Enrique Luis Cointry

Heterotic patterns in hybrids involving cultivar-groups of summer squash, Cucurbita pepo L.

Heterotic response for total yield among five cultivar-groups of summer squash, Cocozelle, Vegetable Marrow, Zucchini, Crookneck and Straightneck, was studied in two sets of diallel crosses evaluated in two harvest seasons. Each diallel cross included two representatives of each the five cultivar-groups. Griffing and diallel GGE biplot (genotype main effect and interaction) analyses were carried out. The relative importance of the specific combining ability variance on total variance was greater than that reported earlier for intragroup crosses. Highly significant heterosis was manifested only in combinations of Crooknecks or Straightnecks crossed to Cocozelles, Vegetable Marrows or Zucchinis. GGE biplots showed a consistent arrangement where testers of ssp. texana interacted with cultivars of ssp. pepo and vice versa. We propose that the heterotic pattern of texana-pepo crosses could be potentially used to achieve increased yields in hybrids by introgressing one group into another in a manner that would maintain fruit attributes of the cultivar-group.

An approach for understanding the heredity of two quality traits (head color and tightness) in globe artichoke (Cynara scolymus L.)

The inheritance of head color and tightness in globe artichoke was studied utilizing crosses between inbreed lines and between clones and self-pollinated clones from different genetic origins. These genetic materials were sowed in a completely randomized design with 20 plants per plot and genotype. Globe artichoke heads were classified into three colors (purple-green, purple and green) and three head tightness types (compact, fairly compact and soft) and the segregating ratios for these traits tested in each offspring using the chi-square test. Crosses between green and purple inbreed lines produced only purple-green heads but F2 generation segregated at a purple-green:purple:green ratio of 9:3:4. The self-pollinated compact head clones produced a compact head:fairly compact head:soft head ratio of 12:3:1. The remaining crosses between lines and among clones and backcrosses verified these ratios. These results suggest that two loci with a simple recessive epistasis are involved in the inheritance of head color and that two loci with simple dominant epistasis are involved in the expression of the different head tightness types. The inheritance models proposed here could be helpful in predicting the appearance of artichoke heads if breeders need to obtain hybrid seeds for a desirable phenotype.

In vitro tissue culture in breeding programs of leguminous pulses: use and current status

Legumes represent a vast family of plants including more than 600 genera and more than 13,000 species. Among them, the term “pulses” refers only to dried seed crops, excluding those grown mostly for oil extraction (like soybean), where dried peas, edible beans, lentils, chickpeas, cowpea, mungbean, blackgram and pigeonpea are the most common cultivated ones for human consumption due to their high nutritional value. They also have the ability of fixing nitrogen into the soil with symbiotic bacteria, which reduces the need for chemical fertilizers in crop rotations. Conventional breeding methods for pulses are laborious and time-consuming before the release of new genotypes. Thus, alternative biotechnological approaches may be advantageous in this area. Tissue culture, plant regeneration strategies, gene transfer and plant transformation are studied in these pulses. Also, anther, microspore, embryo and ovary culture and their opportunity of application in these pulses are discussed.

New genetic maps for globe artichoke and wild cardoon and their alignment with an SSR-based consensus map

An F1 mapping population was bred by crossing an accession of wild cardoon with a single Argentinian globe artichoke plant of the variety Estrella del Sur FCA with a view to generating new Cynara cardunculus linkage maps. Genotyping was conducting using a set of 553 SRAP, SSR, AFLP and SNP markers. The 1,465.5 cM map based on the segregation of alleles present in the wild cardoon parent comprised 214 loci distributed across 16 linkage groups (LGs), while the 910.1 cM globe artichoke-based map featured 141 loci falling into 12 LGs covering the total length. Three of the morphological traits (head spininess, leaf spininess and head color) for which the parents contrasted were inherited monogenically, and the genes conditioning them were mapped. A set of 48 co-dominant loci was used to align the LGs with those derived from a reference SSR-based consensus map of the species.

Early selection of elite plants in Asparagus

In order to establish an efficient selection criterion the variability in three asparagus populations was evaluated defining the most important yield components and analysing its evolution along three growing seasons. The yield components, coefficient of variation (CV) and the proportion of plants contributing to 80% of the total yield were estimated. The elite plants were selected by mean of total yield and clusters techniques. Multiple regression showed that spear number (SN) and spear weight (SW) were the most important yield components. In every population, total yield (TY) and SN showed the highest values of CV, independently of sex. 69% of the plants contributed to the 80% of the total yield in the first year while in the second and third year the contribution was 57%. At the end of the third year, 17 plants were selected by the average of the total yield and 43 by clusters. It is suggested to select for SW in the first year, reducing in 68% the experimental material. In the second year, the selection for SN would reduce to 5% the plants to evaluate for total yield in the third year. In this way the selected plants are the same but the number of plants to evaluate is dramatically reduced along the years, therefore facilitating the breeders work.

