【作者】 谭毅；

【导师】 周伟； 姚雄；

【作者基本信息】 四川农业大学 ， 农业硕士（专业学位）， 2024， 硕士

【摘要】 水稻在我国粮食作物中有举足轻重的地位,其产量和品质对国家粮食安全至关重要。随着人类社会发展全球气候逐渐变暖,再生稻适宜区扩大,中稻-再生稻成为打造“吨粮田”的重要种植模式。与此同时,为适应现代农业的发展需求机插、直播等轻简播栽方式发展迅速,然而不同栽播方式如何影响头季稻和再生稻的营养和卫生品质尚不清楚。因此,本研究通过两年田间试验,探明了手插、机插、直播三种播栽方式在不同氮肥处理(PASP尿素和普通尿素,2022年)和不同水稻品种下(C两优华占和宜香优2115,2023年)对头季稻和再生稻产量、干物质和元素积累与分布的影响。主要结果如下:1.手插和机插处理下,水稻籽粒产量显著高于直播。2022、2023年的头季稻着粒数、实粒数、产量均表现为机插≈手插>直播,机插与手插无显著差异。2022年头季稻两种氮肥处理下,与直播相比,机插处理的着粒数提高12.3%、6.3%,实粒数提高16%、9.7%,最终导致产量提升49.9%、35.2%;相同品种下,机插处理的着粒数、实粒数和产量也显著高于直播,其中着粒数提高25.00%～31.5%,实粒数提高30.0%～35.39%,从而导致产量增加35.20%～42.3%。再生稻有效穗、实粒数和产量均表现为机插≈手插>直播,两个品种下机插产量比直播分别提高51.4%、34.9%,差异达显著水平。2.不同播栽方式对干物质积累的主要时期与各器官分配率存在显著影响,最终导致干物质积累总量和穗部分配率差异。手插处理下干物质积累主要在花前,其中拔节至齐穗期占比最高为33.2%;而机插秧干物质主要集中在生殖生长期,占比高达55.3%,直播再生稻季的干物质占比为12.4%,显著高于手插和机插处理。头季稻拔节期、齐穗期和成熟期,总干物质积累量表现为手插>机插≈直播,再生稻的成熟期则表现为直播>手插≈机插。头季稻成熟期,干物质主要分配在穗部,再生稻主要分配在稻桩中。不同播栽方式下的物质积累特点,导致最终干物质积累量和穗部干物质分配率均表现为手插和机插大于直播,而手插与机插无显著差异。3.不同播栽方式对不同时期水稻各器官的Ca、Cu、Fe、Mn、Zn、As、Cd金属元素含量及累积量有显著性影响。Cd、As在头季稻和再生稻各器官含量和积累量表现为根(>桩)>茎>叶>穗,Ca、Cu元素主要集中在茎、叶和穗中,而Fe、Mn元素大多分布在根和茎中。头季稻各元素积累量均表现为手插高于机插和直播,但穗部有害元素As、Cd的浓度在机插处理下最低(除2023年宜香优2115穗部的As含量外)。4.不同元素浓度间存在复杂的相关性。头季稻和再生稻成熟期各元素在根、茎和叶中的相互关系存在较大差异,但在穗部As、Cd与Ca、Cu、Fe、Mn、Zn之间均表现为正相关关系,且除Zn元素以外,基本都达显著或极显著水平。头季稻和再生稻As元素在各个器官间均呈正相关关系,而头季稻Cd元素穗部与茎鞘呈显著负相关关系,此外再生稻成熟期穗部、叶部及茎部与头季稻的上、下茎及下部叶表现出正相关关系。表明,要同时提升籽粒中有益元素的含量和降低有害元素含量存在较大难度,通过提高Cd在茎鞘中的滞留率可以降低头季稻籽粒含量,但会增加再生稻Cd富集风险。5.穗部各元素浓度与根、茎、穗等器官干物质积累量密切相关。头季稻和再生稻穗部元素浓度均与穗部干物质积累负相关,表现为稀释效应;而头季稻成熟期根、茎的干物质积累量越大,元素则更多的滞留在了根和茎中,从而使头季稻穗部的元素含量降低;并且积累在根、茎中的元素在再生稻季时能向上运输,导致再生稻穗部的元素浓度增加。综上表明,提高Cd、As在头季稻上部茎叶的滞留率,是同步降低头季稻和再生稻重金属污染的有效手段。此外,结合上述主要结果以及归一化处理分析,综合考虑水稻籽粒产量、有毒元素As、Cd含量,以及有益元素Ca、Cu、Fe、Mn、Zn的浓度,机插方式在促进水稻产业绿色高产高效发展和降低重金属积累、提高稻米品质方面具有一定优势,可作为水稻生产的优选播栽方式。更多还原

