Variations in soil moisture and pH tolerance of narra (Pterocarpus indicus Willd.) seedlings

Soil pH gave significant differences in various narra seedling morphological traits in height, root biomass, shoot biomass, total biomass, root/shoot ratio, length of tap root, and number of leaves. Over-all assessment showed superior growth and vigor of narra seedlings at pH 5.8 and 6.4 than pH 7.8. A slightly acidic soil of pH 5.8 and 6.4 therefore enhanced good growth of seedlings. Different provenances of narra gave varying phenotypic variations (morphological as well as physiological) as manifested by seedlings in root collar diameter, shoot biomass, root/shoot ratio, length of tap root, number of leaves and leaf area. P1 (Tacloban City) provenance performed best over other provenances studied and should be the best choice as source of seeds for planting areas where soils were collected. Moisture stress applied to the seedlings at varying levels based on the field capacity gave significant results in root collar diameter, root biomass and total biomass. As expected seedlings grown at 75 percent of the field capacity have superior growth compared to seedlings grown at lower soil moisture applied to the soil. It was also evident that narra seedlings can survive in moisture content up to 35 percent of the field capacity given the same condition in the study as there was no seedling mortality noted. The test for the presence of genotype (G) and environment (E) interactions showed positive response in terms of seedling height, root/shoot ratio, number of leaves, and number of stomates. This resulted in a shift in provenance ranking at varying soil pH and moisture regimes. Interaction of soil pH and moisture regimes showed significant differences on number of stomates. The highest number of stomates was greatest at pH 6.4 and moisture regime M3 (65 percent of the FC [field capacity]). Complex interaction of soil pH, provenance and moisture regimes gave significant differences in height of the seedlings studied. The Tacloban City provenance showed the best seedlings growth at pH 6.4 and 50 percent of the FC, while Baybay, Leyte; Bayombong, Nueva Viscaya; Larena, Siquijor; and Mambusao, Capiz provenances performed better at soil pH 5.8 amd preferred 50-70 percent moisture based on the FC. Finally, the results further showed that morphological traits of seedlings such as height, root collar diameter, shoot, and total biomass can be used to determine variations exhibited by narra seedling response to varying soil moisture and soil pH. Assessment of seedling response to various treatments suggests that height should be used as good indicator of seedling resistance to drought and pH for practical and economical reasons. Drought- and pH- tolerant seedlings have long shoots, bigger root collar diameters, heavier biomass, large leaf areas, and balanced root and shoot in terms of weight