"效益-费用"法在林业公益事业建设项目经济评价中的应用

政府对林业公益事业项目的投资 ,是以谋取公众福利最大化为目的的。企业投资项目的经济评价以财务评价为主 ,而政府对林业公益事业投资的经济评价则以国民经济评价为主。“效益—费用”分析评价法是一种动态经济评价方法 ,其评价结果能直观地反映政府公益性投资的经济效果 ,并且宜于在多方案比选中运用。举例说明其计算方法和评价效果     

Screening of melon (Cucumis melo L.) germplasm for multiple disease resistance

Summary Melon germplasm was screened for cucumber green mottle mosaic virus (CGMMV), powdery mildew (Sphaerotheca fuliginea), downy mildew (Pseudoperonospora cubensis) and Fusarium wilt (Fusarium oxysporum f. sp. melonis) resistance under artificial conditions except downy mildew for which screening was done under natural epiphytotic conditions. High level resistance to all the four diseases was not recorded in any of the collections tested. Nevertheless, ertheless, resistance to three diseases was located in three germplasm. Wild Cucumis species C. figarei exhibited absolute resistance to CGMMV and Fusarium wilt and high level resistance to downy mildew. Phoot or snapmelon (Cucumis melo var. momordica) — a non-dessert from of Indian origin—was highly resistant to downy mildew and resistant to CGMMV and medium resistant to Fusarium wilt. Iroquois was resistant to powdery mildew and medium resistant to downy mildew and CGMMV.     

Genetics of multiple disease resistance in a doubled-haploid population of barley

The barley accession Q21861 possesses resistance to the stem-rust (Puccinia graminis f.sp. tritici), leaf-rust (P. hordei), and powdery-mildew (Blumeria graminis f.sp. hordei) pathogens. An anther-culture-derived doubled-haploid population was produced from F₁ plants from a cross of this accession and the susceptible breeding line SM89010 as a means of rapidly and efficiently determining the genetics of multiple disease resistance. The doubled-haploid population segregated 1:1 (resistant:susceptible) for resistance to the stem rust pathotype QCC indicating the involvement of a single resistance gene, rpg4. Two-gene (3:1) and one-gene (1:1) segregation ratios were observed for resistance to the stem-rust pathotype MCC at low (23–25°c) and high (27–29°C) temperature, respectively. These different segregation patterns were due to a pathotype × temperature interaction exhibited by rpg4 and Rpg1. another stem-rust-resistance gene present in Q21861. One-gene and two-gene segregation ratios were observed in reaction to the leaf rust and powdery mildew pathogens. These data demonstrate the utility of doubled haploid populations for determining the genetics of multiple disease resistance in barley.     

Detection of repeated genotypes among 93 diploid wheat accessions

Summary An objective procedure was developed to find and eliminate repeated genotypes from a set of crop cultivars or accessions which may be used as parents for future plant breeding programs. Nonhierarchical, nonexclusive, exhaustive cluster analysis was used to group 93 diploid wheat accessions using LSD multiple comparisons of accession means based on data measured on seven characters. Beginning with the rarest accessions, i.e. those represented in the fewest clusters resulting from the clusters analysis, a minimum number of the accessions were chosen to represent the phenotypes of all 93 of the accessions. Two analyses were performed, one using data from an irrigated trial, the other from a dryland trial. The dryland trial data was more discriminating in that it required 71 accessions to represent all of the clusters generated from the original 93 accessions while the irrigated trial data required only 60 of the 93 accessions. In addition to the 71 accessions chosen from the dryland trial analysis, the irrigated trial analysis suggested an additional 12 accessions were phenotypically and, therefore, genotypically unique. The total of 83 unique accessions left 10 phenotypically duplicate accessions to be eliminated from the set of potential parents. Four of the 10 duplicated accessions were rare in that they were represented in very few clusters in either the irrigated trial analysis or in the dryland trial analysis. Because their phenotypes were not unique in spite of being rare, we believe such accessions were duplicated genotypically as well as phenotypically. The other six duplicates were common in that they were represented in a large number of clusters. Such accessions may not prove to be duplicates if grown in additional environments (trials), or if measured on additional characters.     

Results of multiple pollination in blueberry (Vaccinium elliottii Chapm.)

Blueberry (Vaccinium section Cyanococcus, family Ericaceae) is a shrub that produces multiple-seeded berries in which only a fraction of the ovules develop into viable seeds. A recessive yellowleaf marker gene was used to evaluate the efectiveness of a single pollination versus multiple pollinations in producing seeds in Vaccinium elliottii Chapm. A multiple-pollination experiment was conducted to see if the first pollen applied or the second produced more progeny, and to see if multiple pollinations increased the number of seedlings produced. Flowers of diploid yellowleaf Vaccinium elliottii were pollinated from one to four times at daily intervals. Pollen from redleaf and yellowleaf plants was used to produce two types of seedlings that could be distinguished visually. Generally, percent berry set, seeds per berry, and seed germination were not increased by multiple pollination. After multiple pollination, the pollen applied first always produced the most seedlings. Prior pollination greatly reduced seed set from subsequent pollination, but subsequent pollination caused little or no decrease in the number of seeds set by the first pollination. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetical Studies on the Mode of Inheritance and Localization of the amo1 (High Amylose) Gene in Barley

In the high amylose starch mutant ‘Glacier AC38’, a single recessive gene designated amo1 is responsible for an amylose content of up to 45%. A rapid technique was established in order to evaluate the amylose/amylopectin ratio in half kernels. To localize this gene, crosses with multiple marker lines and trisormes were conducted. In addition, RFLP markers were used to determine their mapping distance to amo1. Two markers are located 2 cM and 7 cM, respectively, from amo1 on chromosome 5S (1HS). The relationship between the wx and amo1 genes was also examined and the role of the amo1 gene in starch synthesis is discussed.     

