| In order to find out the optimal planting spacing of Jingu 21 and Zhangzagu 10 under their respective suitable planting density(Jingu 21 37.5±0.12 thousand plants /hm2 and Zhangzagu 1018.0±0.06 thousand plants /hm2),Field experiments were carried out in Dingxiang County and Taigu District,Shanxi Province.A randomized block design was adopted,and 8 treatments were set,with row spacing of 30 cm、40 cm、50 cm、 60 cm、 70 cm、 80 cm and narrow-width row spacing of 70 cm+30 cm and narrow-width row spacing of 80 cm+20 cm.The effects of different plant spacing on stem characteristics,photosynthetic characteristics,chlorophyll fluorescence,root system and yield components of foxtail millet were determined at different growth stages.The results showed that:1.In Taigu area,the leaf chlorophyll content(SPAD)of the inverted second leaf of Jinju 21 and Zhangzagu 10 was the largest in the narrow-width row mode of 80 cm+20 cm,followed by the same row spacing of 50 cm,and there was no significant difference between the two treatments.Net photosynthetic rate(Pn),transpiration rate(Tr)and leaf stomatal conductance(GS)of the two species have the same changing trends.Both reached the maximum in the mode of 80cm+20 cm in the width and narrow row,and showed significant difference from that in the mode of 70cm+30cm in the width and narrow row.In the mode of equal row spacing,they showed a trend of first rise and then decline,and reached the maximum in the mode of equal row spacing of50 cm,but there was no significant difference between the planting row spacing of 30 cm and40cm.The Intercellular CO2 concentration of the two cultivars was the lowest in the narrow-width row mode of 80 cm+20 cm,first decreased and then increased with the increase of row spacing in the same row spacing mode,and was the lowest in the same row spacing mode of 50 cm.2.In Taigu area,the photochemical quenching(q P)and Y(II)of Jinju 21 and Zhangzagu 10 increased firstly and then decreased in the same row spacing mode,and reached the maximum in the same row spacing mode of 50 cm.The results indicated that increasing the planting row spacing appropriately would improve the actual light energy conversion efficiency of leaves.The maximal fluorescence yield(Fm)and maximal quantum of PSII in the dark(Fv/Fm)of both cultivars reached the maximum under 80 cm+20 cm planting mode.The photosynthetic use efficiency of the two cultivars was the highest at this time.Minimal fluorescence(Fo)of the two varieties had the same change trend in different growth stages,with the maximum value in the width and narrow line mode of 80 cm+20 cm,and the maximum value in the same line space mode of 50 cm with the increase of line space.The NPQ values of the two cultivars were the minimum in the narrow-width row mode of 80 cm+20 cm,first decreased and then increased with the increase of row spacing in the same row spacing mode,and the minimum in the same row spacing mode of 50 cm.3.In Taigu area,the root length density,root surface area density and root volume of Jinju 21 and Zhangzagu 10 all reached the maximum under the 80 cm+20 cm wide and narrow row pattern.In the equidistant planting pattern,the increase of the following row distance increased first and then decreased,and reached the maximum under the 50 cm equidistant row pattern,but there was no significant difference between them and the 30 cm and 40 cm models.Root activity of the two cultivars increased first and then decreased with the increase of row spacing in the same row spacing mode,and reached the maximum in the same row spacing mode of 50 cm,but had no significant difference from that in the 60 cm pattern.4.In Taigu and Dingxiang areas,the height of center of gravity of Jinju 21 and Zhangzagu 10 both increased first and then decreased with the increase of row spacing,and reached the lowest value in the mode of 80 cm+20 cm in the narrow-width row,which was significantly different from that of 70 cm+30 cm in the narrow-width row.However,there was no significant difference among the treatments with the same row spacing.The basal internode resistance and plumpness of both cultivars reached the maximum value in the mode of narrow and wide row 80 cm +20 cm,followed by the same row 50 cm,and there was no significant difference between the two treatments.In the same row spacing mode,the bending strength of the first and second internodes of the base increased firstly and then decreased,and the bending strength was the largest in the same row spacing mode of 50 cm,but there was no significant difference among the 60 cm,70cm and 80 cm treatments.It was suggested that widening the planting row spacing could increase the stem’s anti-falling ability.5.In Taigu and Dingxiang areas,the spike length of Jingu21 and Zhangzagu 10 showed no significant difference among the treatments,and reached the maximum in the mode of80cm+20cm in the narrow row;In the same row spacing mode,the panicle diameter,panicle weight and 1000-grain weight of both cultivars first increased and then decreased with the increase of planting row spacing,and all reached the maximum value under 50 cm planting row spacing,but there was no significant difference between them and 40 cm,60cm,70 cm and 80 cm planting row spacing.The panicle length,panicle diameter,panicle weight and 1000-grain weight of the two cultivars in the narrow-width row mode of 80cm+20cm were all higher than those in the same row spacing mode of 50 cm,but there was no significant difference between the two treatments.The maximum hectare yield of the two cultivars was 80 cm +20 cm in narrow and wide row,followed by 50 cm in equal row spacing,which indicated that suitable arrangement of plant and row spacing was helpful to improve the yield of millet.Comprehensive comparison shows that:Under the treatment of equal row spacing of 50 cm,the chlorophyll content,net photosynthetic rate,stomatal height and root activity of Jigu 21 and Zhangzagu 10 increased significantly,and the yield increased.However,under the planting mode of 80 cm+20 cm in narrow row spacing,the chlorophyll content and photosynthetic capacity of the two varieties were the highest.Root growth condition is good,root activity is strongest,the basal internode resistance and plenitude are high,the yield components are well coordinated,the yield is high,is suitable for millet planting plant row configuration.One of the possible reasons is that the plant type structure,light distribution and root growth in crop population and stem internode plumpness are different under different plant and row configurations. |
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