| Total of 22 winter wheat varieties were imported from the middle and lower reaches of the Yangtze river region in China. Those varieties were sowed in spring in Xinding basin area of Shanxi province (Shanxi Academy of Agricultural Sciences, Maize Research Institute).The field and pot trials were performed for two years (2013-2014). The traits and physiological characteristics included plant agronomic traits, spike differentiation, photosynthetic characteristics and dry matter accumulation, chlorophyll fluorescence parameters, dynamic changes of endogenous hormones in the main stem and grain yield were tested. In order to make clear the formation mechanism of growth characteristics and yield of wheat varieties suitable for Xinding basin spring sowing, the relationship between light photosynthetic characteristics, endogenous hormones of the main stem and the grain yield were studied. To provide theoretical base for selection of high efficiency and evaluation index in wheat introduction and selection for the northwest of mixed sowing area, the field were carried out. The main results are as follows:1> Effect on wheat spike differentiation and growth of spring sowing of winter wheat20 cultivars (spring or weak spring) imported from the middle and lower reaches of the Yangtze river region in China were sowed in March, spring in Xinding basin area of Shanxi province, can be normal jointing, heading, mature; South bring semi winter wheat variety Wanmai 68 showed not to pull out section, delayed heading, seriously affecting grain yield, not suitable for Xinding basin in spring sowing period; different effects on different wheat varieties, good performance of a variety of Winter Wheat in Xinding basin, such as Yu wheat 12, Yangmai 13, Yangmai 20, Ningmai 13, Chuanmai 42 suitable early sowing, sowing time delayed affected the growth and development, grain yield decreased.The spike differentiation processes were obviously influenced by sowing dates, the time of young spike differentiation became shorter with sowing delay, the days completed spike differentiation were different in I, n, III:40-45d,36-42d,33-41d; The spike differentiation process is different of different cultivars; At the same time, plant morphological characteristics showed consistency with spike differentiation progress. When numbers of wheat leaves reached 3.5-4.8, root numbers was 8-9, the spike differentiation got into double ridge stage; When the number was over 5.6 leaf, root number was than 10, it entered the spike differentiation of pistil and stamen. The spike differentiation process of Qian Mai 18 was slower, single ridge stage lasted longer time; When entering double ridge stage, the number of leaves and root number were increased obviously; During the spike differentiation of pistil and stamen, the external leaf number and root number increased remarkably. Wanmai 68 in different sowing date, plant height were low, slow growth, spike differentiation process were not increased with the leaf number and root number, and always stayed in the single ridge stage, tiller was more, could not adapt to the Xinding basin spring sowing, the same result was obtained from field test. Genetic characteristics of wheat varieties and ecological conditions were influenced the spike differentiation; Different varieties of spring wheat spike differentiation was different in different sowing period, its external morphology showed some differences. Compared to other, spike differentiation of Yumai 12 and Yangmai 13 was fast in early sowing date, only 40d and 41d.Plant height is one of the important indicators of the external morphology of wheat, high too prone to lodging, plant canopy leaves too short so crowded, the lower light transmission was bad, affecting production. Plant height of most varieties in late sowing treatment were lower than early or normal sowing dates, and there was no significant difference between ES and NS. Yangmai 13, Yangmai 20, Ning 2038, Chuanmai 42 varieties such as access to high yield, plant height were between 75-80 cm, but Yumai 9 was high(90.7cm), Yu Mai 7 was only 50.7cm, grain yield of the two species were lower. Panicle initiation, growth stages and morphological characteristics of plant were closed ties with production formed. Yumai 12, Yumai 10, Yangmai 13 early reached heading stage for 1-2 days with control N2038, for 3-5 days earlier than other varieties; Yangmai 13 first entered shedding period, their growth and development rapid reproductive growth stage of a larger proportion of total fertility, but also the earliest maturity, which could effectively avoid the impact of local rainfall and hot wind on grain yield; mature 4-7 days earlier than other varieties, which can effectively avoid the extreme impact of weather on grain yield, compared with other species, their advantage is more obvious under the early sowing treatment. Yumai 12 matured earlier, and it had same advantages as Yangmai 13.2、Effect on photosynthetic characteristics, chlorophyll fluorescence kinetics parameters flag leaf and yield of spring sowing of winter wheatWheat yield formation was closely related to its photosynthetic characteristics. Chlorophyll content, photosynthetic performance indicators for most varieties were ES> NS or LS; Pn flag leaf varieties were higher,such as Yangmai 13 (8.9 umolco2.m-2.s-1), Yunmai 42 (5.6 umolco2.m-2.s-1), Yumai 12 (4.6umolco2.m-2.s-1) (flowering stage); Yangmai 13 (16.7 umolco2.m-2.s-1), Chuanmai 42 (16.5umolco2.m-2.s-1) (filling stage); Tr, Gs, Ci, WUE