Effectiveness of honeycomb selection for yield superiority at three interplant distances: A field simulation study using chickpea (Cicer arietinum L.) inbred lines

The effect of interplant distance on differentiation and selection a) of the superior lines from a mixture of inbred lines, and b) of individual plants originating from the top lines, was studied in chickpeas (Cicer arietinum L.). For this, 28 chickpea inbred lines were evaluated on a single plant basis in a honeycomb design and in the same field at three interplant distances, for four growing seasons, at Larissa, Greece. The interplant distances were 15 cm (520000 plants/ha, strong allo-competition), 30 cm (128630 plants/ha, medium allo-competition) and 100 cm (11500 plants/ha, without competition). In addition, the inbred lines were evaluated in replicated plot trials under an agronomically accepted plant stand (520000 plants/ha, crop environment) and the ranking of the 28 lines based on the average yield per plot over growing seasons was determined. Selection was applied in each season for each interplant distance and the three and six top lines with the highest average yield per plant were identified. These top lines from each interplant distance were compared with the three and six top lines (say: proven superior lines) identified after their evaluation under crop environment over seasons. In addition, selection was applied at the individual plant level with six selection pressures in each season and each interplant distance. Then we determined for each experiment and selection pressure the number of the selected plants which belonged to the six proven top lines. It was observed that the ranking obtained under crop environment was best correlated with the ranking at the intermediate interplant distance (30 cm), followed by the ranking at the high interplant distance (100 cm). In contrast this correlation was very weak for the ranking at low interplant distance (15 cm). In addition, the interplant distance identifying the highest number of the proven high yielding lines after their evaluation in one season was the intermediate interplant distance followed by the high interplant distance and certainly not the low interplant distance. The relative effectiveness was further increased when selection was based on average performance of the lines across seasons. This, together with the relatively small number of seeds produced per plant, renders selection at low interplant distance less favorable than selection at the intermediate or high interplant distance. The individual plant selection was effective at all three interplant distances. Selection effectiveness generally increased as the selection pressure increased. Again the best results were obtained when selection was applied at intermediate or at high interplant distance. It was concluded that line selection as well as individual plant selection was more effective at intermediate interplant distance and certainly not at low interplant distance

Comparative efficiency of honeycomb and conventional pedigree methods of selection for yield and fiber quality in cotton (Gossypium spp.)

The effectiveness of honeycomb pedigree selection (HPS) as compared to conventional pedigree selection (CPS) was studied in one intraspecific (G. hirsutum L. x G. hirsutum L.) cross population (population I) and one interspecific ( G. hirsutum L. x G.barbadense L.) cross population (population II). Combined selection for yield and lint quality traits was applied for four cycles at two locations for population I and at one location for population II. Finally, the best F-6 lines derived by each method, together with the unselected population derived by single seed descent (SSD) and three check cultivars, were tested in comparative experiments, separately for each cross, at the same locations. In both populations the analysis of variance indicated significant differences among the groups of the material tested for seedcotton yield, mean boll weight, micronaire reading, staple length, and uniformity ratio. No significant differences were found with respect to plant height, lint percentage, and fiber strength in population I and with respect to lint percentage and fiber strength in population II. In population I, on the basis of mean seedcotton yield and number of superior lines derived by each method as compared to the check varieties and the unselected SSD population, HPS-lines were superior to CPS-lines for seedcotton yield, fiber length and boll weight. HPS-lines, however, did not differ significantly in seedcotton yield from the best check cultivar Eva. Finally, the material derived by CPS was earlier in maturity than the material derived by HPS and SSD. Also in population II, on the basis of mean seedcotton yield and number of superior lines derived by each method as compared to the unselected SSD population, HPS-lines were superior to CPS-lines. No significant differences, however, were identified between the material of the two methods for lint quality traits. It was concluded that in both populations HPS was more effective than CPS in identifying lines with high yielding ability and good lint quality. This superiority of HPS is attributed, at least partially, to its effectiveness in early generation selection

Prediction criteria of promising F-3 populations in durum wheat: A comparative study

Effective selection of parental material and promising segregating populations is an essential requirement for breeding success. There are many contradictive reports about the best parent selection criterion for the development of promising crosses. For the clarification of this problem field experiments were conducted for four consecutive years to compare the effectiveness of six criteria for the prediction of the most promising F-3 populations in durum wheat (Triticum durum L.): the mid-parent value, the F-1, the F-2, the (F-1 + F-2)/2, and the genetic distance among the parents as it is calculated using the SSR and RAPD molecular markers. During the first growing season (2003-2004) nine commercial cultivars of durum wheat and four landraces were crossed. The following growing season (2004-2005), 17 crosses (F-1 generation) were evaluated under low plant density (1.15 plants m(-2)) in a replicated (R-21) honeycomb design. During the third growing season (2005-2006), the four highest yielding crosses, one cross with an intermediate yield, and the three crosses with the lowest yield (172 generation) were evaluated under low plant density in a R-9 honeycomb design. Finally, in the fourth growing season (2006-2007) progeny of the aforementioned eight crosses (173 generation) and the ten parents were evaluated in a randomized complete block design in two locations. Furthermore, the genetic distance among the parents was determined using the SSR and RAPD molecular markers. It was observed that the three F-3 populations with the lowest yielding ability were the ones with the lowest mid-parental value. In addition, one of the two top F-3 populations was second in the rank according to the mid-parental value. Furthermore, the two top F-3 populations were also the highest yielding in the F-1 and F-2 generations. On the contrary, none of these crosses were predicted by the genetic distance as it was calculated using the SSR and RAPID molecular markers. It was concluded that parental pairs with high mid-parental value and high combined yield (F-1 + F-2)/2 obtained after evaluation of their F-1 and F-2 at low plant density was the most effective way to predict promising F3 populations. (C) 2008 Elsevier B.V. All rights reserved