Effect of Radiation-modified Kappa-carrageenan on the Morpho-agronomic Characteristics of Mungbean [Vigna radiata (L.) R.Wilczek

Abstract

Initially, the effects of radiation-modified kappa-carrageenan (RMKC) at different concentrations (20, 40, 60, 80, and 100 mg/L or ppm) as plant growth promoter were determined on plants of mungbean variety NSIC 2002 Mg 13 (Pagasa 21). RMKC at 60 ppm proved to be the most effective in inducing plants to flower, promoting plant height, and increasing seed yield by enhancing the length of pod and number of seeds produced. In a second experiment, the effectivity of RMKC was compared with those of an inoculant (I), inoculant and inorganic fertilizer (I + F), and a seaweed-based commercial foliar fertilizer using the variety NSIC 2004 Mg 14 (Kulabo). Likewise, in a third experiment comparing RMKC with seaweed extract (SE) irradiated at increasing dose levels, RMKC also enabled the production of higher yield on Kulabo by increasing the length of pod, number of seeds/pod, and 100-seed weight even in the absence of an inoculant. It has been found to be more effective than a seaweed-based commercial foliar fertilizer as well as SEs that have been irradiated with 10, 20, and 30 kGy of gamma radiation probably due to the availability and stability of low molecular weight (Mw) fractions of κ-carrageenan and the micro-nutrients present in it. The use of RMKC as seed treatment and foliar application for Labo, Pagasa 7, and Pagasa 19 at 1 wk, 3 wk, and 5 wk after seedling emergence produced taller plants and gave higher yield. The increase in pod and seed yields are attributed to more flowers that become fruits (higher number of pods), longer pods with more seeds, and extended flowering and fruiting so there was longer harvesting time (number of priming doubled from 3 to 6). Seed yield of mungbean plants grown after rice or corn can be increased by application of 100 ppm RMKC as foliar spray three times – at 1, 3, and 5 wk after germination – with or without the use of a seed inoculant.