[Effects of planting density and spraying PP333 on winter wheat lodging-resistance and grain yield]

Taking two winter wheat varieties Gaocheng 8901 and Yannong 21 with different end-use qualities as test objects, a field experiment was conducted in the experimental farm of Shandong Agricultural University from 2008 to 2010, aimed to study the effects of different planting density and spraying PP333 on the basal stem morphological characteristics, snapping-resistance, lodging-resistant index, and grain yield. Gaocheng 8901 had higher lodging-resistance but lower grain yield than Yannong 21. Comparing with low planting density (180 x 10(4) basic seedlings per hm2), high planting density (240 x 10(4) basic seedlings per hm2) decreased the culm snapping-resistance and lodging-resistant index of the two varieties, especially Yannong 21. Spraying PP333 decreased the plant height and the basal internodes length, increased the snapping-resistance and lodging-resistant index, strengthened the lodging-resistance, and improved the spike number and grain yield. Correlation analysis showed that the second internode length, percentage of basal internodes (1 + 2) length to total internode length, and apparent lodging ratio were significantly negatively correlated with culm lodging resistant index. Therefore, to adopt an appropriate planting density combined with spraying PP333 could improve the lodging-resistance of winter wheat and its grain yield, being an important high-yielding cultivation technique for wheat production in sub-humid zone.