Response of Rapeseed (Brassica napus L.) Growth, Yield, Oil Content and Its Fatty Acids to Nitrogen Rates and Application Times

A steady and progressive increase in rapeseed yield was observed with each increment in applied nitrogen rates up to 213 kg/ha in both seasons. As for nitrogen application times, the analyzed data showed that adding a split dose (either 1/2 or 1/3) before the third irrigation was a common part between high yielding treatments in 1985/86 season. Nitrogen rates X application times interaction affected rapeseed yield significantly during the first winter season. The highest seed yield of 2.5 t/ha was obtained by adding 213 kg N/ha in two split doses at sowing and just before the third irrigation. The second yield value of 2.47 t/ha was produced under the same N rate when applied in two split doses before second and third irrigation. However, in the second season (1986/87), rapeseed plants did not exhibit significant responses to nitrogen rates X application times interaction.
Chemical analyses showed that rapeseed oil content and its fatty acids (Palmetic, Stearic, Oleic, Linoleic, Linolenic, Arachidic and Erucic) percentages were not significantly affected by either nitrogen rates or application times in both seasons. A very low content of Erucic acid (0.1–0.9 %) in all tested sample was noticed.     

The accumulation pattern in developing seeds and its relation to fatty acid variation in soybean

Sixty soybean cultivars from Japan and the USA formed five maturity groups (IIb‐Vc) based on number of days from sowing to flowering and number of days from flowering to maturity. Highly significant intervarietal differences in fatty acid composition were found in all the maturity groups, especially in IIc. Stearic and oleic acids showed a larger variation than palmitic, linoleic and linolenic acids. Principal component analysis suggested that the total variation of fatty acid composition depended mainly on the desaturation levels from oleic to linoleic acid. Three cultivars exhibiting unique fatty acid composition, together with a standard cultivar, were examined for the contents of the five fatty acids, as well as crude oil at eight seed‐filling stages. For all four cultivars, it was found that crude oil content increased sigmoidally with advancing filling stage, and that the accumulation patterns of palmitic, linoleic and linolenic acids were similar to that of crude oil. However, the accumulation pattern of stearic acid was different from that of crude oil and divided the cultivars into two distinct groups. For oleic acid, only the cultivar ‘Aburamame’ showed a rapid increase in proportion with advancing filling stage, although not differing markedly in accumulated content from the other cultivars. These results indicate that analysing the accumulation patterns of fatty acids could explain the latent genetic variation in fatty acid composition of soybean seeds.     

A new sunflower high oleic mutation confers stable oil grain fatty acid composition across environments

The oil industry demands sunflower oils with high oleic acid content. New varieties producing high oleic oils independently of the growing environment are needed as growers could receive an extra prime for offering them. Oil fatty acid composition of high oleic sunflower hybrids currently available carrying the Pervenets mutation could however be affected by the temperature during the grain filling period. A new high oleic mutation has been obtained to attain oils with ultra-high oleic levels (>90%oleic acid content). This new structural mutation would be able to reduce the variation in oleic acid percentage to changes in the minimum night temperature (MNT). The aim of this work was to assess the response of oil fatty acid composition of the new high oleic mutation to MNT compared to traditional and Pervenets genotypes. Field experiments in different sowing dates and locations and one growth chambers experiment were performed to explore a wide range of temperatures (11.8–23.2 °C) during grain filling. The oleic acid percentage in traditional and high oleic Pervenets genotypes varied between 15.0–50.9% and 87.4–91.2%, respectively, while the new mutation genotype presented values of oleic acid between 91.3 and 92.5%. Moreover, the oleic acid percentage of traditional and Pervenets genotypes showed a linear and positive response to temperature (slopes 2.95 and 0.28%oleic acid °C⁻¹, respectively). No response to temperature was detected in the new mutation genotype. The ultra-high oleic quality from the new high oleic sunflower mutant could be obtained in a wide range of environments as the fatty acid composition was not affected by temperature during grain filling, representing an advantage over the high oleic Pervenets and traditional genotypes.     

