Leaf production and curd initiation of winter cauliflower in response to temperature

Summary

In experiments in 1994 and 1995 a range of transplanting dates and thermal crop covering treatments were used to produce different environmental conditions for the growth of two Roscoff cauliflower selections ‘December/January’ and ‘March’. In 1994 non-covered plants of ‘March’ initiated on average 19 d later and with 19 leaves more than ‘December/January’. In the two seasons, covering the crops gave delays in curd initiation of up to 93 d, depending on planting date, and increased the number of leaves produced by up to 50 compared with non-covered crops. Leaf production was best described by an accumulated effective day-degree scale using day-degrees <17°C for ‘December/ January’ and day-degrees <16°C for ‘March’. This shows that both light and temperature are concerned with controlling leaf production. During the juvenile phase of growth, apex diameters expanded linearly with temperature up to a diameter of about 0.2 mm. After this there was a different response to temperature suggesting that a phase change had occurred at an apex diameter of 0.2 mm. When this occurred numbers of leaves ranged from 23 to 28. Vernalization appeared to occur most rapidly in ‘December/January’ between 12 and 16°C with an optimum at about 14°C while in ‘March’ the optimum appeared to be slightly lower than this. Any increase in time spent at temperatures in excess of 16°C delayed curd initiation.     

Modelling development of broccoli (Brassica oleracea L. var. italica) from transplanting to head initiation

Summary

A model is suggested to predict head initiation in broccoli. Head initiation is defined as the time when the apex diameter reaches 0.6 mm and predictions are made from observations of air temperature. The model is constructed from three years of field experiments with three cultivars and four plantings per year. No juvenile phase after transplanting could be estimated and the model consists only of a head induction phase starting at transplanting. The rate of head induction is modelled by a piecewise linear temperature response function with a base, optimum, and maximum temperature. At optimum temperature the duration of the head induction phase is shortest. The estimates for base, optimum, and maximum temperature are 9.98C, 16.18C and 22.38C, respectively. The estimates for cultivar dependent thermal time requirements are 49 day-degrees, 55 day-degrees, and 38 day-degrees for cvs Caravel, Shogun and Emperor, respectively. The three cultivars were anticipated to have the same cardinal temperatures for head induction. The model of the head induction phases can account for 68% of the variation in the observed durations from transplanting to head initiation. A model of leaf appearance is used to standardize transplant size to four visible leaves at planting. The leaf appearance rate is described by a linear relationship to number of leaves and air temperature and the model can account for 89% of the variation in time from transplanting to appearance of a certain number of leaves. The temperature response of leaf appearance rate had a base temperature of about 2 to 38C, depending on cultivar, and showed no indications of having a temperature optimum below 208C. The leaf appearance rate at 158C range from 0.2 leaves per day for plants with four visible leaves to 0.4 leaves per day for plants with 14 visible leaves.     

A model of cauliflower curd growth to predict when curds reach a specified size

A simple model is described which predicts when curds of any specified size will be produced. The model uses a quadratic relationship between the logarithm of curd diameter and accumulated day-degrees >0°C from curd initiation. Work in controlled environment cabinets showed a linear relationship between early curd growth rate and temperature between 8°C and at least 18°C, and that the base temperature for curd growth was 0°C. Data from samples taken after curd initiation are used to predict the number of day- degrees required for the crop to reach a specified size. This requirement is then converted into a predicted date by using long-term average weather data. This prediction can be updated progressively to take account of observed weather data where these deviate from average weather. Differences between the fitted relationships for different sites, years, transplantings and cultivars are discussed and data are presented showing the results of validation of the model.     

