An analysis of the growth of forced tulips. 1. Changes in plant fresh and dry weights during growth at two temperatures

Changes in the fresh and dry weights of the component parts of plants of tulip cv. ‘Apeldoorn’ were followed in bulbs kept at low and high temperatures (9 and 18°C respectively) from the time of completion of flower differentiation until anthesis.There were marked differences between shoot dry weights at the two temperatures. At 9°C the stem, leaves and flower grew exponentially throughout the whole period, but at 18°C the specific growth rate of the stem and leaves declined throughout the period of the experiment. At 9°C the proportion of total dry weight in shoots and daughter bulbs was higher than at 18°C, and the proportion in the mother bulb was correspondingly smaller.At both temperatures the $\text{fresh weight}\text{dry weight}$ ratios of the mother bulb, shoot and daughter bulbs declined during dry storage, the decline being greater at 9°C. After planting, the ratio for all plant parts increased at 9°C, but scarcely changed at 18°C.These results are discussed in relation to dormancy, to the low-temperature requirement for successful and rapid flowering and to flower quality.     

Post-Harvest Studies on Autumn-Drilled Bulb Onions. The Effect of Harvest Date,Conditioning Treatments and Field Drying on Skin Quality and on Storage Performance

Overwintered onion cvs Express Yellow and Senshyu Semi-globe Yellow were harvested at 80% foliar fall-over (early June) and two and four weeks later, in 1975 and 1976. Plants were conditioned for one (1975) or two weeks (1976) at 20°C, 70% RH or 30°C,60% RH or field dried, and then stored at ambient temperature. Measurements of fresh weight loss during the first six weeks after harvest in 1976 indicated that drying was slow and was incomplete after 14 days conditioning at 30°C. Skin staining and splitting generally increased with delay in harvest date. Skin colour improved with delay in harvest date and with conditioning at 20°C. Wastage due to both rotting and sprouting during storage was generally lower when plants from the first two harvest dates were conditioned at 30°C. These bulbs are likely to be useful for long-term storage as total wastage levels of only 20% were reached in both cultivars after 3-5 months storage. Good field drying of the bulbs could not be consistently obtained and consequently storage performance was more variable than for bulbs conditioned at 20 °C and 30 °C before storage.     

ALCEPAS,an onion growth model based on SUCROS87. II. Validation of the model

Summary

A dynamic simulation model for onion growth at potential production level (ALCEPAS), presented in a previous paper, was validated using data on leaf area index, bulb and green leaf dry-matter production, bulb formation and day of fall-over from independent trials at four locations. The model performance in terms of bulb dry-matter production was good under environmental conditions close to the optimum, but insufficient under stress situations. The model overestimated leaf area index and green leaf dry matter. Bulb formation was simulated satisfactorily, while the time of 50% fall-over was simulated too early at low plant densities.     

The effect of intermittent irrigation with cold nutrient solution on the growth of tomato seedlings propagated in rockwool

Seedlings of tomato, cv. Counter, propagated in rockwool blocks were irrigated five times every 24 h with nutrient solution at 10°C or 18°C for up to three weeks. The mean block temperature was lowered by 3.5-4.0 degrees C by irrigation at 10°C. One week of irrigation at the lower temperature caused the seedlings to develop a characteristic dark purplish colour. This treatment reduced fresh weight and leaf area but not dry weight which suggests that water uptake was also reduced. Dry weight was reduced following two or more weeks of irrigation at 10°C. When seedlings which had been irrigated at 10°C were returned to irrigation at 18°C, the purple colour slowly disappeared and the percent dry matter decreased. When plants were grown on, the total yield of fruit was unaffected by these seedling treatments.     

Analysis of the Growth and Yield of Overwintered Onions

The growth of a number of onion cultivars sown on different dates during late summer in several years was assessed by regular sampling. The growth during the winter of five different winter-hardy cultivars was very similar, whereas that of Rijnsburger Bola, a cultivar normally sown in spring, was clearly slower. Sowing date was shown to affect final yield through its effect on overwintering size, which in turn influenced bulb size at harvest, the proportion of plants which bolted and the extent of winter losses. During the winter months the rate of leaf initiation appeared to be decreased to a lesser extent than the growth in dry weight, which itself was decreased less than growth in leaf area. The growth of the winter-hardy cultivars from all sowing dates and seasons was well summarized by a single linear relationship between the logarithm of plant dry weight and the accumulated day-degrees between 6° and 20°C from the day of seedling emergence. Using this relationship together with temperature records from past years it was possible to estimate the best average sowing date and the year-to-year variation in optimum sowing date. This approach may prove useful in predicting optimum sowing dates for other localities from past weather records.     

