Production of Bambusa vulgaris seedlings from rhizomes under brackish water irrigation

ABSTRACT The objective of this study was to evaluate the influence of irrigation with brackish water on the production of bamboo seedlings (Bambusa vulgaris). The experiment was carried out at the Fazenda Experimental Piroás, in the municipality of Redenção, CE, Brazil (4° 14’ 53” S, 38° 45’ 10” W, and altitude of 230 m), in a completely randomized design with five treatments and six repetitions. The treatments consisted of five irrigation water electrical conductivity (ECw): 0.5 (control); 1.5; 2.5; 3.5 and 4.5 dS m-1. At 120 days after the beginning of the application of the treatments the leaf gas exchange, relative chlorophyll index (RCI), plant height (H), shoot dry matter (SDM), H/SDM ratio, and the concentrations of Na+ and K+ in stems and leaves were evaluated. Salt tolerance indexes were calculated based on SDM, H, photosynthesis rate and RCI. The increase in the ECw reduced leaf gas exchange, and the reduction in the photosynthesis rate was caused by stomatal and non-stomatal effects. The salinity affected negatively the growth and quality of bamboo seedlings, with the greatest effects being with ECw equal to or greater than 2.5 dS m-1. Bamboo seedlings present Na+ retention in the stems and low Na+/K+ ratio in the leaves. Bamboo seedlings are tolerant to salinity up to 1.5 dS m-1, indicating that waters with this salinity can be used for seedling production of this species, without loss of growth and quality.

摘要 本研究旨在评估微咸水（brackish water）灌溉对普通竹（Bambusa vulgaris）幼苗培育的影响。试验于巴西塞阿拉州（CE）雷登桑市的皮罗阿斯实验农场（Fazenda Experimental Piroás）开展，试验地坐标为南纬4°14′53″、西经38°45′10″，海拔230米，采用完全随机设计，设置5个处理、6次重复。处理组设置为5个梯度的灌溉水电导率（electrical conductivity of irrigation water, ECw）：0.5（对照组）、1.5、2.5、3.5及4.5 dS·m⁻¹。于处理开始施加120天后，测定叶片气体交换参数、相对叶绿素指数（relative chlorophyll index, RCI）、株高（plant height, H）、地上部干物质（shoot dry matter, SDM）、H/SDM比值以及茎、叶中的Na⁺与K⁺含量。基于SDM、H、光合速率及RCI计算耐盐性指数。灌溉水ECw升高会降低叶片气体交换参数，光合速率下降由气孔因素与非气孔因素共同导致。盐胁迫对竹苗的生长与品质产生负面影响，当ECw≥2.5 dS·m⁻¹时负面影响最为显著。竹苗会在茎部积累Na⁺，且叶片中Na⁺/K⁺比值较低。竹苗可耐受最高1.5 dS·m⁻¹的盐胁迫，说明该盐度的灌溉水可用于该物种的竹苗培育，且不会造成生长与品质损失。