Cultivar and temperature effects on starch in the primary thickening meristem of onion bulbs

Summary

The effect of cultivar and temperature on the temporal pattern of starch occurrence in the primary thickening meristem (PTM) of onion (Allium cepa L. var. cepa) bulbs was studied. Bulbs of four cultivars differing in their sprouting behaviour in dry storage were analysed during bulb development for the concentration of starch in the PTM and inner sprout growth by histochemical analysis and determination of leaf ratio, respectively. Generally, in all cultivars the concentration of starch in the PTM was high during active growth, decreased to a low value during sprout dormancy, and increased before or concomitant with inner sprouting. The duration of the low starch period varied between cultivars. If onions were stored at low (18C), intermediate (158C), or high (308C) temperature, inner sprouting was delayed at low and high temperature compared with the intermediate temperature, whereas starch increased before sprouting at low and intermediate temperature, but became undetectable at high temperature. Moreover, if benzyladenine was injected into onions stored at high temperature, sprouting was readily induced, but starch in the PTM remained undetectable and no root initiation occurred. Since the PTM is not only responsible for the stem thickening but also for root initiation we conclude (i) that low starch in the PTM primarily indicates root dormancy and only indirectly sprout dormancy, and (ii) that high temperature-imposed sprout dormancy is actually based on root dormancy.     

甘肃酒泉油桃越冬抽条程度的调查

通过对不同生态条件下栽培的油桃及间作不同作物的桃园调查看出：甘肃酒泉栽培油桃，越冬后有不同程度的抽条现象。浇水多、不施肥会使抽条加重；新梢生长量大于120cm或短于40cm及枝条过稀、过密也会加重抽条程度。埋土防寒保护越冬方法好，但树大难以实施。桃园间作小麦、西瓜和棉花者抽条重，间作毛叶苕子或不间作则抽条轻。秋季控水，控制新梢生长量使枝条充实，休眠期在枝条上涂油及缠塑料条均有保护越冬的作用，     

Temperature influences nutrient absorption and uptake rates of bananas grown in controlled environments

We explored the influence of temperature on the concentration of nutrients in banana plants, the nutrient uptake rate, apparent root transfer coefficient ($\text{}\text{?}$ga) and the relationship between accumulation of dry matter and nutrient. Young banana plants (Musa (AAA group, Cavendish sub-group) ‘Williams’) were grown at six temperature regimes (17/10–37/30°C) in sunlit growth chambers for 12 weeks.The amount of nutrient absorbed was influenced by the amount of growth made, but the link between the two differed from one element to another. Temperatures less than $\text{29}\text{22°}\text{C}$ reduced the concentration of all elements in the whole plant, except Fe.Temperature influenced the root uptake rate of B 10-fold; K, Na, Ca, Fe and Zn 3–4-fold; and N, P, Mg, Mn, Cu, Cl 1–2-fold. Among the elements the highest recorded rate was 12 mg g^?1 day^?1 for K at $\text{33}\text{26°}\text{C}$. The optimum temperature for nutrient uptake rates differed among the elements. This was accounted for largely by greater growth at those temperatures of organs with high concentration of particular elements.The $\text{}\text{?}$ga (an estimate of efficiency of uptake) of B varied 12-fold among treatments; K, Ca, Mg, Na, Mn, Zn and Cl varied 3–5- fold and N, P, Cu and Fe varied 2–3-fold.The ratio of relative nutrient accumulation rate, R_m, to the relative growth rate, R_w, was most stable across temperatures for N and least stable for B and Na. However, the trend was for $\text{R}{}_{\mathrm{<mtext>m</mtext>}}\text{R}{}_{\mathrm{<mtext>w</mtext>}}$ to increase as temperature rose, indicating an absorption of nutrients greater than might be expected from a change in growth rate as temperature increased, and a decreased efficiency in their utilization for plant growth.     

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.     

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.     

