Assessment of co-inoculation of Bradyrhizobium Japonicum and Bacillus subtilis on yield and metabolic profile of Bambara groundnut and cowpea under glasshouse conditions

Abstract

Bambara groundnut and cowpea are essential legumes that are well adapted to unfavourable environmental conditions and have high dietary values for humans. However, they are under-researched and under-utilised. Thus, there are limited records on yields and metabolic profiling of these leguminous crops co-inoculated with B. japonicum and Bacillus subtilis. Generally, very few studies have reported on the effects of co-inoculation of other plant growth-promoting rhizobacteria and rhizobia strains on leguminous plants. This study therefore assessed the effects of B. subtilis (strain BD233) on germination of Bambara groundnut under different temperature regimes, and evaluated the effects of co-inoculation of B. japonicum and B. subtilis on yields of cowpea under glasshouse conditions. The study also assessed the metabolite profile of the crops using 1H nuclear magnetic resonance (NMR) spectroscopy. The data showed that inoculation of Bacillus subtilis on Bambara groundnut landraces under different temperatures enhanced germination (germination percentage, germination rate indices and plumule length). Furthermore, co-inoculation with B. japonicum and Bacillus subtilis (strain BD233) improved plant yield of cowpea plants. Partial least squares-discriminant analysis (PLS-DA) revealed distinct separations between treatments (co-inoculation of B. japonicum and Bacillus subtilis, inoculation of B. japonicum, uninoculated plus NO3 and zero inoculation) on Bambara groundnut and cowpea plants. The VIP score revealed that co-inoculation with B. japonicum and Bacillus subtilis (strain BD233) resulted in low concentrations of metabolites in Bambara groundnut plants and in contrast, high concentrations of metabolites in cowpea plants. Co-inoculation with B. japonicum and Bacillus subtilis (strain BD233) has a potential of improving yield of both Bambara groundnut and cowpea in sustainable agriculture. The metabolic profile of Bambara groundnut and cowpea subjected to co-inoculation has shown that both crops metabolic composition and profile are highly dependent on co-inoculation.

Phonda na ṋawa ndi mangaṋawa a ndeme ane a kona u tea zwavhuḓi kha nyimele dza vhupo vhune ha si vhe havhuḓi na ndeme ya nṱha ya pfushi kha vhathu. Naho zwo ralo, a hu athu u itwa ṱhoḓisiso dzo linganaho nga hadzo na u sa shumiswa Nga zwenezwo hu na rekhodo dzo pimiwaho nga ha khaṋo na u ela tshileme tsha molekulu ṱhukhu dza methaboḽiki dza zwiliṅwa izwi zwa mangaṋawa u khetha na B. japonicum na Bacillus subtilis. Nga u angaredza, ndi ngudo dzi si nngana dzo no vhigwaho nga ha masiandaitwa a khetha nyaluwo ya zwimela zwine zwa ṱuṱuwedza bakitheria dzine dza baḓekanywa na midzi na bakitheria dzine dza shandukisa naiṱirodzheni u vha amonia kha zwimela zwa mangaṋawa. Ngudo heyi nga zwenezwo yo asesa masiandaitwa a B. subtilis (tshiliṅwa tsha BD233) kha mumelo wa phonda nga fhasi ha ndaulo ya thempheretsha dzo fhambanaho, na u ela masiandaitwa a u khetha B. japonicum na B. subtilis kha khaṋo dza phonda na ṋawa nga fhasi ha nyimele ya fhethu hune ha ṱavhiwa zwimela nga fhasi ha tsireledzo kana ndangulo. Ngudo dzo dovha dza ela tshileme tsha molekulu ṱhukhu dza methaboḽiki dza zwiliṅwa hu tshi shumiswa 1H maanḓa a u tzwonzwiwa ha nyukiḽia nga eḽekiṱhironiki maginethe (NMR) nga u ṱanganelana ha radiesheni ya eḽekiṱhironiki maginethe. Data yo sumbedza u ḓivhadzwa ha Bacillus subtilis kha tshiliṅwa tshapo tsha phonda fhasi ha thempheretsha dzo fhambanaho u khwinisa mumelo (phesenthedzhi ya mumelo, zwisumbi zwa phimo ya muelo na vhulapfu ha pulumule). U isa phanḓa, u ḓivhadzwa hafhu ha B. japonicum na Bacillus subtilis (tshiliṅwa tsha BD233) khaṋo yo khwiniswaho ya tshiliṅwa kha zwimela zwa ṋawa. Musaukanyo wa u khethekanya zwitatisiṱika (Partial least squares-discriminant analysis) (PLS-DA) wo sumbedza khethekanyo dzo fhambanaho vhukati ha kushumisele (u ḓivhadzwa hafhu ha B.japonicum na Bacillus subtilis, u ḓivhadzwa ha B. japonicum, i songo ḓivhadzwaho hafhu na NO3 na ziro i songo ḓivhadzwa hafhu) kha phonda na zwiliṅwa zwa ṋawa. Tshikoro tsha VIP tsho wanulusa uri u ḓivhadzwa hafhu ha B. japonicum na Bacillus subtilis (kha tshiliṅwa tsha BD233) zwo bveledza mutzwonzwo wa fhasi wa methobolaithisi kha zwiliṅwa zwa phonda na phambano, ya mutzwonzwo wa nṱha wa methobolaithisi kha zwiliṅwa zwa ṋawa. U khetha ha B. japonicum na Bacillus subtilis (kha tshiliṅwa tsha BD233) zwo vha na ndeme ya u khwinisa khaṋo ya vhuvhili hazwo phonda na ṋawa kha vhulimi vhu sa nyeṱhi. U ela tshileme tsha molekulu ṱhukhu dza methaboḽiki dza phonda na ṋawa tenda u ḓivhadzwa hafhu ho sumbedza uri vhuvhili ha kubveledzele kwa methaboḽiki ya zwiliṅwa na muelo zwo ḓitika nga maanḓa nga u khetha.