Changes in the Functional Components and Radical Scavenging Activity of Korean Maize Hybrids According to Different Cropping Seasons

We evaluated the proximate composition, free sugar content, fatty acid composition, carotenoid content, total phenol content, and radical scavenging activity of the grain from various Korean maize hybrid cultivars grown in two different cropping seasons. The moisture, crude ash, crude fat, crude protein, total starch, and amylose contents were significantly higher in most of the maize hybrid cultivars when grown in the early-season than when grown in the late-season. The free sugar content, fatty acid composition, carotenoid content, and total phenol content differed significantly between cultivars and cropping seasons. The highest unsaturated fatty acid compositions of maize hybrids of early-season and late-season were 86.05 and 86.29%, respectively, in the Daanok cultivar. The carotenoid contents were significantly higher in maize hybrids of late-season compared to those of early-season. The highest total phenol content was 108.09 mg/100 g in Singwangok of the late-season. The radical scavenging activity of maize hybrids differed significantly between cultivars and cropping seasons.     

Genetic variation for saturated fatty acid content in a collection of European winter oilseed rape material (Brassica napus)

Oil quality is an important issue in oilseed rape breeding programmes. Recently, the seed oil content of saturated fatty acids has received substantial interest, because in a number of industrialized countries dietary recommendations not only limit total fat intake but also intake of saturated fatty acids. The aim of the present study was to analyse the genetic variation for saturated fatty acid content in two sets of modern winter oilseed rape cultivars ( Brassica napus L.) tested in field experiments under typical German growing conditions. The results showed highly significant genetic differences among the cultivars for total saturated fatty acid content, which ranged from 6.8% to 8.1%, with a mean of 7.4%. For both sets medium to high genotypic heritabilities were found for most fatty acids and for oil and protein content. Close negative correlations between palmitic acid, the predominant saturated fatty acid, and oleic acid as well as oil content were found.     

Effect of 1,1-Dimethyl Piperidinium Chloride (Pix) on the Seed, Protein, Oil and Fatty Acids of Egyptian Cotton

Two field experiments were conducted in 1985 and 1986 on the cotton cultivar, Giza 75 (Gossypiitm barbadense L.) to determine the effect of foliar application of Pix at 0, 10, 20, 40, 60, 80 or 100 ppm on cottonseed yield, seed index, protein and oil contents and fatty acid compositions of cottonseed oil. Pix was sprayed once at 90 days or twice at 90 and 110 days from sowing date.
Seed yield/plant or /ha, protein and oil yield/ha, and seed index increased due to the application of Pix compared to the control. The highest response occurred with 40 or 60 ppm Pix and with one application rather than two. The seed protein percentage increased due to Pix application, especially at 10 ppm. A slight increase in seed oil percentage was detected throughout Pix applications. The number of applications had no noticeable effect on seed protein and oil %. Application of Pix caused a general decrease in the saturated fatty acids (myristic, stearic, and palmitic), associated with an increase in the unsaturated fatty acids (oleic and linoleic). These results were confirmed bv the ratio of total unsaturated fatty acids to total saturated (TU/TS). Ten ppm Pix gave the highest TU/TS. Generally, the saturated fatty acids decreased while the unsaturated fatty acids increased with one application rather than two. Palmitic acid was the most abundant saturated fatty acid, whereas linoleic acid was the most abundant unsaturated ones.     

Variation in Seed Yield and Quality Characters of Four Spring Oil Rapeseed Cultivars as Influenced by Population Arrangements and Densities

Variations of yield and quality characters of four spring oilseed rape cultivars ( B. napus L.) arranged in 16 or 32 cm between drills and under three population densities (30, 60 and 90 plants/nr) were investigated in a split-plot design with three replications in 1986 and 1987 in West Germany.
Cultivar Callypso gave the highest seed and oil yields per plot and the highest seed index, harvest index and seed yield/main stem, per branches and per plant. Differences due to arrangements were significant in 1986 only, i.e., the value of a special plant distribution was more pronounced under unsuitable weather condition (as in 1986). With respect to the three population densities, most of the characters showed significantly higher values with 30 plants/nr. Only seed yield and oil yield per plot that showed 7.27% and 5.6% increase, respectively, under the highest population density (90 plants/nr) but the differences were insignificant.
The highest oil content was obtained from cultivar Callypso and from the lowest population density. By contrast, higher protein content was obvious under higher population densities and the differences from the lowest density were significant in both years. Differences in fatty acid composition were not significant for the three main effects.     

