

ABSTRACTTo improve the laboratory mass rearing and the winter greenhouse use of the multicoloured Asian lady beetle Harmonia axyridis (Pallas) (Coleoptera, Coccinellidae), the effects of photoperiod on the development and fecundity of H. axyridis were investigated at 20°C and photoperiods ranging from 0L:24D to 24L:0D. We foun'd photoperiod to significantly affect the pre-imaginal development and reproduction of H. axyridis. The development of the pre-imaginal stage was significantly faster at shorter photoperiods (0–14 h) than at longer ones (16–24 h). The proportion of females laying eggs within the first 30 days after eclosion, the mean number of eggs per ovipositing female, and the long axial length of the first oocyte were all lower at shorter photoperiods (6–12 h) than at longer ones (14–24 h). These results suggest that adult H. axyridis may encounter problems in preying and reproducing in the winter conditions of unheated and unilluminated greenhouses in areas with temperatures lower than 20°C and day lengths shorter than 12 h.

Variation for Tuber Greening in the Diploid Wild Potato Solanum Microdontum

Greening of the tuber skin is an undesirable defect in fresh and processed potato. Tubers of 92 Solanum microdontum families represented by 12 individuals each were generated in the winter greenhouse in 2009–2010. These were evaluated in two trials of family bulks after 4 days of exposure to 200 ft candles of fluorescent white light at room temperature, similar to that observed in local grocery stores, and according to preliminary tests, able to turn some microdontum tubers very green. A qualitative score of green (G) or white (W) was assigned to each tuber. Tubers of about 10 % of families were scored as mostly W. In comparison, when 185 named Solanum tuberosum cultivars were illuminated in the same way, none from Europe or North America scored W. Two replicates of G and W individual tubers were selected from a variety of microdontum families and planted to create a new clonal generation of tubers. Those second generation daughter tubers showed a response to illumination which was consistent with that of the previous clonal generation. Finally, W and G clones were selected and mated. All GxG hybrids were uniformly G, but only three WxW crosses produced families that were nearly uniformly W. Thus some selections were shown to have consistent non-greening over trials spaced in time, over a clonal generation, and, when crossed together produced pure non-greening progeny. On the other hand, several very green selections similarly were consistently very green over time, clonal regeneration, and intermating. Tests of tuber tissue for glycoalkaloids showed that some illuminated clones neither green nor accumulate glycoalkaloids. These materials would make good models for further study of inheritance and physiology of the greening trait, and for breeding.

Uniformity trial size in estimates of plot size in restrict areas

The aim of this study was to determine the uniformity trial size when estimating optimum plot size in order to evaluate fresh phytomass in lettuce plants and fruit weight in sweet peppers. Production data, collected in uniformity trial on lettuce in a plastic greenhouse in both summer and winter, lettuce in plastic tunnels in autumn and winter, and sweet pepper in a plastic greenhouse in the summer-autumn and spring-summer seasons, were used to plan different uniformity trial sizes in crop rows. In all the experiments, each plant was evaluated individually and considered as a basic experimental unit. For each size in a uniformity trial, 3,000 resamples, randomly taken with replacement, were used to estimate optimum plot size. Uniformity trial using 27 basic experimental units to evaluate the fresh phytomass of lettuce plants, and with 29 basic experimental units to assess fruit weight in sweet pepper, are sufficient to estimate optimum plot size, with an amplitude of the 95% confidence interval of less than or equal to two basic experimental units.