Document Type

Thesis - Open Access

Award Date

2021

Degree Name

Master of Science (MS)

Department

Agronomy, Horticulture, and Plant Science

First Advisor

Thandiwe Nleya

Abstract

Canola (Brassica napus L) and carinata (Brassica carinata A. Braun) are potential oilseed crops for diversifying cropping systems and expanding into marginal lands impacted by saline and sodic soils in South Dakota (SD). However, genotypes that are high yielding, with high agronomic adaptability and stability over diverse environments, and salt tolerant have not been selected. One field experiment was conducted at two environments (Brookings - eastern SD and Pierre - western SD) from 2019 to 2020 to evaluate genotypes for growth and yield stability. Three greenhouse experiments were conducted to evaluate genotypes for salt tolerance in soils varying in electrical conductivity (EC), and with or without amendments (biochar and composted manure). The field experiment in 2019 evaluated ten canola and three carinata genotypes, whereas in 2020, twelve canola genotypes were evaluated. The experimental design was RCBD with treatments replicated four times. The earliest genotype to flower was NCC101S reaching 50% flowering at 41 and 36 days after planting (DAP) in 2019 and 2020, respectively. All carinata genotypes were later flowering reaching 50% flowering at >48 DAP. Seed yield for all genotypes averaged 1809 and 1740 kg ha-1 at Brookings and (1384 and 858 kg ha-1) at Pierre in 2019 and 2020, respectively. Similarly, seed oil concentration was greater at Brookings (410 g kg-1) than at Pierre (356 g kg-1) at Pierre in 2019. Environment was the most dominant cause of variation among genotypes, explaining 73.3%, 67.7%, 45.2% and 45.7%, of the variations in biomass yield, pods plant-1, 1000-seed weight, and seed yield, respectively, while genotype by environment interactions (GEi) explained most of the remaining variation. Data indicated that four genotypes, CS2300, DKTF92SC, CS2500, and NCC101S were stable with good yield in the four environments. For greenhouse experiments, the first experiment evaluated ten canola and three carinata genotypes in three soils with EC ranging from non-saline (0.62 mmho/cm), moderately saline (5.17 mmho/cm) and highly saline (8.47 mmho/cm). The experimental design was an RCBD with treatments replicated three times. In the second experiment, two types of biochar (softwood and hardwood were introduced in each soil type at a rate of 5% by volume with an unamended control (no biochar) for each soil and 10 canola and three mustard genotypes were planted at a rate of eight seeds pot-1. The four most promising genotypes identified in experiment two (African cabbage, Brown mustard, DKTF91SC and NCC101S) were evaluated in the third experiment. In this experiment composted manure was added to each soil-biochar combination (as in second experiment) at rated of 0, 30 and 50% by volume. Treatments were arranged in a split-plot design with soil salinity level as the main plot and biochar, composted manure rate and genotype arranged in factorial design within soil salinity level. Seedling emergence had a negative relationship with soil salt content with an average of 65.1%, 17.7% and 11.2% of emerged seedlings in non-saline, moderately saline and highly saline soils in experiment one. The genotypes with the greatest seedling emergence in moderately saline soils were L140P and NCC101S (29.2%), whereas NCC101S in the highly saline soil was the best at 29.2%. Averaged over biochar and genotypes, application of composted manure improved seedling emergence, number of leaves plant-1 and leaf chlorophyll content (SPAD values) as compared to treatments with no composted manure, irrespective of soil salt content (salinity level). However, application of composted manure interacted with biochar type to influence number of leaves plant-1 and (SPAD values) in moderately saline and highly saline soil but not in non-saline soils. The interaction for number of leaves plant-1 was due to better response in moderately saline and highly saline soils amended with softwood biochar compared to soil with no biochar or amended with hardwood biochar to increasing composted manure rate with the greatest number of leaves obtained at the highest rate of 50%. For SPAD values, the interaction between biochar and composted manure was due to high variability in SPAD values response to applied composted manure among biochar treatments. In terms of genotype, there was high variability with all genotypes showing improvement with composted manure application in moderately saline and highly saline soils with or without biochar amendment, but with the best observed in soils amended with softwood biochar. These findings suggest that canola has a potential to become an alternative spring broadleaf oilseed crop for diversifying cropping systems in SD. However, more research is required for this crop to determine the best management practices in saline sodic soils.

Number of Pages

122

Publisher

South Dakota State University

Rights

Copyright © 2021 the Author

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