The influence of transplant age and nutrient feeding regime on cauliflower growth and maturity

Summary

Similar experiments in 1984 and 1985 examined the effects of cauliflower transplant age and ‘high’ or ‘low’ nutrient feeding regimes during plant.raising on the numbers of leaves formed, the timing of curd initiation, maturity and other maturity characters. ‘High’ nutrient feed contained 104 mgl^?1N and 290 mgl^?1K whereas ‘low’ nutrient feed contained 52 mg l^?1 N and 145 mg l^?1 K. In addition, in 1985 the growth of other ‘low-feed’ plants was boosted by giving them ‘high feed’ during the last four days before transplanting. The raising treatments produced transplants which differed in dry weight, in the numbers of leaves formed and especially in dry-matter percentage. In both years the oldest ‘low-feed’ plants had the highest dry-matter percentage at transplanting (mean 22.2%) whereas the youngest ‘high-feed’ plants had the lowest dry-matter percentage (mean 12.9%). After transplanting, differences between treatments rapidly disappeared and there were few significant effects of treatments on the time of curd initiation, the final number of leaves formed, the time of 50% curd maturity and marketable curd yield. It is concluded that when planning cauliflower continuity schedules the time of transplanting is important but the precise age of plants at transplanting and the feeding regime prior to this need not be taken into account provided plant size is kept within normal limits.     

播种期和品种对早熟花椰菜植株生长及异常花球的影响

对3个早熟花椰菜品种进行播种期试验,调查花球形成时植株的生长情况、从定植到花球开始形成的时间和从定植到采收的时间、异常花球种类和发生率。结果表明,随着播种期的推迟,花椰菜植株在花球形成时的最大叶长、叶宽和株高呈明显上升的趋势,花球开始形成时的叶片数则随着播种期的延迟而呈现下降的态势。播种期对花椰菜从定植到花球开始形成的时间以及从定植到采收的时间有显著的影响。花椰菜平均花球质量随着播种期的延迟而呈现上升的趋势,并于适宜播种期达到最大,之后再次下降。花椰菜异常花球包括毛花球、夹叶球、小球、未结球等类型,其发生率和发生的种类随播种期和品种的不同而发生规律性变化。     

The development and evaluation of techniques to predict when to harvest iceberg lettuce heads

Twenty-seven crops of iceberg lettuce, cv. Saladin, were grown in 1988 and 1989 at four sites and sampled twice weekly to study heart growth under a range of environmental conditions. The aim of the work was to develop a technique to predict when heads reached a specified weight or size. Changes in heart fresh weight were best described by a Gompertz curve using effective day-degrees from transplanting as the explanatory variable. Changes in heart diameter were best described by a logistic curve using effective day-degrees from transplanting as the explanatory variable. The accuracy of prediction of the day of maturity was tested on nine independent crops using four mechanistic models describing heart growth and four other empirical models based on the duration of crop growth from transplanting. The deviations of actual from predicted dates of maturity were smaller using the simple empirical models based on days, day-degrees and effective day-degrees from transplanting than using the more general mechanistic models based on heart fresh weight or diameter. This suggests that heart formation and growth is affected in a complex way by environmental conditions during growth.     

A hypothesis to explain the relationship between low-temperature treatment,gibberellin activity,curd initiation and maturity of cauliflower

The effects of cold-treating young cauliflower plants (Brassica oleracea var. botrytis L.) of the cultivars ‘Lero’, ‘Lawyna’, ‘Novo’ and ‘Janavon’, on gibberellin activity and the spreads of curd initiation and maturity are described and discussed in relation to other similar work.Exposure of plants to 0°C for 15 days increased gibberellin activity in the apices of ‘Lero’ and ‘Lawyna’ plants. The spreads of curd initiation and maturity of ‘Lawyna’ were significantly reduced by cold-treatment at 0°C, but ‘Lero’ was not affected, possibly because plants had initiated too many leaves and were thus beyond the stage receptive to low-temperature treatment. This treatment had no effect on gibberellin activity nor on the spreads of curd initiation and maturity of ‘Novo’ or ‘Janavon’, probably because plants had not reached the sensitive stage when cold-treated.It is postulated that the phase of growth during which the curd-initiation period can be shortened by cold treatment is specific for each cultivar, and other data were used to confirm this. It seems likely that the receptive phase occurs at higher leaf-numbers with cultivars which take longer to initiate curds.     