Ditloo tša Bambara ke dipeu tše bohlokwa tšeo di kgonago go phela gabotse go maemo a tikologo yeo e sego ya loka e bile di na le boleng bja godimo bja dijo tšeo di lekanego go batho. Le ge go le bjalo, gona le dinyakišišo tša fase ka tšona le gore ga di šomišwe kudu. Ka gona, go na le direkhoto tše dinnyane ka ga pego ya mehola le tšhomišo ya yona ka ga dibjalo tše tša go dira dipeu tšeo di kopantšhwago le B. japonicum le Bacillus subtilis. Ka kakaretšo, dinyakišišo tše dinnyane kudu di begile ka ga dikhuetšo tša kopantšho ya mehlare e mengwe ya go huetša go gola ga pakteria ya medu (rhizobacteria) le dingangego tša pakteria ya ka gare ga medu (rhizobia) go dibjalo tša dipeu. Nyakišišo ye ka gona e lekotše dikhuetšo tša B. subtilis (strain BD233) go melo ya ditloo tša Bambara ka fase ga maemo a dithempereitšha tša go fapana, le go lekola dikhuetšo tša kopantšho ya B. japonicum le B. subtilis go mehola ya ditloo tša Bambara le dinawa ka fase ga maemo a ntlo ya digalase. Nyakišišo gape e lekotše pego ya tšhomišo ya dibjalo go šomišwa sedirišwa sa go laetša maatlakgogedi sa 1H (NMR). Tshedimošo e bontšhitše gore tsenyo ya Bacillus subtilis go ditloo tša Bambara tša tlwaelo ka fase ga dithempereitšha tša go fapana go kaonafaditše go mela (phesente ya go mela, lebelo la dikelo tša melo le botelele bja kutu ya sebjalo). Gape, kopantšho le B. japonicum le Bacillus subtilis (strain BD233) go kaonafaditše mehola ya dibjalo tša mehlare ya dinawa. Tshekatsheko ya go hwetša tswalano ya dithišu tše pedi (PLS-DS) e utollotše ditlogelano tša go fapana magareng ga mekgwa (kopantšho ya B. japonicum le Bacillus subtilis, tsenyo ya B. japonicum, yeo e sego ya tsenywa le NO3 le tsenyo ya lefeela) go ditloo tša Bambara le dibjalo tša dinawa. Dipoelo tša VIP di utollotše gore kopantšho ya B. japonicum le Bacillus subtilis (strain BD233) e tlišitše dipoelo tša fase tša ditšweletšwa tša dimolekule tša dibjalo tša ditloo tša Bambara e bile gape ge re dira phapanyo, bontšhi bjo bo lego godimo bja ditšweletšwa tša dimolekule ka go dibjalo tša dinawa. Kopantšho ya B. japonicum le Bacillus subtilis (strain BD233) e na le kgonagalo ya go kaonafatša mehola ya bobedi ditloo tša Bambara le dinawa ka go temo ya sa ruri. Seemo sa ditšweletšwa tša ditloo tša Bambara le dinawa tšeo di dirilwe kopantšho se bontšhitše gore bobedi tlhamotšweletšo le seemo sa dibjalo tše di ithekgile kudu mo go kopantšho.