| Rice and wheat are most important food crops in China. The realization of their super-high-yielding (SHY) has great significance in ensuring food security in this country. This study investigated the plant-type characteristics, population indexes, photosynthetic characters during grain filling, fertilizer-requirement rules, fertilizer and water management, and quality effects of SHY cultivation of rice and wheat. The main results are as follows:1. Annual grain yield of SHY rice and wheatThe annual grain yields of SHY rice and wheat in 2005 and 2006 were 21.02 t hm-2 and 22.52 t hm-2, respectively, and 37.9% and 40.8% higher than those of the high-yielding cultivation (CK) of the two crops.2. Plant type characteristics of SHY rice and wheatAccording to cluster analysis in grain yield, 129 mid-season rice cultivars (japonica) could be classified into five groups: super-high-yielding, high-yielding, mid-yielding, mid-low- yielding,and low-yielding. In the total tested cultivars, super-high-yielding cultivars were 3.1%, low-yielding cultivars were 14.7%, and other cultivars were 82.2%. Most of high- and super-high-yielding cultivars had half-erect panicles and erect leaves, produced more biomass, and had greater filled-grain percentage and higher harvest index. The cultivars with good grain quality were mainly existed in the high-yielding and mid-high-yielding groups, and very few in the super-high-yielding and low-yielding groups. The higher percentage of chalky grains was a major problem for the super-high-yielding cultivars. The traits or indexes for a super-high-yielding mid-season japonica rice cultivars (>12 t hm-2) were suggested, i.e., plant height 100-108 cm, whole growth period 150-155 d, half-erect panicles, panicle length 17-18 cm, panicles 320-340×104 hm-2, primary branches 12-15, secondary branches 30-38, spikelets per panicle 160-180, filled-grain percentage > 85%, 1000-grain weight >26 g, the lengths of the flag leaf, and the 2nd and 3rd leaves from the top were 26-28 cm, 35-40 cm, and 32-38 cm, respectively, the angle of the flag leaf < 20 o, and harvest index > 0.5.Twenty-four wheat cultivars could be classified into four groups: super-high-yielding, high-yielding, mid-yielding, and low-yielding according to cluster analysis in grain yield. In the total tested cultivars, super-high-yielding cultivars were 20.8%, low-yielding cultivars were 12.5%, and other cultivars were 66.72%. Most of high- and super-high-yielding cultivars had shorter panicles, more panicle number, higher plant height, shorter base internodes, longer peduncle, smaller and more erect flag leaf, produced more biomass, and had higher harvest index. All SHY wheat cultivars were medium and strong gluten varieties. The traits or indexes for a super-high-yielding wheat (>8.5 t hm-2) cultivar were suggested, i.e., plant height around 75 cm, whole growth period around 225 d, length of the peduncle > 28 cm, plant height index >0.61, spike length 7.5– 8.0 cm, spikelets per spike 14-15, the length and width of the flag leaf 15-17 cm and 1.3 cm, respectively, high effective leaf area 55-60 cm2, the angle of the flag leaf < 25o, productive spike number > 620×104 hm-2, grain number per spike >33, 1000-grain weight > 42 g, and harvest index > 0.45.3. Population and photosynthetic characteristics of SHY rice and wheatSuper-high-yielding rice (grain yield: 10.81-11.64 t hm-2) had more spikelets per panicle and higher filled-grain percentage than the high-yielding rice (grain yield: 8.98-9.16 t hm-2, CK). There was no significant difference in 1000-grain weight between the SHY and the CK. SHY rice exhibited fewer tillers at the early growth stage (from transplanting to jointing), while a higher ratio of productive tillers to total tillers, when compared with the CK. The leaf area index, photosynthetic potential and dry matter accumulation were lower for the SHY rice than those for the CK at the early growth stage, and their differences were not significant between the two rice types at heading, and were greater for the former than the later after heading. The root-shoot ratio at each growth stage, root bleedings from heading to maturity, grain-leaf ratio, translocation percentage of the matter from stems and sheaths and harvest index of SHY rice were greater than those of CK. The leaf area index (LAI), chlorophyll content (SPAD value), photosynthetic rate (Pr) and PS II electron transport efficiency (Fv/Fm) of SHY rice were greater than those of CK, while nonphotochemical quenching coefficient (qN) lower than that of CK. The indexes for the growth and development of SHY (grain yield > 12 t hm-2) mid-season rice population were suggested, i. e., total spikelets > 5.2×104 m-2, filled-grain percentage > 90%, 1000-grain weight > 26 g; ratio of productive tillers > 80%, leaf area index at heading 7.5-8.0, photosynthetic potential during the whole growth period > 5×106 m2 d hm-2, total dry matter weight at maturity > 22 t hm-2, harvest index > 0.51; grain-leaf ratio (No of spikelets per cm2 leaf area) > 0.58; root-shoot ratio at heading > 0.25 and amount of root exudates > 5 g m-2 h-1.Super-high-yielding cultivation (grain yield : 9.61-9.93 t hm-2) of wheat had more grains per spike and higher 1000-grain weight than the high-yielding cultivation (grain yield: 7.38-7.88 t hm-2, CK). There was no significant difference in spike number per unit area between the SHY and the CK. SHY wheat exhibited fewer tillers at the early growth stage (from tillering to jointing), while higher ratio of productive tillers to total tillers, when compared with the CK. The leaf area index and photosynthetic potential were lower for the SHY than those for the CK and there was no difference