Effects of CO2, temperature and their interaction on the growth, development and yield of cauliflower (Brassica oleracea L. botrytis)

Stands of summer cauliflower were grown within polyethylene-covered tunnels along which a temperature gradient was imposed. Two tunnels were maintained at either normal or elevated CO₂ concentrations. At the last harvest (88 days from transplanting) no interaction between CO₂ and temperature on total biomass was detected. The total dry weight of plants grown at 531 μmol mol⁻¹ CO₂ was 34% greater than those grown at 328 μmol mol⁻¹ CO₂, whereas a 1 °C rise reduced dry weight by 6%. From serial harvests the radiation conversion coefficient was 2.01 g MJ⁻¹ and 1.42 g MJ⁻¹ at 531 μmol mol⁻¹ CO₂and 328 μmol mol⁻¹ CO₂, respectively, but was not greatly affected by differences in temperature. No effect of either CO₂ or temperature on the canopy light extinction coefficient was detected. The rate of progress towards curd initiation increased to a maximum at 15.5 °C, and declined thereafter. Provided the effect of temperature was accounted for, CO₂ enrichment did not affect the time of curd initiation. From serial harvests after curd initiation, the logarithm of curd weight or diameter were negative linear functions of mean temperature from initiation. Increases in curd weight and diameter at 531 compared with 328 μmol mol⁻¹ CO₂ were greater at warmer temperatures (27% at 13 °C compared with 47% at 15 °C, 57 days after initiation). Effects of CO₂ on curd diameter were less than those on curd dry weight because the curd dry matter content was greater at 531 compared with 328 μmol mol⁻¹ CO₂. Thus, the effects of elevated CO₂ concentrations on fresh weight based yield parameters of cauliflower were less than the increase in total dry matter production.     

The morphological development of cauliflower and broccoli cultivars depending on temperature

In growth chambers the effect of temperature (12–27°C) on the growth and development of cauliflower cultivars of temperate and tropical climates, as well as of broccoli cultivars, was tested. No difference was found between the cultivars as regards dry matter production and curd growth, but a difference was found in the time of curd initiation. The early cauliflower ‘Aristokrat’ does not form lateral shoots or floral buds before elongation of the inflorescence at any temperature level. This always occurs in broccoli cultivars. The tropical cauliflowers have an intermediate position. At low temperatures (12–17°C) only 12–14 leaves are formed. Many lateral shoots are initiated and a broccoli-like curd with fertile flowers is developed. At high temperatures (22–27°C) the same cultivars produce a considerably higher leaf weight, less lateral shoots are initiated, and a cauliflower-like curd without floral buds is formed.     

橙色松花菜新品种浙橙松100的选育

浙橙松100是浙江省农业科学院蔬菜研究所选育的橙色松花菜杂交新品种。该品种秋季定植后100 d左右收获,春露地定植后70 d左右收获。秋季种植株高约48 cm,开展度约91 cm;花球半松,花梗较细、色淡青,球面橙色,富含β-胡萝卜素,球径24 cm左右,单球质量1.4 kg左右。该品种综合抗性良好,丰产性好,适应性较广;因花球橙色,不用遮叶盖球,对松花菜省工栽培有较大意义。     

花椰菜新品种‘浙801’

 ‘浙801’是通过‘3045-1’ב955’获得的半松散花椰菜杂交一代,生育期约80 d。植株半直立,生长势强,叶面蜡粉多。花球半圆球形,球径约20 cm,单球质量1 kg以上,花蕾细腻,淡青梗。花球含粗蛋白2.12%,维生素C 625 mg · kg-1,可溶性糖2.71%,可用于脱水加工。适宜华东地区种植。     

Initiation of early summer cauliflowers in response to temperature

Summary

Two experiments were conducted with the early summer cauliflower cvs Perfection and Gypsy. The first was in controlled environment cabinets with nine temperatures ranging from 6.3 to 22.88C. The second was in the field with three planting dates and plants grown with and without fleece cover. The experiment in controlled environments enabled a model to be developed which predicted changes in apex development through both the juvenile and curd induction phases. Both the end of juvenility and curd initiation were defined in terms of apex diameter. For cv. Perfection these were respectively 0.25 and 0.55.mm while with cv. Gypsy they were respectively 0.27 and 0.51.mm. The number of leaves produced at the end of juvenility was very different in the two experiments. When applied to the field temperatures from planting, the model predicted the end of juvenility early and therefore estimates of curd initiation were inaccurate. However, when the model was started, with the recorded apex diameter exceeding that at the end of juvenility, it predicted the day of curd initiation well. The temperatures representing the lower limit, optimum and upper limit of curd induction, were estimated to be 2.2, 9.4 and 248C for cv. Perfection and 2.9, 13.0 and 23.18C for cv. Gypsy. The results suggest that juvenility is not adequately described by number of leaves and varies considerably with growing conditions. They indicate that, under optimum conditions, curd induction only takes about six days and that the critical difference between crops is the duration of juvenility.     

