Research Of Ecological Physiological Characteristics Of Different Pecan Varieties

Recently, the pecan have developed rapidly in China due to its high nutrition and economic value.The pecan didn’t spread on a large scale and acquired high yields because of lack of feasiblecultivation and management techniques. And one crucial technique is the choice about the varieties’quality. Based on understanding the difference among the pecan varieties, this paper can rich itsadvanced species and provide scientific evidence for the further promotion. The fourteen naturalbiennial seedlings such as Moneymaker、Chickasaw、Choctaw、Caddo、Mohawk、Kiowa、Woodard、Farley、Colby、Shoshoni、Barton、Melrose、Cheyenne、Mandan and six natural triennial seedlingssuch as Excell、Summer、Desirable、Elliot、Pawnee、Schley are taken as the object of the study. Thisstudy will test their growth index, photosynthetic physiological parameters, chlorophyll fluorescenceparameters and pigment content.The result indicate:1. The difference of growth index among the twenty pecan varietiesFourteen kinds of biennial pecan varieties have significant difference on their growth of height,ground diameter, diameter at breast height, leaf length and leaf width. The height of Moneymaker isthe fastest-growing one while its other indexes also grow quickly. Six kinds of triennial varieties haveno significant difference on their growth indexes in May. In October, the height indexes of theseedlings show obvious difference, in which Summer is the fastest-growing one and Elliot is thesecond.2. The difference of photosynthetic physiological parameters among the twenty pecan varietiesIn the fourteen kinds of biennial seedlings, Moneymaker and Chickasaw both show higherphotosynthetic efficiency and greater use of solar energy; Chickasaw and Kiowa have strong ability toutilize low light, and can better adapt to low light conditions. Elliot’s Amaxis higher than other fivespecies, which shows higher light use efficiency. Its dark reaction capability is also stronger and showgood adaptability on the low light conditions.3. The difference of chlorophyll fluorescence parameters among the twenty pecan varietiesMohawk and Kiowa can well balance between the two optical systems, and the electron transferrate is also faster. Caddo shows strong electron transfer ability and good growth on October. In the sixkinds of triennial seedlings, Elliot has the higher Fv/2, Fv/Fm, Fv/Fo, Yieldand Fm’ except for the lowest NPQ. It is showed that Elliot has stronger activity of PSⅡ reaction center, higher actual photochemicalefficiency and better photosynthetic performance.4. The difference of pigment content among the twenty pecan varietiesIn the fourteen kinds of biennial pecan varieties, Melrose has the highest pigment content. Andthe whole seedlings’ pigment content is decreased to a certain extent in October. The content ofchlorophyll a, chlorophyll b and carotenoids in Barton are the highes. In the six kinds of triennialpecan varieties, about the pigment content side, Desirable as the king is considerable more than Excell.Schley’s changed less whose content is the lowest in May, but it is just inferior to Desirable’s inOctober. Compared with May, Excell’s content of chlorophyll a, chlorophyll b and carotenoids is thelowest in October.