Rhizobiuminoculation of lucerne (Medicago sativaL.)

Abstract

l1he Rhizobium content af cammercial inaculant;; has been increased since the time these preparatians were intraduced to' replace the formerly used agar cultures.Regardless of the presence of ather arganisms, the powder inaculants now in use are effective in lucerne nodulation and nitrogen fixaJtion.NO' benefit was demonstrated in favour af disinfectian af lucerne seed priar to' inoculatian, while in seed pelleted with lime there was a decline in the survival of rhizabia aver a 3-months' periad.In a number of soils where lucerne establishment in the past has failed it has been shawn that indigenous lucerne rhizabia (Rhizobium meliloti) were absent ar ineffective, in sharp cantrast with the abundance and nodulation efficacy af Rhizobium trifolii an subterranean claver. In some of these soils lucerne was established by the inaculation of seed with effective rhizabia, aided by raising the sail pH with lime applicatians and ~he use af inaculated seed, pelle ted with lime ar magnesium.Among seven varieties af lucerne different responses were obtained to' inoculatian wi~ single strains of R. meliloti, but the use af multistrain commercial cultures achieved satisfactary nodulatian and grawth of ~hese varieties.

The production and utilization of lucerne in New Zealand

“…High viable rhizobia counts in inoculants have not always led to satisfactory counts on inoculated seed (Parle el al., 1973) and where sowing conditions are unfavourable or where inoculated seed has been kept too long before sowing, nodulation failures have occurred (Blair, 1971). In a survey in 1971, Blair (1971) found 65% of 119 new luceme stands had poor or non-existent nodulation with most nodulation failures attributable to low soil pH conditions at the time of sowing. Whereas luceme seedlings may establish successfully in a soil with a pH of below 6 0, a pH threshold of 6-5 is needed to achieve good Rhizobium meliloti nodulation (Blair, 1967(Blair, , 1971.…”

“…In a survey in 1971, Blair (1971) found 65% of 119 new luceme stands had poor or non-existent nodulation with most nodulation failures attributable to low soil pH conditions at the time of sowing. Whereas luceme seedlings may establish successfully in a soil with a pH of below 6 0, a pH threshold of 6-5 is needed to achieve good Rhizobium meliloti nodulation (Blair, 1967(Blair, , 1971. Below this pH level survival of Rhizobium on seed can be greatly enhanced by seed pelleting (Hastings and Drake, 1960;Taylor and Lloyd, 1968) and nodulation of luceme markedly improved by using pelleted inoculated seed (White, 1967).…”

Studies onRhizobiumstrains

“…There was evidence enough again, as has been shown in previous work (Blair and Bennett 1960), of a measure of specificity, as for example in Table I where the strain 3DOa6 was relatively inferior on Marlborough lucerne but more effective on Rambler and Glutinosa. Primary inoculation of creeping lucernes can be expected to succeed with standard effective strains, and it seems of little practical consequence that some strains may react in a differential manner in a lucerne variety like Glutinosa.…”

“…It has already been established that some varieties of lucerne do not react equally to rhizobia of anyone specific physiological strain (Burton and Wilson 1939;Blair and Bennett 1960). The current work under report has been concerned with a restricted objective of appraismg the sensitivity or otherwise of the Glutinosa variety (Medicago R/utinosa) to strains of Rhizobium meliloti.…”