Influence of rice cultivar on methane emission from paddy fields

Influence of rice cultivars on CH₄ emissions from a paddy field was studied using four Japonica types, two Indica types, and two Japonica/Indica F₁ hybrids. In addition, the suppression of CH₄ emission by interrupting irrigation at the flowering stage was investigated. Patterns of seasonal variation in CH₄ emission rates were similar among the eight cultivars. Two of the Japonica types showed the maximum and minimum CH₄ emissions among the cultivars investigated. Neither the number of tillers, shoot length, shoot weight, and root weight correlated with the CH₄ emission rates at the tillering and reproductive growth stages. Following temporary interruption of irrigation at the flowering stage, CH₄ emission rates decreased drastically and remained at very low levels until the harvesting stage, indicating its great effectiveness for the suppression of CH₄ emission from rice paddies.     

Effects of Aphis fabae and Uromyces viciae-favae on the growth of a susceptible and an aphid resistant cultivar of Vicia faba

Damaging effects of either black bean aphid (Aphis fabae), broad bean rust (Uromyces viciae-fabae), or the combination of both were investigated on a susceptible (cv. Diana) and an aphid resistant (cv. Bolero) cultivar of Vicia faba. When compared with rust, aphids caused greater reductions of root dry weight, shoot dry weight, leaf area, and mean relative growth rate. The mean unit leaf rate was also reduced whereas the leaf area ratio was not affected. The damage caused per aphid was highest on the susceptible cultivar. Rust induced damage did not differ between the cultivars. Concomitant infestation with both pests only resulted in additive damage. The population development of aphids was delayed on partially resistant plants. High temperature and rust infection reduced the total number of aphids the plants were able to support but not the level of resistance. Thus the specific damaging effect per aphid was increased.     

Influence of phosphorus level on VA Mycorrhizal colonization and growth of cowpea cultivars

Vesicular-arbuscular mycorrhizal (VAM) associations often vary according to the abundance of available soil phosphorus (P). Therefore, understanding the response of crop plants to colonization by VAM fungi necessitates the study of the response of colonized and noncolonized plants, from a range of cultivars, to differing levels of P. Cowpea is grown throughout the world, often on impoverished soils in which it can benefit from formation of mycorrhizae. The present study was conducted to determine the response of four cultivars of cowpea (Vigna unguiculata (L.) Walp.), varying in nitrogen fixation capacity, to inoculation withGlomus fasciculatum at four levels of added P in the rooting medium. In a greenhouse experiment, four cowpea cultivars, Mississippi Silver, Brown Crowder, Six Week Browneye and MI 35, were grown with and without the mycorrhizal fungus at four levels of added P, 0, 10, 20 and 30 ppm. Root colonization (%) was negatively correlated with P content of the growth medium and shoot P concentration. Intraspecific variability was shown for shoot dry weight and leaf area in response to inoculation withG. fasciculatum at different P levels. The range of P required in the growth medium which allowed benefit fromG. fasciculatum was identified for individual cultivars using shoot dry weight and leaf area, and collectively across cultivars for other parameters.     

优质鲜食黄肉猕猴桃新品种‘金圆’的选育及特性分析

‘金圆’是以种间杂交品种‘金艳’（Actinidia chinensis×A.eriantha）为母本、中华猕猴桃（A.chinensis Planch.）为父本,从回交F₁代群体中选育出的中熟黄肉猕猴桃新品种。通过对‘金圆’植物学性状、特异性、营养成分、贮藏性等进行研究,结果显示：‘金圆’果实为短圆形,单果重80~100 g,软熟时果肉橙黄色,质细味浓;‘金圆’的花瓣数和花丝数与母本‘金艳’接近,花冠直径和柱头数较‘金艳’分别增大了9.31%和52%,而花柄长度比‘金艳’短16.75%;萌芽率和果枝率略低于‘金艳’,但比‘海沃德’高出55.26%和43.33%;‘金圆’的可溶性固形物、总糖和可滴定酸含量与‘金艳’相当,但维生素C含量比‘金艳’高4.63%,是‘海沃德’的2.2倍;‘金圆’矿质元素含量丰富,P和K含量分别比‘金艳’高30.86%和22.53%,Mg含量比‘海沃德’高24.86%;‘金圆’的总氨基酸含量丰富（8 mg/g）,E/N和E/T值均高于‘金艳’和‘海沃德’,更接近于理想模式;‘金圆’在低温下（1~2℃,相对湿度90%~95%）贮藏150 d时,好果率在80%以上,200 d后,好果率仍有65%,贮藏性略低于‘金艳’,但显著高于‘海沃德’。利用Geo7-223分子标记扩增‘金圆’基因组得到3个条带,表明其与‘金艳’和‘金桃’在分子水平上具有一定差异。本研究表明‘金圆’具有良好的农艺性状和品质特性。     

Isolation and characterization of microsatellite loci in Fragaria

This study reports the development and characterization of 20 microsatellite primer pairs in wild strawberry Fragaria vesca. One hundred primers were obtained from an AC‐enriched library developed in the cultivar ‘Ilaria’. A set of eight F. vesca genotypes was used to detect the polymorphism resulting in an average of 7.0 alleles, an average observed heterozygosity of 0.32 and an average expected heterozygosity of 0.73. Nineteen (95%) of the primers also amplified the cultivated octoploid strawberry Fragaria×ananassa.     

