Ecofisiologia de sementes e mudas de Commiphoraleptophloeos (Mart.) J.B. Gillett (Burseraceae) sob várias condições hídricas em áreas de caatinga para construção de faixas arbóreas margeando cultivos agrícolas

Abstract

The growing demand for seeds and seedlings from native Caatinga species highlights the need for knowledge regarding their phenological stages and efficient seedling production methods. This thesis explores these aspects for Commiphora leptophloeos. Chapter 1 focused on monitoring the phenological phases and morphological characterization of C. leptophloeos. A total of 30 parent plants from three regions were evaluated for morphology and vegetative and reproductive phenophases.Monthly precipitation and temperature data were recorded. Sprouting began during the dry season (August–September), intensifying during the rainy season (November–December), with new foliage persisting until April. Mature leaves predominate from May to June, and leaf fall was most pronounced from June to November. Sprouting and bud formation occurred from October to December; fruiting occurred from December to April, peaking in March. Fruit and seed dispersal occurred between January and April. It was concluded that phenophases are influenced by water availability and follow seasonal patterns, with the rainy season being ideal for seed collection. Chapter 2 investigated the germination and biometric characterization of C. leptophloeosseeds and seedlings under different collection methods and storage times. Three treatments were evaluated for germination: seeds collected directly from the fruit (A1), seeds collected from the ground (A2), and stored seeds (A3). The seeds from the three treatments were evaluated before and after being buried for three months. Unburied seeds germinated within 96 hours, while buried seeds germinated within 78 hours. The seeds had an initial moisture content of 7.6%. Seeds collected from the ground and buried for three months had higher germination potential (39%) compared to those collected from the fruit (8%) and those stored (5.5%). Seedlings from buried seeds had larger stems and roots. It was concluded that seeds collected from the ground and buried for three months are the most suitable for germination and seedling production of C. leptophloeos. Chapter 3 evaluated the influence of hydration and dehydration (HD) cycles on seeds and irrigation cycles on young C. leptophloeosplants on drought tolerance and survival in rainfed areas. Seedling establishment eight days after germination was influenced by times and cycles. Untreated plants (control 2) produced larger stem sizes in the nursery (180 days) and field (one year) compared to plants from treated seeds. Treated plants increased stem size during rainy periods. HD cycles do not alter the germination of C. leptophloeos, but they reduce germination time and produce water memory in seeds. Chapter 4 evaluated the growth and survival of C. leptophloeos seedlings in Caatinga areas with and without irrigation. Seeds were collected from parent plants dispersed on the ground. Four areas were set up, with 15 plants propagated by seeds and 15 by cuttings in each: two dry areas (shaded and full sun) and two irrigated areas (shaded and full sun). Plant height, stem diameter, and number of leaves were measured monthly for 12 months. The survival rate was 100% for all plants. Larger plants, propagated by seed and cuttings, were found in the irrigated area in full sun. It was concluded that the propagation method had no influence, and the best area for cultivation was the irrigated in full sun.