环境与品种对小麦淀粉理化特性和面条品质的影响

测定了13个小麦品种在3个地点的淀粉理化特性和面条品质,结果表明直链淀粉含量、膨胀势和面条品质主要受遗传因素的控制,品种间变异平方和分别占总变异平方和的57.5%、52.3%和58.6%,但环境因素也有重要影响。RVA主要黏度指标则有所不同,低谷黏度和最终黏度主要受品种的影响,其变异分别占总变异的40.2%和48.0%,而峰值黏     

大豆不同环境下脂肪酸组分含量的QTL分析

大豆油的品质取决于脂肪酸各组分在大豆中的比例, 为发掘控制大豆5种脂肪酸含量的数量性状位点(QTL), 利用冀豆12和黑豆重组自交系群体构建遗传图谱, 采用Windows QTL Cartographer 2.5和QTL Network-2.0软件的CIM和MCIM法对大豆5种脂肪酸组分进行数量性状定位。结果表明,在石家庄和三亚各环境下共检测到16个QTL, 位于连锁群A2、B2、C2、F、G、I、L上。对2个环境联合分析, 检测到13个QTL, 其中9个用2种方法被检测到, 但这13个位点与环境互作的贡献率明显小于加性效应。其中在B2连锁群Satt168~Satt556控制硬脂酸的QTL Ste-1在河北石家庄和海南三亚均能被检测到, 贡献率均为12%, 在双尾群体和间隔挑选群体中也能检测到控制硬脂酸的QTL Ste-1, 说明这一QTL稳定存在于本组合群体中, 为今后大豆硬脂酸的QTL精细定位奠定了基础。     

不同时期施硫对夏玉米硫积累和籽粒品质的影响

为了探明不同时期施硫对夏玉米植株硫积累和籽粒品质的影响,在田间条件下对高产夏玉米（‘农大108’和‘金海5号’）进行不同时期（一次性基施,分别与大喇叭口期、开花期分期施）等量施硫（40 kg/hm2）处理。试验结果表明,在本试验肥力条件下一次性基施、基施和开花期施硫肥均显著提高植株硫积累量;各器官中叶片硫积累量最高,穗轴积累量最低。各时期施硫处理显著提高‘金海5号’籽粒中可溶性糖含量,其中硫肥100%基施和硫肥50%基施+50%开花期分别高于对照21.0%和15.5%,而对‘农大108’影响不显著;各时期施硫处理对两品种籽粒淀粉和粗蛋白含量均没有显著影响。     

Impact of low linolenic acid content on seed yield of winter oilseed rape (Brassica napus L.)

An essential quality improvement of rapeseed oil can be obtained by reduction of its linolenic acid (C18:3) content from about 10% to less than 3% of the total fatty acids. Genotypes low in C18:3 have been developed by mutagenesis. The initial summer rapeseed mutant had been low yielding and highly susceptible to various diseases. It has been debated whether the low C18:3 character can be successfully combined with high seed yield for physiological reasons. Therefore, the low linolenic character of mutant M48 was transferred into high-yielding genotypes by repeated backcrossing to well-adapted low erucic acid, low glucosinolate (00-) winter rapeseed cultivars. Lines with low C18:3 content were selected from BC3 and BC4 generations and examined in 1990–95. Positive selection response for seed yield was shown to continue over the years. Presently, the best lines are yielding as well as the control cultivars being equivalent also in oil and glucosinolate contents. In order to test the effect of a low C18:3 content on seed yield, plants with low and with high C18:3 content, respectively, were selected from 16 segregating BC5-F₂ populations and bulked to form 32 F₃ populations. These ‘isogenic’ bulk populations were tested for field performance at four locations in 1995. The results show that C18:3 content of the seed oil is not associated with seed yield, oil content, beginning of flowering, plant height and disease resistance. Means of relative seed yield for the high and the low linolenic F₃ bulk populations were not significantly different with 88.0% and 86.9% of the control cultivars, respectively. There was a significant interaction between genotypes with high or low C18:3 content and location. This shows that under specific environmental conditions a low C18:3 content may be either favourable or unfavourable. The results indicate that the low C18:3 character of the original mutants per se does not cause a decrease in seed yield, oil content or general field performance.     

