Optimization of conditions for in vitro pollen germination and pollen tube growth of date palm (Phoenix dactylifera L.)

Pollen germination and pollen tube growth might have a significant effect on fruit and seed production. This study was conducted to investigate the best medium for pollen germination and pollen tube growth of date palm male. Significant differences in percentages of pollen germination and pollen tube growth were observed between mediums. The use agar-based medium containing 5% of sucrose, 0.20 g/l boric acid, 0.42 g/l calcium nitrate, 0.1 g/l potassium nitrate and 0.22 g/l magnesium sulfate gave the best results in terms of germination and/or tube growth. The germination percentage was declined with polyethylene glycol and naphthaleneacetic acid, and inhibited completely with fructose, glucose and date extract. These results could have  implications not only for optimizing pollen management in date palm but also to select the best pollinizer for this specie.Keywords:<i> In vitro</i> pollen germination; Sucrose; Fructose; Glucose;  Naphthaleneacetic acid; basal medium

Effects of salicylic acid and spermine foliar application on some morphological and physiological characteristics of isabgol (Plantago ovata Forsk) under water stress

ArticleYield as well as concentration of relevant component in many medical plants are influenced by growing condition water stress. Field experiment was done based on a randomized complete block design with 18 treatments and three replications, at Gonbad Kavous University, Golestan, Iran in winter 2016. Irrigation treatment with three levels (normal irrigation, water stress imposed at flowering stage or at seed filling stage) was placed in main plot. Salicylic acid (SA) with three levels (control, 0.4 and 0.8 mM) and spermine (Spm) with two levels (control and 0.02 mM) were assigned in sub-plots. Result showed the foliar application SA and Spm treatments under normal irrigation and cutoff irrigation at seed filling stage have significantly affected relative water content, electrolyte leakage and membrane stability index, but under cutoff irrigation at flowering stage did not significantly affected measured traits. Exogenous applications of SA and Spm applied increased the plant height, 1,000 grain weight and biological yield in compared to the non-use product at normal irrigation regime. Foliar spraying SA and Spm under cutoff irrigation at flowering stage did not significantly affected measured traits. Application product especially SA0.8 mM and Spm0.02 mM under cutoff irrigation at seed filling stage increased the most characteristics in compared to control. Foliar application of phenolic compounds such as salicylic acid and polyamines like spermine can be considered as an effective measure to reduce the adverse effects of water stress and ultimately increase the yield and yield components of isabgol

New Coordinative Compounds with 4-(4’-pyridyl)pyridinium Disubstituted Monoylides

The complexes with manganese(II), iron(II), cobalt(II), nickel(II) and copper(II) of 2-(4, 4’-bipyridin-1-ium-1-yl)-1-(4-bromophenylamino)-3-(4-methoxyphenyl)-3-oxo-1-thioxopropan-2-ide (ylide, Y) were synthesized and characterized. The obtained compounds with 1 : 2 metal/ligand ratios have been characterized by FTIR, UV Vis spectroscopy, ESI MS spectrometry, molecular conductance, magnetic measurements and thermal analysis. The ylide ligand forms chelates with metallic (II) ions through their amide nitrogen and oxygen atoms

Finding the Positive Nearest-Neighbor in Recommender Systems

Abstract Recommender systems make suggestions about products or services based on matching known or estimated preferences of users with properties of products or services (contentbased), or properties of other users considered to be similar (collaborative filtering). Collaborative filtering is widely used in Ecommerce. To generate accurate recommendations, the properties of a new user must be matched with those of existing users as accurately as possible. The available data is very large, and the matching must be computed in real time. We introduce algorithms that use “positive ” nearest-neighbor matching in the sparse datasets typical of collaborative filtering to find near neighbors whose attribute values exceed those of each new user. The algorithms use singular value decomposition as a dimension-reduction technique. Making this idea effective requires careful attention to details such as normalization. Experimental results are reported for a movie recommendation dataset. For n users and m objects, reasonable matches can be found in time O(m log n), using O(nm) storage

Large-Scale Resource Selection in Grids

Abstract. Grid resource selection requires matching job requirements to available resources. This is a difficult problem when the number of attributes for each resource is large. We present an algorithm that uses the Singular Value Decomposition to encode each resource’s properties by a single value. Jobs are matched by using the same encoding to produce a value that can be rapidly compared to those of the resources. We show that reasonable matches can be found in time O(m log n) where n is the number of resources and m the number of attributes for which a job might have requirements. This is in contrast to “approximate nearest neighbor ” techniques which require either time or storage exponential in m

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In a publish/subscribe paradigm, user service discovery requires matching user preferences to available published services, e.g., a user may want to find if there is a Chinese restaurant close by. This is a difficult problem when users are mobile, wirelessly connected to a network, and dynamically roaming in different environments. The magnitude of the problem increases with respect to the number of attributes for each user’s preference criteria, as matches must be done in real-time. We present an algorithm that uses Singular Value Decomposition to encode each service properties in a few values. Users’ preference criteria are matched by using the same encoding to produce a value that can be rapidly compared to those of the services. We show that reasonable matches can be found in time O(m log n) where n is the number of publications and m the number of attributes in the preference criteria (subscription). This is in contrast to “approximate nearest neighbor ” techniques, which require either time or storage exponential in m. Keywords: Publish/subscribe, nearest neighbor search, multidimensional search, high dimensional data space, Singular Valu