A. Troncoso

Salinity and germination of annual Melilotus from the Guadalquivir delta (SW Spain)

The germination response to NaCl treatments has been studied in Melilotus seed populations collected from saline and non-saline soils in the Guadalquivir delta.The rank orders for salt tolerance and seed weight were the same in the threeMelilotus species living in this area:Melilotus messanensis>M. segetalis>M. indica.Within the species, differences in germination response to salinity were found inM. indica (6 populations) andM. segetalis (8 populations). The relationship between salt tolerance during germination and salinity of maternal habitat is discussed.

The floral biology of the olive: effect of flower number, type and distribution on fruitset

Abstract The effect of flower number and distribution on the fruiting behavior of various olive cultivars was studied over a period of 10 years. The number of staminate flowers within each cultivar had no significant effect on fruitset. Pre-bloom removal of up to 50% of the flowers did not affect fruitset. Variation in prebloom flower-removal position resulted in similar fruitset per inflorescence, whether flowers were removed along the inflorescence axis or from the distal half of each inflorescence. Removal of half of the inflorescences resulted in doubling the fruit set on the remaining ones, except in cv. Koronaiki which normally sets more than one fruit on most of its inflorescences. The distal fruitful inflorescence set more than one fruit (mostly two) on 70–80% of the shoots of various cultivars. In cv. Santa Caterina a clear increase in fruitset per shoot was observed when 80% of the flowers per inflorescence were removed. In this cultivar the lateral flowers were significantly more fruitful than the king flower. This however, was not the case with cv. Manzanillo.

In vitro germination of embryos for speeding up seedling development in olive breeding programmes

Abstract The germination potential of olive seeds without the sclerified endocarp (stoneless seeds) and growth of the seedlings were compared with germination and growth of excised and in vitro cultured embryos of ten olive cultivars. The number of empty stones and the number of stones with two seeds were also determined for each of the cultivars. Isolated embryos of all the cultivars germinated uniformly within 10–14 days in culture, while the mean germination time of stoneless seeds was 55–95 days depending on the cultivar. The percentage of embryo germination was 3–15 fold higher than that of stoneless seeds according to cultivar. Root growth was more rapid in plants originating from seeds than from excised embryos. The growth of plantlets derived from in vitro germinated embryos in the greenhouse was normal. Thus, embryo culture would increase the efficiency and shorten the time for starting initial progeny evaluation of olive breeding programmes.

Beneficial effect of arbuscular mycorrhizas on acclimatization of micropropagated cassava plantlets

Abstract Survival and development of cassava (Manihot esculenta Crantz) plantlets has been increased by modifying tissue culture protocols and by mycorrhizal inoculation. About 90% of plantlets were successfully rooted in vitro and 75% survived after the acclimatization phase. Inoculation with Glomus deserticola early in the post vitro weaning stage enhanced percent survival and improved tolerance to the transplanting stress. Shoot, root and tuber development of the micro-propagated plants was increased following inoculation with different arbuscular mycorrhizal (AM) fungi. Growth responses were dependent on both the cultivar (clone) and the AM fungi involved. G. deserticola was very effective in improving growth of both clones, the effectivity of G. clarum and G. fasciculatum being dependent on the cultivar. These results emphasize the need for selection trials before appropriate plant cultivar/AM fungi combinations can be recommended.

Possible juvenile-related proteins in olive tree tissues

Comparisons of protein composition between juvenile and adult organs of olive trees were made by SDS-polyacrylamide gel electrophoresis analysis. Plant material included leaves, bark and bud tissues obtained from juvenile and adult organs within the same plant as well as from separate plants of both the same and different genetic origin. The amount of protein loaded onto the gels was standardized by adjusting the volume of the extract applied to the gel. The protein population of both juvenile and adult tissue from the same or separate trees was qualitatively similar but at least one group of 29 kDa polypeptides, is more abundant in the juvenile leaf tissues. In contrast, a protein group of 35 kDa is more strongly expressed in the adult tissue. Similar relations between the proteins of juvenile and adult tissues were obtained in various cultivars of different genetic origin. Thus, differences in protein composition between juvenile and adult tissues, although only quantitative, are consistent across genotypes. Although, some protein groups, e.g. 63 kDa might be clone-specific some other protein groups also differ quantitatively between adult and juvenile tissues but to a lesser extent.

Deficit irrigation and fertigation practices in olive growing: Convergences and divergences in two case studies

Abstract The response of mature olive (Olea europaea L.) trees to both regulated deficit irrigation and fertigation was studied for some consecutive years in sub-humid (Italy) and semi-arid conditions (Spain). All cultivars tested in these experiments were preferentially for table olive consumption (pickling and double-aptitude). Data from these long-term studies on field-grown, mature trees are summarized for assessing common effects of water and nutrient supply on plant behaviour and fruit yield. Seasonal yield variations were observed, and showed that the effect of irrigation treatments was somewhat more gradual in the “on” than in the “off” year. Differences amongst cultivars were always marked. Dry matter accumulation in pulp and pit was positively affected by progressively increasing the amount of water supplied to plants, regardless of years and cultivars. The ratio between pulp and pit fresh weight was negatively affected by irrigation, while fruit size was positively influenced by the gradual increase of irrigation water. Average nitrogen levels in leaves were generally above the deficiency threshold at both experimental plantations. Crop yield was not consistently increased by addition of soil nutrients. The effect of fertigation treatments was relatively uninfluential on oil accumulation in fruits. However, polyphenols in oil samples decreased progressively as the addition of nutrients increased. Critical aspects and strategic decisions in modern olive growing are the selection of cultivar, the supply of water, the option of fertilization, together with other orchard management practices. In this paper we outline various aspects of long-term studies in experimental olive plantations with the aim of highlighting inter-regulatory processes, involving plant growth and crop yield, which must be taken into account when planning future field research and modelling exercises.

Growth and mineral composition of grape-vine rootstock cultured in vitro with different levels of ammonium nitrate.

Growth and mineral composition of grape-vine explants (13.3 EVEX rootstock) cultured on a basal medium with 10.4 mM of NO3 −, and respective additions of 5, 10, 15, 20 and 25 mM of NH4NO3 were analysed.

Influence of the nitrogen source and concentration on N fractions and free amino acid levels of grape vine explants

The influence of the source of inorganic nitrogen (KNO3, (NH4)2SO4 and NH4NO3) and its concentration (5, 10, 20 and 30 mM N) on total N incorporation, as well as on N distribution into different fractions (amminiacal, amino, amide and protein) and on free amino acid levels has been determined in grape vine explants cultured in vitro.Increasing concentrations of the nitrogen source resulted in increased total N content in tissues. This effect was small for KNO3, higher for (NH4)2SO4 and maximal for NH4NO3. In addition, nitrate promoted an increase in amino-N only, whereas ammonium increased both the ammoniacal-N and the amino-N fractions. Incorporation of N into amide-N and protein-N were not affected significantly by the N sources tested.The application of increasing quantities of N enhanced the accumulation of most free amino acids, especially arginine, alanine and proline, but to different extents, depending on both the N source and its concentration. The combination of ammonium and nitrate resulted in a higher accumulation of amino acids than that observed with either one of the two forms alone.