Effect of azospirillum inoculation on establishment and growth of bush pepper

Abstract

The study on the effect of Azospririllum inoculation on root induction, establishment and growth of bush pepper was conducted at Collage of Agriculture, Vellayani, Trivandrum during 1992 – 94. Out of the 25 different cultivars of pepper used for initial isolation, Azospirillum was isolated from 16 cultivars. These 16 isolates along with a culture from TNAU were screened for the production of IAA and gibberellins under in vitro conditions. The native isolate 34 produced maximum quantity of IAA equivalent to 69 µg/ml of culture broth. The production of this phytohormone was maximum during the second week of culture growth. However, none of these isolates produced gibberellins under in vitro conditions. Based on the requirement of biotin for growth isolate 34 and TN culture were tentatively identified as Azospirillum brasilense and A. lipoferum respectively. The isolate 34 and TN culture had their maximum growth at pH 6.0 and 8.0 respectively. Azospirillum isolate 34 and TN culture were selected for root induction studies in Panniyur – 1 and Karimunda varieties of bush pepper. The percentage of rooted cuttings varied from 23.3 – 26.8 percent in Panniyur -1 and 17.5 – 17.9 in Karimunda. However, the average number of roots per cuttings and root dry weight were maximum in bacterial treatment. Between the two varieties of bush pepper, root induction was better in Panniyur – 1 variety. The study on the establishment and growth of bush pepper was conducted by using 3 sets of rooted cuttings of Panniyur – 1 and Karimunda varieties where root induction was done by using carrier a based inoculum of Azospirillum and 1000 ppm IBA or without any of the above treatments. These were grown in potting mixture supplemented with 25 g or 100g of isolate 34 and with or without chemical fertilizer application. After 180 days of plant growth, 100 percent establishment was obtained in Panniyur – 1 in treatments such as 100 g Azo 34-F of group 1, 25 g Azo 34-F and 100 g Azo 34+F of group 2 plants. In these treatments the number of roots produced per cutting, fresh and dry weight of roots were significantly high or on par with each other. In Karimunda, also, in treatments such as 25 g Azo 34-F and 100 g Azo 34-F of group 1, 100 g Azo 34-F of group 2 and 25 g Azo 34-F of group 3 plants where 100 percent establishment was obtained, the number of roots produced per cuttings, fresh and dry weights of roots were statistically on par with best treatment for these parameters. The production of new leaves, branches and fresh and dry weight of shoot were significantly high only in Panniyur – 1 and these were in the treatments 100 g Azo 34-F of group 1 and 25 g Azo 34-F of group 2 plants. But in Karimunda, no such treatment effects were noticed except for fresh and dry weight of branches. In Panniyur – 1 the total fresh and dry weight of plants were significant also in 100 g Azo 34-F of group 1 and 25 g Azo 34-F of group 2 plants. In most of the treatments where significant results were obtained, chemical fertilizer application had no significant effect on different growth parameters studied. Further, between the two varieties, Panniyur – 1 responded better than Karimunda in rooting, establishment and growth of bush pepper.