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Pimiento pepper (Capsicum annuum var. annuum L. 'Piquillo') was directly seeded on raised beds in double rows 0.35 cm apart. Plants were thinned within the row to establish densities ranging from 13,333 to 186,667 plants/ha. Marketable yield of pepper increased as plant density increased to 100,000 plants/ha. However, with plant densities >100,000 plants/ha, marketable yield did not increase (2001) or slightly decreased (2000). Plant density affected pepper yield only in the first harvest date. Fruit number and fruit weight per plant decreased with increasing plant populations. Weight per fruit decreased slightly at densities >100,000 plants/ha. The increase in yield per hectare as plant density increased was mainly a result of increased number of fruit per hectare. The intercepted PAR by the pepper canopy increased with increases in plant density to about 100,000 plants/ha and this increased interception of PAR resulted in an increase in yield. Plant densities in the range of 100,000 to 120,000 plants/ha were optimal in terms of marketable yield. [ABSTRACT FROM AUTHOR]

The effect of head position on seed yield was studied on 56 at random taken plants grown in an open-air plot near Zaragoza (Spain) which contained around 150 ‘Imperial Star’ globe artichoke plants. When plants started bolting, primary heads were cut away to favour the development of the remaining heads. Flowering started by mid-May and finished at the end of June. During this period, the week in which flowering started was recorded for 77 secondary, 56 tertiary and 60 quaternary randomly chosen heads. During flowering and seed setting, rainfall and temperatures were recorded. Harvested seeds were classified into viable and non-viable for each of the 193 heads. No significant interaction was found between the week of flowering and head position (secondary, tertiary or quaternary). Seed yield was higher on quaternary and tertiary than on secondary heads. The best seed setting period, the first fortnight of June was associated with absence of rain. In all cases, seed yield was low. [Copyright &y& Elsevier]

To analyse interactions in the Phytophthora capsici-pepper (Capsicum annuum L. ) system, three pepper lines (`Morrón INIA 224', P1201232' and 'SCM 334') with various degrees of resistance to P. capsici and three P. capsici isolates with increasing aggressiveness were used Inoculations were made when plants had 4-6 leaves, either by irrigating the culture substrate with P. capsici zoospore suspensions at increasing concentrations of up to 3 × 105/ml, or by adding mycelial suspension. P. capsici isolate 'Ca' was the least aggressive, followd by '8303' and 'B1'. The logistic function was appropriate to describing cumulative mortalities of pepper seedlings inoculated with different P. capsici zoospore concentrations. The inoculum concentration required for 50% mortality classified pepper lines as susceptible (Morróon INIA224') and resistant ('P1201232' and 'SCM334'), the former being less resistant than the latter Isolates 'Ca' and '8303' caused very different mortalities both with zoospore and mycelial inoculations, which allowed them to be classified as belonging to two different vertical pathotypes (P0 and P1). Isolate 'Bi' acted similarly to isolate '8303' when inoculated on Morrón' and 'SCM334'. but its behaviour was dependent on zoospore concentration when inoculated on 'P1201232' It also proved to be similar to 'Ca'using mycelial inoculation. As the case of `BF would not be an exception among P. capsici isolates, the two vertical pathotypes P1 and P0 would be the higher (isolate `8303') and lower (isolate 'Ca') limits of a range of aggressiveness. Although there are cases of host- parasite interaction, absence of interaction seems to be the rule. [ABSTRACT FROM AUTHOR]

According to our previous investigations, resistance to Phytophthora capsici in Capsicum annuum genotypes, 'Line 29', 'P1201232', 'P1201234' and Serrano Criollo de Morelos 334 ('SCM334'), seems to be controlled by three genes. In order to determine the genic relationships between these four sources of resistance, three experiments were conducted which included the four genotypes, their F1s, F2s, F3s and BC1 generations together with the susceptible pepper genotype 'Morrón INIA 224'. Inoculations were made, when plants had 46 leaves, by irrigating the culture substrate with a zoospore suspension of P. capsici isolate 'Bl'. Though the four genotypes showed percentages of resistance close to a 100%, none of them actually reached this level in the three experiments. 'SCM334' was the most resistant genotype, transmitting a high level of resistance to its F1, F2 and BC1 generations. 'Line 29' was more resistant than 'P1201232' and 'P1201234'. However, the F1, F2 and BC1 generations of these three lines showed similar degrees of resistance. The four genotypes seem to have one of the three genes postulated for their resistance in common. All genes displayed a similar level of resistance, except the specific genes of 'SCM334', the effect of which was slightly higher. Several working procedures are suggested for breeding programmes. [ABSTRACT FROM AUTHOR]

In order to establish a genetic model of the resistance to Phytophthora capsici in Capsicum annuum genotype 'SCM-334', two experiments were conducted which included 'SCM-334', as well as, the susceptible line 'Morrón INIA 224' and their F1, F2, F3 and BC1 generations. We also tried to introgress a recessive gene, hypothetically responsible for resistance to P. capsici, from 'SCM-334' into 'Morrón INIA 224'. Inoculations were made, when plants had 4--6 leaves, by irrigating the culture substrate with a zoospore suspension of P. capsici isolate 'BI'. The χ² test was applied to segregating generations to determine how many genes were involved in resistance. The hypothesis which explained the obtained segregations best, although not completely, was one that assumes 3 genes in 'SCM-334', with at least 3 alleles in the heterozygous condition or 4 at any position, present in any genotype in order to be resistant. The influence of the isolate's aggressiveness and the inoculation method on the results are discussed. [ABSTRACT FROM AUTHOR]