As to tetraploid and diploid that refers to how many chromsome pairs they have . So ask the breeder when buying them is it 3N(tetraploid) and 2N(diploid) OR 4N(quadraploid)
No one has yet crossed Kwanzo day lillies with other types in fact I know of no one who has grown it from seed . I do not believe you can cross the easter lillies with day lillies . But try anyways, just do mot get your hopes up.

You can cross a diploid with a tetraploid. They say it's best use the dip as a seed parent if you do. What you will get will be a triploid.

The reason you may not want to do so is that triploids are generally sterile, and it is rare to get viable pollen from them. It's often accepted as a dead end to a breeding program, unless someone is really looking to break some odds.

As Farmfreedom pointed out, the best way to tell the difference between a diploid, triploid, or a tetraploid is to ask the seller, or maybe ask for some examples of each from the daylily forum, and which ones they recommend for hybridizing. (the link is at the bottom)

I also have a link to a daylily database that shows the heritage of many daylily introductions. If you are looking to hybridize daylilies, it will show you which plants produce seedlings that have been introduced and whether they are tet, trip or dip. Also note that it is possible to convert a plant from tet to dip - they are called tet. conversions.

Tinker's Garden Database

http://db.tinkersgardens.com/?script=3.1

You can't cross daylilies (hemerocallis) and regular lilies (lilium). They are too distantly related, and again, as Farmfreedom pointed out, no one has yet to be successful.

Also, here is the FAQ section from the American Hemerocallis Society, which may have some information that may interest you.

AHS Daylily FAQ

http://www.daylilies.org/AHSfaq1.html

Good luck & enjoy

Here is a link that might be useful: Daylily Forum

"Also note that it is possible to convert a plant from tet to dip - they are called tet. conversions."

That's quite the typo! Sorry!

Tet conversions start out as diploids and are turned into tetraploids.

You can create haploids from diploids with Tissue Culture techniques, so it could be possible to create diploids from tetraploids by the same TC process.

ZM

Hemerocallis 'Kwanso' does not set seed because the flowers have no ovary. I once saw some of the flowers with what looked like attempts at styles, but the plants were growing in a public garden so I could not experiment with them.
http://www.bulbnrose.org/Heredity/FreakyFlowers/Freaky_flowers.html

It has been shown that plants can be forced to reduce their chromosome count (e.g., tetraploid to diploid) by treating the cells with caffeine.

Fundamental and Molecular Mechanisms of Mutagenesis, Vol. 452 (1) (2000) pp. 67-72
Inducing somatic meiosis-like reduction at high frequency by caffeine in root-tip cells of Vicia faba

Yihua Chen, Lihua Zhang, Yihua Zhou, Yuxuan Geng and Zhenghua Chen *zhchen@public.east.cn.net
Institute of Genetics, Chinese Academy of Sciences, Beijing 100101, People's Republic of China

Abstract
Germinated seeds of Vicia faba were treated in caffeine solutions of different concentration for different durations to establish the inducing system of somatic meiosis-like reduction. The highest frequency of somatic meiosis-like reduction could reach up to 54.0% by treating the root tips in 70 mmol/l caffeine solution for 2 h and restoring for 24 h. Two types of somatic meiosis-like reduction were observed. One was reductional grouping, in which the chromosomes in a cell usually separated into two groups, and the role of spindle fibers did not show. The other type was somatic meiosis, which was analogous to meiosis presenting in gametogenesis, and chromosome paring and chiasmata were visualized.

Journal of Agricultural Biothechnology, 2000, 8(2): 147~150
Somatic Meiosis-like Reduction Induced at High Frequency by Nucleotide Analogues in Vicia faba
Zhang Lihua, Chen Yihua, Chen Zhenghua
(Institute of Genetics, Chinese Academy of Sciences, Beijing 100101 )

Abstract: Root tip cells of Vicia faba were treated by caffeine and uracil to induce high frequency of somatic meiosis-like reduction. Optimum treatments including the concentration of the chemicals and the time of restoration were screened out. The highest frequency of somatic meiosis-like reduction approached up to 54.0% and 35.7% for caffeine and uracil treatment respectively. The process of somatic meiosis-like reduction was observed, which existed in two types. One was chromosome reductional grouping, in which chromosomes in a cell usually separated into two groups without the role of spindle fibers. The other type was somatic meiosis, which was analogous to meiosis in gamatogenesis and characterized by pairing and chiasmata of chromosomes. Establishment of this inducing system has a profound meaning in the study of producing haploid cells as well as in cell engineering breeding.

Acta Hort. (ISHS) 300:377-380
Blando, F., Giorgetti, L., Tonelli, M.G. and Nuti Ronchi, V. 1992.
CYTOLOGYCAL CHARACTERIZATION OF CELL SUSPENSION CULTURES OF FRUIT TREES.
http://www.actahort.org/books/300/300_56.htm

Abstract: Using a new suitable method to initiate a cell suspension culture in apple (Malus x domestica Borkh.) and quince (Cydonia oblonga Mill.), it has been possible to detect some cytological mechanisms of chromosome reduction, firstly reported in carrot cell cultures (Nuti Ronchi, 1990; Nuti Ronchi et al., 1990). These segregational events, namely somatic-meiosis and prophase-reduction, are present in all analysed cultures, haploid metaphases (n=17) being 3.2% in apple lines. The importance and role of these phenomena in cell cultures of different non-embryogenic species are discussed in comparison with the carrot cell culture model.

I haven't tried the caffeine treatment, but it sure would be safer than playing with colchicine, and just as useful. It would be interesting to see whether the "braided" petal trait found in many tetraploid daylilies might be expressed in diploids derived from them.
Karl

Here is a link that might be useful: CybeRose & Bulbs