黄花菜花莛剪截促芽扦插育苗试验

利用塑料大棚和露地黄花菜采摘后的花莛,采用剪段、促芽、短截3种不同扦插育苗方式,在田园土加河砂、田园土加草木灰2种基质中进行扦插育苗试验。结果表明,塑料大棚黄花菜花莛剪截促芽扦插育苗是最佳扦插育苗方式。     

Effect of set-size and storage temperature on bolting,bulbing and seed yield in two onion cultivars

The effects of three set-sizes (12.5, 17.5 and 22.5 mm in diameter) and seven storage temperatures (0, 5, 10, 15, 20, 25 and 30 °C) on bolting, bulbing and seed yield in two onion (Allium cepa L.) cultivars ‘Hygro’ and ‘Delta’ were investigated. The incidence of bolting increased linearly with set-size and curvi-linearly with decreasing storage temperature. Time to inflorescence emergence and floret opening showed a curvi-linear response to storage temperature with the earliest inflorescence emergence and floret opening occurring at 5 °C and the latest at 30 °C for ‘Hygro’ and at 25 °C for ‘Delta’. Seed yield per umbel also showed a curvi-linear response to storage temperature with the lowest seed yield occurring at 30 °C for ‘Hygro’ and at 25 °C for ‘Delta’ and the highest seed yield at 5 °C. For a seed crop, storage of large sets (22.5 mm) of these cultivars at 5 °C for 120 days appeared to be optimum with 5–12% higher seed yield per umbel than that of 90 days storage. Bulb yield showed a curvi-linear response to storage temperature with the highest bulb yield occurring at 25 °C and the lowest at 5 °C.     

Effect of cold temperature durations of onion sets in store on the incidence of bolting,bulbing and seed yield

The experiment was conducted at the experimental area of the School of Plant Sciences, University of Reading during 1996. The planting material comprised of sets (graded to 22.5 mm diameter) of two cultivars, Hygro and Delta. The sets were stored at 5 °C for nine chilling durations, between 10 and 90 days. A control treatment (sets stored at room temperature of 20 °C for days) was also included in the experiment for comparison. Sets of both cultivars treated for 90 days at 5 °C, produced nearly seven times more bolters than those treated for 20 days. Cool temperature treatment for 10 days was too short to induce bolting. Number of florets and percentage of seed bearing florets per umbel increased with lengthening cold durations and this resulted in higher seed yield per umbel. Mean bulb weight per plant was found to increase with shortening the period of low temperature treatment. For bulb crop, storage of sets at 20 °C for 90 days appears to be optimum, as it checked bolting and increased average bulb weight and bulb yields m⁻² in both cultivars.     

Effect of photoperiod and temperature on inflorescence appearance and subsequent development towards flowering in onion raised from sets

The plants of two onion cultivars Sturon and Stuttgarter were raised from sets and placed in a growth room at 12 °C, a light flux density of 120 μmol m⁻² s⁻¹ and a 16 h photoperiod. Cultivar Stuttgarter took 195 days to initiate, whereas time for initiation in cv. Sturon was 201 days. After initiation the plants were transferred to wide range of photo-thermal regimes consisting of six set point temperatures (6, 10, 14, 18, 22 and 26 °C) and four photoperiods (8, 11, 14 and 17 h day⁻¹). An overall mean temperature for all developmental stages under each photo thermal combination was 12.2, 12.4, 15.9, 17.8, 23 and 24.4 °C. Time to inflorescence appearance, spathe opening and floret opening decreased linearly as temperature and photoperiod increased. At low to mild temperatures (12.2–17.8 °C), longer photoperiod enhanced florets per umbel, whereas at higher temperatures (23–24.4 °C), the floret number declined with lengthening photoperiods. As the photoperiod extension in each temperature advanced inflorescence appearance, spathe opening and floret opening and this would be beneficial in a programme to accelerate seed production in onion.     

Storage capability at different temperatures of lemons grown in Israel

For prolonged storage of lemons, the best temperature to avoid rots and physiological disorders such as internal browning and peel pitting, was 14°C; for short periods only, storage at lower temperatures, 2–8°C, did not cause damage. Physiological disorders appeared in storage earlier, the lower the storage temperatures, and in fruit picked at a less ripe stage. The general appearance of the fruit is better when stored at the lower temperature. Color development, chemical changes, weight loss, respiration rate and ethylene evolution during storage of lemons at different temperatures and stages of maturity were examined.     

