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221.
Optimum rate and timing application of nitrogen (N) fertilizer are most crucial in achieving high yield in irrigated lowland
rice. In order to assess leaf N status, a semidwarf rice cultivar (Khazar) was grown with different N application treatments
(0, 40, 80, and 120 kg N ha−1 splited at transplanting, midtillering, and panicle initiation stages) in a sandy soil in Guilan Province, Iran, in 2003.
The chlorophyll meter (SPAD 502) readings were recorded and leaf N concentrations were measured on the uppermost fully expanded
leaf in rice plants at 10-day internals from 19 days after transplanting to grain maturity. Regression analysis showed that
the SPAD readings predicted only 23% of changes in the leaf N concentration based on pooled data of leaf dry weight (N
dw) for all growth stages. However, adjusting the SPAD readings for specific leaf weight (SPAD/SLW) improved the estimation
of N
dw, up to 88%. Specific leaf weight (SLW), SPAD readings, leaf area and weight as independent variables in a multiple regression
analysis predicted 96% of the N
dw changes, while SPAD readings independently predicted about 80% of leaf N concentration changes on the basis of leaf area
(N
a). It seems that chlorophyll meter provides a simple, rapid, and nondestructive method to estimate the leaf N concentration
based on leaf area, and could be reliably exploited to predict the exact N fertilizer topdressing in rice. 相似文献
222.
Kohtaro Iseki Rusama Marubodee Hiroshi Ehara Norihiko Tomooka 《Plant Production Science》2017,20(1):144-148
A rapid quantification method for leaf sodium (Na+) and potassium (K+) concentrations was developed using a compact ion meter. Leaf ion concentrations were evaluated for species of Vigna vexillata (L.) A. Rich. after two weeks of treatment with 0–200 mM of sodium chloride. To compare the ion extraction efficiency, extraction solutions of distilled water and ammonium acetate were tested. The ion concentrations of extracts obtained by both solutions were measured using an ion meter, and the values were validated using ion chromatography. For both extraction solutions, the ion meter values were highly correlated with those of the ion chromatograph. However, correlations between ion meter and chromatograph values were largely different for Na+ and K+. The rapid quantification of ion concentrations using an ion meter developed in this study was successfully utilized for evaluating differences in leaf Na+ concentrations, K+ concentrations, and K+/Na+ ratio in species of V. vexillata. 相似文献
223.
采用落盘式测草盘在休闲草地、轮牧草地和连续放牧草地进行了测产试验.结果表明,在天然草地中使用非破坏性的落盘式测草仪测定牧草产量是可行的,牧草压缩高度和牧草产量具有良好的回归关系(r2=0.64~0.90),平均每1 cm压缩高度相当于69~250 kg/hm2的牧草产量. 相似文献
224.
粳稻米淀粉特性与食味间的相关性分析 总被引:49,自引:9,他引:49
对稻米直链淀粉含量、食味官能鉴定、味度和RVA淀粉糊化特性等品质性状的测定进行了分析,结果显示稻米直链淀粉含量与米饭的香味、粘度、综合评价分别达显著或极显著负相关,与外观、硬度达显著正相关。米饭的粘度与外观、硬度及硬度与综合评价间呈负相关,粘度与综合评价呈正相关。味度与米饭香味、硬度无相关性,但与外观、粘度、综合评价达显著或极显著正相关。淀粉糊化特性(最高粘度、最低粘度、碱崩溃度和糊化温度)值与RVA值间的相关系数分别为0.741**、0.536*、0.469*和0.458*。 相似文献
225.
226.
刘贵斌 《大连水产学院学报》1998,13(1):54-57
本文介绍的预付费电子电度表是由美国Motorola公司生产的单片机MC68HC705L1和外转电路组成的,该表降低了计算盲区,提高了电度表的精度,使用IC卡作为预付费的工具,给电业部门的现代化管理提供了必要的条件。 相似文献
227.
为了研究孔板流量计在动态非稳定流态或振荡流态下的瞬时压力-流量特性,理论分析了孔板前后的旋涡域大小随流速变化是引起孔板进出口瞬时流量差的主要原因.借助CFD数值解析方法,建立孔板模型,并在模型入口加载某一频率下的正弦流速,对孔板流量计在振荡流态下的瞬时压力-流量特性进行分析.结果表明:当孔板流量计处于低频振荡流动状态时,孔板两端差压也处于周期振荡状态,差压与节流孔瞬时流量同频不同相,差压幅值随入口流速振幅增大而线性增大,且线性增长系数与振荡频率相关;孔板的入口与出口存在周期波动的瞬时流量差,振荡频率越大或入口流速峰值越小,瞬时流量差的波动越小.由于相位滞后和瞬时流量差的存在,使孔板流量计的测量流量与实际出口流量之间存在偏差.振荡频率越大,偏差也越大. 相似文献
228.
Over application of fertilizer N to cotton is not only a potential threat to environment but also leads to increased costs of cultivation. The study aimed to establish the indicator leaf and its critical greenness for in-season management of fertilizer nitrogen (N) in Bt cotton using chlorophyll (SPAD) meter and leaf color chart (LCC). The response of three varieties and N treatments viz. 0, 30, 60, 90,120, 150 and 180?kg N ha?1 applied in two splits {(50% at thinning and 50% at first flowering) and three splits (50% at thinning, 25% at first flowering and 25% at boll formation)} was studied through split plot design. SPAD values and LCC scores of first, second, third and fourth fully opened leaves from the top of the main stem was recorded at first flowering and boll formation. The physiological efficiency and harvest index was highest for 90?Kg N ha?1 applied in two splits. Beyond 120?kg N ha?1, the N use efficiency parameters were higher for the N treatments applied in three split compared to the respective two split N treatments. The fourth leaf from the top in terms of SPAD values and LCC scores correlated best with N concentration compared to other leaves at all growth stages. The calculated critical SPAD values for the fourth leaf were 45 and 41 at first flowering and boll formation, respectively. Critical score of fourth leaf was 4.1 and 4, respectively at first flowering and boll formation, respectively. It is suggested that color of the fourth leaf from the top of Bt cotton can well indicate N supply from the soil and can help in need based N management. 相似文献
229.
单片机89C52在多功能电度表中的应用研究 总被引:1,自引:0,他引:1
本文研讨了一种以89C52单片机为核心构成的多功能智能电度表,它可以同时具有电能表、自动补偿、分时段测电能等多种功能,并以先进的LCD显示屏显示当前的功率因数、总电能值、所消耗的峰、谷、平、总电能值。 相似文献
230.