Effect of different levels of boron and NaCl on shoot length (cm), root length (cm), number of leaves plant
-1 , leaf area (cm
2 plant
-1) and dry weight (g plant
-1) was recorded at different stages of growth (Table 1). At different stages of growth, the response of plant to different treatments in terms of shoot length was significant and at 45 DAS the highest shoot length was recorded in plants under treatment T
6 (40.97 cm), which was at par with T
5 and T
1. At 45 DAS the highest root length was recorded in plants under treatment T
1, which was at par with T
2, T
4, T
7 and T
8. T
1 (39.40 cm
2/plant
-1) again registered the maximum leaf area plant
-1 . The dry weight plant
-1 was noted maximum at T
4 (1.75 g/ plant
-1), which was at par with T
3 and T
2. Shoot-root length decreases with increased concentrations of salt and boron
(Lata et al., 2017). Although due to strong stimulation of defense sometimes plant shows improved dry weight as compared to control under stress.
Effect of different levels of boron and NaCl on amino acids, proline, soluble sugars, starch and malondialdehyde was recorded at different stages of growth (Table 2). At 60 DAS, plants under T
3 (4.931 mg g
-1 fresh weight) contained significantly higher amount of amino acids. The maximum amount of proline was recorded in plants under T
3 upto 40 DAS and at 60 DAS T
9 (0.214 mg g
-1 fresh weight) showed significantly higher amount.
Samet and Çikili (2019) found significant proline accumulation under excess B, which indicates that B is contributing to the osmotic stress. However,
Mann et al., (2019) observed increase in proline content with increasing levels of salinity. Plants under T
1 (32.67 mg g
-1 fresh weight) showed significantly higher amount of soluble sugars and the minimum amount in plants under T
9 (24.38 mg g
-1 fresh weight)at 40 and 60 DAS. The amount of starch content at 60 DAS under T
1 (102.4 mg g
-1 fresh weight) showed significantly higher and minimum amounts in plants under T
9. A similar result has been reported by
Wang et al., (2021). The maximum MDA content was found in plants under T
8 (2.636 µ mole g
-1 fresh weight) and minimum amount of MDA was found in the plants under T
1. Similar result is reported by
Samet and Çikili (2019).
It is reported that under salinity or boron toxicity, photosynthetic rate is reduced and one of the reasons for reduction in photosynthetic rate is due to reduction in the level of photosynthetic pigments
(Carillo et al., 2011). Hegazi et al., 2018 reported that mild concentrations of boron can increase the photosynthetic pigments. The amount of chlorophyll a, chlorophyll b, their ratio, total chlorophyll and carotenoids in first fully mature leaf from top was measured at 20, 40, 60 DAS (Table 3). The chlorophyll a and b content was high in T
2, which was at par with T
1, however the ratio was high in T
6 (2.164). The carotenoids content was higher in T
7 (0.375 mg g
-1 fresh weight).
The total dry weight plant
-1, total seed weight plant
-1, test weight, number of pods plant
-1, total number of seeds pod
-1 and total number of seeds plant
-1 showed significant difference between the treatments (Table 4). The entire above mentioned yield parameters were observed maximum in plants under T
1. The harvest index obtained showed significant difference between the treatments .The maximum harvest index was observed in plants under T
2, which is at par with T
6. Salinity and/or nutrient toxicity result in reduction in yield and yield attributes of crop (
Mauromicale, 2010)
The RGR, NAR, LAR were measured among different stages (Table 5). Between 15-30 days stage the plants under T
3 showed highest RGR. When RGR was calculated between 45 DAS and harvest stage, plants under T
1 had significantly higher RGR. The NAR measured was found higher under T
2 between 15-30 DAS and T
4 between 30-45 DAS. The LAR showed the highest value under T
6 between 15-30 days stage. Between 30-45 DAS it was significantly higher under T
7. Major effect of salinity and boron toxicity has been reported to decrease photosynthetic processes of plant
(Lovatt, 1984).