| A field experiment was conducted from 2012 to 2014 using a split-plot design at Yangzhou University Experimental Farm of Jiangsu Province, China（32°30’N,119°25’E）. Main plots were assigned with five wheat cultivars, including three waxy cultivars （Yangnuomai 1, Ningnuomai 1, and Huanuo 1） and two non-waxy cultivars （Yangmai 20 and Yangfumai 4）. Sub-plots were assigned with two nitrogen ratios. This experiment was conducted to investigate the grain yield components, population structure, grain quality formation, physiological characteristics of waxy wheat cultivars and the differences between waxy and non-waxy wheat. Another field experiment was conducted from 2010-2014 to study the characteristics of yield component, population development, the accumulation, distribution, and utilization of nutrients, and photosynthesis of waxy Yangnuomai 1 under different levels of seeding density, nitrogen applied amount, ratio of nitrogen applied before seeding and at the growth stages of tillering, elongation, and booting. These studies are theoretically and technologically supportive for high-yielding production of waxy wheat. The main results are as follows:（1） The differences in grain yield among waxy wheat cultivars were studied. The grain yield of Yangnuomai 1 was significantly higher than Ningnuomai 1 and Huanuo 1. But there was no significance in grain yield between Yangnuomai 1 and non-waxy Yangmai 20 and Yangfumai 4. The HY （high-yielding） population of Yangnuomai 1 (≥ 8000 kg hm-2) was characterized with 5.2-5.5 million spikes hm-2,43-46 grains per spike, and thousand-grain weight at 36-39 g in normal growing seasons. These parameters were significantly higher than those in MHY (moderately-high-yielding population,7500-8000 kg hm-2) and MY （middle-yielding population, <7500 kg hm 2）. Compared to the populations of non-waxy Yangmai 20 and Yangfumai 4 at the similar yield levels, Yangnuomai 1 had more spikes per unit area and grains per spike, and lower thousand-grain weight.（2） There were significant differences among cultivars in the number of main stem and tillers, leaf area index （LAI）, dry matter accumulation, number of fertile grains, and grain/leaf ratio. The differences in these parameters were insignificant between Yangnuomai 1, Yangmai 20, and Yangfumai 4, but significant between Ningnuomai 1, Huanuo 1, and non-waxy cultivars. In the HY population of Yangnuomai 1 at jointing stage, the number of main stem and tillers was 2.1-2.5 times of the final spike number, the earing percentage of main stem and tillers was 44-49%, and the earing percentage of tillers was 25-33%. At the stages of booting and milking, the suitable LAIs of HY population of Yangnuomai 1 were 6.2-6.5 and 3.2-4.0, respectively. The dry matter accumulation amount at anthesis was 10000-12300 kg hm-2, and the dry matter accumulated from anthesis to maturity was higher than 5900 kg hm-2. At maturity stage, the grain/leaf ratios of HY population of Yangnuomai 1 were 0.34 grains per cm2 leaf and 12.40 mg grain per cm2 leaf.（3） N accumulation amount （NAA） of waxy and non-waxy wheat increased gradually and reached the maximum level at maturity. The NAA of waxy wheat was higher than non-waxy wheat during wintering. At later growth stages, NAA of Yangnuomai 1 was significantly higher than Ningnuomai 1 and Huanuo 1, but there was no significant difference in NAA between Yangnuomai 1 and non-waxy cultivars. The N and P accumulation amounts （NAA and PAA） of Yangnuomai 1 at different grain yield levels gradually increased and reached the maximum at maturity. The K accumulation （KAA） reached the maximum at anthesis. NAA of Yangnuomai lat booting, anthesis, and maturity were 171-200 kg hm-2,210-229 kg hm-2,255-262 kg hm-2, respectively. PAA at anthesis and maturity were 41-56 kg hm-2 and 86 kg hm-2, respectively. KAA at anthesis and maturity were 328-451 kg hm"2 and 257-359 kg hm-2, respectively. There were no significant differences in N amount producing 100 kg grain, N absorption efficiency, and N harvest index between waxy and non-waxy wheat cultivars. For the HY populations of Yangnuomai 1, the N, P and K amount producing 100 kg grain were 3.14-3.22 kg,1.06-1.07 kg, and 3.16-4.42 kg, respectively; N, P, and K absorption efficiency were 1.02-1.09 kg kg-1 0.60 kg kg-1, and 1.79-2.49 kg kg-1, respectively; and N, P, and K harvest indexes were 0.64-0.69,0.41-0.69, and 0.10-0.13, respectively.