A simple method for maintaining high multiplication of Narcissus shoot cultures in vitro

A simple method for stimulating and maintaining high in vitro multiplication of Narcissus shoot clump cultures was developed. Shoot clumps were subjected either to normal cutting where leaves were trimmed to 20 mm in length at the beginning of each culture passage or to severe cutting where shoot clumps were cut down to the basal plate region removing all green tissue. Severe cutting at the beginning of each culture passage initially doubled the leaf multiplication, compared to normal cutting, but the difference between cutting treatments declined in successive passages. The improvement in leaf multiplication was maintained when shoot clumps were subjected to severe cutting only at every other culture passage, with no cutting in the alternate recovery passages. In vitro multiplication was increased by severe cutting in all seven Narcissus cultivars which were tested.Abbreviations NAA-1 naphthylacetic acid - BAP benzylaminopurine     

Photosynthesis of White Clover (Trifolium Repens L.) Germplasms with Contrasting Leaf Size

In a growth chamber experiment, we determined net photosynthetic rate (PN) and leaf developmental characteristics of cultivars of a relatively small-, intermediate-, and a large-leaf genotype grown under irradiance of 450-500 µmol(photon) m-2 s-1 (HI), shade [140-160 µmol(photon) m-2 s-1] (LI), and after a shade-to-irradiation (LI »HI) transfer. Differences in physiological responses of the genotypes were more pronounced in HI and LI»HI plants than in LI plants. The small- and intermediate-leaf sizes had greater PN in the first measured leaf than the large-leaf type by 70 and 63 % in HI plants, and by 23 and 18 % in LI»HI plants, respectively. Similar relationships were observed in the next developed leaf. The LI plants did not differ significantly in PN. Greater PN in the small- and intermediate-leaf size genotypes were not associated with greater total dry matter of the plant. Under irradiation, the large-leaf genotype accumulated more total nonstructural saccharides (TNS) and starch than the small- or intermediate-leaf size plants. TNS and starch concentrations in LI plants were about one-half those of HI and LI»HI plants. These results should help to develop management practices that capitalize upon the competitive features of white clover in mixed-species swards.     

鸢尾属（Iris L.）植物的杂交育种

1994－1997年在南京进行了鸢尾属（Iris L.)的种间与种内杂交育种试验,结果表明：2个种间杂交组合 亲和力极弱,F1代杂种苗生长不良,6－8周内死亡,3个种内杂杂交组合亲和力较强,F1代杂种苗生长良好,其中2个杂交组合F1代的花色由单基因控制,。未出现花色的分离;不同花色的德国鸢尾（Iris germanica L.)品种LP和PP之间的杂交组合F1代花色受多基因控制F1代杂种花色出现明显分离,从中选出了“紫金”,彩带,金舞娃,红浪,水晶球,紫云和紫盘7个新栽培品种。     

Root growth and nitrate utilization of maize cultivars under field conditions

In a 2-year field study conducted on a high fertilized Gleyic Luvisol in Stuttgart-Hohenheim significant differences among 10 maize cultivars were observed in soil nitrate depletion. The different capability of the cultivars to utilize nitrate particularly from the subsoil was positively correlated with (a) shoot N uptake at maturity, and (b) root length density (L_v) in the subsoil layers at silking. Critical root length densities for nitrate uptake were estimated by (a) calculating uptake rates per unit root length (U), (b) subsequent calculation of needed nitrate concentration in soil solution (C₁) to sustain calculated U according to the Baldwin formula, and (c) reducing measured L_v and proportionate increase of U until needed concentration equaled measured concentration. Uptake rate generally increased with soil depth. Critical root length densities for cultivar Brummi (high measured root length densities and soil nitrate depletion) at 60–90 cm depth ranged from 7 % (generative growth) to 28 % (vegetative growth) of measured L_v Measured root length density of each other cultivar was higher than critical root length density for Brummi indicating that the root system of each cultivar examined would have been able to ensure N uptake of Brummi. Positive relationships between root length density and nitrate utilization as indicated by correlation analysis therefore could not be explained by model calculations. This might be due to simplifying assumptions made in the model, which are in contrast to non-ideal uptake conditions in the field, namely irregular distribution of roots and nitrate in the soil, limited root/soil contact, and differences between root zones in uptake activity. It is concluded from the field experiment that growing of cultivars selected for high N uptake-capacity of the shoots combined with high root length densities in the subsoil may improve the utilization of a high soil nitrate supply.