Nodulation and rooting pattern of summer greengram (Phseolus radiatus) as influenced by irrigation variables

Abstract

An experiment was conducted with core (with 22.5 cm x 20.0 cm cross-section greengram (Phaseolus radiatus L.) during and 20 cm this purpose at depth) was dug for spring seasons of 1985 and 1986 at 45- and 60 day- stages. The acetylene Pantnagar. The soil of the experimental site reduction assay for nitrogenase activity was silty clay loam, having pH 7.4, organic (N,ase), modified method of Hardy et al. carbon content 1.14% available P 35.7 kg/ (1973), was used to determine the ha and available K 297.1 kg/ha in 0-30 cm- nitrogenase activity in the excised roots with soil depth. The treaanents consisting of 4 in tact nodules. greengram cultivars (Pusa Baisakhi, PS Number and dry weight of noduledplant 16. Pant Mung 1 and Pant Mung 2) in differed significantly due to cultivars only at main plots and 5 irrigation schedules [no 60 days after sowing during both the years post-sowing irrigation, single irrigation at 25 (Table 1). Gupta (1982) reported that K days after sowing, irrigation at 20, 15 and 10 851 variety of greengram had maximum cm cumulative pan evaporation (CPE) number of nodules, though the difference values] in subplots were laid out in split-plot among genotypes were not significant. design, with 4 replications. Cultivar effects with respect to root-dry The crop was sown on 26 March 1985 weight/plant were significant only at 45-day and 15 March 1986 in rows, 30 cm apart. stage when root-dry weight was highest in Plant spacing within the rows was .P!j 16 (0.19 g) in 1985 and Pant Mung 12 maintained at 7.5 cm by thinning. The crop (0.12 g) in 1986. was- harvested on 20 June during both the An increase in the nodule number, nodule seasons. It received a basal dose of 150 kg and root-dry weight was obtained with diammonium phosphatelha. Numbers of improvement in moisture supply over no irrigation needed were 3,4 and 6 under 20, post-sowing irrigation treatment, being 15 and 10 cm CPE treatments respectively, maximum under irrigation at 10 cm CPE in 1985, and 2, 3 and 3 irrigations in 1986. flable 1). Reduced carbohydrate supply The total rainfall received during the crop from top due to suppressed growth under season was 11.1 cm in 1985 and 23.1 cm in water stress possibly affected the root 1986. growth adversely ,and decreased the module For study of root and nodulation, 3 number and nodule-dry weight. Root-dry continuous plants were selected and a soil weight was also lowest under no post-sowing