Viral determinants for overcoming Pisum sativum recessive resistance, sbm-2, against the potyvirus Pea seed-borne mosaic virus (PSbMV) were identified in the region encoding the N-terminal part of the P3 protein. Codons conserved between sbm-2 virulent isolates in this region: Q21, K30 and H122 were found to specifically impair sbm-2 virulence when mutated in selected genetic backgrounds. The corresponding amino acids, Gln21 and Lys30, are neighbored by P3 residues strongly conserved among potyviruses and His122 is conserved particularly in potyviral species infecting legumes. The strongest selective inhibition of sbm-2 virulence, however, was observed by elimination of isolate specific length polymorphisms also located in the N-terminal part of the P3 protein. Length variation in N-terminal P3 is common between potyviral species. However, intra-species length polymorphism in this region was found only among PSbMV isolates. Our findings comply with a model for PSbMV pathotypes having evolved by a diversification of the P3 protein likely to extend to the level of function.

Yield stability in sweet corn and its dependence on G x E interaction were investigated in a series of two way experiments. Five Romanian sweet corn hybrids were tested in three years (2008-2010) in three locations of Central Transylvania in different soils and climatic conditions. The experiments were organized in a split plot design in which, on a general level of organic fertilization (40 t/ha manure), four levels of mineral N fertilization were applied (kg/ha, active matter): N0, typical for organic technologies; N50, corresponding to the low-input (sustainable) system; N100 and N150 customary with conventional system of agriculture. Based on ear yield data registered for hybrids in locations x years x cropping system, a phenotypic index (Pi) was computed for each sweet corn hybrid illustrating the stability of their cob yields, with and without husks. The share of genotypic and G x E effects in the total value of Pi have been estimated. In different agricultural systems the tested hybrids were classified differently based on their Pi values. It is concluded that, at least for the time being, the initiation of an organic breeding program for sweet corn, in Romania, is not economically justified since all semiearly and semilate tested hybrids yielded satisfactorily under organic agricultural practices. Moreover, among the recently released sweet corn hybrids one can find certain genotypes highly suitable to organic (i.e. ‘Deliciul verii’, ‘Estival’) or low input (‘Dulcin’, ‘Estival’) agricultural practices. These three hybrids recorded the highes ear yields (with and without husks) over years, locations and agricultural systems.

The present paper reveals the results of a study on the tulip collection in the environmental conditions of "Al. Borza" Botanical Garden Cluj-Napoca, concerning two characteristics: earliness of flowering and blooming time. Most tulip cultivars are originated in the Netherlands where environmental conditions are different from those in Cluj-Napoca. The tulip collection of "Alexandru Borza" Botanical Garden of Cluj-Napoca has been set up in order to maintain its decorative value as long as possible. In this regard, there were planted cultivars with various ranges of earliness of flowering and long duration of blooming period. Flowering time of the tulips, which make up the "Alexandru Borza" Botanical Garden of Cluj-Napoca collection last between 6-22 days. The blooming period of these cultivars is not as homogenous within the groups as expected, each group exhibiting cultivars with shorter or longer flowering period than the mean of experiment. The main objective of this study was to identify the genetic sources for earliness and blooming period, which could be used in a breeding program for early flowering tulips, as it is stated by most of the important tulip breeding.

A review of the most important achievements in rose breeding at Cluj-Napoca, Romania, in the last 30 years is presented. During this period of time more than 90.000 hybrid individuals were obtained and checked concerning their ornamental value and em average•of 2.62% of selection efficiency was encountered. Hybrid combinations with the highest rates of successfit! selections are presented, as examples jar two years of artificial pollination programs. The actual results of this extensive breeding work are represented by nine new rose varieties released in Romania between 1970-1994 (Foe de tabara, Luchian, Simfonia, Rosabunda, Romstar, Incandescent, Auriu de Cluj, Rosalinda and Vigorosa) which are destined to open-air growing either for cutjlowers or as ornamentals in parks, gardens etc. The main growing characteristics of these new varieties are presented as well as their field resistance to blackspot, mildew and rust. The ornamental features of these varieties are also presented both in synthetic tables and in color photos. Additionally, the main growing and ornamental characteristics of other fourteen recent selections of rose are discussed, as well as their behavior in the National Comparative Trial Network. Finally, the prospects of rose breeding activity, at Cluj-Napoca are considered, both from a traditional point of view (for ornamental purposes) and ji•om a new and rather exciting one as a possible means of preventing soil erosion on steep slopes on which there are no or few choices for other antierosional crops.

Streptocarpus is a very popular houseplant with colorful flowers, and has thus piqued the curiosity of plant enthusiasts and breeders. In this study, “Natalie” and “Bristol’s Gum Drop” were artificially hybridized to study the influence of the parental reciprocal crosses (P1×P2 and P2×P1) on vegetative and generative morphological traits of F1 progeny. Mean comparisons for morphological characters of parents and F1 plants from both crosses revealed that F1 plants were able to express hybrid vigor for several valuable morphological characteristics. Pearson correlations showed both significant negative and positive correlations between morphological traits of F1 plants from P1×P2 cross, while in the case of P2×P1 no significant negative correlations were observed (p < 0.05). The Start Codon Targeted (SCoT) genetic profiles of the F1 plants with the identifiers P1×P2.19 and P1×P2.35 were remarkably similar, and they grouped with the maternal parent in a small group, supporting the findings of clustering based on morphological data. The parental combination P2×P1 revealed the presence of closely related progenies to the paternal parent, namely P2×P1.16 and P2×P1.5. Two F1 plants named P1×P2.33 and P2×P1.21 were selected based on their phenotypic characteristics and SCoT molecular fingerprinting. These selected genotypes will be tested in our future breeding programs with the aim to create and promote new valuable Streptocarpus cultivars.