Adaptation of landrace and variety germplasm and selection strategies for lucerne in the Mediterranean basin

Lucerne (Medicago sativa L.) can enhance the economic and environmental sustainability of crop-livestock systems in the western Mediterranean basin, but requires improved adaptation to stressful environments because of a predicted shortage of irrigation water and climate change. This study reports on three-year dry matter yields of five landraces from Morocco, Italy and Tunisia and seven varieties from France, Italy, Australia and USA assessed across 10 agricultural environments of Algeria, Tunisia, Morocco and Italy of which four were rainfed, one was continuously irrigated (oasis management), and five were irrigated but adopted a nine-week suspension of irrigation during summer. Our objectives were targeting cultivars to specific environments, and assisting regional breeding programmes in defining adaptation strategies, genetic resources and opportunities for international co-operation. The crop persisted well in all environments, but environment mean yield was strictly associated (P < 0.01) with annual and spring-summer (April–September) water available. Rainfed cropping implied 42% lower yield with 61% less spring-summer water available relative to irrigation with withheld summer water across three sites hosting both managements. All of these sites showed genotype × management interaction (at least P < 0.10). Cross-over genotype × environment (GE) interaction between top-yielding cultivars occurred across the 10 environments. Total number of harvests (range: 9–23), soil salinity as measured by electrical conductivity (range: 0.20–6.0 dS m⁻¹), and average spring-summer water available (range: 102–932 mm) were selected as significant (P < 0.05) environmental covariates in a factorial regression model explaining 53% of GE interaction variation. This model was exploited for targeting cultivars as a function of site-specific levels of these factors. Its indications agreed largely with those of an additive main effects and multiplicative interaction model with two GE interaction principal components. An Italian landrace exhibited specific adaptation to severely drought-prone environments, whereas landraces from north Africa were not adapted to such environments. One Moroccan landrace was specifically adapted to high number of harvests (partly reflecting frequent mowing). One variety selected for salt tolerance, and one Moroccan landrace, were specifically adapted to salt-stress environments. Environment classification as a function of GE interaction effects indicated three groups which may be object of specific breeding: (i) rainfed or irrigated environments featuring limited spring-summer water available (<350 mm), nil or low soil salinity, and moderate to low number of harvests; (ii) salt-stress environments; and (iii) environments characterized by high number of harvests.     

水库景观设计研究

总结了水库的风景资源及其景观特征，并提出在水库景观设计中应该因水设景，因地制宜。     

水稻穿梭育种研究新进展

概述了８０年代发展起来的新的育种途径—水稻穿梭育种法研究的进展。在理论上初步探明了水稻穿梭育种选择的有效性及其选择规律，在实践中已育成一批各具特色的新品种，有的并用于生产。”同时展望了发展前景。     

QTL analysis of panicle morphology response to irrigation regime in aerobic rice culture

In water-efficient rice production, grain yield is often constrained by panicle size. The objective of this study was to genetically dissect the response of panicle morphology to irrigation regimes in aerobic rice culture. We grew ‘Akihikari’ (a lowland japonica cultivar) × ‘IRAT109’ (an upland japonica cultivar) backcross inbred lines in aerobic soils with full or limited irrigation for 2 years, and examined 4 panicle traits—number of florets per panicle (FPP), number of primary branches per panicle (BPP), number of florets per primary branch (FPB), and frequency of pre-flowering floret abortion (%FA)—and grain yield. QTLs for BPP were detected in both the irrigation regimes but QTLs for FPB and %FA were detected mostly only in either of the irrigation regimes. The QTL for FPP on chromosome 2 (RM3421–RM213) coincided with that for yield under full irrigation, showing that this QTL is related to sink capacity and yield potential in aerobic rice culture. On the other hand, the QTL for FPB on chromosome 1 (RM3148–RM243) coincided with that for yield under limited irrigation, when water deficit was moderate. The QTL for root axis length at vegetative stage, previously identified in the same mapping population, was located near this region. This study unravelled the complicated genetic control on panicle morphology in aerobic rice culture, and suggested the positive roles of the dehydration avoidance mechanism by vigorous root growth on panicle size and yield under dry soil conditions.     

研究效益的未来经济分析：高粱晚施氮素的原因

研究效益的未来经济分析：高粱晚施氮素的原因——（Ｐ．Ｄ．Ｃｈｕｄｌｅｉｇｈ等），ＩｎＰｒｏｃｅｅｄｉｎｇｓｏｆｔｈｅＳｅｃｏｎｄＡｕｓｔ－ｒａｌｉａｎＳｏｒｇｈｕｍＣｏｎｆｅｒｅｎｃｅ，Ｇａｔｔｏｎ，４ｔｏ６Ｆｅｂｒｕａｒｙ１９９２，Ｖｏｌ．２，Ｎｏ...     