Canola oil increases in polyunsaturated fatty acids and decreases in oleic acid in drought-stressed Mediterranean-type environments

Seed fatty acid (FA) composition, oil and protein (meal) was assessed on five canola ( Brassica napus ) varieties in 14 cropping environments in southern Australia, including several low rainfall drought-stressed environments. We modelled the relationship between seed quality attributes and growing season rainfall and temperature using a linear mixed model. Variance components for variety and years within locations were relatively large, but variance components for variety × environment interaction were small or insignificant for most seed quality traits. Mean oleic acid content varied from 57% in 'Surpass 300TT' to 62% in 'ATR-Beacon'. As growing season rainfall decreased from 300 mm (moderate) to 150 mm (severe drought stress), mean oleic acid decreased by 3.8%, linoleic acid increased by 2.0%, linolenic acid increased by 1.7%, and saturated FA decreased by 0.4%. Seed oil (% dry weight) decreased by 3.2% and protein in meal (% dry weight) increased by 3.9% across the same rainfall range. High oleic acid composition was associated with higher rainfall and cooler average minimum and maximum temperatures during the growing season.     

Heterotic patterns in rapeseed (Brassica napus L.): II. Crosses between European winter and Chinese semi-winter lines

Chinese semi-winter rapeseed is genetically diverse from European winter rapeseed. Our objectives were (1) to evaluate the potential of semi-winter rapeseed for winter rapeseed hybrid breeding, (2) to assess the relative importance of general combining ability (GCA) vs. specific combining ability (SCA) among combinations between Chinese semi-winter and European winter rapeseed, and (3) to compare the strategies to predict heterosis based on parental genetic distance (GD) estimated from AFLP marker data and GCA for hybrid performance. Four winter male sterile lines from Germany as testers were crossed with 14 Chinese semi-winter rapeseed lines to develop 56 hybrids, which were evaluated together with their parents and commercial hybrids for seed yield, oil content and protein content under three environments in Germany. The Chinese parental lines were not adapted to local environmental conditions as demonstrated by lacking winter hardiness and poor seed yields per se . However, the hybrids between the Chinese parents and the adapted winter rapeseed lines exhibited high heterosis for seed yield. About 20% of the hybrids were significantly superior to the respective hybrid control under three environments. Additive gene effects mainly contributed to hybrid performance since the variance components of GCA were higher as compared with SCA. The correlation between parental GD and hybrid performance was found to be low whereas the correlation between GCA and hybrid performance was high and significant, with correlation coefficients of 0.95 for seed yield, 0.87 for oil content, and 0.91 for protein content, indicating that GCA can predict hybrid performance. These results demonstrate that Chinese semi-winter rapeseed germplasm has a great potential to increase seed yield in winter rapeseed hybrid breeding programmes in Europe.     

Studying the effect of environmental variables on the genotype × environment interaction of tomato

Genotype × environment interaction (GEI) affects marketable fruit yield and average fruit weight of both hybrid and open-pollinated (OP) tomato genotypes. Cultivars vary significantly for marketable fruit yield, with hybrid cultivars having, on average, higher yield than OP cultivars. However, information is scanty on environmental factors affecting the differential response of tomato genotypes across environments. Hence, the aim of this research was to use factorial regression (FR) and partial least squares (PLS) regression, which incorporate external environmental and genotypic covariables directly into the model for interpreting GEI. In this research, data from an FAO multi-environment trial comprising 15 tomato genotypes (7 hybrid and 8 OP) evaluated in 18 locations of Latin America and the Caribbean were analyzed using FR and PLS. Environmental factors such as days to harvest, soil pH, mean temperature (MET), potassium available in the soil, and phosphorus fertilizer accounted for a sizeable portion of GEI for marketable fruit yield, whereas trimming, irrigation, soil organic matter, and nitrogen and phosphorus fertilizers were important environmental covariables for explaining GEI of average fruit weight. Locations with relatively high minimum and mean temperatures favored the marketable fruit yield of OP heat-tolerant lines CL 5915-223 and CL 5915-93. An OP cultivar (Catalina) and a hybrid (Apla) showed average marketable fruit yield across environments, while two hybrids (Sunny and Luxor) exhibited outstanding marketable fruit yield in high yielding locations (due to lower temperatures and higher pH) but a sharp yield loss in poor environments. Two stable hybrid genotypes in high yielding environments, Narita and BHN-39, also showed high and stable yield in average and low yielding environments.     

