The ecological changes in vegetation and land of an area can be monitored and managed through the assessment of its past and present land use and land cover (LULC). In this study, we assessed the changes in the LULC of Penang Island between 2010 and 2021. We also determined the corresponding impacts on the land surface temperature (LST) and vegetation index in the form of normalized difference vegetation index (NDVI). Landsat-5 and Landsat-8 were selected for the study. The LULC types were classified using both supervised and unsupervised multivariate maximum likelihood techniques. The LULC change analysis revealed a considerable increase in the urbanized areas (45.71%), a slight increase in the forests (1.57%) and a sizeable reduction in the agricultural/herbaceous areas (− 33.49) of the city within the stipulated period. The urbanized areas were observed to have the highest LST in 2010 and 2021 (28.75–34.0 °C) followed by the bare land (29.76–29 °C). The increase in temperature could have been driven by the reduction in the greenness of the city coupled with the openness of vegetation cover. Similarly, strong positive correlations were observed between the LST and NDVI in the urbanized areas (R2 = 0.92), and bare lands (R2 = 0.86). We, therefore, hypothesize that urbanization is the main driver of the LULC changes on Penang Island.
The study was carried out to investigate the responses of drought stress on wheat tissues. Five wheat cultivars Alta 84 (AL), Atila (AT), Cettia (CE), Norman Bourgluk 2008 (NB) and Seri M82 (SE) were cultivated. Four weeks after planting, healthy plants were subjected to four treatments viz-well-watered (D1), watered daily, drought stress (D2), one weekly watering, drought stress (D3), two weekly watering and drought stress (D4), and three weekly watering. The experiment was a factorial experiment conducted in a completely randomized design (CRD) with three replicates; Transverse section (TS) of the leaves collected were sectioned using microtome, stained and observed under compound microscope. Mesophyll cells, vascular bundles, bundle sheaths and xylem tissues were measured using ocular micrometer. Epidermal peels were prepared to determine the number of stomata and trichomes. When drought stress was imposed (D2, D3 and D4), wheat cultivar Cettia developed larger mesophyll cells, xylem tissues, vascular bundles and bundle sheaths than other cultivars. Thus, larger vascular bundles would facilitate faster movement of water and mineral salts up to the shoot from the root. Cultivar Atila developed higher number of trichomes during drought stress D2 than other cultivars which help to reduce the rate of transpiration of water out of the epidermal leaves. Wheat cultivars Cettia and Atila could be drought tolerant cultivars. Generally, wheat cultivars developed stable stomata number and stomata closure mechanism to cope with drought stress. There was an increase in number of trichomes at D2, D3 and D4 which revealed the ecologically adaptation of wheat plants to drought stress.
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