Role of local germplasm and induced mutations in the improvement of the protein content in rice

Summary Ninety local cultivars and 124 induced grain shape mutants were screened for their protein content and the distribution of protein in their endosperm. The protein content varied widely from 4.2 to 12.1% in the local varieties and from 5.5 to 13.7% in the mutants. Some high protein lines like Chinnavadlu, Budumavadlu, etc. with more than 10.0% protein were identified. Protein distribution studies have shown that several mutants, such as IR-8-FG-28, IR-8-FG-33, etc., have a deeper distribution of protein bodies and some local cultivars, like Kakathya and Muchulu, have a relatively more uniform distribution of protein in the endosperm. The protein content at different milling levels revealed that at 12% milling the percentage retention of protein varied from about 79 to 96% irrespective of the percentage of protein, suggesting that the distribution of protein, in addition to the protein content, plays an important role in nutritive value of rice.     

Alfalfa,Medicago sativa L., in highly weathered,acid soils

Summary Seedlings of a broad based population of alfalfa, (Medicago sativa L.), were visually selected for 2 generations (cycles) in an acid Cecil soil (pH=4.8). Simultaneously, 2 generations of selections were made in a limed Cecil soil (pH=6.2) amended with phosphorus. When tested in acid soil (pH=4.8) with added P, the cycle 2 acid selections yielded significantly more top yield than either the limed selections or the original seed. When grown in the limed soil (pH=6.2) without added P, the acid selections yielded significantly less. There were no significant differences among selections in other soil conditions (pH=4.8, no P added and pH=6.2, P added). Root weight and length and nodule fresh weight correlated well with top yield in all treatments. The yield of the 10 parent varieties and polycrossed seed of their cycle 1 acid and cycle 1 limed selections were compared under two soil conditions (acid and limed). The results of this test indicate that some varieties were more responsive to acid soil selection than other. Overall, none of the 10 varieties showed any decreases in total top yield due to one cycle of selection in either the acid or limed soil conditions.     

Ploidy level manipulations in potato through sexual hybridisation

There is no better use of sexual reproduction in regard to breeding and genetic research than the ploidy level manipulations possible in the potato and its relatives. Unique reproductive characteristics of tuber‐bearing Solanum species make possible: the production of gametes with unreduced chromosome number; the presence of an endosperm dosage system that regulates success of interploidy/interspecific crosses; the possibility to easily extract maternal haploids following crosses with S. phureja. This paper reviews results obtained in scaling genomic multiples up and down in potato, and relates these manipulations to breeding strategies for the genetic improvement of the cultivated potato. Several ploidy series have been developed, ranging from the monoploid to the hexaploid level. Cultivated tetraploids were scaled down to the diploid and monoploid level by haploidy. Scaling upward was achieved by sexual polyploidisation via 2n gametes that resulted in triploid, tetraploid, pentaploid, and hexaploid genotypes with a broad genetic base. Altogether, the success of ploidy level manipulations constitutes further proof that sexual polyploidisation played an important role in the polyploid evolution of Solanum species, and supports the idea that gene flow can be relatively easily accomplished through interploid and bridge crosses.     

The role of calcium nutrition in potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis>) microplants in relation to minimal growth over prolonged storage <Emphasis Type="Italic">in vitro</Emphasis>

The present study investigated the effect of different levels of Ca_[ext] (0.3, 3.0, 5.0, 7.0, 9.0 and 11.0 mM) on potato over minimal growth in vitro in relation to varying water stress levels and moisture vapour transmission regimes using ⁴⁵Ca as an isotopic tracer. Ca nutrition was substantially limited when the microplants were grown at enhanced water stress level (MS + 40 g l^-1 sucrose + 20 g l^-1 mannitol) under minimal growth. Ca_[ext] in excess of standard level (3.0 mM), however, resulted in a significant increase in Ca content in microplants. The differential Ca uptake in microplants in relation to water stress and moisture vapour transmission has been discussed in terms of transpiration stream and root pressure water flow under minimal growth. The study showed that poor microplant quality at standard Ca_[ext] over prolonged storage under minimal growth was due to limiting Ca nutrition, and this could be improved by using Ca_[ext]-enriched (5.0-7.0 mM) minimal growth medium for conservation of potato microplants. The role of high Ca_[ext] in reducing the phenotypic abnormalities such as vitrification, flaccidity, hyperhydricity, etc. in potato microplants over extended storage under minimal growth has also been discussed.     