北方白菜型冬油菜的膜脂脂肪酸组分和ATPase活性对温度的响应

为了解北方白菜型冬油菜膜脂脂肪酸和ATPase活性与抗寒性的关系,以抗寒性强的冬油菜品种陇油7号和抗寒性弱的品种天油2号为材料,研究了不同温度处理(25°C、10°C、2°C、–5°C)后叶片和根系膜脂脂肪酸组分和ATPase酶活性的变化。结果表明,低温胁迫下2个冬油菜品种叶片和根系膜脂脂肪酸组分相同,叶片中不饱和脂肪酸以亚麻酸为主,根系不饱和脂肪酸以亚油酸为主。随处理温度的降低,2个冬油菜品种叶片不饱和脂肪酸含量呈先降低(10°C,2°C)后增加(–5°C)的趋势;陇油7号根中不饱和脂肪酸含量逐步增加,天油2号则逐步降低;在低温条件下(2°C,–5°C),陇油7号膜脂U/S比值、IUFA值高于天油2号;ATPase活性表现为陇油7号逐渐高于天油2号。说明2个冬油菜品种的膜脂在低温响应上存在一定差异,低温下不饱和脂肪酸含量和ATPase活性的提高是强抗寒冬油菜品种在北方旱寒区严酷环境条件下能安全越冬的重要原因。     

Development of a New Multifoliate Strain of Berseem Clover (Tricolium alexandrinum L.) in Egypt

The aim of this work was to obtain mukifoiiare types of berseem clover with a great proportion of the leaf weight and increased plant weight. Thereby research an berseem clover over a 10 year period resulted in the transfer of the multicare gene(s) from a mutant plant of the monocut Fahl culrivar which possess such trait to the muiticut trifoliate culrivar Meskawi by crossing between them. A multicut multifoliate strain was developed after rune generations of selection.
The multsfoliate strain gave significantly higher dry forage yield than commercial cultivate Giza 10, Sakha 4, Giza 15, Helaly and Giza 6 by 22.1, 22.5, 24,8, 29.9 and 36.7%, respectively, in the first cut. On the other hand, the moltifoliate strain gave higher seasonal protein yield than cultivars, i.e. Helaly, Giza 10, and Giza 6 by 7.0,10.1, and 121 %, respectively.
The leaves/stems rario trait averaged over cuts was 18.3 % higher than for the five commercial trifoliate cultivars. Therefore, this multifoliate muiricut strain could be useful for forage especially before sowing cotton or other early summer crops. In addition to that, it could he used as a genetic marker for berseem breeders.     

Effect of Nitrogen Fertilization and Foliar Application of Plant Growth Retardants and Zinc on Cottonseed, Protein and Oil Yields and Oil Properties of Cotton

Field experiments were conducted in two successive seasons at the Agricultural Research Centre, Giza, Egypt (on a clay loam soil), to determine the effects of N fertilization (added at rates of 107 and 161 kg N ha^–1) and foliar application of plant growth retardants (Pix, Cycocel and Alar; each applied once at 300 p.p.m., 75 days after planting) and zinc (applied at 0.0 and 50 p.p.m., two times, 80 and 95 days after planting) on cottonseed, protein and oil yields and oil properties of the Egyptian cotton cultivar Giza 75. The higher N rate, as well as the application of all growth retardants and zinc, resulted in an increase in cottonseed yield ha^–1, seed index, seed protein content, oil and protein yields ha^–1, seed oil refractive index, unsaponifiable matter and total unsaturated fatty acid content (oleic and linoleic). However, those treatments decreased the oil acid value, saponification value, and total saturated fatty acid content. The seed oil content tended to decrease when the high N rate was applied, but tended to increase with the application of all growth retardants and zinc. There were some differences between Pix, Cycocel and Alar regarding their effects on the studied characters. The highest increase in seed yield ha^–1, seed index, and oil and protein yields ha^–1 was found with Pix, followed by Cycocel. The Cycocel treatment gave the lowest total saturated fatty acid oil content, followed by Alar.     

