When is corn pollination

Pollen tubes can grow along the outside surface of silks, but the longer they remain on the outside, the greater their vulnerability to dehydration and death.

Silks have a waxy cuticle just like other plant parts, and pollen tubes may not be able to go through the cuticle. Fortunately, there are breaks in the cuticle especially on the hairs.

Pollen tubes usually find places to enter the silks and begin elongating down the inside of the silks. There are pathways within silks that help direct the elongating pollen tubes.

It is possible for more than one pollen tube to enter a silk, but only one pollen tube will grow down the entire length of the silk and enter the ovule for fertilization. The water to drive pollen tube elongation comes from the silk. It takes about 24 hours for the pollen tube to grow the entire silk length and if the silk loses water during that time the pollen tube may not complete its journey. One common result of reduced water status is a collapse of the silk near the ovary.

If this happens, pollen tube growth is prevented. Anything that prevents the pollen tube from entering the ovule will prevent fertilization and a kernel will not form Figures 4, 5, 6. Three nuclei plural of nucleus move from the pollen grain and into the pollen tube. One of the three nuclei directs pollen tube growth and will be not involved in fertilization. The other two nuclei travel down the pollen tube and enter into the ovule once the pollen tube completes its journey.

One male nucleus combines with the female gamete to form the embryo within the kernel. The other male gamete joins with two female nuclei to form the endosperm of the kernel. These two events are called double fertilization and are required for the kernel to form and begin growth.

A day or two after fertilization occurs, the silk separates from the kernel and changes color as it dries. Corn is an amazingly productive plant. One kernel planted returns kernels at harvest. Its unique reproductive characteristics have allowed for an efficient and profitable breeding industry to develop. Lack of precipitation affected silk elongation and the ability of pollen tubes to grow through the entire length of the silk.

High air temperatures may have had some direct effects on pollen viability, but the primary effect of temperature was increased water evaporation that accentuated the problems related to scarce water availability. An aerobiological framework for assessing cross-pollination in maize.

Agricultural and Forrest Meteorology Nielsen, RL Bob. Reproduction at low silk and pollen water potentials in maize. Crop Sci. All rights reserved. DMCA and other copyright information. Figure 1. Pollen grains are borne in anthers, each of which contains a large number of pollen grains. The anthers open and the pollen grains pour out in early to mid morning after dew has dried off the tassels.

Pollen is light and is often carried considerable distances by the wind. However, most of it settles within 20 to 50 feet. Pollen shed is not a continuous process.

It stops when the tassel is too wet or too dry and begins again when temperature conditions are favorable. Pollen stands little chance of being washed off the silks during a rainstorm as little to none is shed when the tassel is wet.

Also, silks are covered with fine, sticky hairs, which serve to catch and anchor pollen grains. Under favorable conditions, pollen grain remains viable for only 18 to 24 hours. Pollen shed begins in the middle of the central spike of the tassel and spreads out later over the whole tassel with the lower branches last to shed pollen. Pollen grains are borne in anthers, each of which contains a large number of pollen grains.

The anthers open and the pollen grains pour out in early to mid- morning after dew has dried off the tassels. Pollen is light and is often carried considerable distances by the wind. However, most of it settles within 20 to 50 feet. Pollen shed is not a continuous process. Pollen from the tassels needs to land on the silks in order to create a good crop. Tassels emerge from the top of the corn plant, then open to disperse pollen on the silks which emerge lower, from the immature corn ear.

Each individual silk is a potential kernel of corn, so if a silk doesn't receive a grain of pollen, no kernel will form in that space on the ear, creating an empty space or "skip". Under ideal conditions, both the tassels and silks emerge at the same time, a synchronicity called "nick".