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.     

An analysis of the growth of forced tulips. 2. Effects of low-temperature treatments during development on plant structure at anthesis

The effects of different periods of storage at low temperature on some plant parameters were examined at anthesis. The duration of the low-temperature storage affected the time taken for plants to reach anthesis, the stem lengths and shoot dry weights. However, flower size and dry weight scarcely altered with the duration of treatment.Despite large differences in the dry weights of the plant components at anthesis following different periods of low-temperature storage, the ratio of total plant dry weight at anthesis to the initial bulb dry weight at the commencement of treatment remained almost constant. Anthesis occurred in all treatments when the total plant dry weight fell to 70% of the original bulb mass.It is possible to relate flower quality to the fresh to dry weight ratio of the flower.     

The effects of pre-harvest dehydration on the composition of once-over harvested sweet paprika

When paprika fruits (Capsicum annuum L.) were allowed to dry in the sun, on the plant itself, before harvest, there was a considerable increase in the dry matter content of the subsequently harvested fruit, along with a decrease in the total fresh yield. The dry matter yield did not vary during the drying period, but the colour intensity of the fruit increased continuously. Early cessation of irrigation accelerated the drying rate and intensified fruit colour, but lowered the total dry matter yield.Removal of seeds, placenta parts and stalk after harvest increased fruit colour intensity but lowered yields.Leaving fruit to dry in the sun before harvest resulted in a considerable saving in transport and storage volume, as well in the amount of energy required otherwise to dry the fruit in the dehydration plant. It also opens up possibilities of once-over mechanized harvesting of high quality fruit.     

Influence of planting geometry on growth,yield and quality of rainfed garlic (Allium sativum L.) cultivated under Mediterranean conditions

Summary

The establishment of the optimum plant population has been shown to be one of the most crucial determinants of the marketable yield of bulbous crops. This study was conducted to determine the best plant arrangements for maximum yields and maximum bulb quality in rainfed garlic (Allium sativum L.) grown under Mediterranean conditions. The effects of row width and plant spacing on the yield and quality of the two cvs. Morado de Pedroneras and Germidour, were investigated on Córdoba, Spain, in Vertisol Chromoxerert soil. In 1987–1988, a wet growing season, higher yields and higher bulb quality were obtained than in 1988–1989; cv. Germidour yielded more per unit of land area of higher quality bulbs during both seasons. Narrow row width and/or narrow plant spacing resulted in higher values of dry matter, LAI, LAD, CGR and yield, whereas wide row spacing and/or wide plant spacing resulted in higher ware-sized bulb yield. LAD was closely related to yield (r² = 0.96**) and total dry matter (r² = 0.90**). Mean leaf surface was affected by plant density and climatic conditions and showed a high positive relationship (r² = 0.90**) with the percentage of Extra grade of bulbs (>50 mm). As a result of this study, a row width of 45–60 cm with plant spacing of 12–16 cm is recommended for cv. Germidour and 45 × 16 cm for cv. Morado, to maximize the proportion of high-quality yield under Mediterranean rainfed cropping systems.     

Physiological response of onion plants to foliar application of putrescine and glutamine

Two field experiments were carried out in Egypt during two successive seasons (2007/2008 and 2008/2009). This study aimed to investigate the response of growth, yield quality and some metabolic constituents of onion (Allium cepa L. cv. ‘Giza 20’) to foliar application of putrescine (Put; 25, 50 and 100 mg L⁻¹) and glutamine (Glut; 50, 100 and 200 mg L⁻¹), the former a diamine and the latter an amino acid, either alone, or in combination. Foliar application of Put and Glut, either alone or in combination, significantly increased plant height, number of leaves, fresh weight of leaves/plant, fresh and dry weight/plant, leaf area, leaf area/plant, bulb length, bulb diameter and weight, as well as yield of onion and quality of bulbs. Total soluble sugars, sulfur compounds, total soluble phenols, total free amino acids and total photosynthetic pigment content in leaves were increased by increasing Put and/or Glut concentrations up to 100 and 200 mg L⁻¹, respectively. Generally, foliar application of Put at 100 mg L⁻¹ and Glut at 200 mg L⁻¹ singly, or combined, effectively increased bulb yield and quality. In conclusion, the yield-contributing characters and quality of onion could be improved by application of Put and/or Glut.     

