Evaluation of carrot and onion cultivars for commercial production in Guyana

Experiments were conducted at two locations (Central Agricultural Station, CAS, Mon Repos, and Black Bush Polder) in Guyana, to evaluate carrot and onion cultivars for adaptability to the climatic conditions. Onion cultivars were tested for the production of dry bulbs as well as for the green tops.‘Chantenay Red Core’, ‘Improved Danvers-126’, ‘Nantes Strong Top’, ‘Nantesa Superior’, and ‘New Kuroda’ carrot produced average yields between 14 and 25 t/ha. Dry bulb yields of ‘Bermuda-986’, ‘Granex’, ‘Red Creole’, ‘San Felipe’, and ‘White Creole’ onion were lowest of all cultivars included in these trials. At the CAS, ‘Texas Grano-502’ and ‘White Alamo’ produced larger onion bulbs with average weights of 82 and 77 g, respectively. At Black Bush Polder ‘El Toro’ produced the largest onion bulbs with an average weight of 77 g. In storage, bulb losses for red onion cultivars, ‘Red Creole’, ‘Red Granex’, ‘Tropicana’, were lowest at all samplings during the 82 days storage period. White onions were most susceptible to loss in storage. Average losses of white onions were 33.3, 63.7, 74.6 and 86.2% at 21, 44, 55, and 82 days in storage, respectively. Storage losses for ‘White Creole’, which was an exception, were 11.1, 35.9, 46.4, and 57.0% for the above-mentioned storage durations respectively. Among four cultivars evaluated for green onion production, ‘Evergreen Bunching’ produced the highest yield (28.6 t/ha).     

洋葱抽薹形成原因及防治措施研究

通过4a的洋葱品比试验和10a的高效栽培技术研究,结果表明,洋葱的抽薹率与品种、播期、光照和温度等密切相关。结合生产实际,针对形成薹葱的影响因素提出了选用西葱1号和西葱2号等优良品种,9月中下旬播种、适时定植,喷施薹葱抑制剂,定植后适时适量追肥,发现抽薹葱人工摘除薹等防治措施。     

The physiology of hyacinth bulbs. XI. The effect of gibberellic acid on the growth and flowering of variously chilled bulbs

The effect of gibberellic acid, GA₃, on the growth and flowering of hyacinth cultivars ‘Pink Pearl’, ‘Delft Blue’ and ‘Carnegie’, chilled in a cold room at 5°C or a garden frame for 28, 42 or 81 days, and either rooted or dry, unrooted, was investigated. GA, was applied to the basal plates of the bulbs in a lanolin paste on 10 October 1975.The growth of the inflorescence and leaves of plants originating from dry-chilled bulbs was generally the same as that of those grown from rooted plants. A similar response to GA₃ treatment was observed in all cultivars. Treatment of bulbs with GA₃ decreased the number of days to flowering, stimulated the growth of inflorescences and leaves, and its effect was most pronounced in the plants chilled for shorter periods.     

Bulbing responses of two cultivars of red tropical onions to photoperiod,light integral and temperature under controlled growth conditions

Summary

The effects of photoperiod, light intensity and temperature on bulb formation and bulb structure of two tropical onion cultivars were investigated. From an initial experiment it was observed that the number of true scales and sheath scales differed significantly between the cultivars ‘Red Creole’ and ‘Agrifound Dark Red’. When these two cultivars were given 11, 12 and 13 h photoperiod treatments, it was found that both cultivars needed at least 12 h photoperiod for bulb formation. Modify the R/FR ratio from 1.22 to 1.16 in the final hour of the 11 h light period did not induce bulbing. The 13 h photoperiod increased the number of true scales and decreased the number of sheath scales compared with the 12 h photoperiod in both cultivars but total scale + leaf sheath numbers remained nearly constant. When onion plants were grown under 0%, 25%, 50% and 75% shading treatments, (12 h photoperiod), only plants receiving 0% and 25% shading bulbed. Low light intensity decreased the number of true scales and increased the number of sheath scales. Four temperature regimes were compared in a growth room experiment. Plants under the 29°348C treatment bulbed within two weeks and matured within six weeks. However, plants receiving the 25°308C treatment delayed bulb initiation more than those plants receiving 17°228C and 21°268C treatments. At the lowest temperature, bigger bulbs with thick necks were produced. This may be due to changes in bulb structure since at low temperature, the number of sheath scales was increased, however the number of true scales remained relatively constant in both cultivars. Dormant leaf initials decreased with decreasing temperature while the number of secondary meristems significantly increased. The results suggest that ‘Red Creole’ was more responsive to shorter photoperiods, bulbing earlier than ‘Agrifound Dark Red’. There was no significant difference in time to bulbing in response to temperature between the two cultivars if measured by bulbing ratio however there were differences in bulb structure which suggested that ‘Red Creole’ bulbed earlier. These effects may be due to the breeding histories of the two cultivars. It is suggested that studying bulb structure may provide a useful method of interpreting onion bulbing responses.     