（4） SPAD reading and the activities of POD, CAT, and SOD in flag leaves increased and then decreased between anthesis and the 28th day after anthesis, with the peaks appeared on the 7th,14th,7th, and 21st day after anthesis, respectively. Photosynthetic rate （Pn） decreased and MDA content increased gradually between anthesis and the 28th day after anthesis. Compared with Ninnuomai 1 and Huanuo 1, SPAD reading, photosynthetic rate （Pn）, and the activities of SOD, POD and CAT in flag leaves of Yangnuomai 1, Yangmai 20, and Yangfumai 4 after anthesis were higher, but MDA content was lower. Compared with the MHY and MY populations of Yangnuomai 1, SPAD reading, photosynthetic rate （Pn） and the activities of SOD, POD and CAT in flag leaves of the HY population of Yanghuomai 1 after anthesis were higher, but MDA content was lower. These differences were more significant at grain-filling stage （from the 14th to 28th day after anthesis）.（5） For both waxy and non-waxy wheat plants, soluble sugar content decreased at first, then increased, and finally decreased again, nitrogen content decreased gradually, and the ratio of soluble sugar to nitrogen （C/N） increased at first and then decreased, with the peak appearing at anthesis. At wintering stage, the soluble sugar content was higher in non-waxy wheat than in waxy wheat, and nitrogen content in Yangnuomai 1 plant was at the similar level as in non-waxy wheat plants, but significantly higher than Ningnuomai 1 and Huanuo 1. The C/N of non-waxy wheat was higher at winter stage and lower after jointing stage as compared with waxy cultivars. The total sugar contents of the waxy wheat plants at the stages of booting, anthesis, and maturity were significantly higher than those of non-waxy wheat plants.（6） The contents, accumulation, and accumulating rate of amylose, amylopectin, and starch between waxy and non-waxy grains were different. The contents and accumulation of starch and amylose were significantly higher in non-waxy wheat after anthesis. ADPG and GBSS activities in waxy wheat grains were significantly lower than in non-waxy wheat grains. SSS and SBE activities of waxy wheat grains were significantly higher than non-waxy wheat grains within 30 days after anthesis. There was no significant difference in the contents of sucrose and total soluble sugar in wheat grain between waxy and non-waxy wheat grains during 5-10 days after anthesis. After 10 days post anthesis, the contents of total soluble sugar and sucrose was significantly higher in waxy wheat than in non-waxy wheat. The SS activities in waxy wheat grains was higher in non-waxy wheat grains within 20 days after anthesis.（7） There was no significant difference in the particle size distribution of the starch of waxy and non-waxy wheat. Compared with the starch of non-waxy wheat, the starch of waxy wheat had higher gelatinization enthalpy and final temperature, and lower initial gelatinization temperature and peak temperature. Compared with non-waxy wheat grain, the waxy wheat grain had higher hardness, water absorption, developmental time, softening degree, valorimeter value, stability time, extension area, extension resistance and extension ratio. Ningnuomai 1 and Huanuo 1 had the highest grain protein content. Yangmai 20 and Yangfumai 4 had the highest extensibility. Compared with the MHY and MY population, the HY population grain had higher grain protein content, volume weight, hardness, sedimentation, wet gluten content, water absorption, amylose, amylopectin and starch contents, and lower sucrose content, total soluble sugar content, peak viscosity, trough viscosity, breakdown, final viscosity, setback, peak time, gelatinization temperature, development time, stability time, and valorimeter value.（8） A cultivation technology system for Yangnuomai 1 achieving HY in rice stubble wheat of Huainan region was preliminarily developed. The suitable seeding date is from late October to early November. The planting density is 225×104 hm-2 by drill sowing, with a line spacing of 30 cm and a seedling depth of 2-3 cm. The applied amount of N, P and K are kept at 240,90, and 90 kg hm-2, respectively, with a nitrogen application ratio of 5:1:2:2 before seeding and at the growth stages of tillering, elongation, and booting. The fertilizer at the stages of basal, tillering, jointing and booting should be applied before sowing, at the 4-5th leaf stage, at the remaining leaf age of 2.5, and at the remaining leaf age of 0.8. The first half amount of P and K is applied before sowing, and the remained is applied at the remaining leaf age of 2.5. |
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