Spatial and temporal effects on hydraulic conductance and other attributes of bamboo (Gigantochloa scortechinii Gamble)

Gigantochloa scortechinii Gamble (Buluh Semantan) is one of the most common bamboo species, and abundant with scattered distribution in Peninsular Malaysia. A study was initiated to determine the structure and variation of most ignored part which is rhizome from three different study sites and four consecutive rhizome ages. The study focused on the variation of physiological, anatomical, chemical, and phytochemical attributes in relation to site and rhizome age. This study was conducted at three different locations of Peninsular Malaysia, namely Amanjaya Forest Reserve (Perak), Kenaboi Forest Reserve (Negeri Sembilan), and Ayer Hitam Forest Reserve (Selangor). The sites were selected due to abundant of G. scortechinii bamboo species distribution at those areas, and also represented different climatic condition such as elevation, precipitation, and temperature. The destructive sampling of four consecutive rhizomes of the bamboo species G. scortechinii was conducted using selective random sampling method from healthy clumps. The four consecutive rhizomes were represented as four different rhizome ages: a) new sprout, b) young, c) premature, and d) mature rhizome. The results showed that hydraulics conductivity (K) varied significantly (p<0.01) among study sites, rhizome ages and their interaction (study site x rhizome ages). Significant correlation was found between K with rhizome morphology; such as number of active buds (r = 0.455, p<0.01), number of damaged buds (r = -0.435, p<0.01) and rhizome branches (r = -0.673, p<0.01). Rhizome morphology such as distance between young and old rhizome, rhizome length, number of internode, rhizome diameter (upper, middle, lower, and mean), rhizome lumen diameter (middle, lower, and mean), rhizome wall thickness upper, middle, lower, and mean), and number of buds (total, active and damaged) varied significantly and correlated with study site. However, rhizome lumen diameter at upper portion and rhizome branches were found insignificantly different with study site. For rhizome age, significant variation (p<0.01) were only found on number of buds, number of active buds, and rhizome branches. Furthermore, number of buds and number of active buds were found decreased with increasing of rhizome age. All the measured anatomical characteristics are significantly different with study site except ground tissue parenchyma (GTP) diameter, GTP lumen diameter, and fiber (Fi) cell wall thickness at p<0.05. With respect to rhizome age, the radial to the tangential ratio (RTR) was found significantly different (p<0.01) with a negative relationship with rhizome age which depicted that the RTR decreased with increasing of age. However, the vascular bundle (VB) diameter, GTP diameter, GTP lumen Diameter, GTP cell wall thickness, Fi diameter, Fi cell wall thickness, Fi length, and runkle ratio (RR) were significantly different (p<0.01) with a significant relationship (r=0.343, 0.400, 0.350, 0.682, 0.367, 0.634, 0.413, and 0.320 respectively) with rhizome age which depicted that they are increased with increasing of rhizome age. All measured anatomical characteristics including the conductance element were found insignificant relationship with Kbg, except the GTP diameter and lumen diameter. Regarding chemical attributes, the results indicate that the ash content (AC), alcohol-acetone soluble (AAS) and holocellulose (HC) were significant different (p<0.01) among study sites. Furthermore, AC, hot water soluble (HWS), AAS, lignin (L), and HC were found significantly different (p<0.01) with a strong relationship (r=-0.823, 0.688, 0.986, 0.945, 0.510 respectively) with rhizome age. The AC showed a significant (p<0.01) positive relationship (r=0.747) with Kbg which depicted that the decreasing of AC in increasing of rhizome age resulted to decreasing of Kbg, but, HWS, AAS, L, and HC showed a significant (p<0.01) negative relationship (r=-0.706, -0.914, -0.857, -0.567 respectively) with Kbg which depicted that the increasing of those chemical attributes in increasing of rhizome age resulted to decreasing of Kbg. The AC is suggested to be related with the nutrient elements which are crucial for fast growth of growing organ than the older bamboo organ. The relationship of AC with nutrient elements changes during maturation period is related with all three hypotheses in previous studies which are (a) the ability to absorb nutrient, (b) metabolically active vascular tissues that translocate the nutrient elements, and (c) the dilution effects of quickly increasing of biomass. Results indicate that several nutrient elements such as nitrogen (N), sulfur (S), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), copper (Cu) (all p<0.01), and ferum (Fe) (p<0.05) concentration were found significantly different with study site. The nutrient elements such as N, P, K, Ca, magnesium (Mg), Cu, and zinc (Zn) were found significantly different (p<0.01) and their concentration decreased with increasing rhizome age (r=-0.912, -0.834, - 0.844, -0.834, -0.899, -0.364, and -0.933 respectively). The changes of N (r=0.827), P (r=0.928), K (r=0.871), Ca (r=0.903), Mg (r=0.836), and Zn (r=0.841) showed a significant (p<0.01) strong positive relationship with AC which depicted that the decreasing of those nutrient elements concentration in increasing of rhizome age resulted to decreasing of AC. Furthermore, the spatial and age-related effect also showed a great variation in phytochemical composition and concentration. Eighteen compounds were found similar at all three study sites; however, their composition and concentration considerably showed age-dependent. It is suggested that the variation of phytochemical composition and concentration is more affected by rhizome age compared to the study site. Results also revealed various beneficial phytochemical compounds such as 4h-pyran-4-one,2,3-dihydro-3,5- dihydroxy-6-methyl, benzofuran, 2,3-dihydro-, phenol,3,4-dimethoxy-, benzoic acid,4-hydroxy-3,5-dimethoxy-, quinic acid, and n-hexadecanoic acid in the ethanolic extract with potential contribution to the plant-derived biomaterial. Results from this study could enhance the understanding beyond the lack information of hydraulic conductance in bamboo rhizome and factors that influence the conductivity. The results can be implementing in bamboo management practices to ensure sustainable and profitable production. However, it should be depending on the objective of the targeted product such as for culm/rhizome, bamboo shoot, or bamboo leaves production. This study also attempts to promote the utilization of bamboo specifically the G. scortechinii species regarding bio-perspective with its great potential for industries. Authors believed that effort on developing national economic and industries can avoid international treats through good practices such as avoid conversion of forest area into plantation or agricultural land, and also by using abundant indigenous natural resources in forest area with a sustainable management practices.

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