4R stewardship-based potassium application to enhance iron, zinc, and copper nutrient levels in wheat (<i>Triticum aestivum</i> L.)

Shanmugam Vijayakumar; Dinesh Kumar; Yashbir Singh Shivay; Dinesh Kumar Sharma; Thirumalai Varatharajan; Shanmugam Vijayakumar; Dinesh Kumar; Yashbir Singh Shivay; Dinesh Kumar Sharma; Thirumalai Varatharajan

doi:10.48130/tia-0024-0021

Figures (6) Tables (5)

Figure 1.
Map showing the study area.
Figure 2.
Effect of different rates, time, methods, and sources of potassium fertilization on zinc harvest index. T1 = No K (control), T2 = 49.8 kg K/ha at basal, T3 = 24.9 kg K/ha at basal, T4 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation, T5 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation, T6 = 2 foliar sprays (1^st active tillering, 2^nd SI) of 2.5% KNO₃, T7 = 49.8 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T8 = 24.9 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T9 = 37.4 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T10 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T11 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T12 = 74.7 kg K/ha at basal.
Figure 3.
Effect of different rate, time, method and source of potassium fertilization on iron harvest index. T1 = No K (control), T2 = 49.8 kg K/ha at basal, T3 = 24.9 kg K/ha at basal, T4 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation, T5 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation, T6 = 2 foliar sprays (1^st active tillering, 2^nd SI) of 2.5% KNO₃, T7 = 49.8 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T8 = 24.9 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T9 = 37.4 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T10 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T11 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T12 = 74.7 kg K/ha at basal.
Figure 4.
Effect of different rate, time, method and source of potassium fertilization on copper harvest index. T1 = No K (control), T2 = 49.8 kg K/ha at basal, T3 = 24.9 kg K/ha at basal, T4 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation, T5 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation, T6 = 2 foliar sprays (1^st active tillering, 2^nd SI) of 2.5% KNO₃, T7 = 49.8 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T8 = 24.9 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T9 = 37.4 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T10 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T11 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T12 = 74.7 kg K/ha at basal.
Figure 5.
Correlation between the nutrients in grain and straw (first year of the experiment).
Figure 6.
Correlation between the nutrients in grain and straw (second year of the experiment).

Trt No.	Details	Kg K/ha
T1	No application of K (control)	0
T2	Basal application of 49.8 kg K/ha through muriate of potash (MOP)	49.8
T3	Basal application of 24.9 kg K/ha through MOP	24.9
T4	Basal application of 24.9 kg K/ha followed by 24.9 kg K/ha at spike initiation (SI) through MOP	49.8
T5	Basal application of 37.4 kg K/ha followed by 12.45 kg K/ha at spike initiation (SI) through MOP	49.8
T6	2 foliar sprays (1^st active tillering, 2^nd SI) of 2.5% KNO₃	8.8
T7	Basal application of 49.8 kg K/ha through MOP followed by 2 foliar sprays (1^st active tillering, 2^nd SI) of 2.5% KNO₃	58.6
T8	Basal application of 24.9 kg K/ha through MOP followed by 2 foliar sprays (1^st active tillering, 2^nd SI) of 2.5% KNO₃	33.7
T9	Basal application of 37.4 kg K/ha followed by 2 foliar sprays (1^st active tillering, 2^nd SI) of 2.5% KNO₃	46.2
T10	Basal application of 24.9 kg K/ha plus 24.9 kg K/ha at SI through MOP followed by 2 foliar sprays (1^st active tillering, 2^nd SI) of 2.5% KNO₃	58.6
T11	Basal application of 37.4 kg K/ha plus 12.45 kg K/ha at PI through MOP followed by 2 foliar sprays (1^st active tillering, 2^nd PI) of 2.5% KNO₃	58.6
T12	Basal application of 74.7 kg K/ha through MOP	74.7

Table 1.

Treatment details.

