| This experiment was carried out in field of Jiangpu Experiment Station of Nanjing Agriculture University with the variety of Sumian 12 from 2001.4 to 2002.11. Six kinds of exogenous regulating substances "BF-1", Sper, CC, NAA, PG, 6-BA were sprayed on early flowering and 20 days later to study effect of the six exogenous regulating substances on cotton fruiting. The results were as follows:Seedcotton yield was changed by spraying "BF-1", Sper, CC, NAA, PG, 6-BA. Seedcotton yield of bolls in hot days and early autumn were increased by PG and BF-1, that in hot days by CC and Sper; that in all time by 6-BA and NAA. At the same time yield composition factors was changed. Number of boll was increased by "BF-1", boll weight was decreased by Sper; boll weight was increased by CC, both number and weight of boll were increased by NAA, PG and 6-BA.Mechanism of cotton fruiting was changed by spraying the exogenous regulating substances. 1) Intensity of fruit retention and retained boll percentage were changed by all treatments. Those in 7-14(21) days after spraying was increased by "BF-1" and PG, those in 7-21(28) days by CC and Sper, those after 14 days by NAA and 6-BA. 2) Spatio-temporal distribution of cotton boll was changed by all treatments. The number of bolls in hot days and early autumn was increased by "BF-1" and PG, that in hot days by Sper and CC, that in hot days and autumn by NAA and 6-BA; that on lower and middle branches by "BF-1", Sper, PG and CC, that on middle and upper branches by NAA and 6-BA. 3) Dry matter accumulation in boll and boll weight were changed. Capacity of transporting nutrition from boll shell to seedcotton and dry matter accumulating intensity of seedcotton were improved by CC, NAA, PG, 6-BA, "BF-1" but Sper, boll weight on lower and middle branches was raised by "BF-1", that on every part was decreased by Sper, that on every part was raised by CC and NAA, that on middle and upper branches was increased by PG and 6-BA.Matter basis of cotton fruiting was changed. Intensity of dry matter accumulation in reproductive organ in 0-45, 0-30, 0-30, 15-75, 0-75, 15-75 days after spraying was intensified by "BF-1", Sper, CC, NAA, PG and 6-BA respectively .Partitioning ratio of dry matter in reproductive organ was increased by all treatments but Sper. Maximal LAIand time of LAI >3 were increased by all treatments but CC.Physiological activity of cotton was regulated by spraying those exogenous regulating substances. All treatments but Sper were useful to increase Chlorophyll content, ratio of nitrogen, soluble protein content ,ammo acid content, capacity of preventing oxidation, functional period, net photosynthetic rate and capacity of metabolizing photosynthetic matter of cotton leaf, capacity of metabolizing nutrition in boll shell and cotton fiber. Spraying them changed content of hormone in young boll. |
