Developmental stages of wheat seed that were identified easil)- have been classfied by two different ways'; one based on the endosperm development (six stagcs of watery, milky, soft dough, hard dough, ripe, and dead ripe) and the other based mainly on the embryo development (five stages of I to V). We examined these two types5 of the developmental stages by obscrving embryo and endosperm development, and appearance of seeds. Since lve find charactoristic developmental stages of wheat seed in res.pects.' of dry weight increase and morpho]ogical development of embryo and en-dosperm, we propose the following six development stages. At stage I (from fcrtilization to days post anthesis (DPA) 5), the embryo is globular and do not yet differentiate. The endosperm grows most rapidly. Thc seeds are lvhite green and less than I mmin length. At stage 2 (from DPA 5 to 10), the embryo differentiates into embryo axis and scutellum. The endosperm still grows rapidly. At stage 3 (from DPA 10 to 15), the scutellum elongate. Dry weight of the seeds increases' most rapidly. The endosperm becomes milky. At stage 4 (from DPA 15 to 20), the primary leaf, root and coleoptilo differentiate in the embryo axis. The size of the endosperm and consequently the size of the seed reach their maximum. The seeds, become fresh green. At stage 5 (from DPA 20 to 30), the embryo differentiates further and its dry weight increases most rapidly. The res.erve accumulation in the endosperm shows the socond peak. The endosperm has a soft dough consistency. The s.eeds show yellolvish part. At stage 6 (from DPA 30 to 50). the seeds desiccate and turn brown. The stages of hard dough, ripe, and dcad ripe are included in the stago 6.

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Mature seeds of 250 sorghum varieties were cultured to evaluate ability of callus formation and plant regeneration. Twenty germinated seeds were placed on callus induction medium and cultured for 30 days. The composition of callus induction medium was MS supplemented with 2 mg/l 2, 4-D, 30 g/l sucrose, 2 g/l Gelrite and pH was adjusted to 6.0 before autocraving. The composition of callus maintenance medium was the same as callus induction medium except that the concentration of 2, 4-D was reduced to 1 mg/l and the calli were cultured for 30 days. The composition of plant regeneration was the same as callus induction medium except that 2, 4-D was omitted. After 30 days of culture on the regeneration medium, plant regeneration was evaluated. In this culture system, most varieties formed compact yellowish calli. Type of plant regeneration was organogenesis and distinct somatic embryogenesis was not observed. In many cases only root formation was observed. Five varieties showed relatively high ability of plant regeneration. They were CK602, CKW5809, PE932 203, PE954 068 and PE954 110. Among the variety groups, Kafir group varieties showed relatively high ability of callus formation and plant regeneration. These five varieties and Kafir group varieties may be useful for iu vitro study of sorghum which requires plant regeneration.

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An isogenic line of Taichung 65 harboring the earliness gene Ef-1 (T65 · ER-1) produced short anthers compared with those of Taichung 65 (T65). To examine the genetic relation between the Ef-1 gene and the anther length, a linkage analysis was performed using F2 plants of a cross, T65 · ER-1/T65, and BIFI plants of the crosses, T65 -ER-1/T65//T65 · ER-1 and T65 · ER-1/T65//T65. Since the anther length was affected by the temperature, segregation of the anther length was examined basing on the ranges of the anther length of two lines, T65 and T65 ·ER-1, and their F1 hybrids, collected during the same period. The results showed that the anther length was controlled by a single gene, and that the short anther trait was incompletely dominant over the long one. No recombinants with early heading and a long anther or with late heading and a short anther segregated in the 973 BIFI Individuals of the cross, T65 · ER-1/T65//T65 and 487 F2 plants. It was, then, concluded from the BIFI data that the recombination value between a gene shortening the anther length and the Ef-1 gene did not exceed 0.5 %, assuming that the anther length is controlled by a gene different from Ef-1 Smaller recombination values than 0.5 % were reported in rice. Consequently, it is possible that the gene that shortens the anther length is present and tightly links with the Ef-1 gene. However, it is also possible that the effect of the Ef-1 gene on the shortening of the anther length is pleiotropic. It was, then, deemed important to identify new earliness genes that do not shorten the anther length for the improvement of the cool tolerance capacity at the booting stage, because it was considered that anther length was positively correlated with the degree of tolerance.

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The adaptation of the brown planthopper (BPH) to mixture of resistant rice lines was studied. The BPH population which had no ability to infest any resistant rice varieties in Japan was reared on the three plots of single resistant lines and the four mixtures of two to three resistant lines. BPH adapted to the single resistant lines by the fifth generation of selection and to the mixtures by the ninth generation. The BPH colonies selected on the mixtures were more virulent than those on the single resistant lines, which enabled to infest all the component lines. These results revealed that the mixtures of twO to three BPH resistant lines were only effective to delay the development of the varietal resistance-breaking populations for some geneartions but ineffective to prevent it.