【Abstract】 In recent years,with the warming of the global climate,the suitable area of ratooning rice has expanded,and middle rice-ratooning rice has become an important planting mode to build "tons of grain field".At the same time,the sowing and planting methods of rice have developed in diversity.However,it is not clear how different planting and sowing methods affect the yield and quality of first-season and ratoning rice.Therefore,a two years experiment were conducted to investigate the effects of three rice sowing and planting methods,including hand transplanting,machine transplanting,and direct seeding,on rice grain yield,dry matter and elements accumulation and distribution of first-season and ratooning rice,under different nitrogen fertilizer type(PASP urea and ordinary urea,2022)and different rice varieties(C Liangyouhuazhan and Yixiangyou 2115).The main results are as follows:1.The ricegrain yield of hand transplanting and machinetransplanting treatments were significantly higher than that of direct seeding treatment.In the first-season of 2022 and 2023,rice grian number,filled grain number,and grian yield all showed machine transplanting≈hand transplanting>direct seeding,and there was no significant difference between machine transplanting and hand transplanting.2022 in the first-season,under two nitrogen fertilizer treatment,the number of grains of mechine transplanting increased by 12.3%and 6.3%,the number of filled grains increased by 16%and 9.7%,which led the grain yield increased by 49.9%and 35.2%,respectively,compared with direct seeding.With the same rice varieties,the number of grains,filled grains of machine transplanting were significantly higher than that of direct seeding,which increased by 25.0%～31.5%,and 30.0%～35.39%,respectively,led to the grain yield increasing by 35.2%～42.3%.The effective panicles,filled grain number and yield of ratooning rice showed machine transplanting≈hand transplanting>direct sowing,and the grian yield of machine transplantingincreased by 51.4%and 34.9%,respectively,and the difference reached a significant level.2.The main period of dry matter accumulation and allocation of organs were significantly affected by different sowing and planting methods,which eventually led to the difference of total dry matter accumulation and allocation rate of panicle.Under hand transplanting,dry matter accumulation was mainly before flowering,and the highest proportion was 33.2%from jointing to full heading stage.The dry matter of machine transplanting was mainly concentrated in the reproductive growth period,accounting for 55.3%,and the dry matter proportion of ratooning rice under direct sowing was 12.4%,which was significantly higher than that of hand and machine transplanting.At jointing stage,full heading stage and mature stage,the dry matter accumulation of single plant and population showed hand transplanting>machine transplanting≈direct seeding,and the mature stage of ratooning rice showeddirect seeding>hand transplanting≈machine transplanting.At the mature stage of the first-season rice,the dry matter was mainly distributed in the panicle,and the ratooning rice was mainly distributed in the rice pile.The characteristics of matter accumulation under different sowing and planting methods led to the total dry matter accumulation and dry matter distribution rate of panicle under hand transplanting and machine transplanting were higher than that of direct seeding,but there was no significant difference between hand transplanting and machine transplanting.3.Different sowing and planting methods had significant effects onthe content and accumulation of Ca,Cu,Fe,Mn,Zn,As and Cd elements in different organs at different periods of rice plants,The contents and accumulation of Cd and As in the organs of first-season rice and ratooning rice were in the order of roots(>piles)>stems>leaves>panicles.The contents and accumulation of Ca and Cu elements were concentrated in stems,leaves and panicles,and Fe and Mn elements were mostly in roots and stems.The accumulation of elements in first-season rice under hand transplanting was higher than that in machine transplanting and direct seeding,but the concentrations of harmful elements As and Cd in panicle were the lowest under machine seeding(except for As in Yixiangyou 2115 panicle in 2023).4.There are complex correlations between the different elements.There were significant differences in the relationships among the elements in roots,stems and leaves at maturity stage of first-season rice and ratooing rice,but the As,Cd and Ca,Cu,Fe,Mn and Zn in panicle were all shoed a positive correlation,and exception of Zn element,they all reached significant or extremely significant levels.There was a positive correlation of As element between different organs of first-season rice and ratooning rice,while there was a significant negative correlation of Cd between panicle and stem sheath.In addition,the panicle,leaf and stem of ratooning rice showed positive correlation with the upper,lower stem and lower leaves of first-season rice at maturity.The results showed that it difficult to increase the content of beneficial elements and reduce the content of harmful elements in the panicle at the same time,the toxic heavy metal pollution of the first-season rice could be reduced by increasing the retention rate of Cd in the stem sheath,but the risk of Cd enrichment in ratooning rice could be increased.5.The concentration of elements in panicle was closely related to dry matter accumulation in root,stem and panicle.The element concentration in ear of first-season rice and ratooning rice was negatively correlated with dry matter accumulation in panicle,showing dilution effect.The higher the dry matter accumulation in the roots and stems of the first-season rice,the more elements were retained in the roots and stems,which reduced the element content in the panicles of the first-season rice.While,the elements accumulated in roots and stems can be transported upward during the ratooning rice season,which leads to the increase of element concentration in the panicles of ratooning rice.In conclusion,increasing the retention rate of Cd and As in the upper stems and leaves of first-season rice is an effective means to simultaneously reduce heavy metal pollution in first-season and ratooning rice.In addition,combined with the above main results and the normalized treatment analysis,comprehensive considering the grain yield,the concentration of toxic elements As and Cd,and beneficial elements Ca,Cu,Fe,Mn,and Za,machine transplanting has certain advantages in promoting the green,high-yield and high-efficiency development of rice industry,reducing heavy metal accumulation and improving rice quality.Therefore,machine transplanting can be used as the optimal planting method for rice production.更多还原