Characteristics of Nutrient Uptake and Accumulation in Wheat and Rice with Continuous Cropping under Super-High-Yielding Cultivation

Abstract

Understanding characteristics of nutrient uptake and accumulation in plants would be highly significant in the realization of high-yielding and high efficiency of resource use in rice and wheat. This study aimed at investigating uptake and accumulation characteristics of nitrogen (N), phosphorous (P), and potassium (K) in rice and wheat plants under super-high-yielding cultivation in the wheat-rice planting system in the lower reaches of Yangtze River of China. Two high-yielding wheat varieties and two rice varieties were field-grown for two years. Two cultivation patterns, the local farmers practice and super-high-yielding cultivation, were used. The super-high-yielding cultivation adopted two new key techniques, i.e., site-specific nitrogen management and alternate wetting and moderate drying irrigation in rice and controlled soil drying irrigation in wheat. In comparison with those under the local farmers practice (wheat yield < 8 t ha~(-1) and rice yield < 9 t ha~(-1)), the total uptake of N, P, or K in plants was significantly increased, and the accumulation of N, P, or K was significantly decreased before stem elongation, whereas it was significantly increased in the durations from the stem elongation to flowering and from flowering to maturity under the super-high-yielding cultivation (wheat yield > 9 t ha~(-1) and rice yield > 12 t ha~(-1)). The total uptake of N, P, and K under the super-high-yielding cultivation was 265, 58, and 256 kg ha~(-1) for wheat and 256, 79, and 321 kg ha~(-1) for rice, respectively. The proportion of N, P, or K accumulated in plants during the mid and late growth period (from stem elongation to maturity) to the total uptake of nutrients was 50-60% for wheat and 60-70% for rice. The super-high-yielding cultivation significantly increased partial factor productivity of N, P, or K (grain yield/amount of N, P, or K applied), internal nutrient efficiency (grain yield/total uptake of N, P, or K at maturity), and harvest index of nutrients (uptake of N, P, or K in grains/ the total uptake of N, P, or K in plants at maturity), and significantly decreased the absorption amount of nutrients for grain production (total uptake of N, P, or K in plants at maturity/grain yield). The results suggest that both wheat and rice absorb relatively smaller nutrients at early growth stages and more nutrients during the mid and late growth period, and the uptake and use efficiency of nutrients could be increased under the super-high-yielding cultivation. 以2个小麦品种和2个水稻品种为材料,大田种植,稻麦连作,重复2年,设置超高产栽培和当地高产栽培两种栽培模式,旨在探明超高产栽培小麦和水稻养分吸收 与积累特征。超高产栽培中,采用实地氮肥管理及水稻轻干湿交替灌溉和小麦控制土壤水分灌溉等关键技术。与当地高产栽培(小麦产量<8 t hm~(-2),水稻产量<10 t hm~(-2))相比,超高产栽培(小麦产量>9 t hm~(-2),水稻产量>12 t hm~(-2))小麦和水稻的氮(N)、磷(P)、钾(K)总吸收量显著增加,并表现为拔节前的吸收和积累量显著降低,拔节至开花、开花至成熟的吸收积累 量显著提高。超高产栽培的N、P、K的总吸收量,小麦分别为265、58和256 kg hm~(-2),水稻分别为256、79和321 kg hm~(-2)。上述3种元素于生育中后期(拔节至成熟)的吸收量占总吸收量的比例,小麦为50%~60%,水稻为60%~70%。超高产栽培显著提高了 N、P、K偏生产力(产量/N、P、K施用量)、养分吸收的养分籽粒生产率(籽粒产量/成熟期植株N、P、K吸收量)和养分收获指数(籽粒N、P、K吸收 量/成熟期植株N、P、K吸收量),降低了生产单位籽粒产量的养分吸收量(成熟期植株N、P、K吸收量/籽粒产量)。本研究结果显示,超高产栽培小麦和水 稻养分吸收与积累具有生育前期较低、生育中期和后期较高的特点,且养分吸收利用效率提高。