on flag leaf were agreed with Pn, which WUE significant differences among varieties.Significantly correlations were observed in the most chlorophyll fluorescence kinetics parameters of different cultivars, except for the chlorophyll content. The variation coefficients of chlorophyll content and PIBS were respectively lower (0.12-0.17) and higher (0.32～0.39), and partial correlation coefficients of them with yield in 2013、2014 were 0.70～0.81 under two sowing dates. Path analysis and multiple stepwise regression analysis indicate that chlorophyll content (filling stages) and PIBS (flowering and filling stages) has an obvious positive effect on grain weight, but Vi in flag leaves at filling stages has a negative effect in early sowing. So, the three factors were determiners of grain yield (account for 81.07%～82.78%). The chlorophyll content, Pn, most chlorophyll fluorescence kinetics parameters and grain yield of Yangmai 13 were significantly difference at p<0.05, and early sowing was suited to it. By multiple statistics, the chlorophyll content (filling stages), PIABS (flowering and filling stages) were considered as important indices in the selection of high photosynthetic efficiency in wheat under early sowing dates.Under the conditions of early sowing, plant dry matter accumulation of wheat are in line with logistic model, the dry matter accumulation before jointing more slowly, after booting the growth rate significantly accelerated. Flowering to milky stage of dry matter accumulation was significantly higher than other varieties of wheat is Yumai 12 and Yu mai 9, especially in the dry matter accumulation Yumai 12 during growth rate showed an increasing trend, the final amount of dry matter accumulation per plant maximum, and significantly higher than other varieties; yield effect early sowing varieties most Southern cited more obvious during the broadcast and the difference is remarkable, two-year test results are basically the same. (2013) Different Sowing average grain yield was 4393.50kg.hm-2 (ES),3871.99 kg.hm-2 (NS),3623.50 kg.hm-2 (LS); The yield of Yumai 12 and Yangmai 13 were significantly higher than other varieties, respectively were 5876.90 kg.hm-2～5351.55 kg.hm"2,4987.05 kg.hm-2～4609.20kg.hm-2,4014.15 kg.hm-2～ 4058.70 kg.hm"2 under three sowing dates; but the response of individual species to sowing dates were different:yield of N2038 was NS> LS> ES; yield of Yumai 9 was LS> NS> ES; but large grain varieties Yunmai 42 was ES> LS> NS. Southern cited winter wheat varieties yield components, spike and grain number to gain some advantages, such as Yangmai 13 (ES) of a spike (618.0×104hm-2) was significantly higher than other varieties, Yumai 12 grains (two years between 35.1～40.6) were significantly higher than other treatments. Visible under winter wheat sowing conditions to improve wheat production should be the main spike and grain number, promote the formation of effective spikelets, on this basis, to strengthen the cultivation and management of post-filling regulation to promote grain filling speed and strength, in order to increased grain weight. Yumai 12, Yangmai 13, Chuanmai 42, etc. have higher photosynthetic efficiency, dry matter accumulation, higher yield.3、Effect on cold tolerance of plants during heading stage of spring sowing of winter wheatLow temperature stress is one of the important factors resulting in the yield reduction of wheat. Spike differentiation stage is more sensitive to low temperature stress, for excellent winter wheat varieties from the Yangtze River, southwest of the introduction of the winter wheat region, Xinding Basin in spring conditions, the panicle initiation stage of resistance, cold resistance strength is Adaptability of One of the important factors to consider. The current study was conducted to investigate the low-temperature response and cold tolerance of winter wheat varieties sowed in spring during spike differentiation stage, the most sensitive period of wheat to temperature. The traits and physiological characteristics tested under low temperature stress included grain yield, total content of chlorophyll photosynthesis, osmotic adjustment, membrane system, ion leakage rate, content of soluble sugar and soluble protein. The cold tolerance level of those wheat varieties were assessed integrative by statistical tools such as ANOVA analysis of grain yields and Principal Component Analysis. Low temperature stress led to increase of wheat leaf ion leakage rate, soluble sugar and protein contents, but reduction of chlorophyll. The folds of changes were different for different varieties tested. According to Principal Component Analysis and D value, Yumai 10, Yangmai 20, and Yunmai 42 were classed as cold sensitive wheat varieties. Yangmai 13,Yumai 12, and Ningmai 13 were classed as stronger cold-resistant wheat genotypes, and the phenotype showed stable through two-year field trials. The D values of each variety calculated for two years were 0.6656～ 0.6596,0.4934-0.4959, and 0.4718-0.5835 for the three cold resistance varieties, respectively while D values for CK1 and CK2 were 0.3682～0.3978,and 0.3285～0.3304, respectively. The grain yield of the cold resistant wheat varieties were significantly higher than other varieties tested(p<0.05). Therefore, Yangmai 13,Yumai 12 and Ningmai 13 could be imported from low latitude areas, and used as the cold tolerant wheat varieties for planting in North Plain of China. However, more studies are needed. |
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