Exploration of relationships between physiological parameters and growth performance of rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) seedlings under salinity stress using multivariate analysis

Knowledge of relationships between physiological parameters and growth performance of seedlings and respective genotypic differences would permit selection of salt tolerance at early growth stages. The goals of this study were to investigate the relationships between physiological parameters and growth performance and quantify the respective genotypic differences using multivariate analysis.. Plants of thirty-one genotypes were grown in sand tanks in a greenhouse and irrigated with Yoshida nutrient solution. Two salinity treatments were imposed at 0.9 dSm^–1 (control) and 6.4 dSm^–1 with sodium chloride and calcium chloride (~ 6: 1 molar ratio). Seedlings were sampled 34 days after planting (7^th to 8^th leaf stage). The characters of Na⁺, K⁺, Ca²⁺, K-Na selectivity (SK,Na) and Na-Ca selectivity (S_Na,Ca) were measured as physiological parameters. The characters of tiller number, leaf area, plant height and shoot dry weight were measured as growth performance. Under salinity stress, S_K,Na increased whereas S_Na,Ca decreased compared to the controls. Canonical correlation analysis indicates a strong relationship between physiological parameters and growth performance. Tiller number is a desirable parameter among the growth parameters analyzed to predict seedling growth under salinity stress. Genotypes grouped into four clusters based on ion contents and ion selectivity using Wards minimum-variance cluster analysis. S_K,Na and shoot Na⁺ content contributed the most to the cluster formation. Similarly, genotypes grouped into four clusters based on growth performance. Ge notypes were classified into three categories based on ion cluster rankings: Category 1 with high S_K,Na and low shoot Na⁺ content; Category 2 with intermediate S_K,Na and shoot Na⁺ content; Category 3 with low S_K,Na and high shoot Na⁺ content. The classification of the genotypes into Categories 1 and 3 based on their high or low S_K,Na was generally consistent with their growth performance under salt stress. In contrast, ion selectivity was a less dominant mechanism controlling salt tolerance in Category 2 with intermediate S_K,Na. It was concluded that ion selectivity was a relatively dominant mechanism controlling salt tolerance among rice genotypes although multiple mechanisms may be involved under moderate salt stress. The results also provide the first example of the effectiveness of cluster analysis for physiological responses to salinity stress.     

小麦种质抗倒性的评价和抗倒性状的相关与通径分析

对９６份小麦种质资源的抗倒性进行了鉴定评价,筛选出高抗型材料９份,其中４份是丰源,表明抗倒性能够与丰产性状很好地协调结合。对抗倒性状的相关分析表明,在株高相差较大的情况下,株高和重心高度对抗倒性十分重要。但在对株高相差不大的情况下,茎秆的机械强度是主要决定因素,对于株高较高的材料,重心高度对抗倒性有较大影响;对于较矮的材料,基部第一节间长度则较为重要。通径分析结果进一步表明,茎秆机械强度对抗倒性的     

茶树种质资源亲缘关系的研究进展

种质资源是现代育种和进行生物技术研究的物质基础 .茶树种质资源亲缘关系的研究将为探讨茶树的起源、进化和分类以及为茶树育种和资源的充分利用提供科学依据 .对茶树种质资源亲缘关系在形态学、化学、染色体、同工酶及DNA等方面的研究成果作了综述 ,并就进一步开展茶树种资源亲缘关系的研究进行了探讨     

The Application of RAPD Markers in Diversity Detection and Variety Identification of Porphyra

RAPD (random amplified polymorphic DNA) markers were generated from filaments of 15 Porphyra lines representing four important groups, P. yezoensis, P. haitanensis, P. katadai var. hemiphylla and P. oligospermatangia. Among the total 69 fragments generated by 6 selected primers (among 50 primers), 67 appeared to be polymorphic (97.1%). Cluster analysis based on the RAPD results was performed. The 15 Porphyra lines were divided into 3 groups. This result was consistent with that from taxonomy analysis. A DNA fingerprinting based on 8 bands amplified with OPN-02 and OPJ-18 was constructed and might be used in Porphyra variety identification. Five specific RAPD fragments of 5 Porphyra lines were isolated and cloned into pGEM-T easy vector. These five RAPD fragments may be useful in germplasm identification and property protection of Porphyra.     

中熟龙眼种质比较研究初报

通过品种、品系、优株的比较试验,研究分析20份中熟龙眼种质材料的枝梢生长和花果发育物候期表现特点,以及树体早期生长和结果性能的差异情况,从中初选出一些综合性状较好的中熟种质,为进一步选育利用提供依据。     

国家果树种质福州龙眼、枇杷圃的研究利用现状

本文阐述国家果树种质福州龙眼枇杷圃的现状、种质资源利用开发情况,提出存在的主要问题,并对今后的研究利用进行展望。