Evaluation of seven asparagus populations ( Asparagus officinalis L.)

The materials of asparagus (Asparagus officinalis L.) that growers have in use are imported by seed dealers and have been selected according to overseas markets requirements. With the aim of selecting proper parents to use in a breeding program, seven populations of Asparagus officinalis (P1 to P7), all rised as white asparagus, were tested during 1993 and 1994, at the Experimental Field of the Facultad de Ciencias Agrarias (Universidad Nacional de Rosario) placed in Zavalla, Santa Fe, Argentina. The evaluation was made on individual plant in a 40 days of harvest period. ANOVA and a cluster analysis were made. In order to improve total and marketable yield, P1, P2 and P3 should be used as females regarding that these ones also have high spear number. To improve spears weight and diameter as well as late production, P5 and P7 are recommended as males, but it should be considered that P5 has a better yield performance.

Caracteres agronómicos en el cultivo de espárrago de diferentes edades y manejos

Age and crop system effects on agronomic response were evaluated in 11 hybrids of Asparagus officinalis L. The experimental design was a complete randomized block with three replicates of 20 plants of 3 or 4 years old, conducted either in mounded soil over plants for blanched asparagus, or in raised beds without ridging for green asparagus. The highest mean values were obtained under the blanched production for days to harvest, market yield, total yield, spears number and the spear mean weight. However, under the green production, the rate of increment from first to second year was superior for market yield and total yield due to an augmented rate of increment of spears number. Type and year of production effects were similar for days to first harvest and spears mean weight, meanwhile days to 50% of sprout plot was affected mainly by the year of production.

Efecto de una generación de endocría sobre caracteres vegetativos y productivos en dos estructuras familiares de alcaucil

Globe artichoke (Cynara scolymus L.) is an allogamous species where vegetative propagated cultivars are not suitable for seed multiplication due to their high heterozigous condition. To obtain homogeneous materials, the inbreeding process is necessary. Inbred lines could be used as cultivars or in hybrid combinations. The effect of one generation of selfing over vegetative and productive traits were evaluated. The Genetic Determination Coefficient was estimated in two different family structures. Two sets of S1 families were originated: one from crosses between clones and the other through open pollination of the same clones. These assays were implanted in the field, in Zavalla, Argentina. The vegetative and reproductive characters were evaluated in a single plant. The importance of the starting material to obtain lines with adequate agronomic performance was demonstrated: S1 families originated from half-sib plants presented a strong endogamic depression in the majority of the traits in comparison to those obtained from full-sibs. Although all characters manifested endogamic depression after one generation of selfing, a genetic variability still remained among sets, among families and plants within families. As a consequence, it could be possible to select elite plants to continue the inbreeding process or to be vegetatively propagated as clones.

Vernalization of seed and plantlets and development of globe artichoke.

Annual production of globe artichoke [Cynara cardunculus var. scolymus (L.) Fiori] requires vernalization of the plants, either through cold treatment of transplants or from natural temperature conditions in the spring. To evaluate cold treatment on productive traits in artichoke, two experiments were performed. In the first experiment, dry seeds, plantlets at the cotyledon stage, and plants with two expanded true leaves were subjected to 3°C for 10 days. In the second experiment, dry seeds, seeds soaked in water, and germinated seeds were subjected to 3°C for 10 days. Days to first harvest (FH), total yield (TY), number of buds (NB), and mean head weight (MW) were evaluated. Treatment did not affect FH, but treatment affected NB and TY in the first experiment. Plants developed from seedlings treated at the two-leaf stage had increased NB and TY. In the second experiment, vernalization decreased NB, bud weight, and TY below that of controls. Cold treatment of seedlings at the two expanded leaf stages may have the potential to enhance yield.

Response of Productive and Morphovegetative Traits of Globe Artichoke (Cynara cardunculus var. scolymus) to Mass Selection and Estimation of their Heritability

There have been few reports on genetic parameters or artificial selection for growth traits in globe artichoke (Cynara cardunculus var. scolymus), the study of the effect of one cycle of mass selection and realized heritability estimates would be valuable for planning breeding strategies in this species. A C0 segregating population was formed from the cross of two contrasting seed-grown cultivars, Imperial Star and Estrella del Sur FCA. Selected plants for productive traits were intercrossed to produce a C1 population. The C1 population along with the C0 population, both parents and the F1 were evaluated obtaining the response to selection and estimating realized heritability. Mass selection for increased yield and precocity was particularly successful, where for the first trait realized heritability reached 0.71 and 0.60 for the second one. For most traits, the observed values for realized heritability in the experiment (0.75, 0.61 and 0.52 for weight of the main head, marketable yield and length of the main head, respectively) indicate that a substantial part of the observed phenotypic variance is of additive nature. Therefore, in general, selection for these traits in seed-grown globe artichoke populations will be effective.