不同种植密度对南疆机采棉叶片生理特性及产量的影响

Effect of planting density on leaf physiological characteristic and yield of machine picked cotton in Southern Xinjiang

关键词:  密度  机采棉  光合特性  荧光参数  产量

Key words:  plant density  machine picked cotton  photosynthetic characteristics  fluorescence parameters  yield

摘要:

为筛选出新疆南疆机采棉适宜的种植密度，试验采用单因子随机区组试验设计，在机采(66 cm+10 cm)一膜六行种植模式下设置9(P1)、12(P2)、15(P3)、18(P4)、21(P5)和24万株/hm²(P6)6个种植密度，以‘中棉所88号’为供试材料，测定不同种植密度处理机采棉叶片的光合特性及产量指标。结果表明:随着种植密度的增大，机采棉叶片SPAD、净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、热耗散的量子比率(F_o/F_m)、光能传递效率(F_v/F_m)、光合性能指数(PIabs)及籽棉产量均呈“先升后降”的变化，胞间CO₂浓度(C_i)则呈“先降后升”的变化趋势。叶片SPAD、P_n、T_r、G_s和F_v/F_m在盛蕾、盛花期均以P₄处理最大，但盛铃期SPAD、P_n、T_r和G_s则均在P₃处理达到峰值，F_v/F_m以P₄处理最大；F_o/F_m盛蕾期以P₃处理最大，盛花期和盛铃期以P₄处理最大；PIabs在测定生育时期内均以P₃处理最大。随种植密度的增加，棉花单株铃数显著降低，单铃重及籽棉产量均呈“先升后降”的变化，以P₅处理籽棉产量最高，为6 272.79 kg/hm²，分别较P1、P2、P3、P4和P₆处理高出28.54%、18.61%、3.87%、2.95%和12.78%，但与P3、P4处理并无显著性差异(P>0.05)。因此，综合考虑各生理指标及产量，建议南疆机采棉可适当降低种植密度，宜控制在15~18万株/hm²。

Abstract:

The aim of this study was to select suitable planting density for machine picked cotton in South Xinjiang. Cultivar ‘Zhongmiansuo 88' was applied as research material, and six planting densities 90 000(P₁), 120 000(P₂), 150 000(P₃), 180 000(P₄), 210 000(P₅)and 240 000 plants/hm²(P₆), were set in a randomized block experimental design. Different indicators of photosynthetic characteristics and yield were observed under different treatments. The results showed that: With the increase of planting density, the SPAD, P_n, T_r, G_s, F_o/F_m, F_v/F_m, PIabs and seed cotton yield of machine picked cotton displayed the trend of “first rise then fall”, while the C_i showed initially decreased and then increased trend. The SPAD, P_n, T_r, G_s and F_v/F_m of leaves were the highest in P₄ treatment at full budding and full flowering stage. The SPAD, P_n, T_r and G_s of leaves were the highest in P₃ treatment at full boll stage. The F_v/F_m was highest at P₄ treatment. The F_o/F_m was highest in P₃ treatment at full bud stage, and was highest in P₄ treatment at full flowering and full boll stage. The PIabs sustained the highest in P₃ treatment at full budding, full flowering and full boll stage. With the increase of planting density, the boll number per plant decreased significantly. The boll weight per plant and the yield of seed cotton presented a “first increase and then decrease” trend. The yield of seed cotton in P₅ treatment was the highest and reached 6 272. 79 kg/hm², which was 28. 54%, 18. 61%, 3. 87%, 2. 95% and 12. 78% higher than that of P1, P2, P3, P4 and P₆ treatment respectively. There was no significant difference with P₃ and P₄ treatment(P>0. 05). Considering the physiological indexes and yield, it was concluded that the planting density should be reduced appropriately, and the planting density should be controlled within the range from 150 000 to 180 000 plants/hm².