Studies on the inheritance of five qualitative characteristics in clusterbean (Cyamopsis tetragonoloba (L.) Taub)

Summary The inheritance of five characteristics namely branching behaviour, clustering pattern, growth habit, leaf size and hairiness was studied in clusterbean. All the traits were controlled by single pairs of genes except branching behaviour which exhibited digenic inheritance. Complementary gene effects were involved in the expression of branching in the F₁ and F₂ generations; the F₂ showing a ratio of 9:7 for branched to unbranched genotypes in the cross FS 277 × NC 70 where both the parents were single shooted. The alleles governing branching, discontinuous clustering, indeterminate growth habit, small leaf size and hairiness were dominant over the alleles controlling non-branching, continuous clustering, determinate growth habit, broad leaf and glabrous leaf and stem.     

Single and Multiple Traits Selection in a Segregating Population of Wheat, Triticum aestivum L.

The breeding materials used in this study were the F₃, F₄ and F₅-generations of the cross between Giza 158 × Sonora 64 (Triticum aestivum L.). The objective of this study was to compare the relative merits of Smith-Hazel, desired gain selection indices, independent culling levels and single trait selection in improving grain yield, heading date and several agronomic traits. Highly significant differences among F₃ families and a satisfactory genotypic coefficient of variability were obtained for all the traits studied. The genotypic correlations were high between yield and each of spike weight, kernels/spike and spikes; plant, intermediate with 1000 kernel weight and very low with heading date, plant height and spike1 length-After two cycles of selection, the results of the gains realized indicated that the most effective method for improving yield was the Smith-Hazel index (SH₇) of seven traits followed by the desired gain index of seven traits (DG₇), SH₅, independent culling levels, DG₅ and direct selection (or grain yield/plant. Direct selection for heading date, plant height and spike length was the best method for improving these traits, but undesirable correlated responses in the other traits were obtained.     

Inheritance of the virgata pattern of partly colored seed coats in ‘Early Giant’ common bean

The inheritance of the virgata pattern of partly colored seed coats found in common bean (Phaseolus vulgaris L.) Early Giant (EG) was studied by a series of test crosses with line 5-593 and genetic stocks developed by backcrossing selected genes into the recurrent parent 5-593, a Florida dry bean breeding line with a self-colored, black seed coat with genotype T Z Bip P [C r] J G B V Rk. Analysis of the F₂ from the cross EG × 5-593 led to the hypothesis that the virgata pattern of EG has genotype t z bip^vgt, where vgt stands for virgata. The test cross EG × t z virgarcus BC₃ 5-593 confirmed the hypothesis that EG carries t z from data recorded in F₁, F₂, and 27 F₃ progenies from randomly selected F₂ plants. The F₃ segregation was also consistent with the hypothesis that a single recessive gene converts virgarcus into virgata. The test cross EG × t z bip bipunctata BC₃ 5-593 failed to show genetic complementation in F₁ progeny, and the F₂ segregated 3:1 for the parental phenotypes virgata and bipunctata, respectively. Including previously published data, all possible crosses were made among bipunctata, virgata, and virgarcus parents, supporting a multiple allelic series at Bip. We propose the gene symbol bip^vgt for the new allele at Bip, where the allelic series has the order of gene dominance Bip > bip^vgt > bip. Based on test crosses, the complete seed-coat color and pattern genotype of EG is tz bip^vgt P [C r] J G B v^lae rk^d.     

Genetic control of irregular striping, a new phenotype in Cucurbita pepo

Longitudinal striping of the fruit exterioris a common trait in Cucurbita pepo(pumpkin, squash, gourd). Striping occursas ten pairs of alternating dark and lightstripes that are regularly situated inaccordance with the ten sub-epidermalcarpellary vein tracts. Usually, the darkstripes occur in the central areas betweenthe vein tracts, with the light stripesoccupying the remainder of the fruitsurface. A new phenotype is described inwhich dark spots or streaks occur in thecentral areas between the vein tracts;these are usually accompanied by darkstreaks or stripes that occur adjacent toand over part or all of the length of someor all of the ten carpellary vein tracts. The inheritance of this irregular stripingpattern was studied by crossing anaccession that bred true for this phenotypewith a near-isogenic line havinglight-colored fruits. The resultsindicated that irregular striping isdominant to light coloration and isconferred by a single gene. Testcrossesfor allelism with regular striping wereprepared by crossing the irregularlystriped accession with near-isogenic lineshaving broad stripes, l-1 ^BSt/l-1 ^BSt, and narrowstripes, l-1 ^St/l-1 ^St. The testcross results revealed thatirregular striping is conferred by anallele at the l-1 locus, designatedl-1 ^iSt. The l-1 ^iStallele is dominant to light-colored (l-1), recessive to dark-colored (L-1), and can be co-dominant or recessiveto broad-striped (l-1 ^BSt) andnarrow-striped (l-1 ^St),depending on whether or not it is fullyexpressed. Dominance relationships at thel-1 locus can, therefore, berepresented as L-1 > (l-1 ^BSt > l-1 ^St) l-1 ^iSt > l-1.