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.     

The effect of thermal environment,planting date and crown size on growth,development and yield of Fragaria × ananassa Duch. cv. Elsanta

Summary

The effects of environmental conditions, planting date and crown size on the timing, intensity and duration of cropping in the strawberry Fragaria × ananassa cv. Elsanta were investigated. Temperature was positively correlated with the rate of progress to fruiting whereas crown size had no effect. The first fruit reached harvest maturity after an estimated 891 day-degrees had elapsed above a base temperature of 2.9°C for waiting bed plants and 831 day-degrees above a base temperature of 2.4°C for cold stored plants. Temperature was negatively correlated with total yield, berry number and average berry weight for both waiting bed and cold stored plants of different crown sizes. Yield, berry number and average berry weight were positively correlated with crown size. The effect of temperature on the yield components appeared to be due to its effect on vegetative growth of the plants: canopy development was more limited at warmer temperatures. These results can be used to generate models to predict the effect of growth environment on cropping in strawberry.     

Effect of the plant raising environment,transplant weight and date of transplanting on the subsequent growth and development of leeks (Allium porrum L.) grown for early production

Leek transplant weight at planting was greater for a given period of growth at 23°C than at 9°C but was unaffected by nutrition. A single line fitted to all the data, using a time-scale based on ‘effective day-degrees’ (with a base of 4°C and an upper limit of 23°C) accounted for over 76% of the variance in transplant weight at planting. Plant weight at harvest was positively related to transplant weight and fitting straight lines to each of the early and late harvest data sets from all the experiments accounted for 75% of the variance in plant weight at harvest. There were no ‘carry-over’ effects of temperature or nutrition from the plant-raising phase other than those on transplant weight. It was calculated, using data from two of the experiments where transplanting date was a factor, that yields fell by between 0.4 to 1.61 ha“1 for each week’s delay in planting over the period early April to mid-June. This loss in yield could be compensated by planting larger plants; 300 g plants could be produced in early August by planting 0.6 g, 0.9 g and 1.7 g plants in mid-April, mid-May and early/mid-June, respectively. The number of plants with flower initials at harvest increased with an increase in transplant weight and exceeded 10% with transplants of 0.5 g fresh weight or more and, for comparable transplant weights, was substantially greater from plants raised at 9° than 12°C. Flower initials were present even in crops from plants raised at 23°C. Transplants raised at 9°C produced up to 30% bolters at harvest but bolters were almost completely absent in crops established from plants raised at 12°C, 18°C or 23°C. Small plants (<0.4 g fresh weight) with 2-3 visible true leaves responded to cold.     

茎瘤芥瘤茎增长过程的研究

以茎瘤芥涪杂1号为试材,研究了瘤茎膨大后瘤茎性状的变化过程。结果表明:用Logistic方程y=k(1+e(a+bt)-1能很好地描述瘤茎纵径、横径、鲜样质量、干样质量的增长过程,而菜形指数的变化过程符合二次回归方程)y=a+b1t+b2t2。瘤茎纵径、横径、干样质量、鲜样质量线性增长始期分别出现在膨大后2.1-9.6d、17.8-19.7d、45.7～48.0d、46.0～50.5d,线性增长持续时间分别为61.6-78,1d、56.1～70.6d、32.9～34.8d、31.6～35.2d;增长高峰期出现在膨大后32.9-48.7d、45.8-55.0d、63.1～64.5d、63.5-66.3d,其最大增长速率分别高达每株每天0.17cm(纵径)、0.16cm(横径)、1.05g(Dw)、16.24g(Fw)。播种晚则瘤茎横径线性增长持续时间短,纵径、干鲜质量增长速率低,而菜形指数的变化由慢到快的递增演变为由快到慢的递减。     

早熟长羊角椒新品种天椒4号的选育

天椒4号是以自交系123为母本、自交系49为父本配制而成的长羊角形辣椒一代杂种。极早熟,始花节位第7～9节,从定植到青果采收40d(天)左右。前期产量高,每667m2前期产量1500～2000kg,总产量2800～4000kg,果纵径26～33cm、横径3.0cm左右,单果质量30～40g,耐辣椒疫病,抗炭疽病,高抗CMV和疮痂病。果色翠绿,果基部皱,辣味中等,皮薄肉厚,口感好,连续结果性好,品质优良。适合保护地栽培。     

The effects of irrigation on the establishment and yield of lettuce and leek transplants raised in peat blocks

The establishment and yield of lettuce and leeks were not reduced by transplanting dry (—0.06 to —0.09 MPa) as compared to saturated peat blocks (3.2 cm cube), provided irrigation was applied immediately after transplanting during the summer. When irrigation was withheld until eight days after transplanting the marketable yield of lettuce was reduced by 30% and 38% when transplanted in saturated and in dry blocks respectively. These reductions were due to reduced survival during establishment and to the more extensive trimming required to produce marketable heads rather than to a reduction in total fresh weight per plant at maturity. The marketable yield of leeks was reduced by 16% and 24% when saturated and dry blocks respectively were transplanted without irrigation, the reduction being largely due to a lower mean shoot weight. Measurements of block and soil water after transplanting suggested that even when the soil was irrigated immediately after transplanting, it was urmble to supply water directly to the blocks for more than a few days.     

