Effects of water and nitrogen coupling on growth,physiology and yield of rice

Water and nitrogen fertilizer are two essential factors for quality and yield formation of rice.Experimental study was carried out to investigate the effects of water and nitrogen fertilizer coupling on yield-related factors,such as growth(height),physiological indicators(chlorophyll and leaf area index(LAI))and yield composition indicators(productive panicles,thousand grain weight and total grains per panicle).Results showed that,the height difference under two irrigation regimes was not significant,and it showed no difference until the tillering stage(p>0.05).The water control method for controlled and mid-gathering irrigation(CMI)was favorable for nutrients converting to rice grain.Meanwhile the height difference for CMI and conventional irrigation(CVI)was the biggest at 80 d after rice transplantation.Variance analysis showed the effect of fertilization on height was significant(p<0.05).With organic fertilizer application,it could control plant growth and promote the nutrients converting to the panicle.The change curve of LAI was similar to chlorophyll content.Organic fertilizer application could not only promote chlorophyll content and LAI,but also delay leaf fading and promote yield.Nitrogen fertilizer factors showed significant difference on rice yield,compared to irrigation regimes showing no significance.Considering the irrigation and fertilizer factors together,the interaction was significant.The descending orders for the effects of water and nitrogen on rice yield were fertilizer,water and fertilizer,water.Regression analysis showed that the productive panicles and total grains per panicle of rice were extremely significant on rice yield,and the direct effect of total grains per panicle on yield was greater than that of productive panicle.This study results could provide theoretical basis for water and nitrogen management to improve rice production.

Effects of nitrogen addition and drought on the relationship between nitrogen-and water-use efficiency in a temperate grassland

Background Nitrogen-and water-use efficiency(NUE and WUE)reflect the capacity of plants to take up and utilize resources in the environments.Although N deposition and drought are known to affect plant growth and persistence,it remains elusive how plants adjust NUE,WUE and their relationship to adapt to the concurrent N deposition and drought under the context of global change.We conducted a field experiment in a temperate grassland in Inner Mongolia,in which N addition(10 g m^(–2)yr^(-1)),drought(reduced 66%precipitation during growing season)and their combination were manipulated,and we explored the responses of both instantaneous(NUE_(INST)and WUE_(INST))and long-term(NUE_(LT)and WUE_(LT))WUE and NUE for six common plant species(Leymus chinensis,Stipa baicalensis,Thermopsis lanceolata,Potentilla bifurca,Thalictrum squarrosum,Klasea centauroide).Results Across all the six species,NUE_(INST)decreased and WUE_(INST)increased with both N addition and drought;NUE_(LT)decreased with both N addition and drought,while WUE_(LT)decreased with N addition and increased with drought.A significant interactive effect between N addition and drought was detected,in that,drought weakened the negative effect of N addition on WUE_(LT)and NUE_(LT),and N addition weakened the negative effect of drought on NUE_(LT),but enhanced the positive effect of drought on WUE_(LT).As a consequence,drought caused a trade-off between NUE and WUE,and N addition brought forth positive correlation between NUE and WUE.Meanwhile,the relationship between NUE and WUE varied among the species of different functional groups.Conclusions Our study demonstrated that NUE,WUE and their relationship play an important role in determining their responses and adaptability to changes in soil nitrogen and water availability induced by N deposition and drought.Our results shed light on the antagonistic,synergetic and neutral effects between nitrogen deposition and drought on resource use efficiency,and further clarified the different adaptability among species of different functional groups,which will conduce to a comprehensive understanding on the role of NUE and WUE in plant persistence and coexistence in grassland ecosystems.

Determination of amount of irrigation and nitrogen for comprehensive growth of greenhouse cucumber based on multi-level fuzzy evaluation

In the northwestern part of China,rational and efficient management of irrigation and nitrogen significantly affects the intensive production of greenhouse cucumbers(Cucumis sativus L).To evaluate the effects of different combinations of water use and nitrogen(N)on yield,quality,and profitability of the greenhouse cucumbers that planted in 2018 Spring,nine combined treatments were applied.Results indicated the optimal irrigation and nitrogen demands for yield,quality and other indicators were different.The irrigation amount significantly affected the yield,and the yield gradually increased with increasing in irrigation.Single fruit weight(SFW)was significantly affected by the amount of irrigation,nitrogen and their interactions,and the higher amounts of N and irrigation were beneficial to the increase of SFW.The partial factor productivity of the applied N(PFPN)gradually increased with the nitrogen amount decline.Irrigation water use efficiency(IWUE)was closely related to the amount of irrigation.The higher irrigation amount would lead to the lower IWUE.When the amounts of irrigation and nitrogen were at an intermediate level,the content of vitamin C(VC)reached the maximum.As the amount of nitrogen was increased or irrigation was decreased,the Nitrate content(NC)would increase.Free amino acid(FAA)and NC followed a similar variation.When the amounts of irrigation and nitrogen both were at medium levels,the total soluble sugar concentration(TSSC)reached the highest.The multi-level fuzzy evaluation method was used to evaluate different indicators of cucumber.The weights of indicators in the first and second layer were determined by analytic hierarchy process(AHP)and entropy weight method,respectively.Then the fuzzy algorithm was used to comprehensively evaluate all the treatments.The evaluation results show that T4(irrigation,1957.6 m3/hm2;N,210 kg/hm2)is the best strategy for greenhouse cucumber irrigation and nitrogen management in the northwestern part of China.