热处理对自繁百合种球生长的影响

以东方百合围径为6~9 cm的自繁种球为试材,采用热水处理的温度分别为39℃和40℃,分别浸泡1.0、1.5、2.0 h,研究其对根螨的灭杀效果及对种球生长的影响,以期为热处理技术在百合种球生产上的应用提供参考。结果表明:在栽种期和采收期,经过不同热处理种球的带虫率显著低于对照(CK)。仅在40℃热处理2.0 h,褐变率为2%,其它处理褐变率均为0%;各处理在膨大期其株高、第一节茎粗、地上部干物质含量,在采收期其地下部鲜质量与鳞茎围径都高于CK。其中39℃热处理2.0 h及40℃热处理1.5 h效果最好;在新鳞茎形成初期,各种热处理组合与CK的淀粉含量相近;从新鳞茎形成期到膨大后期淀粉含量迅速增加,40℃热处理1.5 h在新鳞茎膨大前期开始淀粉含量就高于其它处理,其次是39℃热处理2.0 h,CK淀粉含量最低。40℃热处理1.5 h,新鳞茎的可溶性糖含量从鳞茎形成期到采收期一直高于其它的热处理组合及CK。     

Plant carbohydrate partitioning of Lachenalia cv. Ronina during bulb production

Carbohydrate partitioning was investigated in different plant organs of Lachenalia cv. Ronina during bulb production under a low temperature regime. At 4-week intervals, data were collected on bulb, roots, leaves, inflorescence and carbohydrate composition. The roots and especially the bulb were found to be the main starch sinks of the plant, whilst the leaves and the inflorescence were the main source for soluble sugars. Changes in the starch concentration closely followed dry weight changes in the bulb during the growing season. When bulbs were initially exposed to a low temperature, starch was converted to soluble sugars, but thereafter sugars were low, indicating continued export and conversion to starch. Low sugar levels in the leaves and high levels in the inflorescence, with continuous starch increase in the bulb and roots, probably indicate that the inflorescence, but especially the leaves, produced ample photosynthates during the growing season.     

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.     

In vitro morphogenesis and growth of Narcissus in response to temperature

In vitro morphogenesis and growth of tissues of the Narcissus cultivar ‘Lord Nelson’ have been assessed in constant and alternating temperatures. Tissue of leaf-base and scape origin, producing leafy shoots and bulblets on a defined sterile medium, were grown at constant and alternating temperatures of 15, 20, 25 or 30°C and 15–25 or 20–25°C, respectively, in a 16-h daily photoperiod. The number of leaves, leaf length, volume of tissues, fresh weight (but not percentage dry matter), and the number of shoots that would ultimately produce bulbs, were maximal at a constant temperature of 25°C as compared with all other temperature-regimes tested.     

Effects of Temperature on the Growth of Corchorus Olitorius

Controlled environment experiments were conducted using base-line growth study conditions to evaluate the responses of cvs Angbadu and Yaya of Corchorus olitorius, a tropical leafy vegetable, to day/night temperatures of 25°/20°, 30°/25° and 35°/30°C. Some of the parameters studied were greatest at 35°/30°C and least at 25°/20°C for both cultivars. Dry weights of both cultivars increased with rising temperatures during the first 21 days after emergence, and the greatest leaf area was at 30°/25°C for both. The nearest to the optimum temperature regime for this species was 30°/25°C. Based on leaf area at any temperature, cv Yaya would be preferred, but its superiority over cv Angbadu as indicated by dry weight is due to some extent to its greater stem length which is not composed of nutritionally important tissue.     

High-Temperature Treatment (Blindstoken) of Bulbs of Tulip cv Rose Copland for Flower Killing and Yield Improvement

A three-year experiment on the high-temperature treatment of tulip bulbs established that yield could be increased by between 8 and 31 % for bulb weight or between 14 and 29 % for numbers of large bulbs, depending upon season, associated with a near-complete flower kill. The optimum pre-treatment storage temperature was 17°C, and the best date (of the five tested) for starting blindstoken at 33°C for one week was 20th-21st September.

Yield increases were greater when the blindstoken treatment was applied to bulbs whose shoots were short; later treatment, or treatment after pre-treatments which allowed faster shoot growth, were less effective. For optimum flower kill and yield increase the shoot should be about 1 cm high at treatment. Bulb weight and large bulb number were correlated, suggesting that the treatment increases total bulb weight by increasing bulb size rather than by differentially affecting the growth of daughter bulbs.

No adverse effects of the treatments were observed when the bulbs were forced in a glasshouse the following season.     

