Inheritance and linkage study of isozyme loci and morphological traits in red clover
Information on inheritance of isozymes and linkage maps in Trifolium pratense L is limited. Genetic analysis of 18 isozyme systems and three morphological traits (white vs. pink flower, present vs. absent leaf marker and green vs. sun-red stem) was conducted. Six loci of four isozymes had simple Mendelian inheritance. Joint segregation analyses among 8 isozyme loci and 3 morphological gene markers (55 pair-wise combinations) resulted in the assignment of one linkage group. Two morphological markers coding for flower (c) and stem (gs) color were found to be in the same linkage group based on the analyses of two segregating families. The recombination values of the two progenies for c-gs were 0.079 and 0.113. No linkage was found between any of the isozyme loci and the morphological traits.
Apple shoot multiplication and plantlets reaction to in vitro culture.
The present work aimed to evaluate the expression of several enzymatic systems in apple (Malus domestica Borkh., cvs. Florina, Romus3, Romus4, Colmar, Rebra, Goldrush, Idared) plants grown in vitro in comparison with the in vivo donor plants. In vitro culture was established on Murashige and Skoog (1962) basal medium supplemented with Lee and Fossard (1977) (LF) vitamins, 2 mg l N-benzyladenine, 0.01 mg l α-naphtyl-acetic acid, 30 g l dextrose and 7 g l agar. The highest shoot proliferation was obtained for all cultivars on medium supplemented with 1.0 mg/l N-benzyladenine. Our study shows that in vivo plants have a distinct pattern of izoesterases in comparison with in vitro plantlets. Several izoesterases characteristic for in vitro or in vivo plants were identified. Izoperoxidases are inducible with culture conditions, physiological condition and developmental stage. The pattern of superoxid-dismutases is less variable with the culture conditions which demonstrate that in vitro culture does not occur oxidative stress. According to the pattern of peroxidases, estarases and superoxid-dismutases, there are not significant differences between in vivo and in vitro plants. Valuable apple cultivars could be preserved short or medium term by in vitro culture without genetically changes.
LAND DEGRADATION IN THE DEVELOPING WORLD: ISSUES AND POLICY OPTIONS FOR 2020
Land degradation takes a number of forms, including depletion of soil nutrients, salinization, agrochemical pollution, soil erosion, vegetative degradation as a result of overgrazing, and the cutting of forests for farmland. All of these types of degradation cause a decline in the productive capacity of the land, reducing potential yields. Farmers may need to use more inputs such as fertilizer or manure in order to maintain yields, or they may temporarily or permanently abandon some plots. Degradation may also induce farmers to convert land to lower-value uses. For example, farmers may plant cassava, which demands few nutrients, instead of maize, or convert cropland to grazing land.