جستجوی مقالات مرتبط با کلیدواژه « pollinator » در نشریات گروه « زراعت »

The seed vigor, which shows influence of parents on the life cycle and survival of plants, is also very important in for creating food security for human society. The most important objectives of the present study were to evaluate the general compatibility of parents and the specific combining of crosses, determining the nature and degree of gene action, and finally estimate the heritability of quantitative and qualitative traits of sugar beet hybrids through line-tester analysis.

Eleven pollinator lines of sugar beet were crossed with three male sterile single crosses using controlled pollination in the form of line-tester. A total of 33 obtained hybrids were investigated in terms of different traits related to seed germination in both laboratory and greenhouse conditions. The existence of diversity among the crosses was confirmed, and the calculation of the combining ability of the parents and their genetic effects was done by line-tester analysis.

The results under laboratory conditions showed that there is a significant difference between the crosses in terms of of different germination traits, non-germinated filled cluster, empty cluster and 1000 seed weight. The line had a significant effect on the characteristics of germination capacity, germination uniformity, empty cluster and 1000 seed weight. Tester mean square for germination rate, mean germination time, empty cluster and 1000 seed weight showed a significant difference. Line-tester interaction resulted in a significant difference for the mean germination time, empty cluster and 1000 seed weight. The results of analysis of variance of different traits in greenhouse conditions indicated significant differences between the crosses in terms of the traits of seedling emergence and mean shoot dry weight of a single seedling. The effect of line was significant only on the seedling emergence capacity. The tester factor had a significant effect on all studied traits. Line-tester interaction was significant only for seedling emergence capacity. The general combinability of lines 970023 and 970100 for germination capacity, lines 970038 and 970100 and all three experimental testers for germination rate and 970097 for germination uniformity was significant in positive direction. Line 970097 and tester 474*7112-36-6 decreased the mean germination time and Lines 970038, 970023, 970014, 970100 and tester MS KWS and 7112*SB36 caused a decrease in empty cluster. Testers MS KWS and 7112*SB36 caused the reduction of empty cluster with their negative effect. Regarding the 1000 seed weight, lines 970094, 970014 and 970031 and testers 7112*SB36 and MS KWS had positive and significant general combining ability. In the greenhouse experiment, in relation to the seedling emergence capacity, lines 970100, 970023 and 970038 and MS KWS tester and for seedling emergence rate, lines 970038, 970100 and three testers showed positive and significant general combining ability. For the mean shoot dry weight, line 970098 and tester 7112-36-6*474 had positive significant general combining ability, but tester SB36*7112 caused a decrease in mean shoot dry weight.

Considering that general combining ability shows the additive effects of genes, therefore, parents with high general combining ability also have a high additive effect that can be used in the production of synthetic cultivars. On the other hand, these parents can be used through recurrent selection in the development of inbred lines and also as testers to evaluate new inbred lines. According to the obtained results, the selection of useful compounds for the production of suitable hybrids is determined by the breeding goals. Therefore, by considering the positive or negative specific combining ability value of parental compounds for a trait, it is possible to increase genes with non-additive effect to produce hybrids.

Developing new drought tolerant sugar beet varieties, is one of the most effective ways to decrease the production damage caused by drought stress. In this research 23 superior families selected from 150 half-sib families, crossed with a female parent under drought stress condition. Based on the results four new hybrids were obtained by crossing between, two drought tolerant half-sib families as male parents, with two monogerm female parents. Paya cultivar as one of the hybrids showed the highest average root yield (50.50 t/ha) compared to check variety Gadouk with 36.50 t/ha in preliminary and advanced experiments, during 2010-2014 under drought stress and non-stress conditions. Also, the average seasonal water use of Paya was 15000 and 9500 m3/ha under non-stress and stress conditions respectively, which showed 30-40% saving in water use. The new cultivar indicated superiority root yield 17, 22 and 10 t/ha more than check cultivar Gadouk, under drought stress conditions, in onfarm trials in Karaj, Mashad and Shirvan regions.

In order to increase beet cyst nematode resistance gene frequency, one population named 261*(20314*W-1009) that contains Hs1pro-1 was used in present research. In first year, the population was planted in selection plotes in field. Single plants were labeled and leaf samples were prepared. Then DNA extraction from leaves was done and molecular analysis of plants containing resistance gene accomplished using STS marker and specific PCR test. In second year, gall signs onto resistant vernalized roots were noted and the roots were planted under cages in isolated plots to produce S1 seeds.The S1 seeds were sowed in greenhouse for molecular analysis and in the steckling field to produce the roots. The roots were vernalized in the field in winter season. The molecular results of the S1 plants by Hs1pro-1 marker showed that presence of the resistant gene among the S1 lines is varied 25 to 63 percent. In third year, the vernalized roots were planted under cages in isolated plots to produce new S1 seeds. The new S1 seeds were grown in greenhouse for molecular analysis. The molecular results of the new S1 plants by Hs1pro-1 marker showed enhancement of the resistant gene among the S1 lines that varied 39 to 80 percent. The results showed that resistance gene frequency can be increased by increasing in selfing number and genotypic selection by molecular marker.

Crossing of pollinators and single crosses carrying RZ1 gene resulted in 44 sugar beet hybrids which were evaluated in infected fields in Fars and Khorasan. The seed of six diploid resistant pollinators and seven single crosses were first planted as parents in stekling field. After vernalization، parents were crossed in isolate tents، and hybrid seeds were harvested from female plants. The new hybrids along with resistant and susceptible checks were evaluated in infected condition during 2008-2009. According to the cluster analysis of the two year evaluation for yield، quality and disease severity index، the hybrids (7112*sb36) * 26388، (231*SB36) *26388، (436*SB36) *26388، (419*SB36) *27645، (231*SB36) *27645) and (419*SB36) *26388 were grouped with resistant checks. It seems that selection in the pollinators 26388 and 27645 will result in better hybrids.