Temperature effects on male fertility and flower and fruit development in Capsicum annuum L.

Temperature conditions strongly influenced the development of flowers and fruits of pepper (Capsicum annuum L.) plants. Low temperatures (LTR; 18°C day/15°C night) had much more effect on flowers and fruits than intermediate (ITR; 23°C day/18°C night) or high (HTR; 28°C day/23°C night) temperatures. LTR caused the formation of abnormal petals, stamens and gynoecium in the flowers. Stamens produced were deformed, in some cases partly carpel-like, produced abnormal non-viable pollen, and were thus functionally male-sterile. In the gynoecium, the ovary size of LTR-grown flowers was larger than that of ITR and HTR flowers, but the style elongation was inhibited. Fruits produced under HTR were larger than ITR and were seeded under both temperature regimes. Under LTR, small seedless fruits were produced, but normal seeded fruits were formed if flowers were pollinated with pollen from ITR- or HTR-grown flowers.     

Using a multicriteria assessment model to evaluate the sustainability of conservation agriculture at the cropping system level in France

Several international research and development organizations are promoting conservation agriculture in a wide range of contexts. Conservation agriculture is based on a combination of three main principles: (i) minimal or no mechanical soil disturbance; (ii) diversified crop rotations and (iii) permanent soil cover (consisting of a growing crop or a dead mulch of crop residues). However, in the face of the diversity of practices that can be associated with conservation agriculture, of goals assigned to agricultural systems, and pedoclimatic contexts, there is still no empirical evidence about the overall performance of conservation agriculture in France. Global assessments of conservation agriculture, with the full or partial application of its principles and in different contexts, are required to provide a more comprehensive picture of the performance of such systems. We tackled these objectives simultaneously, by evaluating 31 cropping systems with the MASC^® model (for Multicriteria Assessment of the Sustainability of Cropping Systems). These systems were selected to represent a wide diversity of practices, from ploughed conventional systems to crop sequences based on the full application of conservation agriculture principles. Positive interactions were observed between the key elements of conservation agriculture, resulting in better sustainability performances (particularly in terms of environmental criteria). Nevertheless, the systems most closely respecting the principles of conservation agriculture displayed several weaknesses, principally of a social or technical nature, in this study. Careful attention should be paid to attenuating these weaknesses. A more detailed analysis of the results also suggested that decreasing soil tillage tends to decrease the overall performance of the system unless associated with a diversification of the crop rotation.     

我国粮食生产直接补贴后效应分析

结合社会调查,从粮食生产补贴对中央财政和地方财政的压力、粮食直接补贴的分级负担可能带来的后果、直接补贴对刺激粮食生产的有效性及对其他农产品生产的影响5个方面分析了我国粮食生产直接补贴的后效应。     

Tillering,Lodging and Yield under Deep Water Treatment in Direct-seeded Rice

Abstract

The tillering, lodging and yield of two types of direct-seeded rice (dry and water seeding), under deep water (DW) and ordinary water treatment (OW), were compared in 1994 and 1995. The percentage of productive tillers to maximum tiller number under DW was 85% for transplanted, 60% for water-seeded and 84% for dry-seeded rice (mean 76%), while that under OW was 59, 50 and 74% (mean 61%), respectively, in both years. By DW, longer culm length and fresh weight tended to be increased, thus elevating bending moment, but the culm diameter and culm-breaking weight were increased showing the lower lodging index. In water-seeded rice, the suppression of the development of non-productive tillers by DW was relatively weak compared to that in dry-seeded or transplanted rice. Although the number of panicles was similar under DW and OW, 1000-grain weight and percentage of grain filling were significantly improved by DW. The grain yield was higher under DW, and the mean grain yields of the two years were 4.82 t ha^?1 under DW and 4.48 t ha^?1 under OW.     

Restoring dry Afromontane forest using bird and nurse plant effects: Direct sowing of Olea europaea ssp. cuspidata seeds

To identify the perspectives of seed sowing for reforestation of degraded dry Afromontane savanna in exclosures in northern Ethiopia, seeds of a fleshy-fruited, secondary climax tree, Olea europaea ssp. cuspidata, were placed under two pioneer shrub species (Euclea racemosa and Acacia etbaica) and in open microhabitats. Seed removal and germination rates were examined. The effects of bird ingestion, manual pulp removal and mechanical endocarp treatments on germination rates were also studied.

Pulp removal promoted seed germination, in particular in seeds without endocarp manipulation. Seed removal, presumably by rodents, was concentrated in narrow strips along linear soil conservation structures, and not different between shrubs and open microhabitats. In the absence of water stress, humus types did not have a significant effect on germination rates. Under field conditions however, germination was higher under Euclea canopies. The observed facilitative effect of Euclea shrubs on germination may be attributed to moisture retention effects, related to the deep humus layer and canopy architecture, preventing desiccation and promoting imbibition of seeds. When readily available Olea seeds are not used for seedling production, direct sowing of seeds in the humus under dense Euclea shrubs could offer a cheap complement to planting of nursery-raised seedlings for forest restoration projects in recovering Afromontane savanna.     

植物组织培养中畸形苗发生机理的研究进展

畸形苗是植物组织培养中一种常见的生理异常现象,它严重制约着植物组织培养技术的发展。本文概述了植物组织培养中畸形苗的形态、发生机理及综合防治措施,并对进一步研究进行了展望。     

水稻穗形态建成基因PMM1的遗传分析与初步定位

在水稻粳稻品种中花11T-DNA插入突变体库中鉴定了3个穗形态突变体,它们均表现为植株半矮、叶夹角变小、一次枝梗轮生、复粒、粒长变短、粒宽变宽等突变表型。基因双突变杂交F1表型考查证明这3个突变体为等位突变体,T-DNA标签共分离检测表明这3个突变体的表型与T-DNA插入无关。通过与籼稻品种珍汕97配置3个杂交组合,由经典的孟德尔遗传分离比显示,突变性状受1对隐性基因(panicle morphological mutant 1,PMM1)控制。采用基因图位克隆的方法,已将基因PMM1定位在第4染色体长臂上的RM3866-1和X4(InDel)标记之间,其两侧物理图距为147kb左右。     

中熟中粳连粳7号直播适宜密度研究

[目的]研究直播稻(Oryza sativa L.)播种密度对产量结构及植株茎秆性状的影响,探讨直播稻高产稳产适宜的播种密度。[方法]以中熟中粳连粳7号作为试验品种,按基本苗的不同,设5种密度水平,分别是90万1、20万、150万、180万、210万株/hm2,随机区组排列,重复3次。[结果]随着播种密度的增加,有效穗数总的趋势是上升的,但种植密度对有效穗的调控作用较小,每穗总粒数、颖花结实率和千粒重总的趋势是下降的,基本苗105万株/hm2左右时较适宜。基本苗90万株/hm2处理,植株茎秆第1、2节间长度最短,占茎秆长度的比例最小,第3、4、5节间长度最长,占茎秆长度的比例最大,茎秆重量、粗度及单位长度重量均最大,茎秆单位长度重量承担的稻穗重较小,茎秆抗倒伏力最强。[结论]从高产稳产两方面考虑,直播稻连粳7号基本苗90万～105万株/hm2最佳。     

红松直播造林与植苗更新的对照试验

介绍了红松直播造林与植苗更新的试验方法。通过直播与植苗两种造林方式的对照分析,得出在天然次生林下直播红松是顺应自然的一种更新造林方法,它具有抗性强、免抚易管理的优点,与红松植苗相比既可做到免抚,又能降低生产成本,是加快恢复小兴安岭森林顶极群落--阔叶红松林行之有效的方法。