Treatments	K concentration in grain (%)		K concentration in straw (%)		K uptake by grain (kg/ha)		K uptake by straw (kg/ha)		Total K uptake (kg/ha)
Treatments	1^st year	2^nd year	1^st year	2^nd year	1^st year	2^nd year	1^st year	2^nd year	1^st year	2^nd year
T1	0.33^H	0.33^F	1.24^F	1.30^E	14.3^E	14.3^F	70.4^E	73.5^D	84.7^G	87.8^D
T2	0.46^DE	0.44^BCD	1.49^ABC	1.50^ABC	23.9^C	22.5^C	95.0^AB	96.4^AB	118.9^CD	118.9^AB
T3	0.41^FG	0.41^DE	1.37^DE	1.43^CD	19.5^D	19.2^DE	84.3^CD	87.1^BC	103.7^EF	106.3^BC
T4	0.50^ABCD	0.46^ABC	1.53^ABC	1.55^AB	28.0^A	25.4^AB	97.9^AB	98.7^A	125.9^ABC	124.1^A
T5	0.49^BCD	0.47^AB	1.52^ABC	1.54^AB	27.7^AB	25.8^AB	97.2^AB	98.1^AB	124.8^ABC	123.9^A
T6	0.38^G	0.38^E	1.29^EF	1.36^DE	17.4^D	17.0^EF	75.8^DE	79.0^CD	93.3^FG	96.0^CD
T7	0.51^ABC	0.48^AB	1.54^AB	1.56^AB	29.0^A	26.6^A	99.1^A	99.7^A	128.1^ABC	126.3^A
T8	0.44^EF	0.42^CD	1.43^CD	1.47^BC	23.0^C	21.7^CD	89.2^BC	94.9^AB	112.2^DE	116.6^AB
T9	0.49^BCD	0.47^AB	1.47^BCD	1.54^AB	27.8^A	25.8^AB	95.3^AB	98.0^AB	123.1^ABCD	123.7^A
T10	0.54^A	0.49^A	1.57^A	1.58^A	30.4^A	27.1^A	101.5^A	101.8^A	131.9^AB	128.9^A
T11	0.53^A	0.49^A	1.58^A	1.59^A	30.2^A	27.0^A	103.1^A	102.3^A	133.2^A	129.4^A
T12	0.47^CDE	0.45^ABC	1.53^ABC	1.55^AB	24.7^BC	23.2^BC	97.6^AB	99.4^A	122.3^BCD	122.6^A
SE(d)	0.02	0.02	0.05	0.05	1.44	1.35	4.56	5.40	5.24	6.21
LSD at 5%	0.04	0.04	0.11	0.10	2.99	2.80	9.47	11.20	10.87	12.87
Means followed by a superscripted similar letter within a column are not significantly different (at p < 0.05) according to LSD test. T1 = No K (control), T2 = 49.8 kg K/ha at basal, T3 = 24.9 kg K/ha at basal, T4 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation, T5 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation, T6 = 2 foliar sprays (1^st active tillering, 2^nd SI) of 2.5% KNO₃, T7 = 49.8 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T8 = 24.9 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T9 = 37.4 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T10 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T11 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T12 = 74.7 kg K/ha at basal.

Table 2.

Effect of different rates, time, methods and sources of K application on grain & straw K concentration and total K uptake.