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Tertiary trisomics, cytogenetical variants with an interchang'ed chromosome in addition to the normal chromosome them complemcnt. were produced through systematic three-way crosses, (primary tris'omics reciprocal translocations normal disomics) in rice (Oryza sativa L.). Twenty-five tertiary trisomics were selected on the basis of their morphology and seed fertility in the Fl prog'enies of the three-way crosses. They were identified by obs'crvations.' of the breeding behavior of their selfed progenies and of chromosomal config'urations at meiosis. As the tertiary trisomics pro duced in this .study are useful for cht'omosome mapping, additional production of tertiary trisomics is under way.

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We evaluatod the degree of parthenogrenesis in 32 acccssions and 16 F₁ hybrids of Chinese chive, a facultatively apomictic crop, with a view to idcntifying' non-parthenog'enet, ic plants'. Morphological observations on flower traits of the accessions have revealed that Chinesc chivo consists. of two morphospccios, Allium. tuberosum Rot.tl. and A. ramosum L., and various intermodiatc forms. In each accession or hybrid, at least. 50 ovulos.' of unpollinat.ed flowers were obs.erved five days after anthosis by the aplication of Herr's clearing technique. The degree of parthcnogenesis, calculated as thc percentaoe of ovules containing embryos to ovules with an apparontly fertile embryo sac, ranged between 68 % and 100 % among' the accessions. Although most of the hybrids were as highly parthenogenetic as their parental accos.'sions, in two hybrids (.Hu/Fl-1 and Ka/Hu-2) parthenogcnes'is was.' not observed. These non-parthenog'enetic hybrids, however, inherited a high degree of diplospory from t.heir parents' as cytological observations showed that. 88 % of the ovules were diplosporous in Hu/Fl-1 and 78%in Ka/I-Iu-2. Thes.e fact, s indicatc that two essential components of gametophyt.ic apomixis.', apomeios.is and parthenogcnesis, can be disting'uished both g'enetically and developmentally in Chinese chive.

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To solve the problems in difference of flowering periods among edible Allium species, the pollen of Allium species was stored until pollination. The pollen stored at - 30°Cmaintained higher germinability than that stored at 5°C in all Allium species examined. The results of the pollen viability test, expressed as a pollen germination rate after anthesis, revealed that the pollen should be harvested as soon as anthesis occurs or at latest within 12 hours. In the crossing between A. chinense and A. fistulosum, the optimum conditions for ovary culture of interspecific hybrids were clarified. It was important to initiate ovary culture 5 days after pollination and to culture ovaries on MS medium containing 5 % sucrose at 25 °C. By this ovary culture, the hybird plants between A. chinense and A. fistulosum, two genotypes of A. cepa. A. tuberosum or A. ampeloprasum were obtained and their hybridity was confirmed by DNA analysis.

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We report regeneration of fertile plants from barley (H. vulgale L. cv. Igri) protoplasts isolated from long-term cultures of embryogenic suspension cells. Calli induced from immature embryos were transferred into liquid medium, and suspension cult.ures were established. Protoplasts isolated from suspension cells divided and developed colonies. Somatic embryogenesis from colonies was observed on medium for plant regeneration. These embryogenic structures were transferred to fresh regeneration medium, and subsequently, green or albino shoots were regenerated in four cel] Iines. One of t.hese lines yielded highly regenerable protoplasts even after 9-3 months of subculture. The green shoots regenerated ¥vere transferred to hormone-free medium, and then, plantlets that developed strong root systems were potted in soii. After two monthsof vernalization, these plants were grown in a growth chamber and set. seeds. .

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Hybrids of C. pesicumn. diploid and C. hede, rilolium w'ere synt.hesized for interspecific cross-breeding, but were found to be completcly stcrile from the previous paper. Thus, in vitro coichicine treatmont applied to h) brid ovulcs (.C. persicum diploid XC. hederifoliurn ) and colchicine treatmcnt applied to the mature hybrids (C. pelsicurn diploidXC. hedelifoliuln or C. hederifolium X C. persicum diploid)were usod to produced fertile amphidiploids. Many fertile plants were derived from in vitro culture of the ovules t.reated with0.05% colchicine for 10 and 15 days throughout embryogenic callus formation and scveral of the fertile plants were detected to be amphidiploids with a chromosome number of 2 n=82 On the other hand, hybrids were dcrived from in vitro culture of the ovules without colchicinc treat.ment throughout, germination and t.hey werc sterilc plants.5 with a chromosome number of 2 n = 41. Viable ssoods were baroly produced from the maturc hybrids of C. hederifoliuln X C. persicurn diploid which were t.reated with 0.5% colchicine usingtragacanth gum by self-pollination and the flowering plants developed from the seeds were amphidiploids lvith a chromosome number of 2 n=82. Although each of thc amphidiploids induced by thc two methods' and the hybrids exhibitod thc charactc'ristics of the parents, the amphidiploids showed larger flolvcrs and peduncles. than the hybrids and grelv vig'orously. They sholvod high pollen fertility and yielded viable seeds by self-pollination.