宁强县茶叶产业发展对策建议

近现代科学研究证实茶叶富含多种有益的成分,具有良好的保健功能。伴随经济发展,茶叶消费日趋旺盛：在市场上,茶叶是一种快速消费品;在农业上,茶叶则是一种极宜作为产业发展的经济作物。宁强县是江北地区的一个产茶大县,其茶叶具有独特的品质特征。为明析该县茶叶生产现状,在查阅相关资料的基础上,本文对该县生态环境状况、茶叶发展现状进行了概述,对茶业发展中的问题进行了探讨,以期为该县茶叶生产和发展提供参考。     

稻虾共作对稻田水体环境的影响

为探明稻虾共作对水体环境的理化性质和物质含量的影响,选择湖南省南县实施稻虾共作模式和中稻单作模式的稻田,分析稻虾共作前后的稻田水体物质变化和不同稻作模式下稻田水体环境变化差异.结果表明,相较于自然水体和中稻单作田间水体,稻虾共作田间水体的pH值提高了1.88%和1.37%,色度提高了42.19%和10.98%,TDS提高了1.66%和1.14%,电导率提高了13.08%和10.31%,氧化还原电位提高了14.15%和6.03%,溶解氧降低了17.20%和9.41%.稻虾共作改变了自然水体理化性质,对水体环境的影响程度比中稻单作模式更大,创造了适宜稻虾共同生长的水体环境,在抑制潜水蒸发、提高水体自净能力方面有积极作用.但水体溶氧量的降低,不利于水生植物的生长和部分物质的分解消化,影响稻田水质.在稻虾共作过程中,需充分利用水体环境变化的有利因素,合理人工增氧,以规避水体溶氧降低带来的影响.     

义县日光温室西葫芦“死秧”的绿色防控技术集成与应用

WU Hai -dong(Vegetable Institute,Liaoning Academy of Agricultural Sciences,Shenyang, Liaoning 110161)     

Lucerne shoot and root traits associated with adaptation to favourable or drought-stress environments and to contrasting soil types

Cultivar × location interaction for lucerne forage yield across northern Italy is large, repeatable and associated with summer drought-stress level and soil type. The objectives of this study were: (i) to investigate the genotypic factors associated with cultivar adaptive responses to drought-stress and soil factors; (ii) to identify adaptive traits exploitable for selection of widely adapted or specifically adapted material. Aerial dry matter (DM) over 12 harvests and shoot traits of 13 landraces and four varieties were evaluated in four artificial environments created by the factorial combination of drought-stress level (almost nil or high) and soil type (sandy-loam or silty-clay) (Exp. 1). Aerial and root DM over four or five harvests were evaluated in metal containers 55 cm × 12 cm × 75 cm deep for the factorial combinations of three varieties by two drought-stress levels by two soil types (Exp. 2), or six landraces by two drought-stress levels (Exp. 3). Cultivar × environment interaction was detected for forage yield, plant mortality after the second summer, leaflet size and stem weight. The environments of Exp. 1 reproduced well the variety adaptive responses across agricultural environments. The relationship of cultivar forage yield with shoot traits was environment-specific, i.e.: (i) strictly negative with plant mortality, in no-stress environments (where mortality and plant competition were severe); (ii) positive with stem number per plant and autumn-winter growth, in stress environments; (iii) positive with stem dry weight, in ‘stress/sandy-loam soil’; and (iv) positive with leaflet size, in ‘no-stress/sandy-loam soil’. Cultivars specifically adapted to no-stress or sandy-loam conditions showed consistently greater root DM across three soil layers than material with opposite adaptive response. Entry yields tended to inverse genetic correlation between two environments which represented contrasting geographical subregions and were characterized by different combinations of traits associated with higher yield, i.e.: (i) higher root biomass, lower plant mortality and larger leaflets, for ‘no-stress/sandy-loam soil’; and (ii) more stems per plant and greater autumn-winter growth, for ‘stress/silty-clay soil’. The difficulty of yield-based selection for wide adaptation may hardly be overcome by selection based on adaptive traits. Adaptive trait-based selection for specific adaptation may be envisaged especially for ‘stress/silty-clay soil’ conditions, for which the relevant traits are inexpensive to record, not correlated, and not subject to cultivar × environment interaction.     

水稻覆膜栽培技术研究进展

水稻是我国主要粮食作物之一,随着社会经济的发展,绿色、优质、高效、生态和安全成为水稻栽培的重要目标。水稻覆膜能有效控制杂草生长,减少除草剂施用,提高肥料利用率,是一项具有增产增效、资源高效利用、绿色生态环保效果的优良技术。综述了覆膜对稻田环境和水稻生产的影响,探讨了水稻覆膜技术在发展过程中覆膜方式、膜的材质以及需求等方面的变化,进行了水稻覆膜机插的效益比较,展望了水稻覆膜栽培技术的发展方向,以期为水稻绿色高效栽培技术的发展提供新方法。