结球芥菜的生长动态与叶球形成

结球芥菜自播种至叶球采收可分为发芽、幼苗、叶簇生长和叶球形成4个生长期。植株、根、外叶和叶球的鲜样质量和干样质量随生长进程均逐步增加,呈单峰曲线的增长动态。叶球的鲜样质量和干样质量分别占植株鲜样质量和干样质量的48.2%和48.8%,经济系数近0.5。生育过程中,第1~5展叶是培育幼苗和叶簇的功能叶,第5~9展叶则是叶球形成的主要功能叶。叶球形成过程中球叶数及其叶面积和质量均逐步增加,采收时叶球约有12片球叶。球叶的叶面积和质量都由外而内逐渐减少,叶球的大小和质量主要决定于最外面的6片球叶(占球叶面积的84%和叶球质量的85%),属叶重型叶球     

不同规格的保温材料对辣椒幼苗生长发育的影响

选用4种不同规格的保温材料,研究覆盖后对小拱棚内辣椒幼苗生长发育的影响.结果表明:不同的保温材料对辣椒幼苗生长发育的影响不同,在茄子幼苗前期,在株高、茎粗、叶片数、叶绿素、地上部鲜重、地下部鲜重、总鲜重等性状上存在显著性差异,但在开展度、地上干重、地下干重上不存在显著性差异;在茄子幼苗中期,在株高、开展度、叶片数、叶绿素、地上部鲜重、地下部鲜重、地上部干重等性状上存在显著差异,但在茎粗、地下部干重上不存在显著性差异;在茄子幼苗后期,在株高、叶绿素、叶片数、地上部鲜重、地下部鲜重、地上部干重、总鲜重上存在显著差异,但在开展度、茎粗、地下部干重、总干重上不存在显著差异.综合来看,40 g/cm2加膜无纺布对辣椒子幼苗生长发育最有利,4种保温材料对幼苗期生长发育表现的有利顺序为:A2>A1>A4>A3.     

A study of the effect of the environment during growth on sprouting of bulb onions in store

The partition of dry matter between leaf and bulb with sheath was studied in relation to the post-harvest physiology of cvs Bola and Robusta grown at three sites for two seasons and dried and stored under standardized conditions. Foliar fall-over was synchronous at all sites in each season but the effects of site showed that crops either partitioned dry matter to the bulb early, lost less fresh weight in drying and sprouted later in store, or partitioned dry matter late, lost more fresh weight in drying and sprouted sooner in store. Crops showing the former behaviour were associated with low rainfall and a high number of day degrees between 6° and 20°C during early growth. There was up to 10 days difference between the sites in 50% sprouting dates. Bulbs of cv Bola sprouted earlier than those of cv Robusta, and bulbs harvested when foliar fall-over was negligible sprouted before those from later harvests. There were no site effects on plant maturity, on bulb growth regulator content (cv Robusta one year only), on sugar content at harvest or during storage, on bulb respiration rates at the end of drying or in the spring, or on bulb weight loss during storage.     

Growth rates of glasshouse tomato fruit in relation to final size

The individual growth rates of the first five tomato fruits on 25 trusses of similar age within a crop grown in commercial glasshouse conditions were assessed from anthesis to ripening during April and May. Final size of fruit at ripening was proportional to the maximum rate of increase in fresh weight, about 40 d after anthesis, and related to the maximum rate of increase in diameter, between 15 and 20 d after anthesis, even though ripe fruit fresh weight varied from 20 g to over 100 g. On any one truss these fruit ripened within the same week, regardless of fruit size and prevailing growth rate. These findings suggest that final size was related to the peak fruit growth rate rather than the duration of development. A high growth rate late in development did not delay fruit ripening. The implications for recent continuous measurements of the diameter growth rate in young fruit are discussed.     

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.     

