SEEDLING GROWTH OF NINE GENOTYPES OF Bouteloua curtipendula WITH TWO CARYOPSIS SIZES

Abstract

Establishing rainfed grasslands under arid conditions represents a challenge; thus, rapid seedling development has advantages. This study aimed to evaluate the initial growth of Bouteloua curtipendula (Michx) Torr. coming from two sizes of caryopsis The plant material included the varieties NdeM-125, NdeM-303, NdeM-417, NdeM-La Resolana and genotypes CP-62 (Coahuila), CP-Centauro (Durango), CP-Teloxtoc (Puebla), CP-Ñañú1 (Hidalgo) and CP-Mixe (Oaxaca) with large (LC) and small (SC) caryopsis sizes. Caryopses of each size were planted into seedbeds using soil, tepezil (an inert and light mineral that facilitates aeration and capillarity), and tree bark as substrate at a 2:1:1 ratio. The transplant was carried out into 70 cm³ tubes 21 days after sowing (DAS) under a completely randomized design. Destructive sampling was performed at 43, 56, 67, 81 and 96 DAS under greenhouse conditions. The weight of a morphological components at each sampling was determined, and the absolute growth rate (AGR), specific foliar area (SFA), relative growth rate (RGR) and net assimilation rate (NAR) were calculated. Analysis of variance and Tukey mean comparison test (P ≤ 0.05) were performed. Dry matter (DM) production of morphological components was different (P ≤ 0.05) at 56 DDS; also, planting LC of NdeM-La Resolana resulted in higher both aerial and root DM (P ≤ 0.05) and inflorescence weight at 81 and 96 DAS. The maximum values for NAR and RGR occurred at the initial stages and decreased as plants got older in all materials. For RGR, NdeM-125 SC was higher as the age of the plant advanced, while for NAR, CP-Ñañu1 showed higher values (P ≤ 0.01). SFA was highest for all materials at 81 and 96 DDS, and CP-Mixe with SC was the best treatment. Selection for caryopsis size results in differential seedling development. Plants of NdeM-La Resolana from both caryopsis sizes showed early seed production, which is valuable for self-recovering of rangelands.