Effects of post-harvest storage conditions on the levels of glucosinolates in broccoli sprouts (Brassica oleracea var. italica) grown under different temperature regimes

Summary

Broccoli sprouts have been recognised as a rich source of glucosinolates, particularly 4-methylsulphinylbutyl glucosinolate, the precursor of the potent anti-cancer compound, sulphoraphane. Previous results have shown that temperature can significantly affect the levels of glucosinolates. In this study, we showed how sprout age and storage temperature affected glucosinolate levels in broccoli sprouts grown under different temperature regimes. Experiments were conducted in growth cabinets with day/night temperature regimes of 30°/15°C, 22°/15°C and 18°/12°C. At 9, 10 and 11 d after sowing in the first temperature regime, 10, 11 and 12 d in the second, and 12, 13 and 14 in the third, sprouts were submitted to 4°C or 20°C to simulate refrigerated and room temperature storage. Sampling was done after 1 d or 2 d of exposure to these conditions. The results showed that total glucosinolate levels and the potential health effects of broccoli sprouts depended on the growth temperature regime (P < 0.05), the age of the sprouts (P < 0.001), and the storage conditions (P < 0.01). The highest total glucosinolate levels (65.7 µmoles g^–1 dry weight) were obtained under the 30º/15°C temperature regime for the youngest sprouts (harvested 9 d after emergence), after being submitted to a storage temperature of 4°C for 24 h. However, these levels were much lower than in 3-d-old sprouts. Consuming old sprouts provides less health-protective effects due to reduced levels of glucosinolates.     

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.     

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.     

Substrate temperature fluctuation and dry-weight partitioning of Lantana grown in four green roof growing media

Summary

Four potential green roof substrates were evaluated in a field study for their thermal characteristics and their impact on Lantana camara dry-weight accumulation. The substrates were a) a sandy loam soil (S), b) the sandy loam soil amended with urea formaldehyde resin foam (S:F) at a proportion of 60:40 v/v, c) the sandy loam soil mixed with peat and perlite (S:P:Per) at a proportion of 50:30:20 v/v, respectively and, d) peat amended with urea-formaldehyde resin foam (P:F) at a proportion of 60:40 v/v. Measurements included the monitoring of the substrate temperature and the determination of the dry-weight accumulation rhythm of shoots, leaves and roots. In addition, the lateral spreading of the roots was recorded and the shoot/root ratio determined. Temperature fluctuation within the substrates was found to depend on the type of the substrate, plant growth, and season. Temperature fluctuation was high in S, moderate in S:F and S:P:Per and low in P:F. Shoot and root dry-weight accumulation was reduced in P:F, while root growth was promoted in S substrate. Differences in dry-weight accumulation and the lateral spreading of the roots were affected more by the water holding capacity of the substrate than by the substrate temperature.     

不同地区酿酒葡萄成熟度与葡萄酒质量的研究

含糖量、糖／酸是酿酒葡萄的成熟度指标，决定着葡萄酒的质量，适期采收能达到葡萄酒质与量的统一，成熟期昼夜温差、降水量的不同是造成陕西丹凤、陕西杨陵、甘肃武威三地区葡萄成熟度差异的主要原因，并导致葡萄酒质量的差异。在武威生态条件下，雷司令最佳成熟度的含糖量和糖／酸分别为１９９．２ｇ／Ｌ和２６．４９，法国兰分别为１９４ｇ／Ｌ和２７．２。     

不同土壤水分条件下草莓果实在模拟贮运中的损伤易感性

通过模拟运输振动实验研究了种植在不同土壤水分条件下草莓果实在贮运中的损伤易感性。试验结果表明,栽培在较高土壤水分条件下的果实含有较高的水分,贮运中果实损伤易感性与果实含水量、果实鲜重、土壤湿度呈显著或极显著相关。模拟振动实验发现:在高土壤水分条件下栽培的草莓果实在振动前、振动后及贮藏后的呼吸速率分别为生长在低土壤水分果实的124.9%、119.0%和133.2%。振动的果实比未振动的果实降低了28%-36%的蔗糖,增加了4.5%-9.8%的果糖和7.1%-10.1%葡萄糖,说明运输振动促进了蔗糖降解为葡萄糖和果糖的水解过程。     

