CROSS-BRED MAIZE.

New Zealand Herald, Volume LXVI, Issue 20420, 23 November 1929, Page 22

CROSS-BRED MAIZE.

[MAINTAINING PRODUCTIVITY

REMARKABLE' RESULTS.

[ LESSON FOR NEW ZEALAND.

SI atze growers 111 the Bay of Plenty. Ihe Horthcrn Peninsula, Poverty Bay and elsewhere will bo interested in a report issued from the Connecticut Agricultural Experimental Station at Stors and Mount Carniol. This report states that while pure strains in horses, cattle and poultry are, deemed to produce ihe highest results, with the mule as an exception in ths equine class, it would appear that plants require constant refreshment if their, productivity is to be maintained. This seems to be peculiarly the case with maize.

As much as 116 bushels of shelled maize per acre has been the yield from hybridising what is known as the D. C. BurrLearning variety, " double crossed." In five years' average the yield was fourteen bushels of shelled maize per acre above that of the best varieties grown 011 uncontaminated stalks. Some of the results of cross-breeding sweet maize are remarkable. A cross of two inbred

strains grown for canning purposes yielded six tons of cars per acre, as against three and one-half tons produced from standard evergreen seed without cross-fertilisation.

One curious development, of the experiment was the fact that " nubbins " brought forth just as fine, full ears as the most carefully selected varieties, after hybridisation. Weak, spindling stalks when crossed by dwarfs grew tall and vigorous. The report observes: — v Multiplying Good Qualities.

"When an inbred strain is crossed with Another strain from the same or different variety, there is a very great increase m size and yield 'in the next, generation. . . . due. apparently, to the fact that the good qualities of both parents are expressed in the offspring, while the weak qualities are covered over for the time being. . . .

,What one parent lacks is supplied by the other, and conversely. Hybrid vigour seems to be a wise provision on the part of Xatura to enable the offspring to make the best of a bad ancestry."

The hybrid vigour is, however, not permanent." The second-generation ears fall off about twenty per cent. The uplift of crossbreeding must therefore bo an annual. affair, but the results are so substantial that extra cost of seed and trouble is well invested.

To further quo'.e the report: —" He who invents a new machine or a new process of manufacturing can patent his product and reap a reward for Lis industry and inventiveness. The originator of a new and improved plant or animal ordinarily loses,control of his product as soon as he sells his first seeds or breeding stock.

" With crossed corn the situation is entirely changed. The seed that is sold is used to produce a superior crop of corn, but this in turn cannot be used for further planting, and the only way the same' result can be secured is to obtain se?d from the original producer each year. This is an advantage that will result beneficially to both the seedsman and the one who plants the seeds. This will stimulate the production of better kinds of corn as nothing else has ever done. Larger crops of better corn will be harvested on the same acreage and with the same labour."

Method of Cross Fertilising. The methods employed afc the stations for cross fertilising are simple and interesting. A three-pound paper sack is placed over the ear shoot as soon as it nppears and before any silks are showing. The bag is slipped over the ear shoot and is held in place with a wire clip. At the same time; or a day or two later, nn eight-pound bag is put over the t'asse] and securely fastened around the stalk at the base of the tassel, also with a wire clip. Two or three days later, depending upon the weather, when the silks are out about three inches beyond the tip of the ear, the tassel is bent over and shaken into the tassel bag. which has been unfastened. This ,collects the fine yellow powder—the pollen—which is dusted over the silks. The small bag is replaced quickly over the ear and the larger tassel bag is put over this, thus guarding against breaks in the bags, which will let in pollen from outride. The bags are left on until the ears are gathered in order to mark them.

How to Pollinate, Pollination tan only he done when the hags are dry. Wet. weather or heavy dew. Which causes the pollen to clump together, renders it unfit for use. Only a very small quantity of good pollen is needed, and (his should be applied as rtCon as possible after the silks appear. Care is taken to avoid touchir.g the Bilks with the hands, and also nearby plants are pushed awav so that their pollen will not fall 011 the silks. Hand in this way insures that the ears are fertilised with pollen from the same plant. This is the closest kind of inbreeding and will have very noticeable effects on the resulting progeny.

At the stations the method of obtaining good inbred strains is as follows: A variety is chosen which has been thoroughly tested and is known to be well adapted-to the purposes to which it is to be put. A large number of the best cars of this variety are selected and seed from each ear is planted in a separate row in the field. About 20 to 30 plants are grown in each row. When the plants are ready to silk out, five of the best plants are self-pollinated. The two separate strains of corn must tie maintained free from mixing with each other or any other kind of corn, and these two types must be planted in alternating, rows and all the plants of one of them detasseled before pollen is shed. The seed produced on these castrated plants is used for planting to produced crossed corn.