Consider a family of abelian varieties A i of fixed dimension defined over the function field of a curve over a finite field. We assume finiteness of the Shafarevic-Tate group of A i. We ask then when does the product of the order of the Shafarevic-Tate group by the regulator of A i behave asymptotically like the exponential height of the abelian variety. We give examples of families of abelian varieties for which this analogue of the Brauer-Siegel theorem can be proven unconditionally, but also hint at other situations where the behaviour is different. We also prove interesting inequalities between the degree of the conductor, the height and the number of components of the Néron model of an abelian variety. rez me: Rassmotrim seme stvo abelevyh mnogoobrazii A i nad polem funkci krivo nad koneqnym polem. Dopustim, qto gruppa Xafareviqa-Ta ta koneqna. My spraxivaem, kogda proizvedenie por dka gruppy Xafareviqa-Ta ta na regul tor dl A i asimptotiqeski bedet seb kak ksponencial na vysota abelevyh mnogoobrazi. My privodim primery mno estv abelevyh mnogoobrazii, dl kotoryh my mo em dokazat bezuslovno analog teoremy Brau ra-Zigel , no tak e rassmatrivaem i drugie situacii, kogda asimptotiqeskoe povedenie etih veliqin razliqno. Krome togo, my dokazyvaem interesnye neravenstva, sv zyva wie stepen konduktora, vysotu i qislo komponent modeli Nerona abelevogo mnogoobrazi. Contents 5. An abc theorem for semi-abelian schemes in characteristic p > 0 17 5.1. Preliminaries 17 5.2. Main statement and associated results 17 5.3. Compactification of a universal family 18 5.4. Towards the Kodaira-Spencer map 20 5.5. Case where Kod(φ U) = 0 23 6. Group of connected components 24 6.1. Rigid uniformization 24 6.2. Fourier-Jacobi expansion of theta constants 25 6.3. Jacobians and Noether's formula. 30 7. Special value at s = 1 31 7.1. The L-function of A/K 31 7.2. Lower bounds for the regulator 34 7.3. Lower bounds and small zeroes 35 7.4. An example 36 7.5. Twists 39 7.6. Twists of a constant curve 40 8. Appendix : Invariance of statements 42 References 43 Key words-Abelian varieties, heights, global fields, Brauer-Siegel theorem, Birch & Swinnerton-Dyer conjecture AMS classification-14K (abelian varieties and schemes), 11G (arithmetic algebraic geometry), 11M (Zeta and L-functions, 11R (Algebraic number theory, global fields)