Treatments	Zn concentration in grain (mg/kg)		Zn concentration in straw (mg/kg)		Zn uptake by grain (g/ha)		Zn uptake by straw (g/ha)		Total Zn uptake (g/ha)
Treatments	1^st year	2^nd year	1^st year	2^nd year	1^st year	2^nd year	1^st year	2^nd year	1^st year	2^nd year
T1	34.2^B	35.0^D	22.7^C	21.9	147^D	150^E	129^D	124^C	276^D	274^C
T2	37.2^A	38.0^AB	26.2^AB	25.4	194^B	194^C	167^AB	163^A	360^B	357^A
T3	36.3^AB	36.6^BCD	25.6^AB	24.1	173^C	172^D	157^BC	147^AB	331^C	318^B
T4	37.8^A	38.5^AB	26.8^A	25.1	214^A	213^A	172^AB	160^A	385^AB	373^A
T5	37.7^A	38.3^AB	26.7^A	24.8	212^A	212^AB	170^AB	158^A	382^AB	370^A
T6	34.9^B	35.6^CD	24.2^BC	23.1	160^CD	161^DE	143^CD	134^BC	302^D	295^BC
T7	38.0^A	38.4^AB	27.2^A	25.6	216^A	213^A	175^AB	164^A	391^A	377^A
T8	37.4^A	37.8^ABC	26.6^AB	24.8	194^B	194^C	166^AB	160^A	360^B	354^A
T9	37.6^A	38.0^AB	26.8^A	24.7	213^A	209^ABC	173^AB	158^A	386^AB	366^A
T10	37.5^A	39.1^A	26.5^AB	25.1	213^A	217^A	172^AB	162^A	385^AB	378^A
T11	38.3^A	39.7^A	27.3^A	25.5	218^A	220^A	178^A	164^A	396^A	384^A
T12	37.3^A	38.1^AB	26.3^AB	24.5	195^B	195^BC	168^AB	158^A	363^B	353^A
SE(d)	1.07	1.04	1.15	1.12	6.67	8.13	8.90	10.0	13.15	16.6
LSD at 5%	2.22	2.15	2.38	NS	13.82	16.87	18.45	20.74	27.27	34.3
Means followed by a superscripted similar letter within a column are not significantly different (at p < 0.05) according to LSD test. T1 = No K (control), T2 = 49.8 kg K/ha at basal, T3 = 24.9 kg K/ha at basal, T4 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation, T5 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation, T6 = 2 foliar sprays (1^st active tillering, 2^nd SI) of 2.5% KNO₃, T7 = 49.8 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T8 = 24.9 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T9 = 37.4 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T10 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T11 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T12 = 74.7 kg K/ha at basal.

Table 3.

Effects of different rates, time, methods and sources of K fertilization on total zinc uptake, grain zinc concentration, and straw zinc concentration in wheat.

Treatments	Fe concentration in grain (mg/kg)		Fe concentration in straw (mg/kg)		Fe uptake by grain (g/ha)		Fe uptake by straw (g/ha)		Total Fe uptake (g/ha)
Treatments	1^st year	2^nd year	1^st year	2^nd year	1^st year	2^nd year	1^st year	2^nd year	1^st year	2^nd year
T1	89^E	97	249^C	275^C	381^D	413^E	1416^D	1558^D	1797^E	1971^C
T2	101^CD	109^ABC	263^AB	288^AB	522^B	555^BC	1672^AB	1849^AB	2194^CD	2404^A
T3	98^D	103^CDE	260^AB	284^ABC	466^C	485^D	1601^BC	1729^BC	2067^D	2214^B
T4	108^ABC	112^AB	266^A	291^A	607^A	619^A	1703^AB	1854^AB	2311^ABC	2473^A
T5	109^ABC	113^AB	267^A	292^A	610^A	621^A	1705^AB	1861^AB	2315^ABC	2482^A
T6	94^DE	100^DE	254^BC	280^BC	431^CD	452^DE	1493^CD	1630^CD	1924^E	2081^BC
T7	110^A	115^A	270^A	292^A	625^A	631^A	1737^AB	1870^A	2361^A	2501^A
T8	101^BCD	107^BCD	265^AB	286^AB	524^B	548^C	1659^AB	1847^AB	2183^CD	2394^A
T9	109^AB	111^AB	267^A	288^AB	618^A	611^AB	1728^AB	1834^AB	2346^AB	2445^A
T10	108^ABC	114^AB	271^A	291^A	613^A	629^A	1755^A	1878^A	2369^A	2507^A
T11	110^A	115^A	271^A	292^A	627^A	636^A	1766^A	1878^A	2392^A	2514^A
T12	102^ABCD	110^ABC	265^A	288^AB	533^B	562^BC	1690^AB	1852^AB	2223^BC	2414^A
SE(d)	4.03	3.78	5.36	4.75	27.06	27.54	65.70	63.53	66.3	70.24
LSD at 5%	8.35	7.83	11.11	9.86	56.12	57.12	136.26	131.75	137.5	145.67
Means followed by a superscripted similar letter within a column are not significantly different (at p < 0.05) according to LSD test. T1 = No K (control), T2 = 49.8 kg K/ha at basal, T3 = 24.9 kg K/ha at basal, T4 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation, T5 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation, T6 = 2 foliar sprays (1^st active tillering, 2^nd SI) of 2.5% KNO₃, T7 = 49.8 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T8 = 24.9 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T9 = 37.4 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T10 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T11 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T12 = 74.7 kg K/ha at basal.

