African Journal of Agronomy

African Journal of Agronomy ISSN 2375-1177 Vol. 8 (1), pp. 001-007, January, 2020. © International Scholars Journals

Full Length Research Paper

Arthropod assemblage dynamics on cowpea (Vigna unguiculata L. Walp) in a subtropical agro-ecosystem, South Africa

Augustine Suh Niba

Department of Biological Sciences, Walter Sisulu University, P/B X1 NMD Mthatha 5117, South Africa. E-mail: [email protected].

Accepted 22, November, 2019

Abstract

Arthropod assemblages were monitored on cowpea during the 2008/2009 cropping season in the Transkei area of South Africa. A total of 5953 insects belonging to 21 species, in 12 families and 5 orders (Coleoptera, Hemiptera, Orthoptera, Homoptera and Lepidoptera) were counted from 18 observations on cowpea from seedling to maturity. Aphids, Lepidoptera larvae, blister beetles and pod-sucking bugs accounted for high levels of population infestations, persistence and overall damage inflicted on the crop. Natural enemies recorded during the study were ladybird beetles, wasps, assassin bugs and spiders. Insect pest activity was much concentrated between eight and thirteen weeks after sowing (WAS) corresponding to flower budding and pod formation stages of cowpea respectively. Results from this study have significant implications for the integrated control of the insect pest complex of cowpea in sub-tropical agro ecosystems.

Key words: Cowpea, Vigna unguiculata, insect pests, natural enemies, Transkei.

African Journal of Agronomy ISSN 2375-1177 Vol. 8 (1), pp. 001-011, January, 2020. © International Scholars Journals

Full Length Research Paper

The vertical distribution and their relationship of dissolved organic carbon and exchangeable metals in Chinese old-growth forest soils

Xingkai Xu¹*, Hongyan Miao^1,2 and Zhe Chen¹

¹State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.

²Graduate School of Chinese Academy of Sciences, Beijing 100049, China.

Accepted 12 November, 2019

Abstract

Many unmanaged temperate and tropical old-growth forests are shown to retain their capability to sequester carbon (C) from the atmosphere, but the C sequestration mechanisms in the soil were unknown. Seven thin soil layers within a depth of 20 cm were sampled from one unmanaged tropical seasonal old-growth rain forest and three unmanaged temperate old-growth forests (e.g. Betula ermanii, Picea jezoensis, and Pinus koraiensis mainly mixed with Tilia amurensis, Fraxinus mandshurica and Quercus mongolica) in southwest and Northeast China, respectively, to study the vertical distribution and their relationships of dissolved and total organic matter, microbial biomass C and nitrogen (N), and exchangeable metals concerned in forest soils. There were larger concentrations of all C and N pools and higher pH values in uppermost soil layers under three temperate old-growth forests than in corresponding layers of tropical forest soil, and the concentrations in temperate forest soils decreased more with increasing soil depth. Among the three temperate forests, the soils at less than 10 cm depth under the pine and broadleaf mixed forest had the smallest total C -to -N ratio, and the largest dissolved organic N concentration occurred in the 0 - 2.5-cm soil. Contrary to the exchangeable Al and Pb, the concentrations of exchangeable Ca, Mg and Ba in the 0 to 20 cm profile soils under the three temperate old-growth forests were larger than those under the tropical old-growth rain forest, and the largest values were observed in the profile soils under the pine and broadleaf mixed forest. Hence, the concentration ratios of Ca to Al and (Ca+Mg) to Al in the temperate forest profile soils were larger than those in the tropical forest profile soils. Maximal concentrations of all tested metals (excluding Al and Pb) were observed in uppermost soil layers under the four old-growth forests and varied with tree species. According to the principal component analysis and regression analysis, the vertical distribution of dissolved organic C and organic N concentrations in the soil at the various depths is a function of the decreasing microbial activity and is partly associated with the metals of concern. Together with the soil C availability and microbial metabolic quotient reported earlier, the results would improve our understanding of the C sequestration mechanisms involved in these old-growth forest soils.

Key words: Dissolved organic matter, metals, microbial biomass carbon and nitrogen, old-growth forest soil.

African Journal of Agronomy ISSN 2375-1177 Vol. 8 (1), pp. 001-006, January, 2020. © International Scholars Journals

Full Length Research Paper

Effects of different osmotic solutions on onion seed emergence

Levent Arin, Serdar Polat, Murat Deveci* and Ahmet Salk

Department of Horticulture, Faculty of Agriculture, Namik Kemal University, Tekirdag, Turkey.

