Effects of drought stress on physiological and biochemical adaptation responses in young black locust Robinia pseudoacacia L. clones

Black locust Robinia pseudoacacia L. is a fast growing tree, used in forest establishment. It is an economically important tree for tool production, obtaining timber and fuel as well as an important constituent element for landscapes. Though the tree is abundant, information on genetics, physiology, biology, wood quality and adaptability to different ecological conditions is limited and fragmented. The aim of this research was to study physiological and biochemical adaptation by comparing two black locust Clones that showed different responses to drought. The two Clones were exposed to different water regimes: Medium Stress and High Stress (50 and 25 % of water supplied to control). Physiological and biochemical measurements were made. Stress affected negatively the growth of both Clones. The effect of different stress intensity (MS and HS treatments) was observed on stem shape. When re-watered the stem showed partial recovery. Net photosynthesis rate in drought period did not show marked difference between the Clones. After soil rehydration both Clones recovered photosynthesis level. The Clones 1 did not show differences in osmotic potential when comparing Control and MS or HS trees. The Clone 2 showed increased osmotic potential in relation to stress intensity. The maximum potential in Clone 2 was comparable to the values for Clone 1. Amino acids, especially proline, increased in drought. The soluble sugars increased during the stress period in the stems of Clone 2. The increased absence of osmolytes increase in Clone 1 could be due to the absence of adaptive mechanism. Alternatively, osmolytes concentration was already too high to be increased more by drought. Different osmotic potential and changes during drought can be related to the growth during tree life. Selection of Clones according to osmolyte index could to select better trees for different climate zones

Generative propagation of Robinia x ambigua POIR. – Pink locust

The genus Robinia is a small group of about 10 species of trees and shrubs indigenous only to NorthAmerica. Two species are endemic to Mexico, one being confined to south-western part of the country, while the rest are endemic to the south-eastern part of USA. Of the most important species and varieties of genus Robinia, Robinia x ambigua Poir.(Robinia viscosa x R. pseudo-acacia)-pink locust can be considered as the most significant one for bee-forage and decorative planting. In this paper a generative propagation method is presented for pink locust

Generative propagation of Robinia x ambigua POIR. – Pink locust

The genus Robinia is a small group of about 10 species of trees and shrubs indigenous only to NorthAmerica. Two species are endemicto Mexico, one being confined to south-western part of the country, while the rest are endemic to the south-eastern part of USA. Of the mostimportant species and varieties of genus Robinia, Robinia x ambigua Poir.(Robinia viscosa x R. pseudo-acacia)-pink locust can be considered asthe most significant one for bee-forage and decorative planting. In this paper a generative propagation method is presented for pink locust

Meteorological drought assessment in north east highlands of Ethiopia

Purpose – The purpose of this paper is to investigate the patterns and trends of drought incidence in north east highlands of Ethiopia using monthly rainfall record for the period 1984-2014. Design/methodology/approach – Standard precipitation index and Mann – Kendal test were used to analyze drought incident and trends of drought occurrences, respectively. The spatial extent of droughts in the study area has been interpolated by inverse distance weighted method using the spatial analyst tool of ArcGIS. Findings – Most of the studied stations experienced drought episodes in 1984, 1987/1988, 1992/1993, 1999, 2003/2004 and 2007/2008 which were among the worst drought years in the history of Ethiopia. The year 1984 was the most drastic and distinct-wide extreme drought episode in all studied stations. The Mann–Kendal test shows an increasing tendencies of drought at three-month (spring) timescale at all stations though significant (p < 0.05) only at Mekaneselam and decreasing tendencies at three-month (summer) and 12-month timescales at all stations. The frequency of total drought was the highest in central and north parts of the region in all study seasons. Originality/value – This detail drought characterization can be used as bench mark to take comprehensive drought management measures such as early warning system, preparation and contingency planning, climate change adaptation programs