Vegetative propagation studies of gum arabic trees. 1. Propagation of Acacia senegal (L.) Willd. using lignified cuttings of small diameter with eight nodes

In order to study and monitor rates of rooting, callusing and survival, small diameter stem cuttings (less than 0.4 cm) with eight nodes (12–14 cm long) were taken from trees in the field at different times of the year in tests with small batches of cuttings. Among the four tested substrates, well drained crushed basalt powder placed on a bed of gravel was the best rooting medium. Rooting was generally poor or even non-existent with this type of cutting, but the presence of leaves both promoted rooting and significantly (using Chi square test) improved survival of the cutting. Four leaves were sufficient to assure the necessary metabolic functions. Only stem cuttings collected during the rainy season gave roots and then, only when hormonal treatments were applied to the cuttings. 8%-IBA resulted in significantly better rooting than did 2%-IBA, 0.2%-NAA and 1%-IAA. With 8%-IBA, the rate of rooting varied between 50 and 70% for leafy cuttings collected in the rainy season. Hormonal treatments had a significant effect on the survival rate of the stem cuttings during the two months observation period. Further investigations are being conducted with different types of cuttings.     

Combining ability and heritability of soybean resistance to groundnut leaf miner

Groundnut leaf miner (GLM) (Aproaerema modicella) (Deventer) is one of the most destructive pests of soybean and groundnuts. In this study, the mode of inheritance, general combining ability (GCA), specific combining ability (SCA) effects, maternal effects of resistance to GLM and grain yield ha^?1 were determined. Thirteen soybean parental genotypes and 81 F₂ populations were evaluated for resistance to GLM in a 5?×?19 alpha lattice diallel design with two replications under natural GLM infestation in northern (Arua) and eastern (Iki-iki) Uganda during September to December 2016 rainy season. Highly significant differences were observed among parental genotypes and F₂ populations for GLM incidence, severity, and grain yield. The estimates of GCA effects were significant for GLM incidence and severity scores but not for the number of larvae per plant and grain yield ha^?1. SCA effects were non-significant for all the studied traits, suggesting that GCA effects were the major component responsible for soybean resistance to GLM with additive gene effects being more important for these traits. Baker’s ratio ranged from 0.44-1.0 for most of resistant traits except number of larvae per plant and grain yield ha^?1. The results indicated also that cultivars Maksoy1 N, PI615437, PI578457A and NIIGC4.1-2 were good combiners against GLM incidence and severity. Parent PI615437 was a good combiner for grain yield and Maksoy1 N?×?PI615437 was a superior cross for grain yield and against GLM incidence. There were no maternal effects for the inheritance of resistance to GLM. The study provides a basis for understanding patterns of inheritance of soybean resistance to groundnut leaf miner for an efficient breeding program.     

杭州市绿地中常见园林树种果实引鸟特征研究

  目的  分析果实特性,探究鸟类取食行为与秋冬季食源树种果实特性的相关性,为城市引鸟植物景观营建和生物多样性规划提供理论支撑。  方法  定点定时对鸟类取食行为进行周期性观测记录,根据前期观测结果,选择鸟类最为喜好的10种常见园林树种,拍照记录其果实所处的环境和果实形态变化,检测被取食期间果实的可滴定酸、可溶性糖、淀粉和可溶性蛋白的质量分数,并进行相关性分析。  结果  果实所处植物空间可分为3类:①常绿且枝硬舒展,区分明显内外空间;②常绿且枝软密集,稍区分内外空间等;③落叶且枝硬舒展,不区分内外空间。果实所处植物空间特征的安全隐蔽性和起落便捷性会直接影响鸟类是否倾向于取食该果实,同时果实空间环境的内部特点会影响鸟类取食该果实的方式,针对枝软且复杂逼仄的环境,体形较大的鸟类例如领雀嘴鹎Spizixos semitorques等会选择停留于植物顶部取食,体形较小的鸟类例如大山雀Parus major等会选择进入植物内部取食。果实的形态变化特征可分为2类:①果实形态在果熟后60 d内基本不变;②果实形态在果熟后60 d内随时间增加而逐渐枯萎。其果实挂果状态会影响鸟类的取食倾向,新鲜饱满的果实对鸟类更具吸引力,挂果状态保持较差的树种如垂丝海棠Malus halliana等只在果实成熟的早期阶段被白头鹎Pycnonotus sinensis取食,挂果状态保持良好的树种如樟树Cinnamomum camphora等则被白头鹎和乌鸫Turdus merula长期持续取食。果实的内含物会影响鸟类的取食倾向,含糖量高的果实更易吸引白头鹎和乌鸫,白头鹎更倾向于酸质量分数较高的果实而乌鸫更倾向于蛋白质质量分数较高的果实。  结论  为了提升城市绿地中的鸟类多样性,应保证食源树种种植位置的隐蔽性,重点选择具有较好挂果状态保持能力和较高含糖量的常绿高大乔木作为其食源树种。图9表5参27     

Vegetative propagation studies of gum arabic trees. 2. The vegetative propagation of adult Acacia senegal

Vegetative propagation of Acacia senegal is possible from branch fragments taken from the crown of mature trees (13 years old), without causing ortet destruction.The most responsive planting stock is taken from cuttings 15 cm long (with 12 to 15 nodes) and a diameter of 10 ± 6 mm (wood of 2 to 4 years old). With this material, the ablation of the leaves prior to planting is a factor which furthers development of the cutting's root system.The development of the root system is also highly influenced by the time at which the cutting is taken: results vary from 10% during the dry season to more than 70% during the rainy season (June—October).Cuttings can be taken from branches 50 cm long. It is thus possible to preserve the planting stock for 8 days in a continually humidified jute cloth and then to make the cuttings at the time of establishment in a nursery, without changing their rhizogenic aptitude.The cuttings show characteristics of maturity (slow growth, plagiotropy, fructification). It is nevertheless possible to preserve the collected genotypes in the field, or better, in planting pots in the nursery, so as to further the process of physiologic rejuvenation with the aim of in vitro cloning.researcher at CIRAD/C.T.F.T., detached to ISRA/D.R.P.F.     

