Editor\u27s Column

non

Editor\u27s Column

N/

Editor\u27s Column

N

Editor\u27s Column

N/

Editor\u27s Column

N/

Plant hormones and oxidative stress in Hevea brasiliensis

Plant hormones are naturally occurring organic substances that are produced within the plant at low concentrations which regulate the growth and metabolism. It was observed that over-harvesting latex through high intensity tapping had a direct effect on the endogenous hormone levels in rubber plants. This could induce the development of oxidative stress leading to several complex physiological disorders including tapping panel dryness (TPD). During oxidative stress, the levels of stress hormones increased and the growth hormones decreased in the bark tissue. Both ethylene (ET) and abscisic acid (ABA) concentrations were high in trees that are exposed to oxidative stress. The levels of hydrogen peroxide (H2O2) and its scavenging enzyme, peroxidase (Px), present in healthy trees were appeared to be capable of scavenging the H2O2 molecule produced in the tissue. Hence, the minimum stress response was noticed in the bark tissues of normal trees. The regular wounding of the bark tissues for harvesting latex cannot be avoided in rubber trees. But, the amount of Px produced in the bark tissue was inadequate to detoxify the H2O2 produced under certain physiological state of the tree (TPD) and thus leading to oxidative stress. Accumulation of malondealdehyde (MDA) was evidenced as the peroxidative damage occurred in the bark tissues of stressed trees. The tissue cyanide (CN) level was very high in stressed trees due to the low levels of CN scavenging enzyme, β-cyanolalanine synthase (β-CAS). Trees under oxidative stress had increased levels of stress hormone in the bark tissue and hence, the low levels of growth hormones and high levels of stress hormones in the soft bark tissue would have caused disorders in the cellular differentiation and metabolism in the laticiferous tissues of Hevea trees limiting the production leading to significant crop loss

Keeping the PROMISE: Factors Affecting Timing to Merit Scholarship Loss

Despite increased attention paid to the advent and development of state merit scholarship policies (such as Georgia’s Helping Outstanding Pupils Educationally) and some evidence that suggests differences in scholarship retention by socioeconomic status or other student characteristics, little empirical work has explored factors affecting scholarship retention. Moreover, no work has explored what affects the timing of scholarship loss. This study employs event history modeling to ascertain not only what factors impact students’ retention of the West Virginia PROMISE Scholarship but also when these factors are most influential