Growth and metabolism of <i>Pityrocarpa moniliformis</i> Benth. seedlings under water deficit

Abstract

Pityrocarpa moniliformis Benth. has medicinal properties, forage potential, besides showing rusticity and rapid growth, which confer potential to recover degraded areas. In this context, the objective was to evaluate the growth and biochemical components of Pityrocarpa moniliformis seedlings under water deficit conditions. The design used was randomized blocks, with five treatments and four replicates, with the experimental plot consisting of twenty plants. Treatments were characterized by different periods of water deficit (0; 4; 8; 12 and 16 days without irrigation). At 44 days after sowing (DAS), when the seedlings had two pairs of fully formed true leaves, the treatments began to be applied. The development of the seedlings was evaluated until 60 DAS when they were collected for biometric and biochemical analyses. The variables analyzed were shoot height; collar diameter; number of leaves; shoot dry mass; root dry mass; root/shoot ratio; and Dickson’s quality index. Contents of total chlorophyll, chlorophyll a, chlorophyll b, total free amino acids, total soluble sugar, and proline contents in the leaves were also determined. The treatment most affected by the lack of irrigation was 16 days of water deficit, which resulted in the death of 38.8% of the seedlings. This condition caused a decrease in shoot length, reducing it by approximately 29.2% compared to the control treatment. There was also a reduction in the production of new leaves from the eighth day after the differentiation of treatments. Pityrocarpa moniliformis seedlings can develop under the condition of water deficit for up to 8 days, even with chlorophyll degradation due to stress. Pityrocarpa moniliformis maintains its vegetative development by performing osmotic adjustment through the accumulation of biomolecules (sugars, proline, and amino acids).