Field beans (Phaseolus vulgaris L.) have been considered inferior in nis (nitrogen fixation supportive trait), i.e., in their ability to support and benefit from their symbiotic association with N2‐fixing Rhizobium phaseoli. This paper reports the use of N balance in phytotron studies and 15N isotope dilution in the field to determine the effect of R. phaseoli strains and mineral N levels on the expression of nis in 26 cultivars of field beans. Evaluation for nis under N‐free conditions in the phytotron forced total dependence on seed and atmospheric N and provided a useful screening technique before field experimentation. Ranking of cultivars for nis was highly dependent on R. phaseoli strain, mineral N levels, growth habit, growth stage, and temperature regime during evaluation. R. phaseoli strains 3644 and 8215 resulted in higher N2 fixation with temperate beans while strain 3605 was unique in high N2 fixation with two tropical cultivars, Cargamantn and Sangretoro. The addition, in the field, of 40 kg fertilizer N ha−1 on a Typic Haploboroll soil caused a 10% reduction in percent N derived from atmosphere (% Ndfa) in most cultivars but had no effect on ‘Redkloud’. In contrast, ‘Limelight’ suffered a 60 % reduction in % Ndfa. This indicated a host‐specific reaction in nis to mineral N and potential for breeding this resistance into other bean lines. Both in the phytotron and the field, climbing bean cultivars had higher % Ndfa and thus superior nis than bush cultivars. Some cultivars were superior when evaluated at anthesis but not at maturity, indicating a difference in the N2‐fixing span of the cultivar. In the field, % Ndfa of beans was approximately 50 %, the other 50 % being derived from fertilizer and or soil N. The actual amounts of Nz fixed varied between 40 kg ha−1 and 125 kg ha−1 depending on the cultivar. Thus, R. phaseoli may he considered as efficient as R. japonicum is with soybeans in supplying atmospheric N2 to the plant.
Most soils sown to field beans (Phaseolus vulgaris L.) contain indigenous Rhizobium phaseoli; thus, few studies have evaluated the effect of different strains of R. phaseoli on N2 fixation and yield of bean cultivars. Since western Canadian soils contain no indigenous R phaseoli, strains were screened for their ability to fix N2 in two bean cultivars, Aurora and Kentwood. Initially, the N2‐fixing ability of 19 strains of R phaseoli was determined in vitro. The best were then compared with 16 superior Centro Internacional de Agricultura Tropical strains in a 2‐ year International Bean Inoculation Trial in the field in association with the same two small white bean cultivars. 15N isotope dilution at levels of 15N natural abundance in the field showed the % Ndfa (percentage plant N derived from the atmosphere) averaged 50% for Aurora but only 32% for Kentwood over all 16 strains. The % Ndfa did not vary between the two experimental years, but due to different levels of soil N, yield and actual amounts of N2 fixed did vary. Aurora averaged 70 kg N ha−1 and Kentwood 37 kg N ha−1 fixed. Some strains fixed more than 100 kg N ha−1 in Aurora, resulting in dry matter and N yields in excess of uninoculated treatments receiving 40 or 100 kg fertilizer N ha−1. Strains of R phaseoli from high temperature soils of Latin America fixed high amounts of N2 in association with temperate bean cultivars under conditions of low temperature growth (10 to 23°C). CIAT strains 632,899, 640, and 904 and commercial Nitragin were highly efficient N2 fixers with Aurora as were CIAT strains 952, 161, 166, and commercial Nitragin with Kentwood. Thus, R. phuseoli are as efficient as other rhizobia in supplying fixed N2 to their host plant and, in N2‐fixing mode, certain bean cultivars can meet their genetic yield potential in the field without the addition of fertilizer N.
Dinitrogen (N 1 ) fixation was measured for two bean cultivars, 'Aurora' and 'Kentwood', in a 2-year field experiment, at four growth stages and two levels (10 and 40 kg ha-1 ) offertilizer N, as Ca(N0 3 )z. Both 15 N isotope dilution and nodulation parameters were used to determine if nitrogenase activity at these growth stages could explain Aurora's superiority in symbiotic N 1 fixation. Nodules were actively
The commercial dry bean (Phaseolus vulgaris L) production system in Alberta requires irrigation and the viny cultivars currently used in this production system are prone to outbreaks of white mold caused by Sclerotinia sderotiorum (Lib.) de Bary. The use of beans with an upright growth habit has potential for alleviating the disease problem, but the narrow profile of the upright beans may warrant a different planting pattern to achieve high yield. A study was undertaken to determine the effect of between‐ and within‐row spacings on the occurrence of white mold and seed yield of upright beans. An experimental navy bean composite with upright growth habit, and a susceptible control Red Mexican, UI 37, were evaluated using three between‐row (BR) and three within‐row (WR) spacings in presence or absence of white mold during a 2‐year period. The BR and WR spacings had no effect (P > 0. 05) on disease occurrence in the inoculated upright composite or in the viny control. Regardless of BR and WR spacings, the upright composite had less (P < 0. 01) disease than the control in both years. In general, large differences (P < 0. 05) were found between the upright composite and control spacing treatments in the presence or absence of white mold. BR spacing had a significant effect on seed yield, but WR spacing did not. In most cases, increasing plant density by reducing BR spacings resulted in higher seed yields. These findings suggest that producers may gain in seed yield without increasing risks for white mold occurrence by changing from viny to upright beans and planting in narrower rows.
The effects of low temperatures on several growth phases of the tomato were studied. The tests, each conducted over a 2-week period, included seed germination at 8.5 °C, rate of seedling growth at a night temperature of 10 °C, root and top growth of plants in soil at 15 °C, and fruit set at a night temperature of 4.5 °C.Varietal response to growth rate at low temperatures differed in all phases studied, and varieties that performed well in some phases did not always perform well in others. Of the varieties studied, six grew well under most of the low-temperature conditions. These were: Earlinorth, Bonita, Azerbidzivisky, P.I. 205040, P.I. 280597, and Cold Set.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.