EARLY LUCERNE GROWTH

Press, Volume XCVI, Issue 28471, 28 December 1957, Page 13

EARLY LUCERNE GROWTH

Role Of Seed Coat In Inoculation

To ensure satisfactory inoculation of lucerne seedlings it may not be just a simple matter of securing efficient adhesion of the inoculant to the seed. This is indicated by experiments being carried out by the Department of Agriculture in Christchurch. In pot trials the department is comparing the progress of plants grown from seed, which has had part of its seed coat removed, with seed which has its coat intact. All the seed which was sown in the pots at the end of October came from the same line of certified Marlborough lucerne. Results up till eacly December were quite striking. The seedlings grown from the seed with its coat partly removed were strong and healthy and on the average about three inches high whereas the other seedlings looked stunted and were not more than an inch high. Removal of the seed coat has, however, reduced germination.

Mr W. R. Lobb, assistant fields superintendent of the Department ( of Agriculture in Christchurch, ( said that it was not known . whether the removal of the seed j coat had removed an inhibiting J factor which operated against the ] effective inoculation of the seed- ( ling or whether it had allowed the j bacteria to. enter the seed germ at j an earlier stage in the germina- . tion. Certainly he said the removal < of the seed coat did seem to have f had some effect. ( The bulk of the seed used in 1 the experiment was sown with an • inoculant but one seedling grown ( from a seed which had part of its coat removed but which was not given an inoculant is now growing well. Mr Lobb said that this ; did not, however, indicate that : where the coat was removed it ; might be possible to dispense with J an inoculant. This might only be shown where the seed had been sterilised. i Pelletting Of Seed Mr Lobb said that the results had almost duplicated the effects , obtained when seed pelletted with ; lime and charcoal had been used 1 in pot trials. Both lime and charcoal had proved equally effective in stimulatirig early clover growth when pelletted with an inoculant and seed. The experiments in which part of the seed coat has been removed have been prompted by the work of E. R. Turner at the Rothamstead experimental station in England. His work indicated that the addition of charcoal to the rooting medium of clover plants increased the efficiency of inoculation. Several explanations for this were possible, but from his work .he concluded that the stimulatiblf Uas due to the absorption by charcoal of inhibiting compounds secreted by the roots of clover plants. In confirming this he found that exudate collected from the charcoal and which had been absorbed from the germinating medium could be used to detrimentally effect nodule production. Mr Lobb suggested that it was possible that lime charcoal and skim milk; formerly widely used for attaching inoculant to lucerne seed, might all act as counters to the inhibiting characteristics of the seed coat to inoculation. Seeds scarified to varying degrees have now been planted in another series of pots. Field Trials Results obtained in pot trials using lime and charcoal pelletted clover seed had been difficult to duplicate in the field, said Mr Lobb, but a recent experiment in the Waimate district indicated that similar results might be obtained with lucerne in certain circumstances. The trial, he said, had showed a marked beneficial effect where the seed had been pelletted, irrespective of whether it had been sown with an inoculant. This trial is being followed by a further series of trials in the district, some of which have already been sown.