Background Abiotic stresses like low temperatures are contributory factors to the variations observed among species during plant germination, growth, and development. The present study evaluated the morphological and genetic responses of maize (Zea mays L.) seedling to cold shock induced by a one-time exposure to low temperature. Seeds were originally exposed to distilled water at room temperature for 48 h before they were completely submerged in buckets of ice for 0.5, 1.5, 3, 6, and 12 h, respectively, and then transferred into Petri dishes. The set up was left on the laboratory bench for an additional 5 days, and plant germination parameters were measured. DNA was extracted and this was followed by RAPD—polymerase chain reaction. Results Significant growth impairment upon exposure to cold shock corresponding to the length of time of exposure was shown. The length of the prominent root significantly reduced upon exposure to a cold shock from 141.8 mm to as low as 91.4 mm in those plants exposed at 1.5 h. The length of the prominent leaf also significantly reduced from 100.6 mm in the control to between 62.6 and 85.5 mm in low-temperature-exposed plants (p < 0.05), notwithstanding the time of exposure. There were significant reductions in final germination percent in the low-temperature-exposed germinants (35.8–60.5%) when compared to the control (88.5%). The RAPD marker (OPA04) revealed variations in germinated maize seeds after treatment with different duration of low temperatures. The test plantlets treated for 0, 0.5, and 1.5 h have an unrecognizable complementary sequence to the primer OPA04, whereas the primer amplified regions of the genome of test plantlets treated for 3, 6, and 12 h. Primer OPA05 also presented diversity among maize seedlings stressed for various durations of cold shock. Conclusion The existence of genetic variations in the present study has far-reaching effects on the development of maize exposed to varying degrees of cold stress. Though restricted to germination only, they are important because the development of plants begins at the germination stage. These changes may affect the characteristics of economic importance or perhaps impact on the physiology of the maize plant eventually.

The influence of humans on biodiversity at the genetic, species, community, and ecosystem levels is enormous. This is even more impactful on plant populations, which, being immobile, are at the mercy of their immediate environment. Digitaria horizontalis is a very common grass species in Benin City. Its ruderal nature accounts mostly for its widespread. The current study investigated the existence of possible genetic diversity of the grass in built environment in Benin City. Plant samples were randomly collected from 21 built environment locations within 6 Local Government Council Areas that make up Benin City. Test plants were allowed to acclimatize in experimental bowls and then allowed to grow for 4 weeks after which morphological characteristics were determined. Genetic diversity was determined by Random Amplification of Polymorphic DNA. Significant differences in plant height (33.0 – 59.0 cm) occurred when plants were compared based on location of collection. Changes in patterns of the association with weeds within the vicinity of the test plant was observed. The most prevalent plant species associated with the test plant was Pennisetum purpureum with a 12.18% prevalence. RAPD analysis using primer OPA 04 revealed a locus (about 600bp) that was absent in one or more of the locations with minimum disturbance. This 600pb fragment was however observed in most samples from highly built up and trampled environments. Primer OPA 03 showed monomorphic bands in 2 test samples with a band size of 400bp. It is therefore reported that there is an existence of the genetic diversity in a landscape of grass species (Digitaria horizontalis) found in different built environment in Benin City, Edo State, Nigeria.

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