茎瘤芥新品种‘甬榨4号’

‘甬榨4号’是从‘平阳榨菜’变异株中经历6个世代系统选育而成的茎用芥菜新品种。株形直立，生长势强，基部不贴地，板叶。瘤状茎呈圆形，茎形指数1.1，平均鲜质量420 g，加工品质好。早中熟，全生长期170 d左右。耐寒性较强，耐抽薹，空心率低，产量高，57 975 kg ? hm-2。适宜在浙江省种植。     

春秋结球大白菜潍白6号的选育

潍白6号系以东北材料牡丹江1号的自交不亲和系91-439为母本,以韩国高抗抽薹的自交不亲和系BC4-3A为父本育成的大白菜一代杂种。生长期为山东春播60d(天),黑龙江秋播70 d(天)。该品种叶色深绿,球叶合抱呈炮弹形,顶部呈石榴嘴状。抗病毒病、软腐病,较抗霜霉病,抗抽薹能力强。平均单株质量为3.52 kg,一般每667 m2产量为4 000～6 000 kg。既适合山东3月底4月初露地直播作春白菜栽培,又适于黑龙江等东北地区作秋季早熟大白菜栽培。     

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.     

Short- and long-term growth of navel orange fruit

Summary

Seasonal patterns of fruit development of young and mature `Bellamy' navel orange trees were measured from mid November to late July. Growth of whole fruit, expressed as fresh or dry weight, was best described by a fourparameter logistic curve (R<sup>2</sup>>0.99). The fresh weight growth curves of fruit from young and mature trees were not significantly different. Dry weights and fresh weights were linearly correlated (R<sup>2</sup>>0.99). The relationship between relative growth rate (RGR) of whole fruit and time was best described by two linear regressions (R<sup>2</sup>>0.98, 0.92, respectively). The two linear phases of RGR did not correspond to ontogenic phases of fruit development as described by Bain (1958). Increases in whole fruit and pulp radii, and whole fruit, pulp, rind and albedo volume during fruit development followed single sigmoidal patterns (four parameter logistic function, R<sup>2</sup> >0.99). Relative changes in the volume of the structural parts of the fruit were small during Stage III of fruit development. Diurnal variations in growth and rind temperature of fruit from young (under continuous irrigation) and mature (under weekly irrigation) `Leng' navel orange trees were recorded during Stage II of fruit development. Inelastic growth measured by LVDTs was described better by diurnal diameter means (max 1 min)/2 than diurnal maxima or minima. Diurnal diameter means of fruit from young trees showed a significant (R² = 0.42, P<0.0001) relationship to daily ambient temperature maxima, and the diurnal growth profiles paralleled the diurnal temperature profiles of the rind. In contrast, the diurnal growth rhythms of fruit from mature trees were insensitive to ambient temperature maxima and the diurnal rhythms appeared to reflect the water status of the tree.     

Diagnostic tools to evaluate a spatial land change projection along a gradient of an explanatory variable

This paper proposes a method to quantify the goodness-of-fit of a land change projection along a gradient of an explanatory variable, by classifying pixels as one of four types: null successes, false alarms, hits, and misses. The method shows: (1) how the correctness and error of a land change projection are distributed along the gradient of an explanatory variable, (2) how the gradient of the explanatory variable relates to the stationarity of the land transition processes, and (3) how to use the insights from the previous two points to search for additional explanatory variables. The paper illustrates the method through a case study that applies the model Geomod in Central Massachusetts, USA. Results reveal that the model predicts more than the observed amount of change on flat slopes and less than the observed amount of change on steep slopes. One reason for these types of errors is that the land change process during the calibration interval is different than the process during the prediction interval with respect to slope. The method allows modelers to use the validation step as a diagnostic tool to search for potentially influential missing variables and to gain insight into land transition processes. The technique is designed to be applicable to a variety of types of land change models.     

Susceptibility of shallots to the timing and severity of leaf damage

Summary

The study investigated the response of shallots to different levels of defoliation at different growth stages. The effect of cutting off 50%, 75%, and 100% of leaves of four, six, and eight week old shallot plants was assessed. Defoliation at an early stage of growth, i.e. three-leaf stage imposed stressful conditions, and initially reduced growth rate. Whilst lateral bud numbers increased with the severity of defoliation in four week old shallots, lateral shoots and bulb number decreased. There was significant delay in maturity and a reduction in bulb size and weight in shallots defoliated at six weeks. Six weeks old shallots defoliated at 100% recorded the lowest sucrose content of 6%. Numbers of fresh bulb scales was significantly decreased with increasing defoliation and growth. The effect of defoliation on growth, yield and quality depended on the growth stage of the crop. However, 50% defoliation at all growth stages gave appreciable yield and bulb quality compared with the undefoliated control in this trial.     

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。