Response of some horticultural crops to irrigation in the semi-arid region of Tunisia

Response to a limited water supply was determined for 3 horticultural crops, pepper, melon (cantaloup) and tomato, in the Nebhana Valley, Tunisia. Varying fractions of potential evapotranspiration (PET), as calculated by Penman, were used to define 4 irrigation treatments which were replicated 4 times. The study was conducted on a shallow sandy loam soil in the lower Nebhana Valley, near Monastir. For each of the crops the following production parameters were evaluated: marketable yield; average fruit weight; number of fruits per unit land area. For socio-political reasons, the cost price of the irrigation water to the farmers in the Nebhana Valley is of negligible importance, and thus the economic threshold could be drawn from the relationship between yield and total available water. The marketable yield for pepper, melon and tomato crops was not significantly affected by rationing the seasonal water application volumes to 57, 47 and 67%, respectively, of the calculated PET. To increase the water-use efficiency for the crops studied, limited irrigation is advisable.     

Monitoring populations of Phthorimaea operculella in potato fields and in storage in Senegal

This study provided information on periods of peak trapping for the potato tubermoth (Phthorimaea operculella) in potato fields and in storage facilities in the Niayes area of Senegal. Delta sticky traps baited with P. operculella synthetic pheromone, IT053 ISCA lure, were used to monitor adult male moth populations in 2011 and 2012. In each trapping year, four peaks were observed with the maximum number of moths recorded in February, 2012. A Weibull regression model was developed to predict the incidence of P. operculella in potato fields using the number of male adults caught in pheromone-baited traps. The Weibull model provided a good fit to percentage cumulative mean trap catches for both 2011 and 2012 (R² = 0.99; P < 0.0001). Based on the Weibull models for the sampling periods in 2011 and 2012, 50% of cumulative mean number of moths were trapped by day 85 (26 March) in both years, 63.2% (= α) were trapped by day 103 and 104 (13 April and 14 April), and 95% were trapped by day 179 and 190 (28 June and 9 July), respectively. Male moths continued to be trapped after potatoes were harvested, but the numbers decreased compared to captures before harvest. This information will be useful for predicting the most appropriate times to institute intervention measures to mitigate damage to potatoes by the moth. Laboratory investigation revealed that abandoned tubers in the field were the source of sustained incidence of the moth on farms following the harvesting of potatoes. The number of male moths trapped in stores tapered with the number of weeks the bagged tubers stayed in storage.     

土壤健康与农业绿色发展：机遇与对策

农业绿色发展是农业现代化的必由之路,土壤健康是农业绿色发展的基石。本文系统总结了国内外有关土壤健康的内涵、研究进展和发展趋势,探讨了提升土壤健康的途径和对策,并对我国未来健康土壤培育工程提出了建议和展望。健康土壤培育的核心是消除土壤障碍因子,深入挖掘土壤生物学潜力,增碳提高资源效率,强化生物学过程,协同地上和地下生物互作。通过优化土壤内部调节过程,最小化外部的投入,以实现土壤生产功能和其他生态服务的同步提升。健康土壤的培育是一个系统工程,需要对投入品-生产过程-产品品质-产品加工-废弃物循环等全产业链进行系统综合考虑,多学科交叉创新,政产学研用一体化联合攻关,同时还需要政策保障和激励措施,需要全社会行动起来。     

Simulation studies of Senegalese Grasshopper ecosystem interactions II: the role of egg pod predators and birds

We present a simulation study of the role of birds and egg pod predators in the population dynamics of the Senegalese grasshopper. The model was an energetics-driven ecosystem model that included a natural Sahelian grass, millet, grasshoppers, the egg pod predators bombyliidae and Tenebrionidae, and 24 species of birds that prey on grasshopper nymphs and adults. The model simulated the rain-dependent dynamics and migration along a five-location south–north transect in Niger and Senegal, and the main outputs were the grasshopper pressure on the transect, measured as accumulated transect grasshopper days, and the density of eggs ready to emerge the following rainy season. The model was calibrated using observations from transects in Niger (2003, 2004) and Senegal (2004).

When input data from Niger 2003 and 2004 were applied, simulated reductions in grasshopper pressure during the rainy season from egg pod predators and birds, respectively, were within a range of 18–25%, but taken together the overall reduction in grasshopper pressure ranged between 35 and 37%. Using input from Senegal (2004) the birds accounted for reductions of around 25%.

When the impact of the natural enemies was measured in terms of reduction in the density of eggs hatching the following year, the simulated impact of the egg pod predators ranged between 45 and 83% and that of the birds between 33 and 39%, and the two groups combined caused reductions between 60 and 75%.

Analyses of the sensitivity to the bird species, added one by one, showed ‘predator saturation’ along the Niger transects (with low grasshopper density) but not along the Senegal transect.

For Niger, the sensitivity analyses revealed Cattle Egret, Grey-headed Sparrow, Chestnut-bellied Starling, Buffalo Weaver, Sudan Golden Sparrow, Grey Hornbill, Red-billed Hornbill and Abyssinian Roller to be the most important individual species. For Senegal the top-five individual bird species were Village Weaver, Buffalo Weaver, Savile's Bustard, Grey-headed Sparrow and Abyssinian Roller.