Accepted 09 October, 2019

Abstract

This experiment was aimed at the optimisation of emergence with onion seeds. For this reason, onion seeds (Allium cepa L.) short-days cultivars (Aki and Alix) and long-days cultivars (Banko and Suluova) were primed with different concentrations of polyethylene glycol (PEG ₆₀₀₀) in inorganic salts (KNO₃ and KH₂PO₄) for different periods of time (3 and 6 days or until 1% radicle emergence) at 15°C. After the treatments, the effects of priming on seedling emergence were evaluated at optimal (20°C) and suboptimal (11°C) temperatures, under field conditions. Priming in all KNO₃ and KH₂PO₄ reduced the days to emergence without significant loss in emergence ratio. In contrast, seed priming with PEG was ineffective. In field experiments, which were conducted in different periods (at two week intervals in February and March for spring and in September and October for autumn), the emergences of primed seeds were not earlier than those of untreated seeds, except ‘Alix’. In this variety, seeds primed with KNO₃ and KH₂PO₄ emerged approximately four days earlier than the control seeds, regardless of the sowing date.

Key words: Allium cepa L., polyethylene glycol, potassium salts, priming.

African Journal of Agronomy ISSN 2375-1177 Vol. 7 (12), pp. 001-010, December, 2019. © International Scholars Journals

Full Length Research Paper

Cross compatibility between Lilium x fomolongi group and Lilium.brownii

Behzad asl Hamid and Jong Hwa Kim*

Department of Horticulture, Kangwon National University, South Korea.

Accepted 21 July, 2019

Abstract

Lilium is an ornamental plant with great worldwide commercial importance. Obtaining intra- and interspecific hybrids is a known approach to introduce new traits into the commercial groups and cultivars. However, considering the incompatibility of many intra- and interspecific crosses, resulting from pre-fertilization and post-fertilization barriers, various methods have been employed to obtain new hybrids. L. longiflorum is a Lilium group with great marketability, which exhibits incompatibility in many crosses. Here, we have tried to obtain interspecific L . × fomolongi × L. brownii and L. longiflorum × L. brownii hybrids using the combination of ovary slice and ovule culture. In the study, we obtained some interspecific hybrids in Eorayon 2ho × B (7), and Augusta × B (7), as well as Augusta × KHR, Afjw × KDD, and Augusta × KDD crosses. To the best of our knowledge, this is the first reported successful study obtaining L. xfomolongi × L. brownii hybrids. Evaluating the morphological characteristics of the hybrids obtained, as well as studying the traits introduced from parents, can be topics for future studies

Key words: Lilium, ovule culture, hybrid, ovary slice culture, embryo rescue, SSR.

African Journal of Agronomy ISSN 2375-1177 Vol. 7 (11), pp. 001-007, November, 2019. © International Scholars Journals

Full Length Research Paper

Behavior of aluminum adsorption on cell wall of pineapple root apices

Yong-Hong Lin¹* and Jen-Hshuan Chen²

¹Kaohsiung District Agricultural Research and Extension Station, Pingtung, Taiwan.

²National Chung Hsing University, Taichung, Taiwan.

Accepted 12 May, 2019

Abstract

Pineapple (Ananas comosus (L.) Merrill) is commonly grown in strongly acid soil, in which high aluminum (Al) concentration is often toxic to the roots of plants. The root apices of plants are most sensitive to Al toxicity. This paper is to evaluate the effect of Al on the growth of roots of four pineapple cultivars: Cayenne, Tainung No.6, Tainung No.13 and Tainung No.17 in Taiwan. The differences in the amount of callose and malondialdehyde (MDA) in root apices (1 cm in length) between Al-resistant and Al-sensitive pineapple treated with 0 and 300 µM AlCl₃ were determined. The role that the cell wall of root apices plays in Al-resistant characteristics is also discussed. After treating with 300 µM AlCl₃ in hydroponic solution (pH 4.5) for 72 h, the root elongation of Cayenne, Tainung No. 6, Tainung No. 13 and Tainung No. 17 was 115, 85, 93 and 73% of the values obtained compared to that without Al treatment, respectively. AlCl₃ treatment did not increase callose and MDA contents for Cayenne, but caused significant increase for Tainung No.17. Upon exposure to Al, Al adsorption on cell walls of root apices increased with time and AlCl₃ concentrations for Cayenne and Tainung No.17, but relatively greater in Tainung No.17. It reflects the fact that, Cayenne is Al-resistant and Tainung No.17 is Al-sensitive. When root apices were pretreated with 1 and 10 mM of malic acid, the Al adsorption of the cell walls of Cayenne’s root apex was lower by 18 and 31%, respectively, relative to the values obtained without the malic acid treatment. It indicates that root apex of Cayenne may secrete more malic acid that is capable of Al complexation, as well as reducing the Al binding to cell walls in order to better resist Al toxicity.

Key words: Aluminum, pineapple, root apices, cell wall, adsorption.