Postharvest sprouting of onion bulbs grown in different temperature and C02 environments in the UK

Summary

The effects of different mean growing season temperatures and C0₂ concentrations during bulb production on postharvest bulb sprouting in a common storage environment at Reading, UK, was examined in two cultivars of the Rijnsburger type of onion (Allium cepa L.). Crops were grown in the field in temperature gradient tunnels maintained at either 374 or 532 ppm C0₂. At crop maturity, cohorts of bulbs were harvested, transferred to a constant temperature room (at an average of 11.6°C) and the subsequent duration to sprouting recorded. The duration to the onset of sprouting (expressed as days in storage until the first bulb sprouted) was not affected by cultivar, mean growing season temperature or CO₂ concentration, and was 165 d. The subsequent rate of sprouting (expressed as bulbs per day) was a positive linear function of mean growing season temperature, but no effects of CO₂ or cultivar were detected. Mean rate of sprouting increased from an average of 0.036 bulbs per day at 12.3°C to 0.093 bulbs per day at 18.6°C. Rapid sprouting in storage was associated with lower levels of total non-structural carbohydrate in the bulbs at the time of harvest. Thus, postharvest susceptibility of onion bulbs to sprouting in storage is expected to increase in warmer crop production temperatures.     

Effect of photoperiods before,during and after vernalization on flower initiation and development and its varietal difference in Japanese bunching onion (Allium fistulosum L.)

Summary

To control the bolting of Japanese bunching onion (Allium fistulosum L.) photoperiodically, the effect of photoperiods before, during and after vernalization on flower initiation and development and the varietal differences were investigated using the two mid-season flowering cvs Kincho and Asagi-kujo, and a late-season flowering cv. Cho-etsu. A long-day photoperiod (LD, 16 h) given before vernalization inhibited flower initiation. Especially, the bolting rate of ‘Asagi-kujo’ decreased by about a half, compared with the short-day photoperiod (SD, 8 h). The interaction between the effect of night temperature (3°C, 7°C, 11°C or 15°C) and the effect of the photoperiod (SD and LD) during vernalization was also investigated. In ‘Kincho’, LD did not affect flower initiation at 3°C, but inhibited flower initiation at 7°C, 11°C and 15°C. In ‘Asagi-kujo’, flower initiation was significantly inhibited by LD under all temperature conditions. This inhibitory effect was stronger at 11°C and 15°C than at 3°C and 7°C. In ‘Cho- etsu’, LD significantly inhibited flower initiation at 3°C and 7°C, and flower initiation rarely occurred at 11°C and 15°C. In this study, generally, LD during vernalization inhibited flower initiation in all cultivars. Thus Japanese bunching onion required a short-day photoperiod in flower initiation, which was stronger in ‘Asagi-kujo’ and ‘Cho-etsu’ than in ‘Kincho’. From these results, we conclude that low temperature and a short-day photoperiod complementarily induce flower initiation in Japanese bunching onion. Varietal differences exist in the requirement of low temperature and a short-day photoperiod: the primary requirement in ‘Kincho’ is low temperature and that in ‘Asagi-kujo’ is a short-day. After flower initiation, the early stage of flower development is day-neutral, and after the floret formation stage, a long-day photoperiod promotes flower development and elongation of the seedstalk.     

分蘖洋葱鳞茎总黄酮提取工艺及抗氧化活性

以分蘖洋葱‘M-3’鳞茎为试材,用超声波辅助提取黄酮类化合物,在单因素试验基础上,采用Box-Behnken响应面法优化分蘖洋葱总黄酮提取工艺,用DPPH法对总黄酮化合物抗氧化活性进行评价。结果表明:最佳提取工艺参数为料液比1∶45 g·mL^-1、乙醇体积分数60%、提取时间40 min、提取温度48℃、超声波功率310 W。在该条件下,分蘖洋葱总黄酮的提取率为3.584%,与模型预测值3.622%相近。分蘖洋葱总黄酮提取物对DPPH·具有一定的清除作用,IC50值为0.179 mg·mL^-1。优选的超声波提取工艺提高了分蘖洋葱总黄酮提取率,具有较强的抗氧化活性。     