栽培因素对甘蓝型优质杂交油菜品质组合性状的影响

为了研究播期、密度、施氮量、施磷量、施钾量5个主要栽培因素对甘蓝型优质杂交油菜品质组合性状的影响,以‘油研599’和‘三北98’为材料,运用五元二次正交旋转组合设计进行试验研究。结果表明,脂蛋总量与播期(-0.7493、-0.3846)呈负相关,与氮肥(0.8927*、0.8977*)、钾肥(0.5851、0.7530)呈正相关;不饱和脂肪酸总量与密度(0.2086、0.6696)、氮肥(0.7913、0.6980)呈正相关,与磷肥(-0.6350、-0.4162)呈负相关;不饱和指数与密度(0.5447、0.5721)、氮肥(0.9208*、0.8863*)呈正相关,与磷肥(-0.2442、-0.3468)、钾肥(-0.3562、-0.6703)呈负相关;饱和脂肪酸总量与播期(0.4329、0.7887)、磷肥(0.8928*、0.3449)呈正相关;不饱和脂肪酸总量与饱和脂肪酸总量之比与播期(-0.1264、-0.7246)、磷肥(-0.8513、-0.7480)呈负相关,与氮肥(0.5380、0.5406)呈正相关;18碳脂肪酸总量与密度(0.2387、0.7053)、氮肥(0.7866、0.7200)呈正相关,与磷肥(-0.6438、-0.3948)呈负相关;芥酸支链脂肪酸总量与播期(-0.7400、-0.4480)、氮肥(-0.5999、-0.9558*)呈负相关,与密度(0.8918*、0.0923)呈正相关;不饱和脂肪酸总量与芥酸链脂肪酸总量之比与播期(0.7014、0.3873)、氮肥(0.6824、0.9614**)、钾肥(0.0502、0.0018)呈正相关;油酸与亚油酸之和与密度(0.3146、0.6348)、氮肥(0.7429、0.5280)呈正相关,与磷肥(-0.6286、-0.4431)呈负相关。5个栽培因素对不饱和脂肪酸总量与芥酸链脂肪酸总量之比的影响较大,对脂蛋总量的影响较小。通过调整播期、密度、施氮量、施钾量4个主要栽培因素可一定程度改善油的品质,磷肥对于改善油的品质是一个起负效应的栽培因素。     

Selection for reduced linolenic acid content in Ethiopian mustard (Brassica carinata Braun)

Reducing linolenic acid content is one of the most important objectives for the development of Ethiopian mustard lines with high oil quality. This work was aimed at searching for variability of the fatty acid composition of oil within a germplasm collection of Ethiopian mustard. A total of 217 lines were analysed by gas-liquid chromatography (GLC) in 1991, and one was selected as having reduced values of both linolenic acid content (10.2% versus 14.0% of total fatty acids as the collection average) and linoleic acid desaturation ratio (LDR, 0.34 versus 0.45). After 3 years of pedigree selection for low linolenic acid content, this line showed, in 1995, average values of this fatty acid of 5.4% and 2.4% in two different environments, compared with 11.6% and 8.3%, respectively, in the control. The values of the LDR were 0.18 and 0.09, respectively, compared with 0.36 and 0.27 in the control line.     

Adaptability and phenotypic stability of Lolium perenne L. cultivars of diverse origin grown at the margin of the species distribution

In northern countries, Lolium perenne L. generally survives poorly when grown inland and north of 60°N because of extensive winter damage. With the projected future climate change, it could become a promising option for improving production efficiency of the agricultural sector in these regions. Here, we compare the biomass production potential of cultivars of diverse origin across five locations stretching from Estonia to Iceland over a period of three harvest years, and their freezing tolerance under artificial conditions. The aim was to relate the observed pattern of adaptation to the geographic origin of the cultivars and their response to prevailing agroclimatic conditions. Significant interactions were observed between cultivars and test environments (locations × years), and significant interactions between cultivars and years were detected at four of the five locations. Models of joint regression, additive main effects and multiplicative interaction (AMMI) and factorial regression using several agroclimatic indices showed that cultivars developed in northern countries showed greater yield potential across the test environments and were, thus, generally better adapted than cultivars from Central Europe. Diploid cultivars were more frost tolerant than tetraploid cultivars giving them an advantage in locations which were characterized by low temperatures during the hardening period in autumn and mild and rainy winters, such as at the Icelandic location. Only a few cultivars showed general adaptability to the environmental conditions at the test sites, the most stable cultivar being an admixture of diploids and tetraploids. In future breeding, the best strategy would be to hybridize cultivars developed in northern countries with more exotic materials that combine high yield potential, adequate winter survival and superior disease resistance under northern conditions.