| The two cotton genotypes(103,122) used in the study were screened by the authors' research group from 86 cotton cultivars according to their potassium (K) efficiency during 2001 to 2006.Based on the former study by our research group, the differences of K uptake efficiency and K use efficiency between the two cotton genotypes were studied by root box, water culture, and grafting experiment from 2007 to 2009.The study was conducted from the following 3 aspects:differences of K use efficiency and K uptake efficiency between the two cotton genotypes were studied by root box, and differences of the uptake mechnisms were studied by the water culture, and then to make clear the main difference between the 2 cotton genotypes, the grafting experiment was conducted. The main results were as follows:1.Differences of dynamical growth were existed between the 2 cotton genotypes. Contrary to the low K efficiency genotype 122, the leaves number and plants height of the high K efficiency genotype 103 grew slower after entering the flowering and belling stage, which could show the high K efficiency genotype 103 enter the reproductive growth more earlier than the low K efficiency genotype 122.The initial time of the bolling stage of 103 was eralier than that of 122, and the bolls number were more than 122.It was found that leaves number, squares number and bolls number were much related with the traits of the scion, and plants height was much related with the stock.2.Significant differences of biomass and dry matter weight partition were existed between the 2 cotton genotypes. Whether applied K or not, the whole plant weight of 103 was heavier than that of 122 which shows that 103 can store more nutrient than 122.Root shoot ratio (R/S) of 122 was higher than 103,but when considered the whole plant weight, 103 produced more biomass than 122 with less root, which shows that the root vigor of 103 was more stronger than 122.The dry matter weight of roots, stems and leaves to the whole plant weight ratio of 122 was 70% and 58% at applied K treatment and no K treatment respectively, while the dry matter weight of bells and seed cotton to the whole plant weight ratio was 19% and 25% at applied K treatment and no K treatment respectively. The dry matter weight of roots, stems and leaves to the whole plant weight ratio of 103 was 54% and 54% at applied K treatment and no K treatment respectively, while the dry matter weight of bells and seed cotton to the whole plant weight ratio was 40% and 39% at applied K treatment and no K treatment respectively. As vegetative growth to reproductive growth ratio (V/R), it were higher of 122 than that of 103 whether applied K or not, it was to say that 122 prone to vegetative growth and could not transport dry matter and nutrients to the reproductive organs. The results of the biomass and the partition of dry matter through grafting was according to the above. R/S and V/R of 122 were still bigger than that of 103 whether 122 as stock or scion.3.Differences of yield and harvest index(HI) were existed between the 2 cotton genotypes. The seed cotton weight of 103 were heavier than that of 122,103 increased 136.2% than 122 when applied K, and increased 71.9% when no K treatment. Through grafting, when the stocks were same, the yield of 103 as scion was higher than 122 as scion. When the scions were same, the 2 cotton genotypes as stock have different shows at different K teratments.Yield of 122 as stock was higher than 103 as stock when applied K, while it was on the contrary when at no K teratment which shows that 103 can live better at little K condition. The HI of 103 was higher than that of 122 whether applied K or not, and HI of 103 was 17.2% and 2.5% higher than that of 122 at applied K treatment and no K treatment respectively. At applied K treatments, when the stocks were same, HI of 103 as scion was higher than that of 122 as scion; when the scion were same, HI of 122 as stock was higher than that of 103 as stock, which shows that 103 is opt for as scion and 122 opt for as stock at applied K teratments.4. Differences of K use index (KUI) were existed between the 2 cotton genotypes. KUI of 103 were higher than that of 122 whether applied K or not, KUI of 103 were 9.1% and 14.1% higher than that of 122 at applied K treatment and no K treatment respectively. At applied K treatments, when the stocks were same, KUI of 103 as scion was higher than 122 as scion, KUI of 103/103 was ranked as the top first 21.5%, KUI of 122/103 was at the last 17.6%.when the scion were same, KUI of 122 as stock was higher than that of 103 as stock at applied K treatments. At no K treatments, when the scion were same, KUI of 103 as stock was higher than that of 122 as stock.5.Differences of root morphology, bleeding sap and uptake kinetics were existed between the 2 cotton genotypes.Root morphology parameters of 122 were better than that of 103 at applied K treatment, root morphology parameters of 103 except total root number were higher than that of 122 at no K teratment, but there were no significant difference. Bleeding sap of 103 was much more than that of 122 at no K teratment, which shows that 103 has stronger vigor of uptaking water and nutrients at no K condition. Imax,Km and Cmin of 122 were higher than that of 103.6.Difference of amounts of K accumulation were existed between the 2 cotton genotypes, but there was no significant difference. Amounts of K accumulation of 103 were higher than that of 122 whether applied K or not, there was no significant difference at no K treatments. Through grafting, at applied K treatments, amounts of K accumulation of 122 as stock was higher than that of 103 as stock at applied K treatments. While at no K teratment, amounts of K accumulation of 103 as stock were higher than that of 122, which also shows that 103 is opt for as scion and 122 opt for as stock at applied K teratments, and 103 as stock was better than 122 at no K treatment. We also found that amounts of K accumulation were much related with root, and was influenced by the shoot at the same time. |
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