Table 4.

Effects of different rates, time, methods and sources of K fertilization on total iron uptake, grain iron concentration, and straw iron concentration in wheat.

Treatment	Cu concentration in grain (mg/kg)		Cu concentration in straw (mg/kg)		Cu uptake by grain (g/ha)		Cu uptake by straw (g/ha)		Total Cu uptake (g/ha)
Treatment	1^st year	2^nd year	1^st year	2^nd year	1^st year	2^nd year	1^st year	2^nd year	1^st year	2^nd year
T1	7.26^C	7.49^C	14.37^C	14.97^D	31.1^E	32.0^D	81.7^D	84.7^D	113^D	117^C
T2	8.65^AB	8.92^A	16.83^AB	17.43^AB	45.1^BC	45.5^AB	107.1^AB	111.9^AB	152^AB	157^A
T3	8.13^ABC	8.57^AB	16.10^ABC	16.68^BC	38.8^CD	40.3^BC	99.1^BC	101.5^BC	138^BC	142^B
T4	8.89^A	9.00^A	17.21^AB	17.79^AB	50.2^AB	49.8^A	110.3^AB	113.6^A	160^A	164^A
T5	8.92^A	9.13^A	17.26^AB	17.86^AB	50.2^AB	50.5^A	110.4^AB	113.8^A	161^A	164^A
T6	7.63^BC	8.00^BC	15.11^BC	15.72^CD	34.9^DE	36.1^CD	89.0^CD	91.4^CD	124^CD	128^BC
T7	9.06^A	9.19^A	17.93^A	18.13^A	51.4^AB	50.9^A	115.3^A	116.0^A	167^A	167^A
T8	8.73^AB	9.04^A	17.28^A	17.43^AB	45.5^AB	46.3^AB	108.3^AB	112.4^AB	154^AB	159^A
T9	9.10^A	9.10^A	18.01^A	18.21^A	51.6^AB	49.9^A	116.4^A	116.1^A	168^A	166^A
T10	8.96^A	9.20^A	17.94^A	18.14^A	50.8^AB	51.0^A	115.9^A	117.0^A	167^A	168^A
T11	9.16^A	9.13^A	18.14^A	18.34^A	52.2^A	50.8^A	118.1^A	117.7^A	170^A	169^A
T12	8.73^AB	9.03^A	17.29^A	17.87^AB	45.4^BC	46.3^AB	110.1^AB	115.1^A	156^AB	161^A
SE(d)	0.55	0.40	1.04	0.63	3.24	2.95	7.60	5.53	10.49	7.44
LSD at 5%	1.14	0.84	2.15	1.30	6.73	6.11	15.75	11.46	21.75	15.43
Means followed by a superscripted similar letter within a column are not significantly different (at p < 0.05) according to LSD test. T1 = No K (control), T2 = 49.8 kg K/ha at basal, T3 = 24.9 kg K/ha at basal, T4 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation, T5 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation, T6 = 2 foliar sprays (1^st active tillering, 2^nd SI) of 2.5% KNO₃, T7 = 49.8 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T8 = 24.9 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T9 = 37.4 kg K/ha at basal + 2 foliar sprays of 2.5% KNO₃, T10 = 24.9 kg K/ha at basal + 24.9 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T11 = 37.4 kg K/ha at basal + 12.5 kg K/ha at spike initiation + 2 foliar sprays of 2.5% KNO₃, T12 = 74.7 kg K/ha at basal.

Table 5.

Effect of different rates, time, methods and sources of K application on copper concentration and uptake by wheat.