Abstract Salt stress and heavy metal are instigating hazard to crops, menace to agricultural practices. Single and combined stresses affecting adversely to the growth and metabolism of plants. To explore salt and heavy metal resistant plant lines as phytoremediants is a need of time. Physiological responses are main adaptive responses of the plants towards stresses. This response varies with species and ecotype as well as type and level of stress. Two cucurbit weeds from two ecotypes were selected to evaluate their physiological adaptations against independent and combined stresses of various levels of salt (NaCl) and heavy metal (NiCl2). Various physiological parameters like water potential, osmotic potential, pressure potential, CO2 assimilation rate, stomatal conductance, chlorophyll a and b, carotenoids, and production of adaptive chemicals like SOD, CAT, proteins, sugars and proline were studied. Citrullus colocynthis showed more adaptive response than Cucumis melo agrestis and desert ecotype was more successful than agricultural ecotype against stresses.

Resumo O estresse salino e os metais pesados são um perigo instigante para as plantações e uma ameaça para as práticas agrícolas. Estresses simples e combinados afetam adversamente o crescimento e o metabolismo das plantas. Explorar linhagens de plantas resistentes a sais e metais pesados como fitorremediantes é uma necessidade de tempo. As respostas fisiológicas são as principais respostas adaptativas das plantas aos estresses. Essas respostas variam de acordo com a espécie e o ecótipo, bem como com o tipo e o nível de estresse. Duas plantas daninhas cucurbitáceas de dois ecótipos foram selecionadas para avaliar suas adaptações fisiológicas frente a estresses independentes e combinados de vários níveis de sal (NaCl) e metal pesado (NiCl2). Vários parâmetros fisiológicos, como potencial hídrico, potencial osmótico, potencial de pressão, taxa de assimilação de CO2, condutância estomática, clorofila a e b, carotenoides e produção de produtos químicos adaptativos, por exemplo, SOD, CAT, proteínas, açúcares e prolina, foram estudados. Citrullus colocynthis apresentou resposta mais adaptativa do que Cucumis melo agrestis e o ecótipo deserto foi mais bem-sucedido do que o ecótipo agrícola contra estresses.

Abstract We study the electronic, the optical and the transport properties of both bulk materials ErN and Er0.125Ga0.875N, which crystallize in zinc-blind and wurtzite structures, respectively, and are utilized in quantum well devices. The properties are calculated using density functional theory (DFT), by applying the full-potential linearized augmented plane-wave (FP-LAPW) method with a spin-orbit coupling effect. The analysis of the electronic properties shows that ErN and Er0.125Ga0.875N have a band gap at 0.79 and 3.38 eV, respectively. On the other hand, the technology makes it possible to stack these materials for a quantum well heterostructure of Er0.125Ga0.875N/ErN. The optical properties such as optical coefficients, refractive index and extinction coefficient are discussed in detail. The transport properties of alloys are investigated using the semi-classical Boltzmann theory as implemented in the BoltzTraP code in conjunction with ab initio electronic structure calculations. Our findings suggest that Er doping of wide band gap semiconductors could be a viable option for quantum well devices.