Ecofisiologia inicial de cultivares de cevada sob influência de excesso hídrico e temperatura

Abstract

The present work aims to describe the scientific study carried out with eight barley cultivars, during the initial period and the emergence of plants, under water and temperature stress. In the studies described, the initial behavior of the species Hordeum vulgare L. was evaluated and the following cultivars were used: ABPR 31, ABPR 01431, ANA 01, BRS CAUÊ, BRS BRAU, BRS KORBEL, BRS QUARANTA, KWS IRINA. In chapter 1, in a controlled environment, the plants were sown in trays, in which they were filled with a substrate composed of soil. The experimental design adopted was completely randomized (DIC), in which the factorial scheme used was 8X5 (8 cultivars x 5 flooding periods) with 4 replications. For the factor flooding periods, 0 (field capacity), 24, 48, 72 and 96 hours were used. Simultaneously, from sowing, they were exposed to two temperatures and maintained until the end of the evaluations, at 20ºC (adequate) and 30ºC (stress). In each flooding period, seedlings were collected for the evaluation of shoot and primary root dry mass, in which the masses were measured on a precision scale, and the results expressed as mg seedling-1. It is understood that, regardless of the cultivar, the temperature of 30ºC negatively affects the expression of seed vigor, but the effect of flooding varies among cultivars. Chapter 2 was carried out in a greenhouse with a minimum temperature of 15ºC and a maximum of 28.9ºC. Trays filled with substrate composed of soil were used. The experiment was carried out in a randomized block design, with four replications and 8x2x5 three-factorial, the first factor is the cultivars, the second factor is the soil conditions (field capacity and flooding) and the third factor is the collection times (0, 24, 48, 72, and 96h). In each period, the determination of the chlorophyll a (Cha), b (Chb) and total (Cht) index was performed in 10 plants per treatment repetition, with readings taken in the middle third of the plant. At the end, the 10 plants were collected to evaluate shoot length, shoot and root dry mass. Soil flooding within 96h reduces the variable for cultivars BRS Cauê, BRS Korbel and ANA 01. The chlorophyll index a (Cha) and total (Cht) had a similar behavior, with a decrease in plants under flooding. For the chlorophyll b index (Chb), all plants of all cultivars showed a reduction in the 24-hour period, the cultivar with the highest index in this period was BRS Quaranta. Soil flooding interfered in dry mass partition for BRS Cauê and ABPR 31 cultivars.