花椰菜生长动态与花球组成

花椰菜生长过程植株及根、茎、叶和花球的鲜质量和干质量、叶面积和净同化率等都逐步增长,均以花球形成期增长最快。幼苗期成长的5枚展叶,主要为建成幼苗起作用,叶簇生长期发生和成长的第7-22叶对叶簇形成和花球分化发育都起重要作用。花球干物质占植株干物质少于30％。花球不论大小,其分球质量都由外而内逐渐减轻,最外的15个分球质量占花球质量的大部分;大花球比小花球重是由于分球数较多、分球较重所致。     

早熟花椰菜新品种'雪冠65'

‘雪冠65’花椰菜是以自交不亲和系‘T1644’为母本,以自交系‘M5116’为父本配制的一代杂种。生长势强,植株半直立,株幅50㎝左右。叶色深绿,叶面蜡质层较厚。花球半球形,颜色洁白,口感佳。平均单花球质量1㎏。平均产量30t·hm^-2。定植后约65 d可收获。抗病,耐热,耐旱,耐涝,适合秋季栽培。     

花椰菜新品种‘津品56’

‘津品56’为适宜秋季露地栽培的早熟花椰菜新品种,是以胞质雄性不育系‘FG-2’为母本,自交不亲和系‘W-53’为父本配制而成的胞质不育新品种。秋季栽培50～55 d成熟。株形直立、紧凑,叶片嫩绿色,外叶上冲,中内叶锯齿明显,合抱护球性优。花球雪白、细嫩、平整、无毛、略松,口感甜脆。单球质量0.95 kg,平均产量45 600 kg·hm~(-2)。     

Early leaf harvest reduces yield but not protein concentration of cowpea seeds

Five greenhouse-grown cowpea [Vigna unguiculata (L.) Walp] cultivars were tested in a generalized random complete-block design to determine the effect of early leaf harvest on dry weight and protein concentration of plant parts at maturity. The most recent, fully expanded leaves on each branch from one group of plants were harvested at 5 and 7 weeks after planting. On the other groups of plants, no early leaf harvest was performed. Dry weight and protein concentration (dry weight basis) were determined for leaves, stems, and seeds at maturity and for leaves harvested early. Weight and protein concentration of seeds, leaves, and stems differed significantly between cultivars; protein concentration of leaves harvested at 5 or 7 weeks did not. Dry weight of leaves harvested at 5 vs. 7 weeks did not differ significantly, but leaf protein concentration was significantly higher at 5 weeks compared to 7 weeks. Across all cultivars, early leaf harvest had no significant effect on leaf or stem weight per plant at maturity. However, there was a significant decrease in seed weight when leaves were harvested early. Results suggest that even limited leaf harvest at 5 and 7 weeks has detrimental effects on yield, but not on protein concentration, of cowpea seeds harvested at maturity.     

高原夏菜花椰菜新品种比较试验

通过对6个花椰菜新品种植物学性状和产量进行比较试验,结果表明,参试各品种均长势旺盛,花球洁白,口感好,较耐热抗病.特别是"日本春秋雪宝"长势旺盛,叶色深绿,自覆性好,花球洁白、紧实、产量高;"赛欧"植株健壮,抗逆性较强,自覆性好,花球特白、紧实,大小适中;这两个品种表现较好,适宜在兰州市推广.     

松散型花椰菜新品种‘浙 017’

 ‘浙017’是花球松散型花椰菜杂交一代,其亲本均来自小孢子培养DH 再生植株。植株直立,株形紧凑,叶色深绿,叶面蜡粉多。花球偏平圆形,乳白色,松大,花层薄,球径约23 cm,单球质量1.2 kg 以上,花梗淡绿色。花球含粗蛋白1.0%,维生素C 604 mg · kg^-1,可溶性糖2.6%,可用于鲜食及脱水加工。移栽至定植约65 d,适宜华东地区种植。