极早熟辣椒新品种博辣娇红的选育

博辣娇红是以SF-11为母本、H2887为父本配制的一代杂交组合。该品种极早熟,第一花节位7~8节,果实羊角形,青果浅绿色,果长20㎝左右,果宽1.3㎝,平均单果质量12g左右,果表光亮微皱,皮薄,味辣,风味好;早期产量为1100㎏/667m2左右,总产量2500㎏/667m2左右;果实红熟快,海南地区从播种到采收红椒约70d;连续坐果能力强,早熟不早衰;抗炭疽病、疫病、病毒病;适于嗜辣地区作极早熟大棚或露地栽培、秋延栽培,辣椒果实可鲜食、加工、干制。     

Effects of N–P–K deficiency and temperature regime on the growth and development of Lilium longiflorum ‘Nellie White’ during bulb production under phytotron conditions

One-year-old scale bulblets of Lilium longiflorum Thunb. ‘Nellie White’ (Easter lily) were grown under a combination of six constant day/night temperature regimes and five N–P–K nutrient treatments under short days for 107 d (growing period 1 or GP-1) to compare the effects on growth and development and bulb production. Results during GP-1 were as follows: failure of bulblets to produce a shoot (“no-shows”) was found at high temperatures (30/26 and 26/22 °C) and not influenced by the nutrient treatments. Flower bud abortion was observed in the minus-N, minus-P, and minus-N–P–K treatments at high temperatures (30/26 or 26/22 °C), but not observed at any temperatures in the complete and minus-K treatments. The loss of bulb fresh weight in minus-N treated bulblets was less than in the other treatments resulting in less root and shoot growth in the minus-N treatment. At the intermediate temperatures where growth was highest, omission of N, P, K, or all three resulted in losses in stem bulb fresh weight, stem plus leaf fresh weight, number of flowers, and stem root fresh weight. Omission of N, P, or all three nutrients resulted in lowest basal root fresh weight. Bulb N and K concentrations were lowest in plants grown with complete nutrient solution at the two coldest temperature regimes (14/10 and 10/6 °C). Bulb P concentration was lowest at the three coldest (18/14, 14/10 and 10/6 °C) and the warmest (30/26 °C) temperature regimes. Stem length was shorter when P was omitted. Omission of any of the three nutrients resulted in lower concentrations of the other nutrients. The one exception was where low K did not affect N concentration. In the second phase of the experiment, plants grown at 18/14 °C and irrigated with the complete nutrient solution for 107 d (GP-1) were continued at this day/night temperature regime and five N–P–K nutrient treatments for another 89 d under long days (growing period 2 or GP-2). Results during GP-2 were as follows. Basal bulb yield was not impacted by omission of N, P, or K, or all three. Of all growth measurements, only stem plus leaf fresh weight was lower and only when all three nutrients (minus-N–P–K) were omitted. At the end of GP-2, basal bulb concentrations of N and P did not differ from the concentrations in bulbs at the beginning of GP-1; however, K concentration was lower at the end of GP-2. Omission of N or P further resulted in lower bulb K concentration, suggesting that a moderate supply of N, P, and K be applied during GP-2 since an additional year of bulb production is needed to produce forcing-sized bulbs.     

利用柠条粉发酵料作为育苗基质对甜瓜幼苗质量的影响

以柠条粉发酵料为原料作为育苗基质,以现有育苗基质为对照,通过幼苗生长发育、干物质积累等指标,比较分析柠条粉基质育苗效果。结果表明:柠条粉基质幼苗株高、茎粗、根长、叶片数、地上部鲜质量、地下部鲜质量、全株鲜质量、地上部干质量、地下部干质量、全株干质量和根冠比等生长发育指标与壮苗二号基质幼苗趋于一致,且在出苗后30 d时,柠条粉基质幼苗壮苗指数高于壮苗二号基质幼苗壮苗指数12.12%,该试验结果为柠条粉基质应用及新基质开发提供了参考。     

高温胁迫对辣椒幼苗生长及生理性状的影响

以耐热品种B34和热敏品种B6幼苗为试材,对高温胁迫下辣椒幼苗形态性状及生理特性的变化进行比较分析。结果表明:辣椒不同耐热品种在高温胁迫下,幼苗的茎粗、鲜重和干重无明显差异,株高和根长差异显著,在处理第7天时,耐热品种B34的株高和根长分别比对照降低了6.9%和10.86%。而热敏品种B6的株高和根长分别比对照降低了10.78%和17.8%。不同耐热品种幼苗热害指数随高温胁迫时间的延长而逐渐升高,叶片含水量无明显差异,叶绿素含量逐渐降低,根系活力、POD活性先升高后降低,其中热敏品种比耐热品种表现更为明显。