Effect of precooling at 5 or −1°C on shoot growth,flowering and carbohydrate metabolism in tulip bulbs

Precooling of dry tulip bulbs at ?1°C may be advantageous, compared with precooling at 5°C. Increasing the duration of precooling enhanced the growth of the shoots after planting, improved flower quality, and reduced the number of days to flower. The positive benefit of a stepwise precooling (5°C for 3 weeks, then ?1°C) was evident.Shoot elongation was promoted, and number of days to flower was reduced when the bulbs were precooled at ?1°C for less than 12 weeks. Extension of precooling beyond 12 weeks, however, was more effective with 5°C precooling. With few exceptions, sufficient precooling at either 5 or ?1°C gave a high percentage of flowering plants with first-quality flowers. Short durations (6–8 weeks) of precooling sometimes promoted flower blasting.Precooling at 5 or ?1°C had a similar effect upon the carbohydrate interconversion in scales and shoots of the bulbs, which as a rule is more pronounced at the lower temperature. The shoots accumulated sucrose, and to some extent fructosyl sucroses, during the 15 weeks precooling. Starch was also accumulated, the highest concentration being obtained at 5°C. The amount of starch was reduced in the scales during precooling, while the concentration of sucrose and fructosyl sucroses increased to a maximum value and then slowly diminished after about 9 weeks of precooling. The monosaccharides, glucose and fructose showed very small variations.     

Comparison of changes in sugars and ethylene production of cherimoya fruit grown at different seasons

Summary

Changes in fruit weight, total soluble solids (TSS), sugar content and postharvest ethylene production during fruit development were compared on fruit of cherimoya (Annona cherimola Mill., cv. Big Sister) pollinated at different times (early, at the beginning of April, 1995 and late, at the end of May, 1994). Fruit weight increased by growth, independently of pollination times. Changes in TSS and sugar content were strongly affected by pollination time. In late pollinated fruits, both TSS and sugar content increased during the growth period, 110–160 d after pollination, while neither increased with fruit growth in early pollinated fruit. Moreover, changes in TSS and sugar content after ripening depended not only on pollination time but also on the growth period. With late pollination, fruit harvested after 140 d became edible after ripening. The TSS and total sugar contents, (the sum of fructose, glucose and sucrose contents) increased to about 20° Brix and above 16%, respectively. But early pollinated fruits were not edible after ripening, since total sugar content increased only to about 7%, even though they kept growing for 160 d on the tree. The maximum rate of ethylene production declined and the number of days to the ethylene peak from harvest is also reduced with growth in both cases. These changes were closely correlated with days after pollination (r>0.9) regardless of pollination time. Comparisons of accumulated temperature suggest that temperature at pollination time and during the resting period of growth affected fruit development. These results indicate that neither fruit weight nor number of days after pollination is a suitable index for harvesting time.     

不同环境栽培空心菜、薄荷的生长量及养分吸收量比较分析

为探讨空心菜和薄荷在不同种植环境下的作物生长量和养分吸收量,选择入星云湖河水及其附近农田为种植载体,开展空心菜、薄荷的漂浮水栽与土栽的比较试验.结果表明,空心菜水栽的植株高度、分枝数及茎叶产量分别为41.3 cm、6.2个及4.17 kg·m-2,比土栽的提高45.9％、37.8％及59.8％;水栽空心菜的茎叶全N含量...     

枸杞采后病害及主要病原真菌的分离与鉴定

本文对枸杞采后病害进行了分离、鉴定的研究。从病害的枸杞中分离得到了5株真菌菌株,回接后,发现病害与自然发病症状一致,而且从接种的枸杞果实上又得到了此病病原真菌,经鉴定和致病性确定,确定为真菌：青霉属、链格孢属、曲霉属中的黑曲霉、木霉属、黄曲霉,它们都是该品种枸杞的主要致腐病原真菌。