in dry weight accumulation between the two cultivations at the early growth stage, while the LAI, photosynthetic potential, and dry weight accumulation of SHY were higher than those of CK after heading. The root-shoot ratio and root bleedings of SHY were higher than those of CK at heading, milking, and waxing stages. Grain-leaf ratio, translocation percentage of the matter from stems and sheaths and harvest index of SHY wheat were greater than those of CK. SPAD values, Fv/Fm of SHY wheat were greater than those of CK, while qN lower than that of CK. The indexes for the growth and development of SHY wheat were suggested, i. e., spikes per unit area >680×104 hm-2, grains per spike > 33, 1000-grain weight > 42 g; ratio of productive tillers > 45%, leaf area index at heading 6.5-7.5, photosynthetic potential during the whole growth period > 7×106 m2 d hm-2, total dry matter weight at maturity >20 t hm-2, harvest index > 0.45; grain-leaf ratio (grain weight (mg) per cm2 leaf area ) >14; root-shoot ratio at heading >0.25 and amount of root exudates >7.5 g m-2 h-1.4 Fertilizer-absorption rules of SHY rice and wheatCompared with high-yielding cultivation (CK), plants of SHY rice absorbed and accumulated less nitrogen (N) before the critical stage of productive tillers and more N after the jointing stage, especially at later growth stages. There was no significant difference in potassium (K) absorption and accumulation between the SHY and the CK before the critical stage of productive tillers, whereas SHY plants absorbed more K than in the CK from jointing to maturity. Input of N balanced the output in SHY rice, but the CK showed more input than output in N. There were more outputs than inputs in phosphorus (P) and K for both SHY and high-yielding cultivations, especially the former. The amount absorbed of N, P, and K for the production of 1000 kg grains was 21.6-21.9kg, 6.7-7.2kg, and 24.8-25.6kg, respectively in SHY rice, and 23.8-24.3 kg, 6.8-7.3 kg, and 27.4-29.0 kg, respectively, in the CK.Compared with the CK, SHY wheat was almost the same in N, P, and K absorption before winter, and absorbed more N, P, and K after jointing, especially at later growth stages. Plants of SHY wheat accumulated almost the same N, P, and K from sowing to hibernation, while more N, P, and K in each growth stages after hibernation. The amount absorbed of N, P2O5, and K2O for the production of 1000 kg grains was 30.0-30.5, 9.0-9.8 and 32.7-33.8 kg, respectively in SHY wheat, and 34.5-36.5,10.3-10.830.4-30.8 kg, respectively, in the CK.5. Fertilizer and water management for SHY rice and wheatSite-specific N management (SSNM) for SHY rice was established, i.e., total amount of fertilizer-N,-P, and -K was estimated based on Stanford Equation, the topdressing amount of N was applied according to the critical thresholds of SPAD or leaf color chart (LCC) at main growth stages (tillering, panicle initiation, pistil and stamen differentiation) and to the source-sink characteristics of rice cultivars. The precise irrigation technique (PIT) was put forward for SHY rice: (1) a thin-layer of water was kept in the field from transplanting to green-returning; (2) intermittent irrigation was conducted from green-turning to two leaf-age before the critical leaf-age of productive tillers (N-n-2), the low-limit soil water potential (SWP) was -5 to -15 kPa; (3) mid-season drainage was imposed from (N-n-2) to (N-n), and the low-limit SWP was -15 to -25 kPa and kept this value for one leaf-age; (4) wet-dry alternate irrigation was carried out from (N-n+1) leaf-age to the early differentiation of secondary branches, and the low-limit SWP was -20 to -30 kPa; (5) intermittent irrigation was conducted again from the differentiation of secondary branches to 10 days after heading, and the low-limit SWP was -5 to -15 kPa; and (6) wet-dry alternate irrigation was performed from 11 d to 45 days after heading, and the low-limit SWP was -10 to -20 kPa. SSNM and PIT could significantly increase grain yield, save water and save fertilizer.SSNM for SHY wheat was also established, i.e., total amount of fertilizer-N,-P, and -K was estimated based on Stanford Equation, the topdressing amount of N was applied according to the critical thresholds of SPAD or LCC at main growth stages (tillering and spike initiation). An irrigation pattern for SHY wheat was proposed and practiced: when SWP reached -40 kPa at the leaf-age of 3.5 (before the application of tillering-fertilizer), at the emerging of the flag leaf (before the application of flower-protecting fertilizer) and at the flowering, irrigation should be conducted and the amount of irrigation water at each time was 20-25 m3 667m-2. The SSNM and the irrigation pattern in wheat obtained good effects in raising grain yield and saving water and fertilizer.6. Effects of SHY cultivation on the quality of rice and wheatCompared with the high-yielding cultivation (CK) in rice, the SHY cultivation could significantly reduce chalkiness and chalky grains and increase brown rice, head rice, protein content, total content of amino acids, and the contents of both essential and nonessential amino acids. The differences in amylase content and rapid viscosity analyzer (RVA) values were not significant between SHY the high-yielding cultivations.Compared with high-yielding cultivation (CK) in wheat, the SHY cultivation could significantly increase the capacity and contents of wet gluten, protein, albumin, prolamin and glutelin. There were no significances in globulin content and the ratio of glutelin to prolamin between the SHY and CK. The effects of the cultivations on RVA values varied with wheat cultivars.
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