The physiology of hyacinth bulbs. XV. The effect of gibberellic acid and silver nitrate on dormancy release and growth

The effect of gibberellic acid (GA₃), supplied to dormant hyacinth bulbs of cultivars ‘Lady Derby’ and ‘L'Innocence’ by vacuum infiltration, on growth and flowering was investigated. Results showed that GA₃ in all applied concentrations (50, 500, 1000 and 5000 mg/l) accelerated growth and flowering in both cultivars, after chilling for 42 days in a garden frame in natural conditions or chilled dry in cold storage at 5°C. Bulb infiltration with 10 mg/l AgNO₃ resulted in the acceleration of flowering only in ‘L'Innocence’, but stimulated the growth of the inflorescence stalk and leaves in both cultivars regardless of the mode of chilling.The infiltration method was confirmed to be very promising.     

Evaluation of onion accessions for resistance to thrips in Brazilian semi-arid regions

This study aimed to evaluate onion accessions regarding their resistance to Thrips tabaci Lindeman, in order to enable the development of cultivars that are resistant to this pest. The experiments were carried out without chemical control, in a randomized block design with three replications, in Petrolina, PE and Juazeiro, BA. Six evaluations of thrips populations were carried out starting 15 days after transplanting, each one after 7 days. Simple correlations were estimated among all variables. Statistical differences were observed for the number of adults in different evaluations, while the number of nymphs showed no statistical differences. The largest average yields of commercial bulbs were observed for ‘Vale Ouro IPA 11?, ‘BRS Alfa São Francisco’, ‘Franciscana IPA 10? and ‘Sirius F1? while ‘Red Creole’, ‘Creole Mercosul’ and ‘Conquista’ had the lowest yield. The bulb commercial yield had simple negative correlations with nymph degree of infestation (DI) in the four evaluation phases and adult DIs at 22 days. Negative correlations between commercial bulb yield and central angle of the plant were observed, indicating that plants with higher bulb yield have a lower angle of the central leaves. The results of the study suggest that the resistance mechanism is due mainly to tolerance to the pest.     

Effect of temperature on bulb growth capacity and sensitivity to summer sprouting in Lilium longiflorum Thunb.

The production of Lilium longiflorum bulbs in The Netherlands, with its cool climate, has been a problem because of unsatisfactory bulb growth and the risk of premature sprouting of the daughter bulbs (summer sprouting). To investigate the possibilities of breeding a type of L. longiflorum that can be grown under cool climatic conditions, a collection of 27 L. longiflorum cultivars from Japan, The Netherlands and the United States was tested, together with two Asiatic hybrids and a L. speciosum cultivar, under low phytotron temperatures (10, 14, 17°C) and in field experiments.‘Mount Everest’, ‘Saeki’, ‘Indian Summer’ and ‘White American’ were among the best L. longiflorum cultivars, with less than 20% summer sprouting and good bulb production. This was in contrast to ‘Hinomoto’, ‘Ace’ and some American introductions, which showed more than 60% summer sprouting and low bulb production. The lower the phytotron temperature, the more summer sprouting occurred. The differences observed between the cultivars in the field experiments were in agreement with those observed in the phytotron. The genetic variation proved large enough to start a breeding program for L. longiflorum adapted to cool climate conditions.     

Artificial cold treatment,gibberellin application and flowering response of kohlrabi (Brassica oleracea L. var. gongylodes L.)

Juvenility, cold requirement and the effect of GA₃-application on flowering have been studied for some cultivars. If present, the juvenile phase was very short. Cold treatment for 8–12 weeks at 4 °C followed by 2 weeks at 10 °C gave flowering in all cultivars. Gibberellin sprays (250 or 500 p.p.m., 3 times) after an incomplete cold treatment promoted bolting and flowering even in the slow-bolting ‘Trero’, having the highest cold requirement.     

红皮洋葱新品种‘紫星’

‘紫星’洋葱是以‘意大利红’（Italian Red）为母本,‘陕西高桩红皮’为父本杂交后,经过连续6代系统选育而成的新品种,属中日照、中早熟类型,生育期230 d。鳞茎厚扁球形,球形指数0.70,鳞茎外皮深紫红色,内部鳞片浅紫色,辛辣味淡,口感脆甜,品质好;平均单球质量316 g,产量79 700 kg ? hm-2,高抗紫斑病、霜霉病。适宜中日照中南部地区秋播早夏收露地栽培。     

Effect of ethephon on bulbing,bull-necking,yield and sprouting during storage of two onion cultivars (Allium cepa L.)