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To analyze the characterist], cs of rice varieties in the locations for selection in Toyama Prefecture, the author carried out various statistical studies on yield trial clata collected at 14 Iocations in the prefecture (Fig. 1). Tayama Prefecture has an area of 4, 252 square kilo meters, ancl it lies on the western coast of the central pal't of .Japan betlveen the Sea of Japan ancl the Nortern Japan Alps (Fig. 1). The climate of Toyama is characterized by colcl of 'Toohok pattern' in spring, hi, gh temparature to asc.end urgently with coming in Summer ancl the early autumnal colcl in autumn. This Prefecture ha_s the valous soil type called sancly shallolv or loam shallow tillage, diluvium humic and ill-clrained soil, and so fourth on. It is generally recognizecl that a high-yielding Iocation is suitable for tests. However the variance components and heritability values based on the analysis of variance failecl to reveal any relationship betlveen the heritability of yield ancl mean yield, indicatin'g that hig'h yield locations w'ere not allvays suitable selection sites in terms of heritability values (Table 1, 2). The heritability values of yield were high in Kurobe. Fuchu, Toide. Oyabe, Himi and Namerikalv, a (Table 3, Fig. 5). 'there was sig nificant c.orrelation between the regression coefficient and primary principal component score with the year variance, indicating the presence of large val'iations among years (Fig. 6). Reg'ression analysis, principal c, omponent analysis ancl cluster anaalysis enablecl to identify highly suitable locations. Such as Nyuzen, Kurobe. Namerikawa. Toide, Fukuno, Fuchu, Takaoka. Himi and Yatsuo (Table 4, 5, 6, 7, Fig. 2, 3, 4). From these results, it is conciclerecl that the exc.ellent variants from hybricl populations are selected efficiently by utilizing the above characteristic (for height in yield ability, heritability and regression coefficient, also, for magnitude in genetic year error variance and the 1st principal component score) of locations coincided with the breeclin'g objective.

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In japonica rice varieties, the leaf color and nitrogen content of leaf lacle are positively correlatec (Matsuza ki 1974). Also positive corl elationw'as observed between nltlogen content of leaf blade and brown rice (Honjyo 1971). In this. paperw'e investigatecl the relationship betw'een nitrogen contentof I ice ograin ancl leaf color so as to clarify the varietal and environmentaldiffel'ences. in nitlogeen content of rlce graln. I.eaf color of flag Ieaveswas measured by chlorophyll meter, SPAD 501 (MINOLTA) at full headino date. 1. Varietal difference of nitrgen content of rice grain and leaf color

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Repeated DNA sequences cloned from Agropyron intermedium (2n =42, E₁E₁E₂E₂XX) enabled to identify the Ag. intermedium chromosomes in the common wheat genome by Southern and in situ hybridization. Four repetitive DNA clones that did not hybridize to the total genomic DNA of Triticum aestivum cv. Chinese Spring (CS) were screened from the Mbol-digested genomic DNA Iibrary of Ag. intermedium.

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lida et al. (1993) evaluated reactions of Japanese two-rowed barley cultivars to strain II of barley yellow mosaic virus (BaYMV), and found a relationship between the reactions and esterase isozyme genotypes consisting of allelic combinations at ESt1. ESt2 and ESt4 10ci which are tightly linked as a geneblock. In order to clarify a linkage relationship between the resistance gene and the esterase isozyme geneblock, Kanto Nakate Gold and Tochigi Golden Melon, both of which were Susceptible to the virus and carried Ca-Dr-Nz genotype for esterase isozymes, were crossed with Miho Golden and Prior, resistant and Pr-Fr-Su genotype, respective-ly. The esterase isozyme genotype was detected in F2 individuals by starch gel electrophoresis, and the reac-tion was examined in their F3 progenies grown in the field infected by BaYMV strain II

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Five mutant lines resistant to shattering were induced from an indica rice variety "Nan-jing 11" to breed high yielding varieties and to analyse the mechanism of the shattering habit in rice. Base on the estlmatlon of the shattering degree and abscission layer development, it was assumed that five mutant lines were controlled by three differnt and independent genetic factors. Four mutant lines obtained among 21, 000 M2 seedlinb" irradiated with 60Co-rays (20KR) were designated as SR-1, SR-2 and SR-5 (Hokuriku 143). One line obtained among 20, 000 M2 seedlings treated with 50 mM Ethylmethanesulfonate solution was designated as SR-6. These mutant lines were classified into three groups based on the degrees of shattering. SR-1 with belonges to the first group showed a very strong resistance to shattering. The second b"'roup containes the three mutant lines, SR-4, Hokuriku No. 143 (SR-5) and SR-6, which were comparatively resistant to shattering. The last one, SR-2 showed a moderate resistance to shattering.

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Environmental risk evaluation of transgenic melon plants introduced with the coat protein gene of cucumber mosaic virus was carried out in a closed and a semi-closed greenhouse as describecl in previous studies

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[in Japanese]

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[in Japanese]

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