Growth and physiological response of dendrobium cv earsakul in different growing conditions

Abstract

The study on 'Growth and physiological response of Dendrobium cv. Earsakul in different growing conditions' was conducted at College of Horticulture, Vellanikkara, Kerala from April 2011 to March 2013. The main objective was to assess the response of combination of nutrients, plant growth regulators and plant growth promoting root endophyte (PGPRE) in two age groups of Dendrobium cv. Earsakul plants (six month old and three year old at planting time) under three growing systems viz., two level shade house (SI), top ventilated polyhouse (S2) and fan and pad system (S3). Attempts were also made to examine the symbiotic association between the host and PGPRE. Among growth characters, plant height, number of shoots per plant, girth of shoot and internodal length were highest in the treatment POP + OM + VW + PGPRE + Bone meal (T3). Number of leaves per plant was also the highest in the treatment POP + OM + VW + PGPRE + Bone meal + GR (T4) irrespective of the age of the plants. Among the three systems of growing, maximum growth characters were recorded in top ventilated polyhouse (S2). Number of leaves and shoots per plant were the highest in the treatment combination of POP + OM + VW + PGPRE + Bone meal + GR (T4) and top ventilated polyhouse (S2). The treatment POP + OM + VW + PGPRE + Bone meal + GR (T4) resulted in longer spike (31.34 cm), more number of flowers per spike (6.54) and longer vase life (30.00 days), whereas, the treatment NPK + GR + OM + VW + PGPRE + Bone meal (T 6) was the best with respect to time taken for first flower opening and number of spikes per plant (2.62) in six month old plants. In three year old plants, the treatment POP + OM + VW + PGPRE + Bone meal + GR (T4) was the best with respect to time taken for flowering, days to last flower opening, number of spikes (2.63) and vase life (28.26 days), whereas, length of the spike (30.46 cm) and number of flowers (5.08) were the highest in the treatment NPK + GR + OM + VW + PGPRE + Bone meal (T6). Among systems of growing, plants grown under top ventilated polyhouse (S2) had maximum flower characters. Interaction effect of POP + OM + VW + PGPRE + Bone meal + GR

(T4) and top ventilated polyhouse (S2) was significantly supenor III flower characters irrespective of the age of the plants. Leaf area, relative growth rate and number of stomata were highest in six month old plants, whereas, dry matter production and crop growth rate were highest in three year old plants in the treatment POP + OM + VW + POPRE + Bone meal + OR (T4). Dry matter production, crop growth rate, rate of photosynthesis and transpiration rate during day time were highest in the treatment POP + OM + VW + POPRE + Bone meal (T3) in six month old plants. Among the systems of growing, maximum values for physiological parameters were recorded in top ventilated polyhouse. The interaction of plant growth promoters and systems of growing had significant effect on physiological parameters. Highest number of roots, root volume and root colonization (in three year old plants) resulted from the treatment NPK+ OR + OM + VW + POPRE + Bone meal (T 6) in both stages of plants, whereas, POP + OM + VW + POPRE + Bone meal + OR (T4) resulted in highest root length and root colonization in six month old plants. Among systems of growing, plants grown in top ventilated polyhouse (S2) recorded highest number of roots per plant, root length, root volume and root colonization. The combination of POP + OM + VW + POPRE + Bone meal + OR (T4) and top ventilated polyhouse recorded highest number of roots, root length, root volume and root colonization of Piriformospora indica. Highest N, P and K contents in six month old plants was recorded in the treatment POP + OM + VW + POPRE + Bone meal + OR (T4), whereas POP + OM + VW + POPRE + Bone meal (T3) recorded highest Nand P contents in three year old plants. Among systems of growing, plants grown in top ventilated polyhouse recorded highest N, P and K contents. Interaction POP + OM + VW + POPRE + Bone meal + OR (T4) and top ventilated poly house recorded highest N, P and K contents in six month old plants.

Autoradiography showed that orchid roots absorbed 32p from labelled nutrient solution N: P205:K20 (1:2:2). Radio assay study revealed that radioactivity was highest in pseudobulbs than in roots and leaves. In anatomical studies, P. indica fungus association was confined to cortical tissues. Hyphae multiplied within cortical tissues and never traversed to aerial portion of the plant. It was concluded that plant growth promoters POP + OM + VW + PGPRE + Bone meal + GR and top ventilated polyhouse had maximum influence on plant growth, yield parameters and physiological parameters like leaf area, DMP, CGR and RGR. The canonical correlation further reinforced the results that plant growth and yield of the plant was significantly influenced. The nutrient contents of N, P and K were highest in plants grown under top ventilated polyhouse. The association of P. indica in root system of Dendrobium cv . Earsakul was highly significant and the P. indica fungus enhances higher root absorption and facilitates the growth parameters significantly.