Ethephon at 1 000 and 3 000 mg l^?1 applied either on one occasion or three times at weekly intervals to two onion cultivars reduced average bulb weight and total yield by 14% to 67%. In cv Hygro the percentage of bull-neck bulbs was reduced by ethephon but cv Cepavon was unaffected. The number of bulbs sprouting in store was reduced in both cultivars by all ethephon treatments except the single 1000 mg l^?1 application.     

Accelerated storage losses in onion subjected to water deficit during bulb filling

Withholding irrigation during last stages of onion crops is a common practice to minimize losses in storage due to rots. However, it is unclear whether extended periods of water deprivation may affect bulb postharvest behaviour. In this study we analyze the effects of water deficit during the crop cycle on bulb weight loss and sprouting during storage. Two experiments were conducted: one in a glasshouse with two onion cultivars subjected to three treatments of water availability (100%, 80% and 60% of field capacity); the other in the field, with one of these cultivars, subjected to two water availability treatments (dryland and irrigated twice during bulb filling). In both experiments five destructive samplings were done along crop development to assess plant height, number of green leaves, bulb and neck diameter, and whole-plant dry weight. Bulbs were harvested when 50% or more of the tops fell over. Harvested bulbs were classified by weight and then kept in a ventilated chamber at a mean temperature of 15 °C and weighted every two weeks, up to six months. Water deficit led to a significant reduction of bulb size, an acceleration of sprouting and an increased rate of weight loss during storage in both cultivars and under both experimental conditions. Hence, restricted irrigation during extended periods may have negative effects on the conservation of stored onion bulbs which suggests the need to finely adjust water management in this crop.     

洋葱鳞茎栽植时期对种株生长发育和种子产量及质量的影响

 研究了9月20日、10月10日、10月30日和11月20日4个洋葱鳞茎栽植时期对种株生长发育和种子产量及质量的影响。结果表明,9月20日栽植,虽越冬前植株营养生长旺盛,但翌年春生长势减弱,植株早衰,影响生殖生长;11月20日栽植,则翌年春植株营养生长受抑制,也不利于抽薹、开花、结实;10月10日和10月30日栽植,植株营养生长旺盛,花薹粗壮。种子收获时,9月20日、10月10日、10月30日和11月20日4个栽植日期的单株种子产量分别为8.98、13.74、14.56和11.46g,千粒质量分别为3.86、4.02、4.07和3.95g。此外,不同栽植时期采收的种子发芽势和发芽率也差异显著,各处理的种子发芽势依次为80.2%、90.9%、95.1%和86.2%。表明山东地区洋葱鳞茎的适宜栽植期为10月10～30日。     

Resistance to white rot infections in bulb onion seed lots

Five seed lots and the self- and open-pollinated progenies of the cultivar ‘Ailsa Craig’ were tested for disease reaction to Sclerotium cepivorum, the causal fungus of onion white rot. Field tests were conducted on S. cepjuorum-infested soil in Burnaby, British Columbia, from 1976 to 1980. No significant differences were observed between ‘Ailsa Craig’ and ‘Autumn Spice’ with respect to disease resistance during the 1979 and 1980 tests, whereas resistance of ‘Ailsa Craig’ had been noted in previous years. Tests indicated that resistance varied with seed lot, thus providing a possible explanation for the 1979 and 1980 results. ‘Ailsa Craig’ selfed progeny selection had significantly fewer infections than its parental seed lot and the local recommended cultivar ‘Autumn Spice’. Resistance to infection by S. cepivorum should be assigned to seed lots or breeding lines and not to presently named cultivars. These results suggest that differences in infection by S. cepivorum occur, and are available for the development of white rot resistant cultivars.     

Analysis of genetic diversity among Indian short-day onion (Allium cepa L.) cultivars using RAPD markers.

Summary

Randomly amplified polymorphic DNA (RAPD) markers were used to estimate genetic diversity among 24 cultivars of short-day onions. Total genomic DNA was extracted and subjected to RAPD analysis using 90 arbitrary 10-mer primers. Of these, 15 primers were selected which yielded 137 bands, 91.24% of which were polymorphic. None of the primers produced a unique banding pattern for each cultivar. RAPD data were used to calculate a Squared-Euclidian Distance matrix which revealed a minimum genetic distance between cultivars ‘AFLR-722’ and ‘PBR-140’, and a maximum genetic distance between cultivars ‘PBR-139’ and ‘A.Kalyan’, and ‘MS-48’ and ‘A.Kalyan’. Based on the distance matrix, cluster analysis was done using a minimum variance algorithm.The dendrogram thus generated, based on Ward’s method, grouped the 24 onion cultivars into two major clusters. The first cluster consisted of cultivars from the northern region, and the second of cultivars from the southern region of India. The present study shows that there is high diversity among the onion cultivars selected and indicates the potential of RAPD markers for identification and maintenance of onion germplasm for crop improvement purposes.     

