棉株果枝部位、温光复合因子及施氮量对纤维伸长的影响

Effects of Fruiting Branch Position,Temperature-light Factors and Nitrogen Rates on Cotton(Gossypium hirsutum L.)Fiber Elongation

以杂交棉(科棉1号)和常规棉(美棉33B)品种为材料,设置异地分期播种和施氮量试验,使棉株不同果枝部位棉铃处于相同环境条件下或相同果枝部位棉铃处于不同环境条件下,研究棉株果枝部位、温光复合因子及施氮量对纤维伸长的影响。结果表明,在相同环境条件下,棉株中部果枝铃的纤维长度虽稍高于其他部位,但纤维伸长动态变化及最终纤维长度在不同果枝部位间的差异均未达显著水平。棉纤维伸长发育期的累积辐热积PTP可综合温光复合因子的效应,其与棉纤维最大伸长速率Vmax呈极显著线性正相关,与纤维快速伸长持续期T呈极显著线性负相关,与棉纤维长度理论最大值Lenm呈二次曲线函数关系,可以作为表征棉纤维伸长发育温光复合因子的指标。当棉纤维伸长发育期内PTP在335MJ m-2左右时,Lenm最大(科棉1号、美棉33B分别为30.94、30.31mm),Vmax在1.3mm d-1左右,T在16d左右。氮素水平与温光复合因子对纤维长度的影响存在补偿效应,随施氮量的增加,棉纤维长度达到最大值时对应的PTP减小。当棉纤维伸长发育期内PTP达到240MJ m-2时(科棉1号、美棉33B分别为237.6、241.6MJ m-2),240kg N hm-2施氮量下的棉铃对位叶叶氮浓度(NA)更适宜棉纤维伸长;PTP低于此值时,增加施氮量(480kg N hm-2)可减小因累积辐热积降低而造成的棉纤维长度缩短的幅度。

Cotton fiber length is one of the important criteria of cotton quality,and fiber elongation is influenced by many factors.To study effect of fruiting-branch position,temperature-light factor and nitrogen rates on dynamic changes of cotton fiber length,we carried out the field experiments in Nanjing（118°50’E,32°02’N,middle lower reaches of Yangtze River Valley）and Xuzhou （117°11’E,34°15’N,Yellow River Valley）.Cotton cultivars of Kemian 1 and NuCOTN 33B were used.Two sowing dates and three nitrogen application levels were applied,thus cotton fiber developing process can be arranged at different fruiting-branch position and ecological conditions.The results showed that cotton bolls developed in the middle-branch position produced longer fiber than that in lower-and upper-branch positions,but the dynamic changes of fiber length were not significant among different fruiting branches.PTP can be an indicator assessing temperature-light effect during cotton fiber elongation period.The maximum elongation rate（Vmax）and duration of fiber speedy elongation period（T）were linearly corelated with PTP,while the theoretical maximum of cotton fiber length（Lenm）was quadratic with PTP.The longest Lenm（30.94 and 30.31 mm for Kemian 1 and NuCOTN 33B,respectively）was obtained at PTP of 335 MJ m-2 in cotton fiber elongation period（333.3 and 337.9 MJ m-2 for Ke-mian 1 and NuCOTN 33B,respectively）,when Vmax was 1.3 mm d-1and T was 16 d.There exists an interaction between N fertilization and PTP on fiber elongation.As N fertilization increased,values of PTP for obtaining the longest Lenm decreased.And when PTP was greater than 240 MJ m-2（237.6 and 241.6 MJ m-2 for Kemian 1 and NuCOTN 33B,respectively）,NA under 240kg N ha-1 was more suitable for the elongation of cotton fiber;while PTP was less than that value,NA under 480 kg N ha-1 was more appropriate.