Biochemical changes involved in self-incompatibility in two cultivars of olive (Olea europaea L.) during flower development

Biochemical analyses were carried out to characterise the basis of self-incompatibility in the olive (Olea europaea L.) cultivars ‘Amygdalolia’ and ‘Konservalia’. Multiple interactions between cells of different types, origin, and function occur in the pistil. Endogenous factors play important roles in ovary and fruit development before (Stage 1) and during pollination (Stage 2), and after fertilisation (Stage 3). Changes in carbohydrate, protein, H₂O_2, and calcium ion concentrations, and in peroxidase, catalase, superoxide dismutase, and ascorbate peroxidase activities in pistil tissue before and during pollination, and after fertilisation were investigated. In both cultivars, H₂O₂ concentrations were significantly higher in pistil tissue before pollination, after which they started to decrease in Stage 2 and continued non-significantly in Stage 3. Peroxidase, catalase, superoxide dismutase, and ascorbate peroxidase activities were lower at Stage 1 and Stage 2, whereas these enzyme activities increased at Stage 3 in both cultivars. The lowest concentration of calcium ions was observed at Stage 1, whereas at Stage 2, calcium ion concentrations increased and reached their highest level, then decreased at Stage 3. Calcium ion concentrations in ‘Konservalia’ were higher than in ‘Amygdalolia’. In ‘Konservalia’, the highest protein concentration was observed at Stage 2. No significant differences were found in carbohydrate concentrations between the two cultivars. The biological significance of the presence of these products may differ between Stage 1, when they have a defence function, Stage 2 when there are interactions between pollen and pistil, and Stage 3 after fertilisation. This study provides support for the hypothesis that there is a correlation between self-incompatibility, stress-related enzyme activities, and calcium ion concentrations in the pistils of olive.     

Yields and the extent and causes of damage in cauliflower,bulb onion,and carrot grown under organic or conventional regimes

Summary

The effects of organic vs. conventional growing practices on yield, pest attacks, N uptake, and NO₃^– contents of three vegetable crops were examined. A range of cultivars of cauliflower (Brassica oleracea L. cv. Botrytis), bulb onion (Allium cepa L.), and carrot (Daucus carota L.) were grown organically and conventionally in a sandy-loam soil. Ranking of cultivars according to yield and susceptibility towards insect attack and fungal disease was similar in the two systems. Yields of cauliflower and onion were 20% and 45% higher, respectively, when grown conventionally. No differences in carrot yields and discard rates were observed between the two systems. Generally, the reasons for discarding varied between the two systems. In organically grown cauliflower, damage by slugs was the main reason for discarding, with 9% discarded, while hollow stem was more prevalent in conventionally grown cauliflowers, where 7% was discarded. No statistically significant differences were found between discard rates or causes in bulb onions grown organically or conventionally. Conventionally grown carrots were significantly more damaged by carrot root fly with 5% of carrots discarded, even though the flies were also present in the organic system. In contrast, more carrots with morphological defects were seen in the organic system, where 29% were discarded. The lower yields in organically grown vegetables can be explained mainly by the management practices specific to the organic system that are designed to facilitate weed and pest management. In addition, inadequate early nutrient supply provides a possible explanation for the lower yields in organically grown cauliflowers and onions, as well as the lower planting density of onions.     

Fertilization of special precooled (5°C) tulips for cut-flower forcing

Ca(NO₃)₂ or 20-8.8-16.6 fertilizer applied as aqueous solutions beginning 14 days after planting, or Osmocote (14-6.2-11.6) applied as a surface application immediately after planting tulips, cultivars ‘Apeldoorn’, ‘Golden Melody’ and ‘Orient Express’, decreased flower abortions and increased flower size and fresh weight. Fertilizers had no marked effect on plant height and in most instances small (1–5 days) delays in flowering occurred. Supplementary fertilization of special precooled tulips forced in a soil-based planting-medium will aid in producing high-quality cut flowers. These nutrition experiments also demonstrated that fertilization is absolutely essential for tulip bulbs forced hydroponically in pea gravel.